System and methods for thermal isolation of components used

Abstract

An isolator system for preventing the conduction of thermal energy between the metal components of a wall assembly comprising isolator plates adapted to be placed between the metal components of a wall assembly and made of an insulating material. The isolator plates include at least one opening for receiving a fastener, said opening has an annular shoulder adapted to extend into an opening for receiving said fastener in a metal component of a wall assembly. Also disclosed herein is a thermal isolation washer and a girt for use with polymer panel construction.

Claims

1. A system for reducing the conduction of thermal energy between two metal components of a wall assembly, the two metal components including a wall stud and a fastening member, the system comprising: an isolator plate adapted to be placed between the wall stud and the fastening member, said fastening member having a first side adapted to be placed opposite an outside facing aspect of the wall stud, wherein the isolator plate consists of a thermal insulating material having lower thermal conductivity than a thermal conductivity of the wall stud and the fastening member and is sized to be approximately coextensive with the first side of the fastening member, wherein the isolator plate includes at least one first opening for receiving a fastener, and wherein the isolator plate further includes at least one positioning structure spaced from the first opening and configured to attach the isolator plate to the fastening member.

2. The system of claim 1 further comprising an isolating washer comprising insulating material and adapted to encircle a shaft of the fastener.

3. The system of claim 2, wherein the isolating washer further comprises a layer composed of metal.

4. The system of claim 1, wherein the thermal insulating material comprises a polymeric or ceramic material.

5. The system of claim 1, wherein the at least one positioning structure includes tabs for removably affixing the isolator plate to the fastening member.

6. The system of claim 1, wherein the isolator plate includes an interior air space.

7. The isolator system of claim 1, wherein the isolator plate includes an annular shoulder adapted to extend into a second opening of the fastening member.

8. The isolator system of claim 1, wherein the at least one positioning structure is configured to removably attach the isolator plate to the fastening member.

9. The isolator system of claim 1, wherein the at least one positioning structure is disposed at a perimeter of the isolator plate.

10. A wall assembly comprising: a support structure comprising metal studs, wherein a sheathing is attached to an outside facing aspect of the metal studs; a fastening member comprising metal, the fastening member having a first side adjacent to a side of the sheathing opposite the outside facing aspect of the metal studs; an isolator plate comprising insulating material and located in and configured to be approximately coextensive with a region defined between the first side of the fastening member and the sheathing; a fastener extending through an opening in the support structure, an opening in the fastening member, and an opening in the isolator plate; and wherein the isolator plate includes a positioning structure spaced from the opening in the isolator plate and configured to attach the isolator plate to the fastening member.

11. The wall assembly of claim 10 further comprising an isolating washer comprising insulating material and adapted to encircle a shaft of the fastener.

12. The wall assembly of claim 11, wherein the isolating washer further comprises a layer composed of metal.

13. The wall assembly of claim 10, wherein the insulating material comprises a polymer.

14. The wall assembly of claim 10, wherein the isolator plate includes tabs for removably affixing the isolator plate to the fastening member.

15. The wall assembly of claim 10, wherein the isolator plate includes an interior air space.

16. The wall assembly of claim 10, wherein the isolator plate includes an annular shoulder adapted to extend into the opening in the fastening member.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a cross sectional view of a conventional wall assembly.

(2) FIG. 2 is a perspective view of one embodiment of the isolating plate disclosed herein.

(3) FIG. 3 is a perspective view of one embodiment of the isolating plate disclosed herein mounted on a bracket.

(4) FIG. 4 is a perspective view of one embodiment of the isolating plate disclosed herein mounted on a bracket.

(5) FIG. 5 is a perspective view of one embodiment of the isolating plate disclosed herein.

(6) FIG. 6 is a perspective view of one embodiment of the isolating plate disclosed herein mounted on a bracket.

(7) FIG. 7 is a perspective view of one embodiment of the isolating plate disclosed herein mounted on a bracket.

(8) FIG. 8 is a perspective view of one embodiment of the isolating plate disclosed herein.

(9) FIG. 9 is a perspective view of one embodiment of the isolating plate disclosed herein.

