Compound fenestration assembly mull joints and methods

Abstract

Compound fenestration assembly mull joints, compound fenestration assemblies using those mull joints, and methods of making and using the same are described herein. The mull joints in compound fenestration assemblies as described herein use universal joining strips to form both sides of a mull joint, as well as other universal components such as, e.g., corner gussets, locator plates, end plugs, seal members, etc. that may be used as needed to form mull joints as required in a compound fenestration assembly.

Claims

1. A compound fenestration assembly comprising: a first frame member of a first fenestration unit attached to a second frame member of a second fenestration unit along a mull joint having a first end and a second end, wherein the mull joint defines a mull joint axis extending along a length of the mull joint between the first and second ends of the mull joint, wherein the first and second frame members comprise exterior sides facing in the same direction and interior sides facing in an opposite direction from the exterior sides, wherein an interior/exterior axis extends between the interior and exterior sides in a direction transverse to the mull joint axis, wherein the first frame member faces the second frame member across the mull joint, wherein a separation axis extends through the mull joint between the first and second frame members, the separation axis extending in a direction transverse to both the mull joint axis and the interior/exterior axis; a first joining strip attached to the first frame member of the first fenestration unit, the first joining strip comprising a first end proximate the first end of the mull joint and a second end proximate the second end of the mull joint, wherein the first joining strip comprises a pair of channels extending along the length of the first frame member, wherein each channel of the pair of channels is aligned with the mull joint axis and opens towards the exterior side of the first fenestration unit; a second joining strip attached to the second frame member of the second fenestration unit, the second joining strip comprising a first end proximate the first end of the mull joint and a second end proximate the second end of the mull joint, wherein the second joining strip comprises a pair of channels extending along the length of the second frame member, wherein each channel of the pair of channels on the second joining strip is aligned with the mull joint axis and opens towards the interior side of the second fenestration unit such that each channel of the pair of channels on the first joining strip mechanically interlocks with one channel of the pair of channels on the second joining strip, wherein the mechanically interlocking channels prevent movement of the first frame member away from the second frame member along the separation axis, prevent movement of the first frame member towards the exterior side of the second frame member along the interior/exterior axis, and prevent movement of the second frame member towards the interior side of the first frame member along the interior/exterior axis; wherein the second joining strip is a mirror image of the first joining strip across the mull joint such that the channels on the second joining strip face the channels on the first joining strip and the channels on the second joining strip and the channels on the first joining strip open in opposite directions; a first corner gusset attached to the first fenestration unit, wherein the first corner gusset comprises: a first gusset plate leg positioned between the first joining strip and the first frame member of the first fenestration unit at the first end of the mull joint, and a first base plate attached to the first gusset plate leg and extending away from a corner of the first fenestration unit proximate the first end of the mull joint, wherein the first base plate extends away from the first fenestration unit in a direction aligned with the separation axis, wherein first base plate is configured for attachment to an interior surface of an opening in which the first fenestration unit is located; and a second corner gusset attached to the second fenestration unit, wherein the second corner gusset comprises: a second gusset plate leg positioned between the second joining strip and the second frame member of the second fenestration unit at the first end of the mull joint, and a second base plate attached to the second gusset plate leg, wherein the second base plate extends over and is attached to a frame member of the second fenestration unit meeting the second frame member at a corner of the second fenestration unit proximate the first end of the mull joint; wherein the second base plate is stacked with the first base plate when the channels on the first joining strip on the first fenestration unit mechanically interlock with the channels on the second joining strip on the second fenestration unit such that the second base plate is located between the first base plate and the second fenestration unit.

2. An assembly according to claim 1, wherein the first joining strip extends over a majority of the length of the first frame member and the second joining strip extends over a majority of the length of the second frame member.

3. An assembly according to claim 1, wherein the pair of channels of the first joining strip extend along the entire length of the of the first joining strip and wherein the pair of channels of the second joining strip extend along the entire length of the of the second joining strip.

4. An assembly according to claim 1, wherein the interior and exterior sides of the first and second frame members define a frame depth along the interior/exterior axis, and wherein the mechanically interlocking channels on the first and second joining strips are positioned such that a bottom of the channel on the first joining strip that is closest to the interior side of the first frame member is located within 20% or less of the frame depth from the interior side of the first frame member and a bottom of the channel on the second joining strip that is closest to the exterior side of the second frame member is located within 20% or less of the frame depth from the exterior side of the second frame member.

5. An assembly according to claim 1, wherein the interior and exterior sides of the first and second frame members define a frame depth along the interior/exterior axis, and wherein the mechanically interlocking channels on the first and second joining strips are positioned such that a bottom of the channel on the first joining strip that is closest to the interior side of the first frame member is located within 15% or less of the frame depth from the interior side of the first frame member and a bottom of the channel on the second joining strip that is closest to the exterior side of the second frame member is located within 15% or less of the frame depth from the exterior side of the second frame member.

6. An assembly according to claim 1, wherein a first locator plate is positioned between the first joining strip and the first frame member, the first locator plate comprising a frame surface facing the first frame member and a joining strip surface facing the first joining strip, wherein the frame surface and the first frame member comprise complementary mating features configured to position the first locator plate in one selected location and orientation relative to the first frame member, and wherein the joining strip surface and the first joining strip comprise complementary mating features configured to position the first locator plate in one selected location and orientation relative to the first joining strip such that the first locator plate is configured to position the first joining strip in one selected orientation relative to the first frame member and in one selected location on the first frame member along the interior/exterior axis.

7. An assembly according to claim 6, wherein a second locator plate is positioned between the second joining strip and the second frame member, the second locator plate comprising a frame surface facing the second frame member and a joining strip surface facing the second joining strip, wherein the frame surface of the second locator plate and the second frame member comprise complementary mating features configured to position the second locator plate in one selected location and orientation relative to the second frame member, and wherein the joining strip surface of the second locator plate and the second joining strip comprise complementary mating features configured to position the second locator plate in one selected location and orientation relative to the second joining strip such that the second locator plate is configured to position the second joining strip in one selected orientation relative to the second frame member and in one selected location on the second frame member along the interior/exterior axis.

8. An assembly according to claim 1, wherein the first and second joining strips are separate and discrete lengths of a common profile.

9. An assembly according to claim 1, wherein the first and second joining strips consist essentially of one or more non-metallic materials.

10. An assembly according to claim 1, wherein the assembly further comprises: an intermediate end plug cavity formed between the first joining strip and the second joining strip, wherein the intermediate end plug cavity comprises a first opening at the first ends of the first and second joining strips and a second opening at the second ends of the first and second joining strips; and a first end plug comprising a base and a cavity leg extending away from the base, wherein the cavity leg is positioned in the first opening of the intermediate end plug cavity when the base is positioned between the first and second frame members at the first ends of the first and second joining strips, wherein the cavity leg prevents disengagement of the mechanically interlocking channels on the first and second joining strips at the first ends of first and second joining strips.

11. An assembly according to claim 10, wherein the intermediate end plug cavity is located between the pairs of channels on the first and second joining strips.

12. An assembly according to claim 10, wherein the assembly further comprises a second end plug comprising a base and a cavity leg extending away from the base, wherein the cavity leg is positioned in the second opening of the intermediate end plug cavity when the base of the second end plug is positioned between the first and second frame members at the second ends of the first and second joining strips, wherein the cavity leg of the second end plug prevents disengagement of the mechanically interlocking channels on the first and second joining strips at the second ends of first and second joining strips.

13. An assembly according to claim 10, wherein a first end seal member is located between the first and second frame members at the first ends of the first and second joining strips, wherein the first end seal member is located in a first recess between the base of the first end plug and the exterior sides of the first and second frame members, wherein the first end seal member comprises a sealant port in fluid communication with a sealant reservoir positioned between the first and second frame members and the first ends of the first and second joining strips.

14. An assembly according to claim 10, wherein the assembly further comprises a gusset plate attached to the base of the first end plug, wherein the gusset plate spans the first end of the mull joint such that the base of the first end plug is located between the first ends of the first and second joining strips and the gusset plate, wherein the gusset plate is directly attached to the first and second fenestration units on opposite sides of the first end of the mull joint.

15. An assembly according to claim 1, wherein the first ends of the first and second joining strips terminate at a recessed location between the first frame member of the first fenestration unit and the second frame member of the second fenestration unit at the first end of the mull joint, wherein a first recess is formed at the first end of the mull joint between the first and second frame members; and wherein the assembly further comprises a locking clip located in the first recess between the first and second frame members at the first ends of the first and second joining strips, wherein the locking clip plug mechanically interlocks with the first gusset plate leg and the second gusset plate leg to restrict disengagement of the channels on the first and second joining strips at the first ends of first and second joining strips.

16. An assembly according to claim 15, wherein a retaining plug is positioned in the locking clip in the first recess.

17. An assembly according to claim 16, wherein the retainer plug comprises a sealant port in fluid communication with a sealant reservoir positioned between the first and second frame members and the first ends of the first and second joining strips.

18. An assembly according to claim 1, wherein the first ends of the first and second joining strips terminate at a recessed location between the first frame member of the first fenestration unit and the second frame member of the second fenestration unit at the first end of the mull joint, wherein a first recess is formed at the first end of the mull joint between the first and second frame members; and wherein the assembly further comprises a retainer plug located in the first recess between the first and second frame members at the first ends of the first and second joining strips, wherein the retainer plug mechanically interlocks with the first gusset plate leg and the second gusset plate leg to restrict disengagement of the channels on the first and second joining strips at the first ends of first and second joining strips.

19. An assembly according to claim 18, wherein the retainer plug is located in the first recess and comprises a sealant port in fluid communication with a sealant reservoir positioned between the first and second frame members and the first ends of the first and second joining strips.

20. An assembly according to claim 19, wherein the sealant port faces the same direction as the exterior sides of the of the first and second frame members.

21. An assembly according to claim 19, wherein the sealant port faces a direction aligned with the mull joint axis.

22. A compound fenestration assembly comprising: a first frame member of a first fenestration unit attached to a second frame member of a second fenestration unit along a mull joint having a first end and a second end, wherein the mull joint defines a mull joint axis extending along a length of the mull joint between the first and second ends of the mull joint, wherein the first and second frame members comprise exterior sides facing in the same direction and interior sides facing in an opposite direction from the exterior sides, wherein an interior/exterior axis extends between the interior and exterior sides in a direction transverse to the mull joint axis, wherein the first frame member faces the second frame member across the mull joint, wherein a separation axis extends through the mull joint between the first and second frame members, the separation axis extending in a direction transverse to both the mull joint axis and the interior/exterior axis; a first joining strip attached to the first frame member of the first fenestration unit, the first joining strip comprising a first end proximate the first end of the mull joint and a second end proximate the second end of the mull joint, wherein the first joining strip comprises a pair of channels extending along the length of the first frame member, wherein each channel of the pair of channels is aligned with the mull joint axis and opens towards the exterior side of the first fenestration unit; a second joining strip attached to the second frame member of the second fenestration unit, the second joining strip comprising a first end proximate the first end of the mull joint and a second end proximate the second end of the mull joint, wherein the second joining strip comprises a pair of channels extending along the length of the second frame member, wherein each channel of the pair of channels on the second joining strip is aligned with the mull joint axis and opens towards the interior side of the second fenestration unit such that each channel of the pair of channels on the first joining strip mechanically interlocks with one channel of the pair of channels on the second joining strip, wherein the mechanically interlocking channels prevent movement of the first frame member away from the second frame member along the separation axis, prevent movement of the first frame member towards the exterior side of the second frame member along the interior/exterior axis, and prevent movement of the second frame member towards the interior side of the first frame member along the interior/exterior axis; wherein the second joining strip is a mirror image of the first joining strip across the mull joint such that the channels on the second joining strip face the channels on the first joining strip and the channels on the second joining strip and the channels on the first joining strip open in opposite directions; a first flanged corner gusset attached to the first fenestration unit, wherein the first flanged corner gusset comprises: a first gusset plate leg positioned between the first joining strip and the first frame member of the first fenestration unit at the first end of the mull joint; a first base plate attached to the first gusset plate leg, wherein the first base plate extends over and is attached to a frame member of the first fenestration unit meeting the first frame member at a corner of the first fenestration unit proximate the first end of the mull joint; a first gusset flange attached to an edge of the first base plate and extending away from the first fenestration unit, wherein the first gusset flange is configured for attachment to an exterior surface of an opening in which the first fenestration unit is located; and a second flanged corner gusset attached to the second fenestration unit, wherein the second flanged corner gusset comprises: a second gusset plate leg positioned between the second joining strip and the second frame member of the second fenestration unit at the first end of the mull joint; a second base plate attached to the second gusset plate leg, wherein the second base plate extends over and is attached to a frame member of the second fenestration unit meeting the second frame member at a corner of the second fenestration unit proximate the first end of the mull joint; a second gusset flange attached to an edge of the second base plate and extending away from the second fenestration unit, wherein the second gusset flange is configured for attachment to an exterior surface of an opening in which the second fenestration unit is located.

