EXTERIOR WALLS WITH STUCCO OR OTHER EXTERIOR WALL FINISHES APPLIED TO LIGHTWEIGHT COMPOSITE PANELS

Abstract

Exterior wall structures include exterior walls and lightweight composite panels to which an exterior finish is applied. Exterior wall structures may include wooden or metal studs to which sheathing (e.g., OSB panels or composite sheathing panels) are fastened. A drainage layer can be positioned between sheathing and lightweight composite panels to which an exterior finish is applied. Lightweight composite panels are fastened to sheathing and/or studs by screws, nails, rivets, other mechanical fasteners, and/or adhesive. Lightweight composite panels can include a polymer foam core with interior and exterior surfaces and fiber mesh reinforced cementitious layers formed over and covering the foam core surfaces. Joints between adjacent lightweight composite panels can be sealed using sealing tape, mesh tape and a seam coat, polyurethane foam, and/or other sealants. The exterior wall structure is waterproof, fire-resistant, and facilitates application of different finishes, such as stucco, tiles, or stone, masonry, or brick veneers.

Claims

1. A method of constructing an exterior wall finish, comprising: forming or providing an exterior wall structure of a building or enclosure; fastening a plurality of lightweight composite panels to an exterior side of the exterior wall structure, the lightweight composite panels each comprising: a foam core having a first surface and a second surface opposite the first surface; a first protective layer selected from a first fiber reinforced cementitious layer, thermoset polymer layer, or magnesium oxide layer formed over and covering at least a portion of the first surface of the foam core; and a second protective layer selected from a second fiber reinforced cementitious layer, thermoset polymer layer, or magnesium oxide layer formed over and covering at least a portion of the second surface of the foam core, wherein the lightweight composite panels are positioned so that one protective layer faces toward and another protective layer faces away from the exterior wall structure of the building or enclosure; and applying an exterior finish to the lightweight composite panels.

2. The method of claim 1, wherein the exterior wall structure comprises at least one of wooden studs or metal studs and sheathing fastened to the wooden studs or metal studs.

3. The method of claim 2, wherein the sheathing comprises the plurality of lightweight composite panels to which the exterior finish is applied.

4. The method of claim 2, wherein the sheathing comprises a plurality of oriented strand boards and/or an underlying layer of lightweight composite panels different than the plurality of lightweight composite panels to which the exterior finish is applied.

5. The method of claim 5, further comprising at least one of a waterproofing membrane or a drainage layer positioned between the sheathing and the plurality of lightweight composite panels to which the exterior finish is applied.

6. The method of claim 1, further comprising applying a seam coat over exposed fasteners and joints or seams between adjacent lightweight composite panels to which the exterior finish is applied, and wherein the exterior finish is applied over the seam coat.

7. The method of claim 1, wherein the plurality of lightweight composite panels to which the exterior finish is applied are fastened to studs or sheathing of the exterior wall structure by a plurality of screws, other mechanical fasteners, and/or an adhesive.

8. The method of claim 7, wherein the screws or other mechanical fasteners include corresponding washers, enlarged heads, pan head screws, or screws with integrated washers that are at least about 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 m, 65 cm, 70 cm, 75 mm, or 80 mm, in diameter to prevent penetration of and damage to an exterior protective layer of the lightweight composite panels.

9. The method of claim 8, wherein the washers further include a plurality of penetrating prongs configured to penetrate at least partially through the corresponding lightweight composite panel, including through the exterior protective layer and at least partially through the foam core, such as where the penetrating prongs penetrate all the way through the lightweight composite panel and make abutment with studs or sheathing of the exterior wall structure.

10. The method of claim 1, wherein the exterior finish comprises a stucco finish.

11. The method of claim 1, wherein the exterior finish comprises brick veneers, stone and masonry, or tiles.

12. The method of claim 1, wherein the foam core comprises a polymer selected from the group consisting of extruded polystyrene (XPS), expanded polystyrene (EPS), polyisocyanurate, polyurethane (PUR), phenolic polymers (e.g., phenol-formaldehyde), melamine polymers (e.g., melamine-formaldehyde), and other thermoplastic and thermoset polymers that can be formed into a rigid or semi-rigid polymer foam structure.

13. The method of claim 1, wherein the foam core comprises an inorganic foam material selected from the group consisting of silica gel, aerogel, silicate foams, urea-silicate foams, SiOC/SiC, ceramic foams, and refractory foams.

14. The method of claim 1, wherein at least one of the first or second fiber reinforced cementitious layers is included and comprises fiber reinforcement embedded within a hardened cementitious composition.

15. The method of claim 14, wherein the fiber reinforcement is selected from fiber mesh, alkali-resistant fiberglass mesh, embedded fibers, fabric, woven, scrim, felt, and non-woven, wherein the fiber reinforcement comprise at least one of plant fibers, polymer fibers, and inorganic fibers, which are selected from fibers or filaments formed from glass, basalt, rock wool, or carbon.

16. The method of claim 14, wherein the at least one of the first or second fiber reinforced cementitious layers has a cross-sectional thickness in a range of about 0.5 mm to about 3 mm, or about 0.75 mm to about 2.5 mm, or about 1 mm to about 2 mm, or about 1.25 mm to about 1.75 mm.

17. The method of claim 1, wherein at least one of the first or second thermoset polymer layers is included and comprises polyurea or polyaspartic and is optionally fiber-reinforced.

18. The method of claim 17, wherein the at least one of the first or second thermoset polymer layers has a cross-sectional thickness in a range of about 1 mm to about 5 mm, or about 2 mm to about 4 mm.