(10) FIG. 10 is a perspective view of one embodiment of the isolating plate disclosed herein.

(11) FIG. 11 is a perspective view of one embodiment of the isolating plate disclosed herein.

(12) FIG. 12 is a perspective view of one embodiment of the isolating washer disclosed herein.

(13) FIG. 13 is a perspective view of one embodiment of the isolating washer disclosed herein.

(14) FIG. 14 is a perspective view of one embodiment of the isolating plate disclosed herein.

(15) FIG. 15 is a perspective view of one embodiment of the isolating plate disclosed herein and a bracket upon which it may be mounted.

(16) FIG. 16 is a perspective view of one embodiment of the isolating plate disclosed herein.

(17) FIG. 17 is a perspective view of a fastener with one embodiment of the isolating washer disclosed herein mounted upon it.

(18) FIG. 18 is a cross sectional view of a girt and a bracket attached thereto with one embodiment of the thermal isolation system disclosed herein used.

(19) FIG. 19 is a cross sectional view of a fastening member and isolating washer and plate.

(20) FIG. 20 is a cross sectional view of a fastening member and isolating washer and plate.

(21) FIG. 21 is a cross sectional view of a wall assembly employing one embodiment of the invention disclosed herein.

(22) FIG. 22 is a cross sectional view of one embodiment of the invention disclosed herein.

(23) FIG. 23 is a perspective view of one embodiment of the invention disclosed herein.

DETAILED DESCRIPTION

(24) As shown in FIG. 1, a wall structure is commonly formed of vertical wall studs 8 that are spaced apart from each other and attached to a wall plate (not shown) at one end and a ceiling plate (not shown) at the other end. The studs form cavities 16 between them, and are commonly formed from steel. They are rigidly interconnected to both the wall plate and the ceiling plate, forming a support structure 14. The support structure 14 has an opposing inside facing aspect 18 and an outside facing aspect 20, corresponding to the building interior facing aspect of the wall and the building exterior facing aspect of the wall. Adjoining walls form corners with various angles, and window openings and door openings are commonly defined.

(25) The elements of the building envelope are attached to the support structure 14. Conventionally, sheathing 22 such as plywood, oriented strand board, or exterior grade gypsum board may be attached to the outside facing aspect 20 of the support structure 14 to form a rigid envelope layer. Insulation 17 such as mineral wool is attached to the structure, as is a weather resistant barrier (not shown). Cladding (not shown) is affixed as the outermost layer of the building envelope.

(26) Alternatively, stiff, insulating polymer foam boards 19 such as DuPont THERMAX boards may be attached directly to the support structure 14 and the sheathing and mineral wool insulation layers may be omitted. An additional weather resistant barrier may be affixed directly to the support structure or to the polymer boards. Cladding is affixed as the outermost layer of the building envelope.

(27) Conventionally, all of the layers of the building envelope must be fastened securely to the support structure 14 in a way that allows them to withstand wind, gravity, and occupant loads as well as moisture and temperature changes. Screws, brackets, and girts made of steel are conventionally used to accomplish this. Gifts are typically horizontal structural members, but they can be used in a vertical orientation as well. They can have a variety of cross sections, including Z shapes. A Z girt 21 is shown in FIG. 1. They can be used as stabilizing elements in the primary structure, and they can support wall cladding or other elements of the building envelope. In order to perform these functions, they need to be securely fastened to the steel studs 8 which make up the support structure 14. Typically they are bolted or screwed to the studs 8. The screws that fasten girts to studs may extend through layers of intervening material, such as sheathing or even insulation. If a girt is fastened directly to a stud, a portion of the surface area of the girt and a portion of the surface area of the stud are in direct contact. If material such as sheathing is placed between the girt and the stud, then the corresponding surface area 29 of the girt 21 and the surface area 31 of the stud 8 are in communication with one another, in that stress felt by the girt is transmitted to the stud via the communicating surface areas. Because they typically support loads exerted against the cladding by gravity and because they are subject to shear forces, negative pressures, and positive pressures, girts typically maximize surface contact with or communication with steel studs so that the stress exerted on the girt is spread over as much surface area as possible, and this communication or contact between relatively large surface areas reduces the load on the bolts or screws connecting the two components together.