23. An assembly according to claim 22, wherein the first joining strip extends over a majority of the length of the first frame member and the second joining strip extends over a majority of the length of the second frame member.

24. An assembly according to claim 22, wherein the pair of channels of the first joining strip extend along the entire length of the of the first joining strip and wherein the pair of channels of the second joining strip extend along the entire length of the of the second joining strip.

25. An assembly according to claim 22, wherein the interior and exterior sides of the first and second frame members define a frame depth along the interior/exterior axis, and wherein the mechanically interlocking channels on the first and second joining strips are positioned such that a bottom of the channel on the first joining strip that is closest to the interior side of the first frame member is located within 20% or less of the frame depth from the interior side of the first frame member and a bottom of the channel on the second joining strip that is closest to the exterior side of the second frame member is located within 20% or less of the frame depth from the exterior side of the second frame member.

26. An assembly according to claim 22, wherein a first locator plate is positioned between the first joining strip and the first frame member, the first locator plate comprising a frame surface facing the first frame member and a joining strip surface facing the first joining strip, wherein the frame surface and the first frame member comprise complementary mating features configured to position the first locator plate in one selected location and orientation relative to the first frame member, and wherein the joining strip surface and the first joining strip comprise complementary mating features configured to position the first locator plate in one selected location and orientation relative to the first joining strip such that the first locator plate is configured to position the first joining strip in one selected orientation relative to the first frame member and in one selected location on the first frame member along the interior/exterior axis.

27. An assembly according to claim 26, wherein a second locator plate is positioned between the second joining strip and the second frame member, the second locator plate comprising a frame surface facing the second frame member and a joining strip surface facing the second joining strip, wherein the frame surface of the second locator plate and the second frame member comprise complementary mating features configured to position the second locator plate in one selected location and orientation relative to the second frame member, and wherein the joining strip surface of the second locator plate and the second joining strip comprise complementary mating features configured to position the second locator plate in one selected location and orientation relative to the second joining strip such that the second locator plate is configured to position the second joining strip in one selected orientation relative to the second frame member and in one selected location on the second frame member along the interior/exterior axis.

28. An assembly according to claim 22, wherein the assembly further comprises: an intermediate end plug cavity formed between the first joining strip and the second joining strip, wherein the intermediate end plug cavity comprises a first opening at the first ends of the first and second joining strips and a second opening at the second ends of the first and second joining strips; and a first end plug comprising a base and a cavity leg extending away from the base, wherein the cavity leg is positioned in the first opening of the intermediate end plug cavity when the base is positioned between the first and second frame members at the first ends of the first and second joining strips, wherein the cavity leg prevents disengagement of the mechanically interlocking channels on the first and second joining strips at the first ends of first and second joining strips.

29. An assembly according to claim 28, wherein a first end seal member is located between the first and second frame members at the first ends of the first and second joining strips, wherein the first end seal member is located in a first recess between the base of the first end plug and the exterior sides of the first and second frame members, wherein the first end seal member comprises a sealant port in fluid communication with a sealant reservoir positioned between the first and second frame members and the first ends of the first and second joining strips.

30. An assembly according to claim 28, wherein the assembly further comprises a gusset plate attached to the base of the first end plug, wherein the gusset plate spans the first end of the mull joint such that the base of the first end plug is located between the first ends of the first and second joining strips and the gusset plate, wherein the gusset plate is directly attached to the first and second fenestration units on opposite sides of the first end of the mull joint.

31. An assembly according to claim 22, wherein the first ends of the first and second joining strips terminate at a recessed location between the first frame member of the first fenestration unit and the second frame member of the second fenestration unit at the first end of the mull joint, wherein a first recess is formed at the first end of the mull joint between the first and second frame members; and wherein the assembly further comprises a locking clip located in the first recess between the first and second frame members at the first ends of the first and second joining strips, wherein the locking clip plug mechanically interlocks with the first gusset plate leg and the second gusset plate leg to restrict disengagement of the channels on the first and second joining strips at the first ends of first and second joining strips.

32. An assembly according to claim 22, wherein the first ends of the first and second joining strips terminate at a recessed location between the first frame member of the first fenestration unit and the second frame member of the second fenestration unit at the first end of the mull joint, wherein a first recess is formed at the first end of the mull joint between the first and second frame members; and wherein the assembly further comprises a retainer plug located in the first recess between the first and second frame members at the first ends of the first and second joining strips, wherein the retainer plug mechanically interlocks with the first gusset plate leg and the second gusset plate leg to restrict disengagement of the channels on the first and second joining strips at the first ends of first and second joining strips.

33. A compound fenestration assembly comprising: a first frame member of a first fenestration unit attached to a second frame member of a second fenestration unit along a mull joint having a first end and a second end, wherein the mull joint defines a mull joint axis extending along a length of the mull joint between the first and second ends of the mull joint, wherein the first and second frame members comprise exterior sides facing in the same direction and interior sides facing in an opposite direction from the exterior sides, wherein an interior/exterior axis extends between the interior and exterior sides in a direction transverse to the mull joint axis, wherein the first frame member faces the second frame member across the mull joint, wherein a separation axis extends through the mull joint between the first and second frame members, the separation axis extending in a direction transverse to both the mull joint axis and the interior/exterior axis; a first joining strip attached to the first frame member of the first fenestration unit, the first joining strip comprising a first end proximate the first end of the mull joint and a second end proximate the second end of the mull joint, wherein the first joining strip comprises a pair of channels extending along the length of the first frame member, wherein each channel of the pair of channels is aligned with the mull joint axis and opens towards the exterior side of the first fenestration unit; a second joining strip attached to the second frame member of the second fenestration unit, the second joining strip comprising a first end proximate the first end of the mull joint and a second end proximate the second end of the mull joint, wherein the second joining strip comprises a pair of channels extending along the length of the second frame member, wherein each channel of the pair of channels on the second joining strip is aligned with the mull joint axis and opens towards the interior side of the second fenestration unit such that each channel of the pair of channels on the first joining strip mechanically interlocks with one channel of the pair of channels on the second joining strip, wherein the mechanically interlocking channels prevent movement of the first frame member away from the second frame member along the separation axis, prevent movement of the first frame member towards the exterior side of the second frame member along the interior/exterior axis, and prevent movement of the second frame member towards the interior side of the first frame member along the interior/exterior axis; wherein the second joining strip is a mirror image of the first joining strip across the mull joint such that the channels on the second joining strip face the channels on the first joining strip and the channels on the second joining strip and the channels on the first joining strip open in opposite directions; and a first locator plate positioned between the first joining strip and the first frame member, the first locator plate comprising a frame surface facing the first frame member and a joining strip surface facing the first joining strip, wherein the frame surface and the first frame member comprise complementary mating features configured to position the first locator plate in one selected location and orientation relative to the first frame member, and wherein the joining strip surface and the first joining strip comprise complementary mating features configured to position the first locator plate in one selected location and orientation relative to the first joining strip such that the first locator plate is configured to position the first joining strip in one selected orientation relative to the first frame member and in one selected location on the first frame member along the interior/exterior axis.

34. An assembly according to claim 33, wherein the first joining strip extends over a majority of the length of the first frame member and the second joining strip extends over a majority of the length of the second frame member.

35. An assembly according to claim 33, wherein the pair of channels of the first joining strip extend along the entire length of the of the first joining strip and wherein the pair of channels of the second joining strip extend along the entire length of the of the second joining strip.

36. An assembly according to claim 33, wherein the interior and exterior sides of the first and second frame members define a frame depth along the interior/exterior axis, and wherein the mechanically interlocking channels on the first and second joining strips are positioned such that a bottom of the channel on the first joining strip that is closest to the interior side of the first frame member is located within 20% or less of the frame depth from the interior side of the first frame member and a bottom of the channel on the second joining strip that is closest to the exterior side of the second frame member is located within 20% or less of the frame depth from the exterior side of the second frame member.

37. An assembly according to claim 33, wherein a second locator plate is positioned between the second joining strip and the second frame member, the second locator plate comprising a frame surface facing the second frame member and a joining strip surface facing the second joining strip, wherein the frame surface of the second locator plate and the second frame member comprise complementary mating features configured to position the second locator plate in one selected location and orientation relative to the second frame member, and wherein the joining strip surface of the second locator plate and the second joining strip comprise complementary mating features configured to position the second locator plate in one selected location and orientation relative to the second joining strip such that the second locator plate is configured to position the second joining strip in one selected orientation relative to the second frame member and in one selected location on the second frame member along the interior/exterior axis.

38. An assembly according to claim 33, wherein the first and second joining strips are separate and discrete lengths of a common profile.

39. An assembly according to claim 33, wherein the assembly further comprises: an intermediate end plug cavity formed between the first joining strip and the second joining strip, wherein the intermediate end plug cavity comprises a first opening at the first ends of the first and second joining strips and a second opening at the second ends of the first and second joining strips; and a first end plug comprising a base and a cavity leg extending away from the base, wherein the cavity leg is positioned in the first opening of the intermediate end plug cavity when the base is positioned between the first and second frame members at the first ends of the first and second joining strips, wherein the cavity leg prevents disengagement of the mechanically interlocking channels on the first and second joining strips at the first ends of first and second joining strips.

40. An assembly according to claim 39, wherein the intermediate end plug cavity is located between the pairs of channels on the first and second joining strips.

41. An assembly according to claim 39, wherein a first end seal member is located between the first and second frame members at the first ends of the first and second joining strips, wherein the first end seal member is located in a first recess between the base of the first end plug and the exterior sides of the first and second frame members, wherein the first end seal member comprises a sealant port in fluid communication with a sealant reservoir positioned between the first and second frame members and the first ends of the first and second joining strips.

42. An assembly according to claim 39, wherein the assembly further comprises a gusset plate attached to the base of the first end plug, wherein the gusset plate spans the first end of the mull joint such that the base of the first end plug is located between the first ends of the first and second joining strips and the gusset plate, wherein the gusset plate is directly attached to the first and second fenestration units on opposite sides of the first end of the mull joint.

Description

BRIEF DESCRIPTION OF THE VIEWS OF THE DRAWING

(1) FIG. 1 is a cross-sectional view of one illustrative embodiment of a mull joint in a compound fenestration assembly as described herein in which the components on opposite sides of the mull joint are separated prior to joining.

(2) FIG. 2A is a cross-sectional view of the mull joint of FIG. 1 after the components are joined.

(3) FIG. 2B is a cross-sectional view of another illustrative embodiment of a mull joint in an alternative compound fenestration assembly with a trim piece attached along one edge of the mull joint.

(4) FIG. 3 is an end view of one illustrative embodiment of a locator plate and joining strip which may be used in one or more embodiments of mull joints as described herein.