19. An exterior wall finish of a building or enclosure constructed according to the method of claim 1.

20. An exterior wall finish, comprising: an exterior wall structure of a building or enclosure; a plurality of lightweight composite panels fastened to an exterior side of the exterior wall structure, wherein the lightweight composite panels each comprise: a foam core having a first surface and a second surface opposite the first surface; a first protective layer selected from a first fiber reinforced cementitious layer, thermoset polymer layer, or magnesium oxide layer formed over and covering at least a portion of the first surface of the foam core; and a second protective layer selected from a second fiber reinforced cementitious layer, thermoset polymer layer, or magnesium oxide layer formed over and covering at least a portion of the second surface of the foam core, wherein the lightweight composite panels are positioned so that one protective layer faces toward and another protective layer faces away from the exterior wall structure of the building or enclosure; and an exterior finish applied to the lightweight composite applies.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Various objects, features, characteristics, and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings and the appended claims, all of which form a part of this specification. In the Drawings, like reference numerals may be utilized to designate corresponding or similar parts in the various Figures, and the various elements depicted are not necessarily drawn to scale, wherein:

[0024] FIG. 1A illustrates a framed house with exposed studs forming exterior wall frames prior to attachment of OSB panels;

[0025] FIG. 1B illustrates a framed house with OSB panels attached to the exterior wall frames of the framed house;

[0026] FIG. 1C illustrates a framed house to which a waterproof polymer membrane has been applied over the OSB exterior sheathing;

[0027] FIG. 1D illustrates a building to which a stucco finish is being applied with the assistance of scaffolding;

[0028] FIG. 2A illustrates a modified OSB panel that includes an OSB layer, a water-resistive barrier (WRB) layer on an outer surface, and optionally an insulating layer on an inner surface;

[0029] FIG. 2B illustrates a wall frame to which modified OSB panels have been attached, with joints or seams between adjacent modified OSB panels sealed using tape;

[0030] FIG. 3A illustrates a traditional stucco system, including the various layers applied over exterior sheathing comprising OSB panels;

[0031] FIG. 3B illustrates an exterior insulation and finish system (EIFS), including the various layers applied over exterior wall sheathing;

[0032] FIG. 4 provides a side-by-side comparison of a simplified stucco system of the disclosure to a traditional stucco system;

[0033] FIG. 5A is a side perspective view that illustrates examples of differently sized lightweight composite panels that can be used as substrates for applying stucco or other finishes to an exterior wall structure;

[0034] FIG. 5B is a top perspective view that illustrates the differently sized lightweight composite panels of FIG. 5A;

[0035] FIG. 6 is an exploded diagram that schematically illustrates the layered structure of the lightweight composite panels of FIGS. 5A and 5B;

[0036] FIG. 7A is an exploded view of an embodiment of a stucco system that incorporates a stucco layer, lightweight composite panel, drainage layer, and OSB panels as sheathing;

[0037] FIG. 7B schematically illustrates an assembled view of the stucco system of FIG. 7A;

[0038] FIG. 8A is a perspective view that illustrates an embodiment of a stucco system made using lightweight composite panels attached to sheathing (e.g., OSB panels) of an exterior wall structure;

[0039] FIG. 8B is another perspective view of the example stucco system of FIG. 8A;

[0040] FIG. 9A illustrates another embodiment of a stucco system made using lightweight composite panels attached to sheathing (e.g., OSB panels) of an exterior wall structure;

[0041] FIG. 9B is another perspective view of the example stucco system of FIG. 9A;

[0042] FIG. 10 illustrates an exterior wall that includes lightweight composite panels before applying a desired exterior finish according to the disclosure;

[0043] FIG. 11A illustrates an exterior wall that includes lightweight composite panels attached over exterior wall sheathing and a stucco finish applied onto a portion of the lightweight composite panels;

[0044] FIG. 11B illustrates an exterior wall that includes lightweight composite panels attached over an exterior wall structure and various exterior finishes applied to the lightweight composite panels, including stucco, thin bricks, and tiles applied over different portions of the lightweight composite panels;

[0045] FIG. 12 illustrates mesh tape used as a template for proper placement of screws or other mechanical fasteners when fastening lightweight composite panels to studs or other structural elements of an exterior wall structure;

[0046] FIG. 13 illustrates a lightweight composite panel with holes caused by screws with heads that penetrated through the exterior fiber mesh reinforced cementitious layer and a screw with a washer that did not penetrate through the cementitious layer; and

[0047] FIGS. 14A-14D illustrate embodiments of specialized washers with multiple prongs designed to penetrate at least partially through and become embedded within the lightweight composite panel.

DETAILED DESCRIPTION

I. Overview

[0048] Disclosed are methods and systems for constructing exterior wall finishes, such as stucco, brick veneers, stone and masonry, tiles, or other finishes on exterior walls of houses, other buildings, or enclosures. The methods and systems for constructing exterior wall finishes utilize lightweight composite panels as substrates and reduce the number of required layers of materials, reduce time and cost, and improve safety compared to traditional stucco systems and other exterior finishes.

[0049] The lightweight composite panels can provide a surface to which a variety of different finishes can be directly applied and adhered without the need for lath and other underlying layers. Lightweight composite panels include a strong, yet lightweight, foam core (e.g., polymer or inorganic foam) sandwiched between relatively thin protective layers selected from fiber mesh reinforced cementitious layer, thermoset polymer layer, or other rigid material. As a result, the lightweight composite panels are strong and can support relatively heavy loads, such as multiple layers of stucco finish, brick veneers, stone and masonry, tiles, light fixtures, and other fixtures using screws, nails, other hangers, construction adhesive, or other wall attachment systems. The lightweight composite panels are waterproof and lightweight, yet have high structural strength (i.e., high tensile and flexural strength and high toughness). In some embodiments lightweight composite panels can function as sheathing to form a a shear wall but are much lighter than OSB or other plywood panels. The exterior-facing fiber mesh reinforced cementitious (or other protective) layer can form a textured surface or grid pattern, which provides a bonding surface that facilitates application of adhesives, thin sent mortar, stucco, or other materials thereto. The lightweight composite panels can be cut, drilled, and screwed, fastened and/or glued onto structural elements of buildings, such as studs and sheathing. The interior-facing fiber mesh reinforced cementitious (or other protective) layer can provide a bonding surface that facilitates adhesion of lightweight composite panels to an exterior wall structure.

[0050] Additional information and features relating to lightweight composite panels and their uses in making various building products are disclosed in U.S. Prov. App. No. 63/686,489, filed Aug. 23, 2024; U.S. Prov. App. No. 63/692,563, filed Sep. 9, 2024; U.S. Prov. App. No. 63/703,834, filed Oct. 4, 2024; U.S. Prov. App. No. 63/720,649, filed Nov. 14, 2024; U.S. Prov. App. No. 63/729,637, filed Dec. 9, 2024; U.S. Prov. App. No. 63/744,115, filed Jan. 10, 2025; U.S. Prov. App. No. 63/747,543, filed Jan. 1, 2025; U.S. Prov. App. No. 63/753,600, filed Feb. 4, 2025; U.S. Prov. App. No. 63/764,354, filed Feb. 27, 2025; U.S. Prov. App. No. 63/788,276, filed Apr. 14, 2025; U.S. Prov. App. No. 63/849,709, filed Jul. 23, 2025, U.S. Prov. App. No. 63/855,715, filed Aug. 1, 2025, U.S. Prov. App. No. 63/857,807, filed Aug. 5, 2025, and U.S. Prov. App. No. 63/862,235, filed Aug. 12, 2025. The foregoing applications are incorporated by reference in their entirety.