(28) A variety of fastening members 32 can be used to fasten elements of a building envelope to a support structure, including girts, brackets, and other structures. Fasteners which are used to attach fastening members to support structures include screws, bolts, and tacks.

(29) The fastening members 32 must support the cladding and resist loads without compacting, crushing, or deforming the insulation 17 which may be placed between the fastening member 32 and the stud 8. Mineral wool insulation is especially vulnerable to crushing, and its surface cannot be used to support the load exerted by the cladding and associated structures. For that reason, when mineral wool insulation is used in a wall, fastening members used to support cladding must do so in a way that does not transfer any of the load from the cladding on to the insulation. The fastening members must support the weight of the cladding and all environmental loads on the cladding, and must transfer force to the studs 8 rather than mineral wool insulation. The cladding may be separated from the studs by several inches of insulation, and so the force exerted by that cladding and borne by the brackets or girts is increased by the lever effect.

(30) The structure conventionally used to accomplish these tasks is shown in FIG. 1. Metal studs 8 form the support structure 14 of the wall. Sheathing 22 such as gypsum board or a similar structure is placed in contact with the studs 8. A fastening member 32 such as a Z girt 21 is held in place proximal to the gypsum board by a bolt or screw 23 which extends through the Z girt and the gypsum board and attaches to the metal stud 8. Cladding is attached to the distal end of the Z girt 24. The cladding creates a gap 26 of several inches in which insulation 17 may reside. The Z girt 21 in combination with the metal screw or bolt 23 forms a thermal bridge which extends through the insulation 16 from the stud 8 to the exterior of the building 28.

(31) This thermal bridge reduces the R value of the wall construct. The conventional approach to this problem is to use a thicker layer of insulation. However, the inventor has discovered that thicker insulation does not resolve the problem of heat loss through thermal bridging. Instead, the inventor has discovered that the use of thermal isolators can have an unexpected beneficial impact on heat loss due to fastener thermal bridges, and does not adversely impact the integrity of the fastener systems.

(32) Disclosed herein is a system and method for interruption of thermal bridges formed by fastening systems which does not compromise the function or structural integrity of those fastening systems.

(33) Thermal isolation system components are made from ceramics or polymers. Suitable polymeric materials include nylon, polyamide, polyester, PVC, polyoxymethylene, or the like, or blends thereof. Preferably they are highly crystalline or highly cross-linked thermoplastic materials, but thermoset materials can also be used. Preferably, the thermal isolator system components are molded, but they could be machined or even extruded.

(34) As shown in FIGS. 2-16, the thermal isolator system comprises a plate 30 suitable for attachment to a metal fastening member 32 such as a bracket or girt. The plate 30 has a size and shape suitable to be approximately coextensive with that portion of the surface of a fastening component 32 which is in contact or communication with a portion of the support structure or additional fastening member. The plate may cover an entire face of a fastening member but may not extend significantly beyond the face of that fastening member. The thermal isolation plate 30 fits between metal components, as shown for example in FIG. 18, in order to reduce or eliminate metal to metal contact. Heat transfer between metal components via conduction is minimized because contact is minimized or prevented by the insulating properties of the isolation plate.

(35) The plate has a body which may have a variety of cross sections and shapes, as shown in FIGS. 2-16. It may be substantially flat. Alternatively, it may define an interior air space 34 for additional insulation value, as shown for example in FIGS. 5-7 and 9-11. The air space 34 is defined by peripheral walls 36. Reinforcing members 38 within the peripheral walls impart strength and rigidity to the structure. One of ordinary skill in the art will appreciate that the reinforcing members can be present in a variety of different configurations. The reinforcing members should define apertures 40 as discussed below.