(5) FIG. 4 is a plan view of a portion of the illustrative embodiment of a joining strip depicted in FIG. 3.

(6) FIG. 5 is a perspective view of the locator plate and joining strip depicted in FIG. 3.

(7) FIG. 6 is a perspective view of one illustrative embodiment of a pair of joining strips and associated locator plates that may be used to form a mull joint of a compound fenestration assembly as described herein.

(8) FIG. 7 is a perspective view of one illustrative embodiment of the joining strips and associated locator plates of FIG. 6 positioned between fenestration units during one illustrative embodiment of assembly of a compound fenestration assembly as described herein.

(9) FIG. 8 is a perspective view of the compound fenestration assembly of FIG. 7 depicting one illustrative method of attaching joining strips to fenestration units as described herein.

(10) FIG. 9 is a perspective view of one illustrative method of assembling fenestration units to form a mull joint between the units as described herein.

(11) FIG. 10 is a perspective view of the compound fenestration assembly of FIGS. 7-9, depicting insertion of one illustrative embodiment of end plugs in the mull joints between fenestration units as described herein.

(12) FIG. 11 is an enlarged perspective view of one illustrative embodiment of an end plug partially inserted into an intermediate end plug cavity formed between joining strips used in one illustrative embodiment of a mull joint in a compound fenestration assembly as described herein.

(13) FIG. 12 is a perspective view of the illustrative embodiment of the end plug of FIG. 11 with an end seal member attached thereto prior to insertion of the end plug into the depicted mull joint of the depicted compound fenestration assembly.

(14) FIG. 13 is a perspective view of the compound fenestration assembly of FIGS. 7-10 depicting placement of one illustrative embodiment of a gusset plate over selected mull joint ends.

(15) FIG. 14 is a perspective view of the compound fenestration assembly of FIG. 13 depicting attachment of the gusset plate over the selected mull joint ends.

(16) FIG. 15 is a perspective view of the compound fenestration assembly of FIG. 14 depicting placement of one illustrative embodiment of intersection plates on selected mull joint ends.

(17) FIG. 16 is an enlarged perspective view of one illustrative embodiment of an intersection plate attached to one illustrative embodiment of an end plug, both of which may be used in one or more embodiments of mull joints in compound fenestration assemblies as described herein.

(18) FIG. 17 is a perspective view of the compound fenestration assembly of FIG. 16 in the process of being measured for attachment of joining strips as described herein.

(19) FIG. 18 is a perspective view of one illustrative embodiment of a pair of joining strips and associated locator plates to be attached to fenestration units in one illustrative embodiment of a compound fenestration assembly as described herein.

(20) FIG. 19 is a perspective view of the joining strips and associated locator plates in position for attachment to the compound fenestration assemblies depicted in FIG. 18.

(21) FIG. 20 is a perspective view of one illustrative embodiment of attaching the joining strips and associated locator plates of FIG. 19 to the compound fenestration assemblies depicted in FIGS. 18-19.

(22) FIG. 21 is a perspective view of one illustrative embodiment of joining fenestration units in one illustrative embodiment of a compound fenestration assembly as described herein.

(23) FIG. 22 is a perspective view depicting installation of one illustrative embodiment of end plugs in selected mull joints of the illustrative embodiment of a compound fenestration assembly as described herein.

(24) FIG. 23 is a perspective view of one illustrative embodiment of a compound fenestration assembly depicting placement and attachment of one illustrative embodiment of gusset plates on selected ends of mull joints as described herein.

(25) FIG. 24 is a perspective view depicting one illustrative embodiment of placement of end seal members in selected mull joint ends of the depicted illustrative embodiment of a compound fenestration assembly.

(26) FIG. 25 is an enlarged perspective view of illustrative embodiments of an end plug and an end seal member that may be used in connection with mull joints in compound fenestration assemblies as described herein.

(27) FIG. 26 is a perspective view of one illustrative embodiment of delivery of sealant into the end seal members in the compound fenestration assembly depicted in FIG. 25.

(28) FIGS. 27 and 28 depict installation of one illustrative embodiment of trim members in mull joints in compound fenestration assemblies as described herein.

(29) FIG. 29 is a perspective view of one illustrative embodiment of a bracket plate and one illustrative embodiment of an associated end plug that may be used to secure a compound fenestration unit assembly in an opening as described herein.

(30) FIG. 30 is a perspective view of the bracket plate and fastener after removal of the end plug from the assembly depicted in FIG. 29.

(31) FIG. 31 is an enlarged perspective view of the end plug of FIG. 29 positioned in an intermediate end plug cavity formed between one illustrative embodiment of a pair of joining strips that may be used in a mull joint of a compound fenestration assembly as described herein.

(32) FIG. 32 is a perspective view of the bracket plate and end plug partially inserted into the end of a mull joint of one illustrative embodiment of a compound fenestration assembly as described herein.

(33) FIG. 33 is a perspective view of a compound end plug assembly that may be used in place of the end plug depicted in FIGS. 29 and 31-32 in a mull joint of a compound fenestration assembly as described herein.

(34) FIG. 34 is a perspective view of the compound end plug assembly of FIG. 33 with one illustrative embodiment of a threaded fastener positioned therein.

(35) FIG. 35 is a perspective view of a bracket plate and the compound end plug assembly of FIGS. 33-34 partially inserted into the end of a mull joint of one illustrative embodiment of a compound fenestration assembly as described herein.

(36) FIG. 36 is a perspective view of one illustrative embodiment of a compound fenestration assembly using flanged corner gusset as described herein.

(37) FIG. 37 is a perspective view of one illustrative embodiment of installation of a compound fenestration assembly using a flanged corner gusset.

(38) FIG. 38 is a perspective view of a compound fenestration assembly using one illustrative embodiment of a stacked corner gusset assembly as described herein.

(39) FIG. 39 is an enlarged perspective view of the stacked corner gusset assembly depicted in FIG. 38.

(40) FIG. 40 is an alternative view of the stacked corner gusset assembly of FIG. 39 with one of the corner gussets removed to expose the locking clip attached to the depicted corner gusset.

(41) FIG. 41 is an end view of the stacked corner gusset assembly as seen in FIG. 40 taken along the mull joint axis (the Z axis).

(42) FIG. 42 is an enlarged perspective view of one illustrative embodiment of a retainer plug which may be used in connection with the corner gusset assemblies described herein.

(43) FIG. 43 is a plan view of the retainer plug of FIG. 42.

(44) FIG. 44 is an end view of the stacked corner gusset assembly as seen in FIG. 41 with the opposing joining strip and fenestration unit depicted, along with a retainer plug positioned in the recess formed at the end of the mull joint.

(45) FIG. 45 is a perspective view of one alternative embodiment of a corner gusset assembly along with an alternative embodiment of a retainer plug that may be used in connection with the corner gusset assemblies described herein.

(46) FIG. 46 is an enlarged perspective view of the alternative illustrative embodiment of the retainer plug depicted in FIG. 45.

(47) FIG. 47 is a plan view of the retainer plug of FIG. 46.

(48) FIG. 48 is a perspective view of one illustrative embodiment of a method of installing a compound fenestration assembly using one illustrative embodiment of a stacked corner gusset assembly as described herein.

(49) FIG. 49 is an enlarged perspective view of the corner gusset seen in FIG. 48.

(50) FIGS. 50-51 are perspective views of one illustrative method of installing a compound fenestration assembly using a stacked corner gusset assembly as described herein, with FIG. 51 being an enlarged view of portion C of FIG. 50.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(51) In the following description of illustrative embodiments, reference is made to the accompanying figures of the drawing which form a part hereof, and in which are shown, by way of illustration, specific embodiments. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.

(52) One illustrative embodiment of a mull joint which may be used in a compound fenestration assembly as described herein is depicted in FIGS. 1, 2A, and 2B. FIG. 1 is a cross-sectional view in which the components are depicted as being slightly separated prior to joining the components to form the mull joint, while FIG. 2A is a cross-sectional view of the mull joint of FIG. 1 after the components are joined. FIG. 2B is a cross-sectional view of another illustrative embodiment of a mull joint in an alternative compound fenestration assembly with a trim piece attached along one edge of the mull joint. For reference, one set of mull joints which may be constructed in accordance with the mull joints depicted in FIGS. 1, 2A, and 2B are depicted in the process of assembly in, e.g., FIGS. 7-9.

(53) The depicted illustrative embodiment of the mull joint in FIGS. 1, 2A, and 2B includes a joining strip 20 attached to a frame member 10 on one side of the mull joint and a joining strip 30 attached to the frame member 12 on the opposite side of the mull joint. Frame members 10 and 12 are frame members on different fenestration units that are to be attached in a compound fenestration assembly as described herein.

(54) Although not seen in FIGS. 1, 2A, and 2B, the mull joints of compound fenestration assemblies as described herein may include weatherstripping or other sealing features to limit the penetration of air and or water between the interior and exterior sides of a compound fenestration assembly through the mull joint. For example, in one or more embodiments, the weatherstripping or other sealing features may be located between the joining strips 20 and 30 and their respective frame members 10 and 12 and/or between the joining strips 20 and 30.

(55) In the depicted illustrative embodiment, joining strip 20 includes channels 22 and 24 while joining strip 30 includes channels 32 and 34. In particular, channels 22 and 24 of joining strip 20 may be described as opening towards an interior side 17 of the fenestration unit that includes frame member 10 as a part thereof. Channels 32 and 34 of joining strip 30 may be described as opening towards an exterior side 19 of the fenestration unit that includes frame member 12 as a part thereof. As discussed herein, the joining strips 20 and 30 are oriented such that the legs of the joining strips 20 and 30 forming channels 22 and 32 interlock with the opposing channel in the opposing joining strip as seen in, e.g., the mull joints depicted in both FIGS. 2A and 2B. Similarly, the legs of joining strips 20 and 30 forming channels 24 and 34 mechanically interlock with the opposing channel in the opposing joining strip.

(56) As a result, a secure connection between the joining strips is obtained through the mechanical interlocking of the channel structures in the opposing joining strips 20 and 30, with the mechanically interlocking joining strips resisting movement of their respective frame members and fenestration units relative to each other. For example, in one or more embodiments, the mull joints and compound fenestration assemblies in which the mull joints are found, may define an interior/exterior axis that extends between the interior side 17 and the exterior side 19 of the mull joint formed by joining strips 20 and 30. In, e.g., FIGS. 1, 2A, and 2B, the interior/exterior axis is aligned with they direction.

(57) The first frame member 10 may, in one or more embodiments, be described as facing the second frame member 12 across the mull joint, with a separation axis extending through the mull joint between the first and second frame members 10 and 12. In, e.g., FIGS. 1, 2A, and 2B, the separation axis is aligned in the x direction.

(58) While the interior/exterior axis is aligned in the y direction and the separation axis is aligned in the x direction, mull joints in compound fenestration assemblies as described herein also define a mull joint axis that extends along a length of the mull joint between first and second ends of each of the mull joints. In, e.g., FIGS. 1, 2A, and 2B, the mull joint axis would be aligned in a z direction extending into the page in each of FIGS. 1, 2A, and 2B.

(59) The interior/exterior axis, separation axis, and a mull joint axis are all, in one or more embodiments, transverse to each other. These relationships can be seen in many of the figures including, e.g., FIGS. 7-10, where, as described herein, the interior/exterior axis corresponds to the y direction, the separation axis corresponds to the x direction, and the mull joint axis corresponds to the z direction.

(60) In one or more embodiments, the mechanically interlocking channels 22/32 and 24/34 of the joining strips 20 and 30 may be described as preventing movement of the frame member 10 away from frame member 12 along the separation axis (i.e., the x direction), preventing movement of the frame member 10 towards the interior side 17 of the frame member 12 along the interior/exterior axis (i.e., the y direction), and preventing movement of the frame member 12 towards the exterior side 19 of the frame member 10 along the interior/exterior axis (i.e., the y direction).