[0051] FIG. 4 illustrates and compares two exterior stucco finishes, including an example inventive stucco system 400 made according to the disclosure and a traditional stucco system 450. The example inventive stucco system 400 and the traditional stucco system 450 both include an OSB panel 410, which is an example of wall sheathing of an exterior wall structure of a building or enclosure. A waterproof polymer membrane 412 is attached over the OSB panel 410 to protect it from moisture and optionally create an air barrier over joints or seams between adjacent OSB panels.

[0052] The example inventive stucco system 400 includes a lightweight composite panel 420, which includes an exterior-facing fiber mesh reinforced cementitious (or other protective) layer 422 as a bonding substrate. The lightweight composite panel 420 is fastened to the OSB panel 410 by means of screws 424. Two of the screws 424 are shown covered by patches of a seam coat (e.g., thin set mortar or fine-sanded stucco) 426 to create a smooth surface (although it is understood that all screws or other fasteners can be covered with the seam coat 426). A stucco finish 428 is applied over the fiber mesh reinforced cementitious (or other protective) layer 422 and patches of seam coat 426. Both cement-based stucco and acrylic stucco can readily adhere directly to the fiber mesh reinforced cementitious (or other protective) layer 422 and seam coat 426. A primer is typically not required when using acrylic-based stucco, although a primer can be used if desired. Any primer known in the art for acrylic-based stucco can be used.

[0053] The traditional stucco system 450 includes black backing paper 452 for additional moisture protection applied over the waterproof polymer membrane 412. The black backing paper 452 can be attached to the OSB panel 410 by means of staples or nails (not shown). Wire lath 454 is applied over the black backing paper 452 and attached to the OSB panel 410 by means of nails 456. A scratch coat 458 made from sand, cement, water, and optional components is applied over and embedded within the wire lath 454 using a trowel or sprayer. A scarifier tool is used to form horizontal ridges and troughs in the scratch coat 458 while the scratch coat 458 is in a plastic state. After the scratch coat 458 has hardened, typically after at least one day, a brown coat 460 made from sand, cement, water, and optional components is applied over the scratch coat 458 using a trowel or sprayer to form a smooth surface. The horizontal ridges and troughs in the scratch coat 458 create a good mechanical bond between the brown coat 460 and the scratch coat 458. Finally, after the brown coat 460 has hardened, typically after at least one day, a stucco finish 462 is applied over the brown coat 460. Cement-based stucco can adhere directly to the brown coat 460. In the case where the stucco layer 428 is acrylic-based stucco, a primer (not shown) is typically applied over the brown coat 460 to improve adhesion.

II. Lightweight Composite Panels

[0054] Lightweight composite panels disclosed herein can be used to make wall structures, including exterior wall structures to which one or more desired finishes can be applied. Lightweight composite panels comprise a strong, yet lightweight, foam core and a a protective layer selected from fiber reinforced cementitious compositions, thermoset polymer, or magnesium oxide on opposing sides of the foam core. As a result, the lightweight composite panels are strong and can support relatively heavy loads, such as decorative or structural features attached to exterior wall structures or roofing decks. Examples include, but are not limited to, one or more layers of stucco (underlying and finished layers), brick veneers, stone and masonry, shingles, clay tiles, light fixtures, metal roof cladding, and fixtures using nails, screws, other hangers, or other wall attachment systems.

[0055] FIGS. 5A and 5B illustrate examples of lightweight composite panels 500a, 500b, 500c of varying cross-sectional thickness that can be used as is or modified with other features for a specific purpose. FIGS. 5A and 5B show the layered structure of the lightweight composite panels 500a, 500b, 500c, including strong, lightweight, and moisture-resistant extruded polystyrene (XPS) foam cores 510a, 510b, 510c sandwiched between first fiber mesh reinforced cementitious layers 520a, 520b, 520c and second fiber mesh reinforced cementitious layers 530a, 530b, 530c. As discussed below, in other embodiments the foam core 510 may comprise other polymer or inorganic foam materials, and one or both protective layers may comprise a thermoset polymer or other rigid protective material.

[0056] The cross-sectional thickness of lightweight composite panels 500a, 500b, 500c can be selected based on a combination of desired properties for their intended use, such as strength, insulation, spacing between wall elements, and the like. As illustrated in FIGS. 5A and 5B, the cross-sectional thicknesses of the lightweight composite panels 500a, 500b, 500c varies mostly or entirely depending on the cross-sectional thickness of the foam cores 510a, 510b, 510c. Although not shown, when lightweight composite panels 500 of greater cross-sectional thickness are desired, it may be desirable to increase the thickness of the fiber mesh reinforced cementitious layers 520, 530 (e.g., to account for possible strength reduction caused by including a foam core 510 of greater cross sectional thickness).

[0057] FIG. 6 is in an exploded view that schematically illustrates the layered structure of a lightweight composite panel 600, which is similar or identical to the lightweight composite panels 500a, 500b, 500c of FIGS. 5A and 5B. The foam core 610 can be a lightweight polymer foam made from closed cell extruded polystyrene (XPS), is lightweight, rigid, highly water-resistant, and thermally insulating, and includes two outer surfaces or faces. In some embodiments, the foam core 610 may have a density of about 30-45 kg/m.sup.3 and a compressive strength of about 250-400 kPa.

[0058] Alternatively, the foam cores 510, 610 discussed above can be made from a different polymer foam material, such as, but not limited to, expanded polystyrene foam (EPS), polyisocyanurate foam, polyurethane (PUR) foam, phenolic polymer (e.g., phenol-formaldehyde) foam, melamine polymer (e.g., melamine-formaldehyde) foam, and/or other thermoplastic or thermoset polymer known in the art that can be formed into rigid or semi-rigid foam layers. An advantage of thermoset polymer foam materials is they are generally more fire- and heat-resistant than thermoplastic polymers, with thermoset phenolic polymers in particular providing a high level of fire and heat resistance.