(36) The plate includes optional positioning structures such as tabs 42 or hooks 44 which may correspond to the edges of a fastening member such as a bracket or girt, as shown, for example, in FIGS. 2-4, or to notches 46 in the bracket or girt, as shown in FIG. 15. Tabs 42 or other such protrusions insert into notches 46 or grooves in brackets or girts. Hooks 44 on one or more sides of the plate correspond to the edges of a bracket or girt and embrace those edges. Alternatively, a bracket or girt could be wedged between two or more protrusions on the edges of a thermal isolation plate. The positioning structures permit the thermal isolation plate to be removably attached to a bracket or girt during construction. The positioning structures hold the thermal isolation plate in position as the wall assembly is constructed. Alternatively or additionally, brackets or girts can be sold with isolation plates already attached, either through tabs or hooks or through means such as adhesive.

(37) Where the girt or bracket contains one or more openings 50 for receiving a fastener such as a bolt or screw, the thermal isolator plate has a corresponding aperture 40. The plate aperture 40 may have an annular protrusion 48 which extends through the opening 50 in the girt or bracket. The annular protrusion 48 has an internal diameter which is sized to receive a screw or bolt, and the annular protrusion prevents the screw or bolt from contacting the interior surface 52 of the opening in the bracket or girt.

(38) The thermal isolator system also can include a washer 54 also made of a ceramic or a polymer. The thermal isolator washer 54 can be attached to a metal washer 56. It must be sized so as to have an outer diameter larger than the head of the screw or bolt 23, and must have an inner diameter that fits around the shaft of the bolt or screw 23. A thermal isolator washer may have a shoulder 58 which fits into an opening in a plate or girt that accommodates a screw or bolt 23, as shown for example in FIG. 20.

(39) As shown in FIG. 21, a screw or bolt 23 extends through the base 60 of a girt 62 and into a stud 8. A thermal isolating washer 54 separates the bolt 23 from the girt 62 so that there is no unbroken metal to metal thermal bridge between the stud 8 and the bracket. At the distal end of the girt 64, a bracket 66, which may be used to attach cladding to the structure, is attached with an additional fastener 22. A thermal isolation plate 30 with an annular protrusion 48 which fits within the opening 40 in the brackets separates the two metal fastening members 62 and 66 and prevents the screw from contacting the inner surface of the openings in the two brackets. A thermal isolating washer 54 prevents the metal head of the screw from contacting the metal bracket 66. In this way, there is no thermal bridge between the stud and the outside of the building 28.

(40) Acting in concert, wherever two metal components are fastened to one another, one or more thermal isolator washers and plates can be used to prevent metal components from contacting one another, and to prevent contact between the bolt head and a metal component, thus preventing the creation of thermal bridges. Additional washers or plates can optionally be used, for example between a nut and a plate. These thermal isolator system components can be used whenever metal systems are fastened together in building construction. Because these thermal isolation system components are specifically placed within the construction, they have a surprisingly positive effect on the R value of a wall, but do not add significantly to the cost or labor intensivity of construction. They also do not negatively affect the function of the fastener systems, gifts, or brackets used in construction.

(41) Conventionally, Z girts are used to attach insulation to building envelopes. Z girts are fastened to the studs, perhaps through sheathing. Strips of insulation are installed between the Z girts so that the Z girts boarder the insulation strips. In this way, Z girts offer continuous support to the edges of a panel of insulation, and insulation such as mineral wool requires that level of support in order to avoid being deformed by its own weight or the weight of adjacent components such as cladding. Dow has recently invented and THERMAX foam boards, which are strong enough to eliminate the need for a separate sheathing requirement. Builders have been using conventional building techniques such as Z girts to attach THERMAX boards directly to support structures. However, this building method has a tremendous disadvantage, in that it creates substantial thermal bridges between the studs and the outside of the building. The Z girts directly contact the studs via fasteners, and extend through the insulation layer. This structure causes a loss of up to 50% of the R-value of the wall.

(42) The inventor has developed a new girt apparatus and building method which take advantage of the structural properties and material characteristics of foam wall boards such as THERMAX to create a wall construct with no thermal bridges.