(61) As described herein, the channels in opposing joining strips mechanically interlock with each other to assist with formation and retention of the mull joint in a compound fenestration assembly. In one or more embodiments, the phrase mechanically interlock means that the interlocking channels in the opposing joining strips 20 and 30 cannot be separated from each other along the separation axis (the x direction) without permanent destruction of the channel structures in one or both of the joining strips used to form mull joints in compound fenestration assemblies as described herein. Permanent destruction means that the channel structures undergo permanent deformation (i.e., non-elastic deformation) and/or fracturing or separation of components forming the channels in the joining strips.

(62) In one or more embodiments, the joining strips forming one or more embodiments of mull joints as described herein are separate and discrete lengths of a common profile. The use of a common profile to form joining strips for one or more embodiments of mull joints as described herein may reduce the number of different parts needed to construct mull joints of compound fenestration assemblies as described herein because joining strips having only one common profile (i.e., shape) may be produced. In one or more embodiments, the common profiles used for joining strips as described herein may be formed through, e.g., extrusion or other suitable techniques, with longer lengths of joining strips being cut or separated to form discrete joining strips that may be used in mull joints as described herein. In other words, the joining strips used in one or more embodiments of mull joints as described herein are mirror images of each other, with, for example, one joining strip being rotated (relative to the opposing joining strip) 180 about the mull joint axis (i.e., the z axis) such that the channels on the two opposing joining strips face each other and open in opposite directions such that the channels can mechanically interlock with each other as described herein.

(63) In one or more embodiments, the joining strips used in mull joints of compound fenestration assemblies as described herein may be constructed of one or more materials that provide sufficient mechanical strength as well as limiting thermal conductivity to enhance the thermal performance of compound fenestration assemblies as described herein. In one or more embodiments, the joining strips may be constructed of, e.g., one or more of fiberglass, polymeric materials, metals, etc. In one or more embodiments, the joining strips may be constructed of materials such as, e.g., fiberglass, polymeric materials, etc. that have lower thermal conductivity than, e.g., metals. In one or more embodiments, however, metals (or other more thermally conductive materials) may be used to construct the joining strips where, for example, a thermal break or other feature may be provided to limit thermal conductivity through the joining strips between the exterior and interior sides of a compound fenestration assembly as described herein.

(64) A variety of other features that may be found in one or more embodiments of the components forming mull joints of compound fenestration assemblies as described herein are also depicted in FIGS. 1, 2A, and 2B. For example, in one or more embodiments, joining strip 20 may include a number of features facing the interior surface of the frame member 10 such as, e.g., slots 25 which, as described herein, can be used to assist in locating the joining strip 20 in a selected location on the frame member 10. The slots 25 may form part of a side cavity 51 located between the joining strip 20 and the surface 11 of the first frame member 10. A similar side cavity 51 may, in one or more embodiments, be located between the joining strip 30 and the surface 13 of the frame member 12, with the joining strips 30 including slots 35 which may form a portion of the side cavity 51 located between the joining strip 30 and the surface 13 of the frame member 12.

(65) One or both of the side cavities 51 may be used as described herein to provide a space for one or more locator plates (see, e.g., locator plates 40) as described in connection with, e.g., FIGS. 3-6. In one or more embodiments, one or both of the side cavities 51 may be used as described herein to provide a space for one or more composite bracket plugs as described herein in connection with, e.g., FIGS. 33-35. In one or more embodiments, one or both of the side cavities 51 may include a first opening at a first end of the joining strips 20 and 30 and a second opening at the second or opposite end of the joining strips 20 and 30. In other words both ends of a mull joint formed using joining strips 20 and 30 may include openings into one or both of the side cavities 51. Further, one or both of the side cavities 51 may, in one or more embodiments, extend along the entire length of the joining strips 20 and 30 forming the mull joint.

(66) In one or more embodiments, the joining strip 20 may also include an inset area 23 facing the opposing joining strip 30 across the mull joint, with the opposing joining strip 30 also including an inset area 33. When the joining strips 20 and 30 are interlocked to form the mull joint as seen in, e.g., FIGS. 2A and 2B, the inset areas 23 and 33 are directly opposite each other and form an intermediate end plug cavity between the joining strip 20 and the joining strip 30. In one or more embodiments, the intermediate end plug cavity 50 may include a first opening at a first end of the joining strips 20 and 30 and a second opening at the second or opposite end of the joining strips 20 and 30. In other words, both ends of a mull joint formed using joining strips 20 and 30 may include openings into this intermediate end plug cavity 50 which may, in one or more embodiments, extend along the entire length of the joining strips 20 and 30 forming the mull joint. In one or more embodiments, the intermediate end plug cavity 50 may be described as being located between the channels 22/32 and 24/34 on the first and second joining strips 20 and 30.

(67) In one or more embodiments of mull joints in compound fenestration assemblies as described herein, an end plug having a cavity leg may be inserted into the intermediate end plug cavity 50 at one end of the joining strips 20 and 30 to prevent disengagement of the mechanically interlocking channels on the joining strips 20 and 30 at that end of the mull joint formed by the joining strips 20 and 30. This feature and illustrative embodiments of end plugs having cavity legs are depicted and/or described herein in connection with, e.g., FIGS. 10-12, 29, and 31. In essence, insertion of a components such as, e.g., a cavity leg into the intermediate end plug cavity locks the joining strips 20 and 30 relative to each other such that the channels 22/32 and 24/34 cannot be backed out of engagement with each other.

(68) In one or more embodiments, the channels in the joining strips used to construct mull joints in compound fenestration assemblies as described herein may provide positioning of the interlocking channels within a selected distance of the interior and exterior side 17 and 19 of the frame members 10 and 12 being connected across the mull joint. Positioning the channels closer to the interior and exterior sides 17 and 19 may provide stronger mull joints as compared to mull joints in which the connections are located farther inward within a mull joint from the interior and/or exterior sides of the frame members of fenestration units connected across the mull joint.

(69) In one or more embodiments, the frame members connected by mull joints in the compound fenestration assemblies as described herein may be constructed of multiple components, with different components defining the interior and exterior sides of the frame members. For example, in the illustrative embodiment of the mull joint as depicted in FIG. 2A, frame members 10 and 12 may each be constructed of an outer frame member 10a/12a, jamb 10b/12b, and inside stop 10c/12c. In the alternative embodiment depicted in FIG. 2B, the frame members 10 and 12 include outer frame members 10a/12a, jambs 10b/12b, and inside stops 10c/12c.

(70) Although additional components such as, e.g., extension jams, trim pieces, etc. may be attached to the frame members 10 and 12 on the interior side 17 of the compound fenestration assembly as a part of finishing the installation of the assembly, the compound fenestration assemblies described herein would typically first be installed in a rough opening followed by addition of such additional components (although in some instances extension jambs may be applied by a manufacturer at the factory). In contrast to the additional components that may be installed on the interior side 17 of a compound fenestration assembly as described herein, however, additional components are not typically added to the components that define the exterior sides of the frame members (with the exception of a potential trim strip, one illustrative embodiment of which is described herein in connection with FIG. 2B and/or exterior brick mould or other decorative trim that can be applied to the exterior sides of the frame members).

(71) As depicted in, e.g., FIGS. 2A and 2B, the interior and exterior sides 17 and 19 of the first and second frame members 10 and 12 define a frame depth d along the interior/exterior axis (i.e., the y direction). As discussed herein, the mechanically interlocking channels 22/32 and 24/34 on the joining strips 20 and 30 are positioned such that the bottom of channel 32 on the joining strip 30 (where the bottom is the interior surface of the channel 32 that is closest to the interior side 17 of the frame members 10 and 12) is located within 20% or less of the frame depth d from the interior side 17 of the frame members 10 and 12 and the bottom of channel 24 on the joining strip 20 (where the bottom is the interior surface of the channel 24 that is closest to the exterior side 19 of the frame members 10 and 12) is located within 20% or less of the frame depth d from the exterior sides 19 of the frame members 10 and 12. In one or more alternative embodiments, the channels 32 and 24 may be located even closer to the interior and exterior side 17 and 19, e.g., the bottoms of the channels 32 and 24 may be located within 15% or less of the frame depth d from the respective interior sides 17 or exterior sides 19 of the frame members 10 and 12.

(72) Other optional features which may be provided in one or more embodiments of a mull joint in a compound fenestration assembly as described herein may include trim slots 21 and 31 located at opposite ends of the mull joint. In one or more embodiments, the trim slots 21 and/or 31 may be sized and positioned to receive and retain a fin 64 extending from a body 62 of a trim strip 60 such that the trim strip 60 is retained in position on one side of the mull joint (see, e.g., FIG. 2B). In one or more embodiments, the joining strips 20 and 30 may include raised ridges, ribs, or other features 26 that assist in retaining the fin 64 of a trim strip 60 within the trim slots 31 and/or 21.

(73) Typically, a trim strip 60 will be used on an exterior side of the mull joint, however, in one or more embodiments, trim strips may be used on one or both of the exterior and interior sides of a mull joint of a compound fenestration assembly as described herein. The trim strip 60 may provide a more aesthetically pleasing appearance and, in one or more embodiments, may include weatherstripping or other sealing features to limit the passage of air and/or water between the interior and exterior sides of the mull joint.

(74) In one or more embodiments of mull joints used in compound fenestration assemblies as described herein, a seal and and/or adhesive may be provided in one or both of the trim slots 21 and/or 31 to further assist in locking the joining strips 20 and 30 together when the opposing channels are mechanically interlocked with each other. Suitable sealants and/or adhesives may include, e.g., silicones, urethanes, epoxies, etc.

(75) In one or more embodiments of mull joints used in compound fenestration assemblies as described herein, positioning of the joining strips on the frame members to be attached by a mull joint may be assisted through the use of, e.g., locator plates positioned between the joining strips and the frame members to which they are attached. In one or more embodiments, one, two, three or more locator plates may be positioned between a joining strip and the frame member to which the joining strip is attached. In one or more embodiments, the locator plate(s) may include a frame surface facing the frame member to which the joining strip is attached and a joining strip surface facing the joining strip. The frame surface of each locator plate and the frame member may include complementary mating features configured to position the locator plate in one selected location and orientation relative to the frame member. Furthermore, the joining strip surface of each locator plate and the first joining strip may include complementary mating features configured to position the locator plate in one selected location and orientation relative to the joining strip. The combination of complementary mating features on the frame surface and joining strip surface of the locator plates are, in one or more embodiments, configured to position the joining strip in one selected orientation relative to the frame member and in one selected location on the frame member along the interior/exterior axis (i.e., the y direction).

(76) One illustrative embodiment of an optional locator plate 40 that may be used in connection with the depicted illustrative embodiment of joining strip 20 is depicted in FIGS. 3-5. The depicted illustrative embodiment of locator plate 40 includes a body 42 having one or more raised joining strip alignment features 45 on a joining strip surface facing the joining strip 20. In one or more embodiments, the raised joining strip alignment features 45 may be in the form of one or more ribs or other raised features which are sized and positioned to mate with slots 25 formed in joining strip 20 (or slots 35 in joining strip 30 if used in combination with joining strip 30).

(77) The depicted illustrative embodiment of locator plate 40 also includes a pin 44 which is sized and positioned to fit within an aperture 27 provided in the joining strip 20. In one or more embodiments, the joining strip 20 may include a plurality of apertures 27. Although only one such aperture 27 is used to accept pin 44 of locator plate 40, one or both of the other apertures 27 may be used to provide proper placement of a fastener (e.g., a threaded fastener, etc.) they can be used to secure the joining strips to frame members as described herein. Such placement of fasteners proximate the locator plates may also be advantageous in fixing the location of the locator plates relative to the joining strips and preventing movement of the locator plates after attachment of the joining strip to a frame member of a fenestration unit of a compound fenestration assembly as described herein.