[0059] The properties of various polymers that can be used to make foam core layers 510, 610 are set forth in Tables 1-3.

TABLE-US-00001 TABLE 1 Property XPS/EPS Phenolic Material Type Thermoplastic Thermoset (phenol- polystyrene formaldehyde) Thermal Conductivity 0.028-0.033 0.018-0.022 (W/m .Math. K) R-Value per inch ~5.0 6.5-7.2 Fire Resistance Poor - melts, drips Excellent - chars, low smoke Flame Spread (ASTM E84) 75-200 <25 (Class A) (W/O Facer Smoke Development (W/O >450 <50 Facer) (often) Thermal Stability ~93 C. (melts) 150-175 C. Water Resistance Excellent Good (closed-cell) Compressive Strength 200-300 kPa 100-150 kPa Flexural Strength Flexible, good Brittle Recyclability Yes (thermoplastic) No Weight (kg/m.sup.3) 25-35 35-50 Cost Low-Moderate High

TABLE-US-00002 TABLE 2 Property Melamine PUR Material Type Thermoset (melamine- Thermoset (polyol + formaldehyde) isocyanate) Thermal Conductivity 0.032-0.036 0.020-0.025 (W/m .Math. K) R-Value per inch ~4.1-4.5 ~6.0-6.5 Fire Resistance Excellent - non- Poor - needs FR melting, self- additives extinguishing Flame Spread (ASTM E84) <25 (Class A) Varies (often >25) (W/O Facer Smoke Development (W/O Very low High Facer) Thermal Stability ~240 C. ~100-120 C. Water Resistance Poor unless sealed Good Compressive Strength Low 150-300 kPa Flexural Strength Very brittle Strong Recyclability Limited No Weight (kg/m.sup.3) 7-12 30-45 Cost High Moderate

TABLE-US-00003 TABLE 3 Property Polyiso Material Type Thermoset (polyisocyanurate) Thermal Conductivity (W/m .Math. K) 0.020-0.023 R-Value per inch ~6.0-6.5 Fire Resistance Good - chars, often Class A with facer Flame Spread (ASTM E84) (W/O Facer <25 (Class A with facer) Smoke Development (W/O Facer) <150 Thermal Stability ~150 C. Water Resistance Fair (can degrade if unprotected) Compressive Strength 140-200 kPa Flexural Strength Moderate Recyclability Rarely recycled Weight (kg/m.sup.3) 30-42 Cost Moderate-High

[0060] With reference to FIG. 6, formed over first and second outer surfaces of the foam core 610 are first and second layers of fiber (e.g., fiberglass) mesh 620b, 630b, respectively, which become embedded within respective first and second layers of fresh cementitious composition applied over the fiber mesh layers 620b, 630b, which harden or cure to form first and second cementitious layers 620a, 630a. Together, the hardened cementitious layers 620a, 630a and embedded fiberglass mesh layers 620b, 630b form first and second fiber mesh reinforced cementitious layers 620, 630, which adhere to the foam core 610 to form a strong but lightweight composite panel structure. The fiber mesh layers 620b, 630b can alternatively include other fibers or filaments, such as carbon fibers or filaments.

[0061] The lightweight foam core is typically made from extruded polystyrene foam (XPS), but can alternately comprise expanded polystyrene foam (EPS), polyisocyanurate foam, polyurethane (PUR) foam, phenolic polymer (e.g., phenol-formaldehyde) foam, melamine polymer (e.g., melamine-formaldehyde) foam, and/or other thermoplastic or thermoset polymer known in the art that can be formed into rigid or semi-rigid foam layers. The lightweight foam core can be made of closed cell polystyrene foam to provide a water-resistant barrier (e.g., 100% waterproof).

[0062] Alternatively, the foam core may comprise an inorganic foam, such as a refractory foam material, to provide additional fire-resistance. Examples include silica gel, aerogel, silicate foams, urea-silicate foam, SiOC/SiC, ceramic foams, refractory foams, and the like. The inorganic foam core can resist melting even when exposed to fire or intense heat in order for the lightweight composite panel to maintain its structural integrity.

[0063] In some embodiments, the lightweight composite panels are manufactured by applying a fiber (e.g., fiberglass) mesh and fresh cementitious composition onto first and second surfaces of a rigid polymer (e.g., XPS) or inorganic foam core and causing or allowing the applied cementitious composition to harden. The fiber mesh becomes embedded in the hardened cementitious layer to enhance strength, increase toughness, and prevent cracking of the hardened cementitious layer. Alternatively, at least one of the hardened cementitious layers can be replaced or augmented with a cured polymer layer.

[0064] The layers of fiber mesh reinforced cementitious composition are generally thin (e.g., typically less than about 3 mm, less than about 2.5 mm, less than about 2 mm, or less than about 1.5 mm, such as about 1 mm, or between about 0.5-3 mm, about 0.75-2.5 mm, or about 1-2 mm in cross-sectional thickness). The fiber mesh reinforced cementitious layers can be very lightweight yet waterproof and have high structural strength (i.e., high tensile and flexural strength and high toughness). The fiber mesh component is typically fiberglass fiber or glass filament mesh, but can be made of other strong fibers or filaments, such as carbon fibers or filaments. In some embodiments, fiberglass mesh is formed of an alkali-resistant material and may have nominal mesh size of 44 mm with a strand diameter of about 0.5-1.0 mm.

[0065] In some embodiments, the fresh cementitious composition comprises mixture products of water, hydraulic cement, silicon dioxide powder, calcium oxide, iron oxide, plaster of Paris (gypsum hemihydrate), water-reducing agent, defoamer, styrene, and acrylic acid. The fresh cementitious composition may optionally include supplementary cementitious materials (SCMs), such as ground granulated blast furnace slag (GGBFS), fly ash, natural pozzolan, silica fume, microsilica, metakaoline, ground glass, calcined clay, finely ground quartz, limestone powder, and the like. The cementitious composition may include other components, such as natural hydraulic lime, calcium silicate, and/or expanded glass, which can increase fire and heat resistance.