(43) A CI girt 68 preferably has a box shape, having a square or rectangular cross section which creates a rigid structural element, as shown in FIGS. 22 and 23. It can have three or four sides, and one side may be broken. The girt has openings 70 in the external facing side 72 large enough to accommodate the heads of fasteners, so that the entire fastener can be inserted through the opening 70 in the external facing side 72. The internal facing side 74 has corresponding openings 76 which may be threaded.

(44) In accordance with the inventive method, insulation panels 18 such as foam wall boards are held against the structural support 14 in a known manner. CI girts 68 are placed against the outward facing side of the insulation panels 18 and aligned with the studs 8 in the support structure. Screws or bolts which carry thermal isolating washers 54 are inserted through the openings 70 in the external facing side of the CI girt 68, and are passed through the insulation panel 18 and into the steel stud 8.

(45) The insulation panels abut one another, and can be sealed in a conventional manner. The CI girt is fastened outside of the insulation panels. The insulation panels separate the CI girts from the studs. The only metal component which breaks the insulation layer is the fastener used to fasten the CI girt to the studs. A thermal isolation washer is used to interrupt thermal bridging otherwise caused by that fastener. In this way, foam wall boards are used in a way that provides truly continuous insulation. Additionally, the CI girt's rigid shape transfers wind and gravity load evenly to the surface area of the insulation, which makes it possible to add heavier cladding.

(46) In contrast, conventional insulation panels are placed between Z girts so that no insulation separates the Z girts from the studs and Z girts border the insulation panels, and substantial thermal bridges are created.

(47) A fastening system for the attachment of cladding 76 can then be affixed to the CI girts using fasteners which do not extend through the insulation panels, which permits the CI girts to both attach the insulation panels to the studs and to attach the cladding to the building envelope.

(48) A moisture proof membrane or other envelope materials can be placed between the CI girts and the insulation panels, or between the insulation panels and the studs.

(49) Thermal modeling and analysis of wall assemblies demonstrates that the use of the inventive CI girts and thermal isolation system provides a significant and unexpected benefit in R value.

(50) Morrison Hershfield, an independent third party, conducted a thermal analysis to determine the effective R values of wall assemblies which employed Z girts to attach THERMAX wall boards to metal studs and wall assemblies which employed the inventive CI girts and thermal isolator washers to attach wall board to metal studs in a way that avoided the creation of thermal bridges.

(51) Cases G through F were modeled. Cases G and H employed conventional girts and no thermal isolators, and cases I though J employed CI girts with thermal isolators.

(52) TABLE-US-00001 TABLE 3 Assembly U-Values and Effective R-Values for modeled cases with no interior insulation Exterior Exterior Insulation Assembly Insulation Nominal Nominal Assembly Assembly Thickness R-Value R-Value U-Value Effective R Case (In) (hr .Math. ft.sup.2 .Math. F./BTU) (hr .Math. ft.sup.2 .Math. F./BTU) (hr .Math. ft.sup.2 .Math. F./BTU) (hr .Math. ft.sup.2 .Math. F./BTU) % Effective G 1.55 10.1 13.3 0.118 8.4 63% Vertical Girts (Girts spaced horizontally 16o.c., no interior sprayfoam) H 1.55 10.1 13.3 0.105 9.5 71% Horizontal Girts (Girts spaced vertically 24o.c., no interior sprayfoam) I 1.55 10.1 12.8 0.080 12.5 98% CI System (Fasteners vertically spaced 16o.c., no sprayfoam) J 3.00 19.0 21.7 0.048 20.7 95% CI System (Fasteners vertically spaced 16o.c., no sprayfoam)

(53) The results establish that the inventive systems for minimizing thermal bridges work extremely well. In cases H and G, the thermal bridging created by the conventional use of girts cost the insulation 29% and 37% of its effectiveness. In contrast, when CI girts and thermal isolators were used, the invention maintained 95% and 98% of its effectiveness. Cases I and J had effective R values which were very close to their nominal R values. Case I actually had a lower nominal R value than cases G or H. The conventional thinking in this field would expect that Case I would have a lower effective R value, however, due to the use of an embodiment of the invention disclosed and claimed herein, it had a significantly higher effective R value.