(78) While the raised joining strip alignment features and the complementary recesses formed in the joining strip provide for placement of the locator plate 40 in a selected position and orientation on the joining strip 20, one or more embodiments of the locator plate 40 may also include frame alignment features on frame surface of the locator plate 40, i.e., the surface of the locator plate 40 that faces the frame member 10 to which the joining strip 20 is attached. In one or more embodiments, the frame alignment features on the frame surface of the locator plate 40 are configured to fit within a complementary recess in the frame member to which the joining strip 20 is attached. For example, in one or more embodiments, frame members 10 and 12 may respectively include frame slots 14 and 15.

(79) In the depicted illustrative embodiment, locator plate 40 includes a frame alignment rib 46 that extends away from the joining strip 20. In one or more embodiments, the frame alignment rib 46 may preferably fit within the frame slot 14 in frame member 10 of the mull joint depicted in FIGS. 1 and 2A. The frame alignment rib 46 and frame slot 14 of frame member 10 may, in one or more embodiments, preferably cooperate to position the joining strip in a selected location on the frame member 10 in a mull joint of a compound fenestration assembly as described herein.

(80) Although alignment features could potentially be formed directly in the joining strip 20, such an alignment feature may or may not be properly positioned with respect to a complementary recess in a frame member if the joining strip 20 is rotated to provide a joining strip on the opposite side of a mull joint as described herein. As a result, the use of a universal locator plate 40 that can be rotated independently of the joining strip 20 may be advantageous in one or more embodiments of compound fenestration assemblies as described herein.

(81) Although the pin 44 and ribs 45 along with slots 25 and 35 in joining strips 20 and 30 provide one example of complementary mating features configured to position a locator plate in one selected orientation and location with respect to a joining strip, many other complementary mating structures could be used in place of those depicted in connection with the illustrative embodiment of locator plate 40. Similarly, although rib 46 on the frame surface of the locator plate 40 and corresponding frame slots 14 and 15 in frame members 10 and 12 provide one example of complementary mating features configured to position a locator plate in one selected location and orientation with respect to a frame member, many other complementary mating structures could be used in place of those depicted in connection with the illustrative embodiment of locator plate 40.

(82) Furthermore, the illustrative embodiments of joining strips 20 and 30 depicted in connection with FIGS. 1-5 represent only illustrative examples of joining strips that may be used to form mull joints of compound fenestration assemblies as described herein. Other joining strips and/or locator plates may be used to form mull joints of compound fenestration assemblies as described herein which may have a different appearance while offering the same sets of functional features required to form a mull joint as described herein.

(83) Although the locator plates are described as being attached to the joining strips first, in one or more embodiments, one or more locator plates may be attached to the frame member of a fenestration unit first, with the joining strip being subsequently placed over the locator plate. In such embodiments, the locator plates and frame members to which they are attached may, in one or more embodiments, include complementary mating features such as, e.g., ribs 46 on the locator plates 40 and corresponding frame slots 14 and 15 in frame members 10 and 12 to properly align the locator plates on the frame members. Further, locator plates and joining strips may include complementary features such as, e.g., ribs 45 on locator plates 40 along with slots 25 and 35 in joining strips 20 and 30, to properly align the joining strips relative to the locator plates. As a result of these different sets of complementary mating features, the joining strips may be properly aligned on the frame members.

(84) Turning now to FIG. 6, a perspective view is provided of one illustrative embodiment of joining strips 120 and 130 and associated locator plates 140 that may be used to form a mull joint of a compound fenestration assembly as described herein. Although a set of three locator plates 140 is provided in connection with each of the joining strips 120 and 130, any number of locator plates 140 may be provided with one or both of joining strips 120 and 130 so long as the number of locator plates 140 is sufficient to accurately align the respective joining strip along a frame member of a fenestration unit of a compound fenestration assembly as described herein. In one or more embodiments, for example, as few as one locator plate could be used with each of the joining strips (with, for example, a single locator plate having an extended length as compared to the illustrative embodiments depicted in the figures).

(85) FIG. 7 is a perspective view of the joining strips 120 and 130 along with their associated locator plates 140 positioned between pairs of fenestration units 102 and 104 during assembly of one illustrative embodiment of a compound fenestration assembly as described herein. In particular, joining strips 120 are depicted as being positioned below frame members 110 of upper fenestration units 102 while joining strips 130 are depicted as positioned above frame members 112 of lower fenestration units 104. In one or more embodiments, the joining strips 120 and 130 may be described as extending over a majority of a length of the frame members to which they are attached. Doing so may, in one or more embodiments, enhance the strength of the mull joint formed by the joining strips 120 and 130.

(86) FIG. 8 is a perspective view of the compound fenestration assembly of FIG. 7 depicting one illustrative embodiment of attachment of the joining strips 120 and 130 to fenestration units 102 and 104 (noting that joining strips 120 are in position on the bottom of the fenestration units 102 and, as a result, are not visible in the view of FIG. 8). In the depicted illustrative embodiment, the joining strips are attached to their respective fenestration units 102 or 104 using threaded fasteners 129. It will be understood, however, that the joining strips 120 and 130 may be attached to their respective fenestration units using other techniques or components such as, e.g., nails, rivets, adhesives, etc.

(87) Before proceeding with the description of joining strips, it should be noted that although the illustrative compound fenestration assemblies depicted in, e.g., include fenestration units connected using horizontally oriented joining strips and related components (see, e.g., FIGS. 7-9), followed by attachment of vertically oriented joining strips to the compound fenestration assemblies containing the horizontally oriented joining strips (see, e.g., FIGS. 18-21), one or more alternative embodiments of the compound fenestration unit assemblies described herein may be constructed by attaching the vertically oriented joining strips. In such an embodiment, the fenestration units 102 are, e.g., connected to each other and fenestration units 104 are connected to each other before horizontally oriented joining strips are attached to the junction between the connected pair of fenestration units 102 and the connected pair of fenestration units 104. As a result, the horizontally oriented joining strips would span the vertical joints between the pair of fenestration units 102 and the pair of fenestration units 104. Further, in larger compound fenestration units, the longer joining strips that span joints may be arranged both vertically and horizontally if doing so would, e.g., simplify the assembly and installation process.

(88) FIG. 9 is a perspective view of one illustrative embodiment of assembly of the fenestration units 102 and 104 to form a mull joint between each of the depicted compound fenestration assemblies. As discussed herein, the lower joining strip 130 on the lower fenestration unit 104 will, in one or more embodiments, include channels opening towards the exterior side 105 of the fenestration unit 104 while the joining strip attached to the upper fenestration unit 102 will, in one or more embodiments, include channels opening towards the interior side 106 of the fenestration unit 104 so that the channels on the opposing joining strips can form a mechanically interlocking connection with each other as described herein.

(89) FIG. 10 is a perspective view of the compound fenestration assemblies of FIGS. 7-9, depicting insertion of one illustrative embodiment of end plugs 152 in the mull joints between the fenestration units 102 and 104 as described herein. As depicted, end plugs 152 are inserted into both ends of the mull joints formed between the respective pairs of upper and lower fenestration units 102 and 104.

(90) FIG. 11 is an enlarged perspective view of one illustrative embodiment of an end plug 152 partially inserted into an intermediate end plug cavity 150 formed between joining strips 120 and 130 used in one illustrative embodiment of a mull joint in a compound fenestration assembly as described herein. The joining strips 120 and 130 have been removed from their respective fenestration units to provide additional clarity in the arrangement and insertion of end plugs in an intermediate end plug cavity formed between joining strips in one or more embodiments of mull joints as described herein. As seen in, e.g., FIG. 11, the illustrative embodiment of end plug 152 includes a base 154 and a cavity leg 156 that extends away from the base 154. The cavity leg 156 is the portion of the end plug 152 that is positioned in the intermediate end plug cavity 150 at each end of the mull joints formed using joining strips 120 and 130.

(91) As described herein, the cavity leg 156 may, when inserted into the intermediate end plug cavity 150, prevent disengagement of the mechanically interlocking channels on the joining strips 120 and 130 at that end of the mull joint formed by the joining strips 120 and 130. In essence, insertion of the cavity leg 156 into the intermediate end plug cavity 150 locks the joining strips 120 and 130 relative to each other such that the channels cannot be backed out of engagement with each other.

(92) In one or more embodiments, the end plug 152 may include one or more openings 158 in the base 154 that are configured to receive a threaded fastener to attach other components to the end plug and, therefore, the mull joint as described herein.

(93) FIG. 12 is a perspective view of the illustrative embodiment of end plug 152 before insertion into a mull joint formed between fenestration units 102 and 104. In the view seen in FIG. 12, the joining strips 120 and 130 terminate at a recessed location between the frame member 110 of the fenestration unit 102 and the frame member 112 of the fenestration unit 104 at the end of the depicted mull joint. As a result, a recess 153 is formed at the end of the mull joint between the frame members 110 and 112. When the cavity leg 156 of the end plug 152 is fully inserted into the intermediate end plug cavity 150 formed between the joining strips 120 and 130, the base 154 is, in one or more embodiments, completely contained within the recess 153 formed between frame members 110 and 112.

(94) In the view of FIG. 12, an optional end seal member 190 is depicted as attached to the base 154 of the end plug 152 prior to insertion of the cavity leg 156 of the end plug 152 into the mull joint of the compound fenestration assembly. If so provided, the end seal member 190 may also be described as being located within the recess 153 formed between the frame members 110 and 112 at the ends of the joining strips 120 and 130. As described herein, however, the end seal member 190 may be positioned in the recess 153 at a later time. Further, additional details with respect to the end seal member 190 and its function with respect to the delivery of sealant into the mull joints described herein will be described below.

(95) FIG. 13 is a perspective view of the compound fenestration assembly of FIG. 10 after insertion of end plugs 152 in the mull joints formed between fenestration units 102 and 104, depicting placement of one illustrative embodiment of a gusset plate 170 over selected mull joint ends of the depicted compound fenestration assembly. In one or more embodiments, each of the gusset plates 170 may be attached to the base 154 of the end plug 152 over which the gusset plates 170 are located. In one or more embodiments, the gusset plates 170 may be attached to the base 154 of the end plugs 152 using threaded fasteners or other fastening components inserted into the apertures 158 in the illustrative embodiment of end plug 152 as depicted in, e.g., FIG. 11. In one or more embodiments, the gusset plates 170 may be described as spanning the ends of the mull joints on which they are located such that the base 154 of an end plug 152 is located between the ends of the joining strips 120 and 130 of the mull joint and the gusset plate 170 (i.e., in the recess 153 located between frame members 110 and 112 as seen in, e.g., FIG. 12). Furthermore, in one or more embodiments the gusset plates 170 may be directly attached to the fenestration units 102 and 104 on opposite sides of the mull joints over which the gusset plates 170 are positioned. As used herein, directly attached means that the gusset plates 170 may be secured to the frame members of the fenestration units 102 and 104 using, e.g., one or more threaded fasteners, rivets, adhesives, etc. In particular, FIG. 14 is a perspective view of the compound fenestration assembly of FIG. 13 depicting attachment of the gusset plates 170 over the selected mull joints of the depicted compound fenestration assemblies using threaded fasteners 129.

(96) FIG. 15 is a perspective view of the compound fenestration assembly of FIG. 14 depicting placement of one illustrative embodiment of intersection plates 174 on selected mull joint ends of the depicted compound fenestration assemblies. In the set of three compound fenestration assemblies depicted in FIGS. 14 and 15, selection of the mull joint ends over which gusset plates 170 are located as opposed to the mull joint ends over which intersection plates 174 are located may, in one or more embodiments, be selected based on the location of those mull joint ends in the finished compound fenestration assembly.