[0066] In a more particular embodiment, the cementitious composition applied to the outer surfaces of the foam core to form fiber mesh reinforced cementitious layers of the lightweight composite panels can be formed by mixing together the following components (expressed in weight percent) to form a fresh flowable cementitious composition, which is applied to the foam core surfaces, together with fiber mesh, and then allowed to harden or cure:

TABLE-US-00004 Hydraulic cement 30-50% Silicon dioxide 40-60% Calcium oxide 2-5% Iron oxide 0.2-1% Gypsum hemihydrate 3-8% Water-reducing agent 0.2-0.6% Defoamer 0.2-0.6% Styrene 1-2% Acrylic acid 1-2% Water (16-20%, preferably 18.4% of dry ingredients above)

[0067] The hydraulic cement typically includes Portland cement clinker interground with gypsum for set control, but may also include other interground minerals, such as limestone filler (e.g., 5-10% by weight of the hydraulic cement), and optionally one or more supplementary cementitious materials (SCMs), such as ground granulated blast furnace slag (GGBFS), fly ash, natural pozzolan, silica fume, microsilica, metakaoline, ground glass, calcined clay, finely ground quartz, and the like. The silicon dioxide can be 150 mesh ground quartz sand. The water reducer can be a low-range water reducer, such as a compound of carboxylic acid grafted multi-polymer and other effective additives. The defoamer can reduce the surface tension of water, solution, suspension, etc., prevent the formation of foam, or reduce or eliminate the original foam. The main component of the defoamer can be polydimethylsiloxane (Me.sub.3SiO(Me.sub.2SiO)nSiMe.sub.3) (Me=methyl). In the case where very fine SCMs (e.g., silica fume, microsilica, or metakaoline), it may be desirable to use a high range water reducer (e.g., polycarboxylate ether) to obtain good flow. The styrene and acrylic acid components, which may be a copolymer, can form a chemical bond to the extruded polystyrene foam core, in addition to the physical bond.

[0068] The components of the cementitious composition can be mixed by high-performance mixing equipment through precise batching, and then fed into a mixing barrel in sequence for high-speed dispersion and mixing, thus yielding a fresh cementitious mixture. The fresh cementitious mixture is blended in a tank to make it into liquid or plastic form. The liquid cementitious mixture is then pumped into a machine variously called a waterfall machine, commonly known as a curtain coater or enrobing coater/machine, which has flow control of the liquid cementitious mixture and which will apply the liquid cementitious mixture onto surfaces of an extruded polystyrene foam sheet or other material to be coated. The liquid cementitious mixture is applied like a waterfall or curtain through a blade applicator to evenly apply it to the polymer foam surfaces or other surface to be coated. The product is then cured and left to stand for approximately 7 days as usual practice. However, if ambient conditions are dry and hot, the curing period could be shortened to approximately 3-4 days.

[0069] In general, the hardened fiber mesh reinforced cementitious composition can adhere and bond strongly to the polymer or inorganic foam core to form a strong lightweight composite panel structure that does not delaminate. The bond between the cementitious layers and the foam layer is likely a combination of physical and chemical interactions. When applied to the polymer or inorganic foam layer, the liquid cementitious composition can penetrate into surface pores of the foam layer, which upon hardening of the cementitious composition, forms a strong mechanical bond. This bond can be further enhanced through the inclusion of very fine pozzolans, such as silica fume, microsilica, or metakaoline on the cementitious composition, which creates a very high strength cementitious layer and are able to fill very small micropores. The polymer components of the cementitious composition may also interact with components of the foam layer to form a type of chemical bond between the cementitious layers and the foam (e.g., polymer) layer. Regardless of how bonding occurs, it is demonstrably very strong and does not delaminate during specified use. Curable resins also adhere and bond strongly to the foam core.

[0070] In some embodiments, when manufacturing the lightweight composite panel structure, the fiberglass mesh is first laid down on a polymer (e.g., extruded polystyrene) or inorganic foam sheet. A transportation belt then transports the foam sheet with the fiberglass mesh through the waterfall machine (commonly known as a curtain coater or enrobing coater/machine), which causes the liquid cementitious mixture to flow down like a waterfall or curtain, with control of the liquid cementitious mixture flow, onto the foam sheet or other substrate. In this way, the fiberglass mesh becomes embedded in the liquid cementitious mixture and essentially floats in the middle of the cementitious mixture. In other words, a portion of the liquid cementitious mixture will be positioned between the fiberglass mesh and the foam sheet in order to directly adhere to the foam sheet, and another portion of the liquid cementitious mixture will cover and encapsulate the fiber mesh to form the top surface of the lightweight composite panel structure. The result is a layered composite structure, with an interior polymer or inorganic foam sheet, an underlying layer of cementitious composition in direct contact with the foam sheet, a fiberglass mesh in the middle, and a top layer of cementitious composition covering the fiberglass mesh

[0071] In addition to, or instead of, a fiber mesh reinformed cementitious layer, one or both protective layers of the lightweight composite panel may comprise other materials in addition to or instead of the cementitious composition. Examples include one or more of rigid magnesium oxide material, water-resistant polymer, or a composite material comprising a resin or polymer with embedded fibers, fiber mesh, fabric, scrim, felt, or non-woven. The material forming the fibers, fiber mesh, fabric, scrim, felt, or non-woven can be selected from plant fibers, polymer fibers, and inorganic fibers (e.g., basalt, rock wool, and the like). The resin or polymer may comprise a thermoplastic or thermoset material, such as UV-cured resins, polypropylene, polycarbonate, polyethylene terephthalate, polystyrene, acrylate, methacrylate, polyurea, polyaspartic, or epoxy. Protective layers of thermoset polymer can be slightly thicker than fiber mesh reinforced cementitious layers, such as between about 1-5 mm or about 2-3 mm.

[0072] Polyurea is a type of elastomer that is derived from the reaction product of an isocyanate component and an amine component. The isocyanate can be aromatic or aliphatic in nature. It can be monomer, polymer, or any variant reaction of isocyanates, quasi-prepolymer or a prepolymer. The prepolymer, or quasi-prepolymer, can be made of an amine-terminated polymer resin, or a hydroxyl-terminated polymer resin. The resin blend can include amine-terminated polymer resins and/or amine-terminated chain extenders. The resin blend may also contain additives or non-primary components, such as pigments pre-dispersed in a polyol carrier. Normally, the resin blend does not contain a catalyst. This is because the reaction between an isocyanate and amine is extremely fast and hence does not need catalysis.

[0073] The chemical structure of polyurea is as follows:

##STR00001##

[0074] In a polyurea, alternating monomer units of isocyanates and amines react with each other to form urea linkages, as shown below.