(97) In particular, the depicted set of three compound fenestration assemblies, each of which includes an upper fenestration unit 102 and a lower fenestration unit 104, are designed to be attached to each other to form a 32 array of fenestration units in the finished compound fenestration assembly. As a result, the outermost mull joint ends covered by gusset plates 170 will not be located adjacent another fenestration unit. As a result, the gusset plates 170 located on the outermost mull joint ends may be, in one or more embodiments, configured for attachment to a framing member of an opening in which the 32 unit compound fenestration assembly is located.

(98) In contrast, the intersection plates 174 may be located over mull joint ends that would be located in an interior mull joint formed between fenestration units in the finished 32 unit compound fenestration assembly. As with gusset plates 170, the intersection plates 174 may also be attached to the base 154 of an end plug 152 having its cavity leg 156 located in an intermediate end plug cavity facing the mull joint and over which the intersection plate 174 is positioned.

(99) A subassembly including one illustrative embodiment of an intersection plate 174 attached to a base 154 of an end plug 152 is seen in an enlarged perspective view in FIG. 16. As with the gusset plates 170, the intersection plate 174 may also be attached to the base 154 using, e.g., threaded fasteners 129 (although other fastening techniques using, e.g., rivets, adhesives, etc. may be used in place of threaded fasteners).

(100) In one or more embodiments, the intersection plates 174 used in interior mull joints such as those depicted in, e.g., FIG. 15, may include ribs 176 or other features that, in one or more embodiments, are designed to mate with recesses or other complementary features found in a joining strip to be located over the intersection plate 174. In particular, the ribs 176 may be sized and positioned to fit within slots formed in the backside of a joining strip such as, e.g., slots 25 in joining strip 20 or slots 35 in joining strip 30 as seen in, e.g., FIGS. 1-4.

(101) In one or more embodiments, the complementary features found on the intersection plate 174 and a joining strip located over the intersection plate 174 as a part of constructing a mull joint as described herein may be used to assist in aligning the joining strip along the side of a compound fenestration assembly. In one or more embodiments, the complementary features found on the intersection plate 174 and the joining strip located over the intersection plate as a part of constructing a mull joint as described herein may be used to transfer mechanical loads (e.g., wind loads, etc.) between a set of vertical mull joints and a set of horizontal mull joints such as would be found in a 32 unit compound fenestration assembly manufactured using the set of three compound fenestration unit assemblies seen in, e.g., FIG. 15. In particular, intersection plates used in mull joints in compound fenestration unit assemblies as described herein, such as, e.g., intersection plates 174, may be useful in transferring loads between a pair of horizontal and vertical mull joints that meet at the intersection of a pair of mull joint assemblies that are connected together as depicted in, e.g., FIG. 17.

(102) In one or more embodiments, the intersection plates 174 may include apertures 175 to provide for passage of fasteners driven through locator plates used to assist in locating a joining strip over the intersection plate 174 in a compound fenestration assembly as described herein.

(103) FIG. 17 is a perspective view of the compound fenestration assembly of FIG. 16 in which the interior mull joints along which intersection plates 174 are located are in the process of being measured for attachment of joining strips 220 and 230 as depicted in, e.g., FIG. 18. Measurement of the mull joints as depicted in FIG. 17 provides an installer/assembler with the information needed to properly size the joining strips such that recesses with the proper depth can be formed at each end of the mull joints to receive the base of an end plug (see, e.g., the view of FIG. 12 and its associated description). The joining strips 220 and 230 are depicted in FIG. 18 along with associated locator plates 240 that may be used to assist in locating the joining strips 220 and 230 properly along the interior mull joints of a compound fenestration assembly as described herein.

(104) FIG. 19 is a perspective view of the joining strips 220 and 230 and associated locator plates 240 in position for attachment to the interior mull joints of the compound fenestration assemblies depicted in FIG. 18, while FIG. 20 is a perspective view depicting attachment of the joining strips 220 and 230 and associated locator plates 240 to the compound fenestration assemblies depicted in FIGS. 18-19 (over locator plates 174.

(105) With the joining strips 220 and 230 attached to the 12 unit compound fenestration assemblies, FIG. 21 depicts joining of the 12 unit compound fenestration assemblies to form a 32 unit compound fenestration assembly as described herein. As discussed herein in connection with other mull joints, the joining strips 220 and 230 have corresponding channels facing in opposite directions which form a mechanically interlocking connection in the interior mull joints between the 12 unit compound fenestration assemblies of the larger 32 unit compound fenestration assembly.

(106) With the larger 32 unit compound fenestration assembly arranged as seen in, e.g., FIG. 22, end plugs 152 may be positioned in the mull joint ends at the top and bottoms of the interior vertical mull joints formed between the adjacent 12 unit compound fenestration assemblies including an upper fenestration unit 102 and a lower fenestration unit 104.

(107) FIG. 23 is a perspective view of one illustrative embodiment of a compound fenestration assembly depicting placement and attachment of one illustrative embodiment of gusset plates on selected ends of mull joints as described herein.

(108) FIG. 23 is a perspective view of the compound fenestration assembly of FIG. 10 after insertion of end plugs 152 in the interior mull joints formed between the 12 unit compound fenestration assemblies depicting placement of one illustrative embodiment of a gusset plate 180 over the interior mull joint ends. In one or more embodiments, each of the gusset plates 180 may be attached to the base 154 of the end plug 152 over which the gusset plates 180 are located. In one or more embodiments, the gusset plates 180 may be attached to the bases 154 of the end plugs 152 using threaded fasteners or other fastening components inserted into the apertures 158 in the illustrative embodiment of end plug 152 as depicted in, e.g., FIG. 11. In one or more embodiments, the gusset plates 180 may be described as spanning the ends of the interior mull joints on which they are located such that the base 154 of an end plug 152 is located between the ends of the joining strips 220 and 230 of each interior mull joint and the gusset plate 180 (i.e., in the recess 153 located between frame members on each side of the mull joint as seen in, e.g., FIG. 12). Furthermore, in one or more embodiments the gusset plates 180 may be directly attached to the fenestration units 104 on opposite sides of the interior mull joints over which the gusset plates 180 are positioned. As used herein, directly attached means that the gusset plates 180 may be secured to the frame members of the fenestration units 104 using, e.g., one or more threaded fasteners, rivets, adhesives, etc.

(109) The gusset plates 180 depicted as being positioned over interior mull joints in, e.g., FIG. 23, may include a base 182 and a flange 184. The base 182 may be configured for attachment to the frame members of the fenestration units 102 or 104 on opposite sides of the mull joints, while the flanges 184 may be configured for attachment to e.g., a framing member defining an opening in which the compound fenestration assembly is located.

(110) FIG. 24 is a perspective view of the compound fenestration assembly of FIG. 23 depicting one illustrative embodiment of placement of end seal members 190 in the recesses formed in the selected mull joint ends (see, e.g., FIG. 12 for a depiction of the recess 153 formed at the ends of mull joints in compound fenestration assemblies as described herein). The end seal members 190 may be used to assist in sealing the ends of the mull joints to limit the penetration of air and/or water into the mull joints at the ends thereof.

(111) FIG. 25 is an enlarged perspective view of one illustrative embodiment of an end seal member 190 attached to a base 154 of an end plug 152 having a cavity leg 156. In one or more embodiments, the end seal member 190 may include features designed to attach the end seal member 190 to the base 154 although such an arrangement may not be required in all embodiments. Reference to the end seal member 190 as depicted in FIG. 12 in addition to FIG. 25 may assist the reader in understanding the features, functions, and arrangement of one or more embodiments of end seal members in mull joints as described herein.

(112) In one or more embodiments, the end seal member 190 may include a sealant port 192 which opens away from the base 154 of the end plug 152. In one or more embodiments, the end seal member 190 may be located on an exterior side of the compound fenestration assembly such that the sealant port 192 opens in the same direction as the exterior side of the compound fenestration assembly. The sealant port 192 is, in one or more embodiments, in fluid communication with a sealant reservoir 193 positioned between the frame members 110 and 112 located on each side of the recess 153 in which the end seal member 190 is positioned. The sealant reservoir 193 is defined by walls 194 on each side of the sealant reservoir 193. A sealant dam 195 may, in one or more embodiments, be provided on the exterior of the reservoir wall 194 such that sealant escaping from the reservoir 193 flows over the exterior of the reservoir wall 194 (between a frame member and the reservoir wall 194) until it reaches the sealant dam 195, at which point the sealant flows along the exterior wall 194 towards the sealant port 192. As the sealant reservoir 193 and the channel formed between exterior wall 194 and sealant dam 195 fills with sealant, the sealant escapes through opening 196 alongside reservoir wall 194 in the direction of sealant port 192. As a result, the person delivering sealant through sealant port 192 can observe when the sealant has filled the reservoir 193 and formed a seal between end seal member 190, the opposing frame members between which the end seal member 190 is located, and the ends of the joining strips.

(113) In one or more alternative embodiments, the end seal member may be optional where, for example, a gusset plate or other cover may be placed over the end of a mull joint to allow for the injection of sealant into the recess 153 formed between frame members 110 and 112 of a mull joint in a compound fenestration assembly as described herein.

(114) FIG. 26 is a perspective view of one illustrative embodiment of delivery of sealant into the end seal members 190 after they have been inserted into the mull joint ends in the compound fenestration assembly depicted in FIG. 25.

(115) FIGS. 27 and 28 depict installation of one illustrative embodiment of trim strips 160 in mull joints of compound fenestration assemblies as described herein. Reference to, e.g., FIG. 2B may assist the reader in understanding assembly of the trim strips 60/160 into trim slots 31 and/or 21 located at opposite ends of the mull joints in compound fenestration assemblies as described herein. As described in connection with FIG. 2B, the trim slots in one or more embodiments of the mull joints may be sized and positioned to receive and retain a fin extending from a body of each trim strip 160 such that the trim strip 160 is retained in position on one side of the mull joint.

(116) Although gusset plates having both a base and a flange (e.g., illustrative embodiments of gusset plates 170 and 180 as depicted in, e.g., FIGS. 13-15 and 23) can be used to secure a compound fenestration assembly as described herein within a rough opening in a manner that transfers mechanical loads (such as, e.g., wind loads, etc.) from the compound fenestration assembly to the framing members defining the rough opening, the base and flange construction of such gusset plates can be used primarily in new construction where access to the framing members is available.

(117) FIGS. 29-35 depict illustrative embodiments of bracket plates and end plugs that can be used in connection with the joining strips of mull joints as described herein to secure a compound fenestration assembly in an existing opening in which access to vertical surfaces of the frame members defining a rough opening is not easily available.

(118) One illustrative embodiment of a bracket plate 384 is depicted in FIGS. 29-32 along with an alternative embodiment of a bracket plug 352 configured for use with the bracket plate 384 to secure a compound fenestration assembly as described herein within an opening. The bracket plate 384 includes a base 385 that is configured for attachment to only an interior surface of an opening in which a compound fenestration assembly as described herein may be located using fastener openings 386. The bracket plug 352 includes a base 354 and a cavity leg 356 that is configured to be positioned in an intermediate end plug cavity formed between a pair of joining strips used to construct a mull joint in a compound fenestration assembly as described herein. In addition, the base 354 of the bracket plug 352 includes a base fastener bore aligned with an interior/exterior axis 301. A threaded fastener 389 is depicted in the base fastener bore in the base 354 in FIG. 29 (although a threaded fastener 389 is depicted, other structures such as, e.g., pins, rods, etc. could be used in place of a threaded fastener).

(119) The bracket plate 384 includes a fastener block 387 attached to the base 385. In one or more embodiments, the fastener block 387 is sized and configured to be located between frame members at an end of a mull joint in a manner similar to the end plug bases and end seal members as described herein. The fastener block 387 includes a block fastener bore aligned with the base fastener bore formed in the base 354 such that threaded fastener 389 can be inserted through the base fastener bore in the base 354 and connect into the block fastener bore in the fastener block 387 to secure the bracket plug 352 to the fastener block 387 which, in turn, is attached to the base 385 of the bracket plate 384.

(120) The base 385 and attached fastener block 387 of bracket plate 384 are depicted without the bracket plug 352 in FIG. 30. As seen in that figure, the threaded fastener 389 is aligned along interior/exterior axis 301. Furthermore, another optional feature depicted in connection with this illustrative embodiment of bracket plate 384 are slots 388 used to attach fastener block 387 to the base 385. In one or more embodiments, the slots 388 and corresponding features on the fastener block 387 are configured to allow the fastener block 387 to move relative to the base 385 of the bracket plate 384. Movement of the fastener block 387 relative to the base 385 may assist in connection of the bracket plug 352 to the fastener block 387 and, therefore, to the bracket plate 384 in situations where some variation in spacing and placement of the mull joint relative to the base 385 of the bracket plate 384 occur.

(121) Although movement of the fastener block 387 along the plane defined by the base 385 of the bracket plate 384 is allowed, the fastener block 387 is attached to base 385 in a manner that prevents lifting of the fastener block 387 away from the base 385 and, furthermore, substantially limits movement of the fastener block 387 along the interior/exterior axis 301. As a result, the bracket plate 384 can, along with bracket plug 352 and fastener 389, be used to transfer mechanical loads from a compound fenestration assembly to the bracket plate 384 and into the framing members to which the base 385 of the bracket plate 384 is attached.

(122) FIG. 31 is an enlarged perspective view of the bracket plug 352 of FIG. 29 positioned in an intermediate end plug cavity 350 formed between one illustrative embodiment of a pair of joining strips 320 and 330 that may be used in a mull joint of a compound fenestration assembly as described herein. The bracket plug 352 includes, as described herein, a base 354 and cavity leg 356, with the cavity leg 356 being configured for insertion into the intermediate end plug cavity 350. The base fastener bore 351 in the base 354 of the bracket plug 352 is also seen in this view, with the base fastener bore 351 aligned with the interior/exterior axis 301 as described herein.

(123) As described herein, the cavity leg 356 may, when inserted into the intermediate end plug cavity 350, prevent disengagement of the mechanically interlocking channels on the joining strips 320 and 330 at that end of the mull joint formed by the joining strips 320 and 330. In essence, insertion of the cavity leg 356 into the intermediate end plug cavity 350 locks the joining strips 320 and 330 relative to each other such that the channels cannot be backed out of engagement with each other.

(124) FIG. 32 is a perspective view of the bracket plate 384 slightly removed from a mull joint end in one illustrative embodiment of a compound fenestration assembly as described herein. The compound fenestration assembly includes a mull joint formed by joining strips 320 and 330 located between frame members 310 and 312. As described herein, the joining strips 320 and 330 do not extend to the ends of the frame members 310 and 312. Rather, a recess 353 is formed in the end of the mull joint. As described herein in connection with other and the plugs, that recess 353 is used to contain the base 354 of bracket plug 352 along with the fastener block 387 attached to base 385 of the bracket plate 384. Although the bracket plate 384 and bracket plug 352 are shown as being slightly removed from the fenestration units forming the compound fenestration assembly, movement of the components towards the fenestration units can be easily envisioned in FIG. 32 as the cavity leg 356 is advanced into an intermediate end plug cavity formed between joining strips 320 and 330.

(125) Furthermore, positioning of the cavity leg 356 in the intermediate end plug cavity formed between joining strips 320 and 330 can be adjusted (e.g., inwardly or outwardly) to compensate for variations in the distance between a rough opening and the fenestration units making up the compound fenestration assemblies described herein.

(126) The bracket plug 352 depicted in connection with bracket plate 385 can be used to secure a compound fenestration assembly in an opening when the fenestration units being joined along a mull joint are already connected to each other before placement in the rough opening. FIGS. 33-35 depict one alternative embodiment of a composite bracket plug assembly that can be used to secure a mull joint in a compound fenestration assembly to a bracket plate in a rough opening when the mull joint is also being assembled in the rough opening, in other words, when the fenestration units connected by the mull joint are not connected to each other before placement in the rough opening.

(127) In one or more embodiments, such a composite bracket plug assembly may include a pair of composite bracket plugs as seen in, e.g., FIG. 33. In particular, the composite bracket plug assembly includes a first composite bracket plug 452a and a second composite bracket plug 452b. Each of the composite bracket plugs 452a and 452b are, in one or more embodiments, configured to be located within cavities formed by the joining strips 420 and 430 with their respective frame members. With reference to, e.g., FIGS. 2A and 2B, each of the composite bracket plugs 452a and 452b is configured for insertion into the cavities 51 located between joining strip 20 and its frame member 10 and joining strip 30 and its frame member 12.

(128) In particular, composite bracket plug 452a includes a cavity leg 456a that is configured to be inserted into a cavity formed between joining strip 420 and its attached frame member, while composite bracket plug 452b includes a cavity leg 456b configured to be inserted into a cavity formed between joining strip 430 and its attached frame member. In one or more embodiments in which the joining strips include slots such as, e.g., slots 435 as seen in, e.g., FIG. 33, the cavity leg 456b may include ribs 457 configured to fit within slots 435 to assist in accurate placement and retention of the composite bracket plug 452b. A similar arrangement may be used in connection with joining strip 420 and composite bracket plug 452a which includes a cavity leg 456a having ribs 457 configured to fit within a complementary set of slots in the joining strip 420 (see, e.g., slots 25 in joining strip 20 in FIG. 2A).

(129) Each of the composite bracket plugs depicted in FIGS. 33-34 includes a base having a fastener bore. In one or more embodiments, the fastener bores in the bases can be aligned with an interior/exterior axis that, in a manner similar to interior/exterior axis 301 described above, extends between the interior and exterior sides of fenestration units and/or a composite fenestration assembly as described herein. The fastener bores in the bases 454a and 454b are shown in alignment in FIG. 34 such that threaded fastener 489 can be inserted through the fastener bores in the bases 454a and 454b along interior/exterior axis 401. In one or more embodiments, the composite bracket plugs 452a and 452b can be described as a single end plug 452 when their bases and fastener bores are aligned as seen in, e.g., FIG. 34.

(130) FIG. 35 is a perspective view of a bracket plate and the compound end plug assembly of FIGS. 33-34 partially inserted into the end of a mull joint of one illustrative embodiment of a compound fenestration assembly as described herein. In particular, the compound fenestration assembly includes a mull joint formed by joining strips 420 and 430 located between frame members 410 and 412 of a pair of fenestration units. The legs 456a and 456b of the composite bracket plug 452 are shown partially inserted into cavities formed between each of the joining strips 420 and 430 and their respective frame members 410 and 412. A threaded fastener 489 is shown inserted through the base fastener bores of the composite bracket plug 452. Also seen in FIG. 35 is the base 485 of a bracket plate 484 with a fastener block 487 attached to the base 485. As discussed herein, the base 485 can be attached on a framing member of an opening in which the fenestration units are to be located and connected before the fenestration units are located in that opening. Positioning the fenestration units such that the joining strips 420 and 430 on opposing frame members 410 and 412 are connected as described herein also positions the two components of the composite bracket plug 452 such that there base fastener bores align to allow insertion of a threaded fastener 489 through those base fastener bores and into a bore formed in the fastener block 487. As a result, the compound fenestration assembly can be attached to a framing member in an opening even in situations in which the fenestration units must be attached to each other within that opening as well.

(131) Although illustrative embodiments of compound fenestration assemblies having gusset plates that span mull joint ends formed between fenestration units are described herein, in one or more embodiments the compound fenestration assemblies described herein may include corner gussets that do not span mull joint ends. One illustrative embodiment of a set of corner gusset assemblies that may be used in connection with the mull joints in compound fenestration assemblies described herein are depicted in FIG. 36-41.

(132) In particular, FIGS. 36 and 37 are perspective views of one embodiment of a compound fenestration assembly depicting placement of illustrative embodiments of a flanged corner gusset assembly including flanged corner gussets that may be attached to the fenestration units of the depicted compound fenestration assembly. In the view of FIG. 36, flanged corner gussets 680 are depicted as being attached to fenestration units 602 and 604. Each of the flanged corner gussets 680 includes a base plate 682 and an attached gusset plate leg 683. The gusset plate leg 683 is positioned between a joining strip (see, e.g., joining strips 620) and a frame member of the fenestration unit to which the flanged corner gusset 680 is being attached.

(133) In one or more embodiments, the gusset plate leg 683 fits within the cavity in which locator plates are positioned between the joining strips and frame members on fenestration units as described herein. The base plate 682 may be attached to a frame member of the fenestration unit meeting the frame member to which the joining strip is attached at the corner over which the flanged corner gusset 680 is positioned proximate an end of the mull joint. In one or more embodiments, that frame member to which base plate 682 is attached will typically, but not necessarily, be a frame member that faces the sill or header of an opening in which compound fenestration assembly is positioned for attachment.

(134) The flanged corner gussets 680 also include a gusset flange 684 extending away from the base plate 682 and away from the fenestration unit 602 or 604 to which the flanged corner gusset 680 is attached. In one or more embodiments, the gusset flange 682 on each of the flanged corner gussets 680 is configured for attachment to an exterior surface of an opening 600 in which the fenestration unit is located. Referring to FIG. 37, the gusset flanges 684 of flanged corner gussets 680 are attached to the exterior surface of opening member 601 which defines the opening 600 in which the compound fenestration assemblies are being installed. The gusset flanges 684 may be attached to the members defining the opening 600 using any suitable fastening technique, e.g., threaded fasteners, nails, rivets, adhesives, etc.

(135) Positioning the gusset plate legs of the corner gussets described herein between the joining strips and frame members on fenestration units as described herein may assist in transferring loads (e.g., wind loads, etc.) from the fenestration units to the corner gusset plate for transfer to the opening in which the fenestration units are located. In one or more embodiments, the gusset plate legs of corner gussets described herein may be located in the same space in between the joining strips and the frame members as the locator plates used to position the joining strips on frame members of fenestration units as described herein. In particular, the gusset plate legs of the corner gussets described herein may include raised features such as, e.g., ribs which are sized and positioned to mate with slots formed in the joining strips (see, e.g., slots 25 in joining strip 20 or slots 35 in joining strip 30 as described herein).

(136) In some instances access to an exterior surface of the opening in which a compound fenestration assembly as described herein is to be installed is difficult or impossible. Illustrative embodiments of a corner gusset assembly that does not include flanges are depicted in FIGS. 38-51. The depicted corner gusset assemblies may be described as stacked corner gusset assemblies because the base plates of each pair of corner gussets are stacked between one of the fenestration units and the opening in which the fenestration units are located as described herein.

(137) FIG. 38 is a perspective view of a pair of fenestration units 702 and 704 positioned next to each other and an exploded assembly view of one illustrative embodiment of a stacked corner gusset assembly including corner gussets 770 and 780, along with a retainer plug 790. These components will be further described in more detail below.

(138) Referring to FIG. 39, the exploded assembly view of the stacked corner gusset assembly of FIG. 38 is enlarged to illustrate more details with respect to one embodiment of a stacked corner gusset assembly as described herein. The stacked corner gusset assembly includes a first corner gusset 770 which is attached to the first fenestration unit 702. In particular, the first corner gusset 770 includes a base plate 772 attached to a gusset plate leg 776. The gusset plate leg 776 is positioned between a first joining strip 720 and the frame member of fenestration unit 702 to which joining strip 720 is attached. The base plate 772 of the first corner gusset 770 extends away from the corner of the fenestration unit 702 proximate the end of the mull joint formed by joining strip 720 and 730. The base plate 772 extends away from the fenestration unit 702 in a direction aligned with the separation axis (i.e., the X axis). The base plate 772 is configured for attachment to an interior surface of an opening in which the fenestration unit 702 is located with this feature being further described herein below.