##STR00002##

[0075] Polyaspartic resin is a solvent-free, aliphatic amine coating material based on aspartic acid, polyaspartic acid, or polyaspartic ester, which reacts with an isocyanate to create extremely durable protective coatings with rapid cure times, excellent abrasion resistance. An example of a curable polyaspartic resin has the following reactants and final cured polymer structure:

##STR00003##

[0076] The curable resin can be applied by spray coating while in a flowable state to one or both surfaces of the foam core and allowing it to cure and form a solid protective layer. Multiple parts of the curable resin can be mixed just prior to entering or within the nozzle used to spray coat the foam core. Where it is desired to incorporate a fiberglass mesh sheet in the polymer layer, an initial coating of curable resin can be applied to the foam core, followed by applying the fiberglass mesh sheet over the resin, followed by applying a final coating of the curable resin.

[0077] In some embodiments, the outlines of the fiberglass mesh embedded within the hardened cementitious or cured resin layer can be visible and form a grid-like texture that improves adhesion of structural and/or decorative materials thereto, such as cementitious coatings, adhesives, stucco, paint, brick veneers, stone and masonry, shingles, clay tiles, metal cladding, and the like. For example, one or more stucco layers can directly adhere to the fiber mesh reinforced cementitious layer without the need for wire mesh, scratch coat, and brown coat used in conventional stucco systems. Nevertheless, it may be desirable to apply a layer of thin set mortar to cover screws, sealants, holes, or other discontinuities in the lightweight composite panels prior to applying a finished stucco layer (which can be cementitious or acrylic based).

[0078] The textured surface provided by the fiber mesh reinforced cementitious (or other protective) layer can also facilitate adhesion of lightweight composite panels to a wall structure, such as an exterior wall structure, in order for the lightweight composite panels to provide a substrate for application of one or more finishes. In some embodiments, an appropriate adhesive, such as construction adhesive or foam adhesive, can be used to adhere lightweight composite panels to an exterior wall frame or structure, including studs and/or exterior sheathing, either in addition to or instead of screws or other mechanical fasteners. The use of an adhesive provides a much more continuous bond interface between the lightweight composite panels and studs or sheathing, thereby distributing the load more evenly and improving shear strength of the wall. The use of adhesive attachment in addition to or instead of screws can eliminate discrete attachment points, creating a more solid and continuous bond that can better resist lateral forces and improve shear strength of the exterior wall structure.

[0079] U.S. Provisional Application Nos. 63/686,489, 63/692,563, 63/703,834, and 63/788,276, incorporated by reference, disclose modified lightweight composite panels that can be used as interior panels to substitute for traditional drywall, such as to form a complete wall system that includes lightweight composite panels on both sides of a wall frame comprising studs. Modified lightweight composite panels can include a light colored (e.g., white or off white) cementitious or polymer layer bonded over at least the show side, and optionally the side edges, giving the modified lightweight composite panels the appearance of gypsum board without paper. Modified lightweight composite panels can also include a paper layer similar to traditional drywall panels.

[0080] Modified lightweight composite panels can include fiber mesh reinforced cementitious layers, along with a waterproof interior polymer foam core, making them lighter, waterproof, and substantially stronger than conventional gypsum board. Modified lightweight composite panels can be used, for example, in embodiments where it is desired to construct an exterior wall structure with lightweight composite panels forming the outer wall structure and modified lightweight composite panels of similar construction forming an interior wall to form a complete wall system. Examples of a complete wall system are disclosed in U.S. Provisional Application No. 63/720,649, incorporated by reference.

III. Exterior Wall Finishes

[0081] The lightweight composite panels to which one or more exterior wall finishes are applied can be fastened to an exterior wall structure using mechanical fasteners and adhesives known in the art, such as wood screws, self-drilling/tapping metal nails, rivets, and construction adhesive. Because the lightweight composite panels are used to make exterior wall finishes, screws or other mechanical fasteners are advantageously made from corrosion-resistant materials, such as stainless steel, galvanized steel, high strength polymers, and the like. Strips of tape (mesh or solid) that line up with underlying studs, sheathing, or other structural elements of the exterior wall frame can be used as a template to ensure proper placement and securement of screws or other mechanical fasteners through the lightweight composite panels and into the studs, sheathing, or other structural elements of the exterior wall or roof frame. To prevent screws from tearing through or otherwise damaging the exterior-facing fiber mesh reinforced cementitious (or other protective) layer, screws can be used with enlarged washers or pan head screws or screws with integrated washers having high surface area to distribute the pressure or load over a correspondingly higher surface area of the fiber mesh reinforced cementitious (or other protective) layer of the lightweight composite panels.

[0082] In some embodiments, specialized washers with penetrating prongs can be used. When screws with specialized washers are driven through the lightweight composite panels and into an underlying wooden or metal stud sheathing, or other structural element of an exterior wall structure, the penetrating prongs of the washers will penetrate into and become embedded within the lightweight composite panels, including at least the exterior-facing fiber mesh reinforced cementitious (or other protective) layer and at least partially through the foam core. The interaction between washer prongs and lightweight composite panels prevents the washers from rotating out of place during placement and provides additional lateral strength to hold the lightweight composite panels in place relative to the exterior wall structure. In addition, rectangular or other appropriately shaped washers with multiple prongs on either side of the screw can be used to tie adjacent lightweight composite panels together, which can improve the structural integrity and shear strength of a wall structure, such as an exterior wall structure carrying an exterior wall finish.

[0083] In some embodiments, the length of penetrating prongs of the washers can be made to correspond to the cross-sectional thickness of the lightweight composite panels used to make a wall structure, such as an exterior wall structure carrying the exterior wall finish. Advantageously, the length of the penetrating prongs can be slightly less than, equal to, or slightly exceed the cross-sectional thickness of the lightweight composite panels. This allows the penetrating prongs to penetrate all the way through the foam core and the interior fiber mesh reinforced cementitious (or other protective) layer and make abutment with studs, sheathing, or other structural element of the exterior wall structure. This provides a stop that limits further movement of the enlarged washer toward the lightweight composite panels, preventing unwanted crushing of the lightweight composite panels and ensuring that the screw and washer ensemble does not break through and damage the exterior fiber mesh reinforced cementitious (or other protective) layer. However, it may be desirable for the length of the prongs to permit slight compression of the exterior fiber mesh reinforced cementitious (or other protective) layer without damaging it. This ensures that appropriately strong pressure is applied by the washer to the exterior fiber mesh reinforced cementitious or other protective) layer to securely fasten the lightweight composite panels to a wall structure. Where the underlying studs or other structural element are metal, the length of the penetrating prongs can be approximately equal to or slightly less than the cross-sectional thickness of the lightweight composite panels. Alternatively, where the underlying studs, sheathing, or other structural elements are made of wood, the length of the penetrating prongs can be slightly greater than the cross-sectional thickness of the lightweight composite panels in order to for the prongs to partially penetrate into the wood, thereby potentially further increasing the lateral and shear strength provided by the lightweight composite panels of a wall structure, such as an exterior wall structure to which an exterior finish is applied.