(139) The stacked corner gusset assembly also includes a second corner gusset 780 which is attached to the second fenestration unit 704. The second corner gusset 780 includes a base plate 782 attached to a gusset plate leg 786. The gusset plate leg 786 is positioned between the joining strip 730 and the frame member to which that joining strip is attached at the end of the mull joint formed by joining strips 720 and 730. The second corner gusset 780 includes a base plate 782 that extends over and is attached to a frame member 713 of the fenestration unit 704 forming a corner with the frame member to which the joining strip 730 is attached. When the fenestration units 702 and 704 are assembled in an opening and form a mull joint as described herein using joining strips 720 and 730, the base plate 782 of corner gusset 780 is stacked with the base plate 772 of corner gusset 770 such that the base plate 782 is located between the base plate 772 and the fenestration unit 704 (e.g., between frame member 713 and base plate 772).

(140) Gusset plate leg 786 of corner gusset 780 may, in one or more embodiments, include raised ribs 787 or other similar features which may mate with slots formed in joining strip 730 in the same manner as locator plates 40 mate with slots 25 in joining strips 20 as depicted in, e.g., FIGS. 3 and 5. Similarly, gusset plate leg 776 of corner gusset 770 may, in one or more embodiments, include raised ribs 777 (only one of which is seen in FIG. 39) or other features which may mate with slots formed in joining strip 720 in the same manner as locator plates 40 mate with slots 25 in joining strips 20 as depicted in, e.g., FIGS. 3 and 5.

(141) With reference to, e.g., FIGS. 40, 41, and 44, another optional feature depicted in connection with this illustrative embodiment of the corner gusset assemblies described herein such as, e.g., a stacked corner gusset assembly, is locking clip 750 which may be attached to corner gusset 780, more particularly, attached to the gusset plate leg 786 of corner gusset 780. Locking clip includes arms 754 and 756. In the depicted embodiment, the locking clip 750 is attached to gusset plate leg 786 using mechanical interference with a flange 752 provided on gusset plate leg 786. Flange 752 cooperates with an opening 753 on locking clip 750 although any suitable technique for attaching locking clip 750 to gusset plate leg 786 may be used (e.g., threaded fasteners, adhesives, rivets, etc.). In one or more embodiments, the locking clip 750 may be located in a recess formed at one end of a mull joint as described herein due to the termination of joining strips 720 and 730 short of the ends of the fenestration unit frame members to which the joining strips are attached as described herein.

(142) Locking clip 750 is provided to assist in retaining fenestration unit 702 in position relative to fenestration unit 704 when both fenestration units are assembled in an opening, but not yet secured therein. To accomplish that function, the arm 754 of locking clip 750 may, in one or more embodiments, mechanically interlock with raised ribs 787 on gusset plate leg 786 while arm 756 mechanically interlocks with one of the raised ribs 777 on gusset plate leg 776 of opposing corner gusset 770 (see, e.g., FIG. 44). In other words, movement of the fenestration units 702 and 704 relative to each other along the Y-axis such that the opposing channels on joining strips 720 and 730 can disengage from each other may be restricted by the mechanical interference of the arms 754/756 of locking clip 750 with the raised ribs 777/787 on gusset plate legs 776/786 of corner gussets 770/780 when assembled in an opening. Further, although depicted in connection with the stacked corner gusset assembly, it should be understood that a locking clip 750 may also be used in connection with unstacked corner gussets at the end of a mull joint, e.g., the corner gussets 680 of the corner gusset assemblies depicted in FIGS. 36 and 37. In either case, the fenestration unit carrying the locking clip on a gusset plate leg would be placed in an opening first, followed by placement of the opposite fenestration unit such that arm 756 would interlock with the gusset plate leg on that fenestration unit.

(143) Another optional feature which may be used in connection with the stacked or unstacked corner gusset assemblies described herein, such as, e.g., the illustrative embodiment of a stacked corner gusset assembly, is a retainer plug 790 as seen in combination with the stacked corner gusset assembly in, e.g., FIGS. 39, 40, and 44. As discussed herein the joining strips used in mull joints as described herein may, in one or more embodiments, terminate at a recessed location between the frame members of the fenestration units to which the joining strips are attached. Because the joining strips terminate at a recessed location, they may form a recess at the end of the mull joint between the frame members to which the joining strips are attached. In one or more embodiments, a retainer plug such as, e.g., illustrative embodiment of a retainer plug 790, may be positioned in that recess between the frame members of the fenestration units joined together by the mull joint.

(144) One illustrative embodiment of a retainer plug that may be used in one or more embodiments of the stacked or unstacked corner gusset assemblies described herein is depicted in more detail in FIGS. 42-43. The retainer plug depicted in those figures may, in one or more embodiments, mechanically interlock with the gusset plate legs of the stacked or unstacked corner gusset assembly to restrict disengagement of the channels on the joining strips forming the mull joint between the attached fenestration units. In the depicted illustrative embodiment, retainer plug 790 includes wings 791 biased outwardly from a center of the retainer plug 790. In one or more embodiments, those wings 791 may act outwardly against the arms 754 and 756 of the locking clip 750 and, therefore, the ribs 787 and 777 on the gusset plate legs 786 and 776 (see, e.g., FIG. 44). Although the illustrative embodiment of retainer plug 790 includes wings 791 biased outwardly away from each other, it will be understood that many other structures could be used in place of wings 791 to assist with the mechanical interlock of the arms 754/756 of locking clip 750 with the gusset plate legs of the corner gusset assemblies described herein.

(145) In one or more embodiments, retainer plugs used in connection with stacked or unstacked corner gusset assemblies as described herein may also include one or more sealant ports in fluid communication with a sealant reservoir positioned between the frame members of the fenestration units attached by a mull joint as described herein. Because the retainer plugs fit within the recess formed between those frame members and the ends of the joining strips used to form the mull joint, the sealant reservoir is also positioned in that same recess.

(146) In the depicted illustrative embodiment, retainer plug 790 includes a sealant reservoir 793 which faces the ends of the first and second joining strips 720 and 730 attached using the stacked or unstacked corner gusset assembly described herein. In particular, the depicted illustrative embodiment of retainer plug 790 includes a sealant port 792 opening towards an exterior side of the fenestration units 702 and 704 in a manner similar to the sealant ports described in connection with other plugs herein (see, e.g., FIGS. 25-26 and the corresponding description). The depicted illustrative embodiment of retainer plug 790 may also include sealant dams 795 on the exterior of the reservoir such that sealant escaping from the reservoir 793 flows over the exterior of the reservoir until it reaches a sealant dam 795 to control sealant flow as discussed above in connection with, e.g., sealant reservoir 193 on end seal member 190.

(147) In addition to exterior sealant port 792, the depicted illustrative embodiment of retainer plug 790 includes an intermediate sealant port 797 positioned between an exterior end of the retainer plug 790 (where the exterior sealant port 792 is located) and the wings 791 inserted into an interior of the recess found at the end of the mull joint. In one or more embodiments, an intermediate sealant port 797 may be described as being aligned with the mull joint axis defined by the joining plates of the mull joint. In other words, the intermediate sealant port may face away from the ends of the joining strips forming the mull joint. In one or more embodiments, both sealant port 792 and 797 may be provided in a retainer plug 790 as depicted in, e.g., this illustrative embodiment of retainer plug. In one or more alternative embodiments, however, a retainer plug configured for use with a stacked or unstacked corner gusset assembly may include only one or the other of the exterior sealant port and an intermediate sealant port.

(148) One alternative illustrative embodiment of a corner gusset assembly that may be used in mull joints as described herein is depicted in FIG. 45. The depicted illustrative embodiment of the corner gusset assembly depicted there includes corner gussets 870 and 880 having both base plates 872 and 882 along with gusset plate legs 876 and 886 as described above in connection with the first illustrative embodiment of a stacked corner gusset assembly that may be used to connect fenestration units 802 and 804 in a similar manner. A retainer plug 890 is also used in connection with the stacked corner gusset assembly and, similar to the illustrative embodiment of retainer plug 790, retainer plug 890 includes a sealant reservoir 893 along with an exterior sealant port 892 and an intermediate sealant port 897. The depicted illustrative embodiment of retainer plug 890 may also include sealant dams 895 to control sealant flow as discussed above in connection with, e.g., sealant reservoir 193 on end seal member 190.

(149) Although depicted in connection with the stacked corner gusset assembly, it should be understood that the depicted illustrative embodiment of retainer plug 890 may also be used in connection with unstacked corner gussets at the end of a mull joint, e.g., the corner gussets 680 of the corner gusset assemblies depicted in FIGS. 36 and 37.

(150) One difference, however, is that the illustrative embodiment of the corner gusset assembly using corner gussets 870 and 880 does not include a locking clip (see, e.g., locking clip 750 in FIGS. 39-41 and 44) to restrict movement of the fenestration units along the Y-axis.

(151) Another difference is that the retainer plug 890 used in connection with corner gussets 870 and 880 includes multiple sets of wings configured to act against features such as ribs found on the gusset plate legs of corner gussets 870 and 880. In particular, the retainer plug 890 includes a first set of wings 891 located closer to the sealant reservoir 893 and a second set of wings 899 located further away from the sealant port 893 of retainer plug 890. The wings 891 may, in one or more embodiments, be configured to act against the raised ribs on gusset plate legs 876 and 886 that are closer to the sealant reservoir 893 of the retainer plug 890, while the wings 899 may be configured to act against the raised ribs on the gusset plate legs 876 and 886 that are farther away from the sealant reservoir of the retainer plug 890.

(152) One illustrative method of installing a pair of fenestration units and forming a mull joint between those fenestration units using a stacked corner gusset assembly as described herein is depicted in connection with FIGS. 48-51. One illustrative embodiment of a fenestration unit 702 having a corner gusset 770 attached thereto is depicted in FIGS. 48 and 49 with the base plate 772 of the corner gusset 770 attached to a framing member 701 forming an opening in which the fenestration unit 702 is attached. In this view, the framing member 701 may be a header running along a top of an opening, however, it should be understood that this method may be utilized on the opposite end of the fenestration unit 702 (i.e., the bottom or sill end).

(153) The base plate 772 extends away from the corner of the fenestration unit 702 while the corner gusset 770 includes a gusset plate leg 776 having ribs 777 located between the fenestration unit 702 and the joining strip 720 attached thereto (see, e.g., FIG. 49). The base plate 772 of corner gusset 770 may be attached to framing member 701 by any suitable fastening technique, e.g., threaded fasteners, nails, rivets, adhesives, etc.

(154) Turning to FIGS. 50 and 51, with fenestration unit 702 secured in the opening defined by framing member 701 the second fenestration unit 704 may be positioned to form a mull joint between the fenestration units 702 and 704 using joining strips as described herein. The second fenestration unit 704 includes a corner gusset having a gusset plate 782 attached to the upper frame member 713 of fenestration unit 704 as discussed in connection with the corner gusset assemblies described herein. As a result, positioning fenestration unit 704 in the opening next to the fenestration unit 702 to form a mull joint therebetween will position the base plate 782 between the base plate 772 of the corner gusset attached to the first fenestration unit 702 such that the base plates are in a stacked arrangement as described herein.

(155) The mulling system components described herein may be constructed of any suitable material or combination of materials e.g., metal, wood, plastic, fiberglass, etc.

(156) The complete disclosure of the patents, patent documents, and publications identified herein are incorporated by reference in their entirety as if each were individually incorporated. To the extent there is a conflict or discrepancy between this document and the disclosure in any such incorporated document, this document will control.

(157) Illustrative embodiments of fenestration mulling systems and methods are discussed herein some possible variations have been described. These and other variations and modifications in the invention will be apparent to those skilled in the art without departing from the scope of the invention, and it should be understood that this invention is not limited to the illustrative embodiments set forth herein. Accordingly, the invention is to be limited only by the claims provided below and equivalents thereof. It should also be understood that this invention also may be suitably practiced in the absence of any element not specifically disclosed as necessary herein.