[0084] In some embodiments, the fiber mesh reinforced cementitious (or other protective) layers of the lightweight composite panels can have a grid pattern or other discontinuity that can facilitate adhesion of cementitious materials, thin set mortar, stucco (cement- and acrylic-based), adhesives, paint, or other coatings to exposed surfaces of the lightweight composite panels. For example, one or more stucco layers can directly adhere to the exterior-facing fiber mesh reinforced cementitious (or other protective) layer without the need for wire mesh, scratch coat, and brown coat used in conventional stucco systems. Nevertheless, it may be desirable to apply patches of an appropriate seam coat (e.g., thin set mortar or fine-sanded stucco) to cover screws, sealants, holes, or other discontinuities prior to applying a finished stucco layer (which can be cementitious or acrylic based).

[0085] A water drainage layer can be positioned between exterior wall sheathing and the lightweight composite panels to which the exterior finish is applied to facilitate removal of moisture and prevent damage beneath the exterior finish.

[0086] Reference is now made to FIGS. 7-14, which illustrate lightweight composite panels, stucco, other exterior finishes, and fasteners used in making exterior wall finishes of a building or enclosure. Reference is also made to FIGS. 1-2, which can be modified to use lightweight composite panels instead of OSB units as the exterior wall sheathing.

[0087] By way of example, FIG. 1A illustrates a framed house 100 with studs 110 that form exterior wall and roof frames to which appropriate exterior sheathing can be attached to form exterior wall structures and roofing decks. FIG. 1B illustrates a framed house 100 that includes exterior shear walls and roofing deck formed using OSB panels 120, but which can be modified to instead use lightweight composite panels in place of some or all of the OSB panels 120. FIG. 1C illustrates a framed house 100 with OSB panels 120 forming an outer wall and house wrap 130 on the outer surface of the OSB panels 120 to form a waterproof exterior wall. The house wrap 130 is typically a waterproof polymer membrane that protects the OSB panels 120 from water damage and can also provide an air barrier that prevents unwanted air leakage. FIG. 1D illustrates a framed house 100 to which a stucco finish 160 is being applied with the aid of scaffolding.

[0088] FIG. 2A illustrates a modified OSB panels 200 that includes an OSB layer 210, a water-resistant barrier layer 220 on an exterior surface of the OSB layer 210, and an insulating foam layer 230 on the interior surface of the OSB layer 210. FIG. 2B illustrates a wall 240 that includes a wall frame 242 comprising studs 244 and a plurality of modified OSB panels 200 attached to the wall frame 242. Some or all of the OSB panels 100 shown in FIG. 1B and modified OSB panels 200 shown in FIG. 2B can be replaced with lightweight composite panels, such as those illustrated in FIGS. 5 and 6, as sheathing. FIG. 3B illustrates how joints or seams between adjacent OSB panels 200 are sealed using flexible tape 236. Similar sealing means can be employed when using lightweight composite panels as sheathing.

[0089] FIGS. 7A and 7B schematically illustrate an embodiment of an exterior stucco system 700 made using a lightweight composite panel 740 as a substrate for a stucco finish. FIG. 7A shows an exploded view of the exterior stucco system 700, and FIG. 7B shows an assembled view of the exterior stucco system 700. The exterior stucco system 700 includes an OSB panel 710 as wall sheathing and a waterproof polymer membrane 720 (e.g., house wrap) applied over the OSB panel 710 to protect it from moisture and optionally to form an air barrier over seams or joints between adjacent OSB panels 710. A water drainage layer 730 is positioned over the waterproof polymer membrane 720 to provide a path for any moisture that may collect between the lightweight composite panel 740 and the waterproof polymer membrane 720. The drainage layer 730 facilitates drainage and removal of water by the force of gravity and/or evaporation. The lightweight composite panel 740 can be fastened to the OSB panel 710 using screws, nails, rivets, or other fasteners known in the art. A stucco finish 760 (cement-based or acrylic-based) is applied over an exterior-facing fiber mesh reinforced cementitious (or other protective) layer 750 of the lightweight composite panel 740. Indentations or other surface defects caused by screws or other mechanical fasteners can be covered by patches of a seam coat (not shown) to form a more uniform surface over which the stucco finish 760 is applied.

[0090] FIGS. 8A and 8B are different perspective views that illustrate a mockup of an example stucco system 800 according to the disclosure. The example stucco system 800 includes an exterior wall structure 802 formed using studs 804 and an OSB panel 806. A lightweight composite panel 808 is fastened to the OSB panel 806 using a plurality of screws 810. A patch of seam coat (e.g., thin set mortar or fine-sanded stucco) 812 is shown applied over one of the screws 810 and a portion of an exterior-facing fiber mesh reinforced cementitious layer 814 to form a more uniform surface to which a stucco finish can be applied.

[0091] The example stucco system 800 includes first and second corners 816, 818 formed between adjacent lightweight composite panels 808 positioned at 90 angles. The first corner 816 is protected by fiber mesh 820 and a first corner layer of an appropriate seam coat (e.g., thin set mortar or fine-sanded stucco) 822 in which the fiber mesh 820 is embedded. The second corner 818 is protected by a rigid or semi-rigid corner bend 824, which can be made of metal or polymer, such as polyvinyl chloride (PVC), and a second corner layer of seam coat 826 in which the corner bend 824 is embedded. It will be understood that the fiber mesh 820 and corner bend 824 are alternative embodiments and need not be included in the same embodiment. Rather, some embodiments may use the fiber mesh 820 and other embodiments may use the corner bend 824 (e.g., to provide greater protection against mechanical damage caused by blunt force to wall corners). One or more layers of stucco finish 828 (cement- or acrylic-based) is applied over the exterior-facing fiber mesh reinforced cementitious (or other protective) layer 814, patches of seam coat 812, and first and second corner layers of seam coat 822, 826. A primer is typically not required when using acrylic-based stucco, though one can be used if desired.

[0092] FIGS. 9A and 9B are different perspective views of a mockup of another example stucco system 900 according to the disclosure. The main difference between this embodiment and that of FIGS. 8A and 8B is that the embodiment of FIGS. 9A and 9B utilizes screws 910 pared with enlarged washers 911 to fasten a pair of adjacent lightweight composite panels 908a, 908b to the exterior wall structure 902, which is formed using studs 904 and an OSB sheath 906. A vertical concourse of screws 910 and enlarged washers 911 are used to interconnect adjacent lightweight composite panels 908a, 908b fastened to the OSB sheath 906. A vertical strip of fiber mesh tape 930 is placed over the vertical concourse of screws 910 and enlarged washers 911 and a portion of exterior-facing fiber reinforced (or other protective) layers 914a, 914b of the adjacent lightweight composite panels 908a, 908b, followed by applying a vertical strip of an appropriate seam coat (e.g., thin set mortar or fine-sanded stucco) 932 over the fiber mesh tape 930, screws 910 and enlarged washers 911, and a portion of the exterior-facing fiber reinforced (or other protective) layers 914a, 914b to further tie the adjacent lightweight composite panels 908a, 908b together. This further helps prevent separation and potential formation of cracks in the stucco finish 928 at the joint between the adjacent lightweight composite panels 908a, 908b. The vertical strip of scam coat 932 also forms a more uniform surface to which the stucco finish 928 can be applied.

[0093] The example stucco system 900 also includes first and second corners 916, 918 formed between adjacent lightweight composite panels 908 positioned at 90 angles. The first corner 916 is protected by fiber mesh 920 and a first corner layer of an appropriate seam coat (e.g., thin set mortar or fine-sanded stucco) 922 in which the fiber mesh 920 is embedded. The second corner 918 is protected by a rigid metal corner bend 924, which can be made of galvanized steel, and a second corner layer of seam coat 926 covering the metal corner bend 924. It will be understood that the fiber mesh 920 and metal corner bend 924 are alternative embodiments and need not be included in the same embodiment. Rather, some embodiments may use the fiber mesh 920 and other embodiments may use the metal corner bend 924 (e.g., to provide greater protection against mechanical damage caused by blunt force to wall corners). One or more layers of stucco finish 928 (cement- or acrylic-based) is applied over the exterior-facing fiber mesh reinforced cementitious (or other protective) layers 914a, 914b, vertical strip of seam coat 932, and first and second corner layers of seam coat 922, 926.

[0094] FIG. 10 illustrates an exterior wall 1000 that includes lightweight composite panels 1002 fastened by means of screws 1004 to an exterior wall structure (not shown) comprising studs and optionally sheathing made from OSB panels. The lightweight composite panels 1002 form a substrate to which an exterior finish can be directly applied, including stucco, thin bricks, tiles, stone veneers, stone and masonry, and other exterior finishes known in the art. In some embodiments, the lightweight composite panels 1002 can replace OSB panels as the sheathing forming the structure of the exterior wall 1000. In such cases, the lightweight composite panels 1002 can function as the shear wall. Seams or joints between adjacent lightweight composite panels 1002 and other structural elements of the exterior wall 1000 will need to be sealed, such as by using polymer sealing tape 246 illustrated in FIG. 2B.

[0095] FIG. 10 further shows that a corner bend 1006 with integrated fiber mesh tape 1008 are applied over the corner formed by adjacent lightweight composite panels 1002 placed at a right angle. A layer of seam coat (not shown) is thereafter applied over the corner bend 1006 and fiber mesh tape 1008 to form a reinforced corner 1010. A horizontal strip of fiber mesh tape (not shown) is placed over the horizontal seam or joint between adjacent vertically stacked lightweight composite panels 1002a, 1002b. A horizontal strip of scam coat 1012 is placed over the horizontal strip of fiber mesh tape to tie the adjacent vertically stacked lightweight composite panels 1002a, 1002b together. This helps prevent separation and potential formation of cracks in a stucco finish applied over the joint between the vertically stacked lightweight composite panels 1002a, 1002b. Finally, a desired exterior finish is applied and adhered to the exterior wall 1000, including over the exterior surfaces of lightweight composite panels 1002 and any seam coat or other underlying layers applied to the lightweight composite panels 1002.

[0096] FIG. 11A illustrates an exterior wall 1110 that includes lightweight composite panels 1112 fastened to a wrapped exterior wall structure 1114 using screws and enlarged washer ensembles 1116 to sheathing (not shown) of the wrapped exterior wall structure 1114. A layer of an appropriate seam coat (e.g., thin set mortar or fine-sanded stucco) 1118 is shown having been applied over a portion of the lightweight composite panels 1112 to cover enlarged washer ensembles 1116 (not shown) placed beneath the layer of seam coat 1118. A first stucco layer 1120 is shown having been applied over the seam coat 1118. A stucco finish 1122 is shown having been applied over the first stucco layer 1120. In this case, the first stucco layer 1120 may be functionally similar to the brown coat of a traditional stucco system, but without having to first apply lath and a scratch coat. The first stucco layer 1120 may form a more uniform surface over which the stucco finish 1122 is applied and/or may enhance the bond of the stucco finish 1122 to the lightweight composite panels 1112 and/or may increase the strength and durability of the stucco system.

[0097] FIG. 11B illustrates an exterior wall 1150 that includes lightweight composite panels 1152 attached over an exterior wall structure (now shown) and illustrates various exterior finishes applied to the lightweight composite panels 1152. These include a stucco finish 1152, thin bricks 1154, and tiles 1156 applied over different portions of the lightweight composite panels 1152. A layer of fiber mesh 1158 and a layer of an appropriate bonding layer (e.g., thin set mortar or fine-sanded stucco) 1160 covering the fiber mesh 118 are applied over a portion of lightweight composite panels 1152 to which the various finished are applied. The stucco finish 1152 (cement- or acrylic-based) can be applied directly over the bonding layer 1160. The thin bricks 1154 can be adhered to the bonding layer 1160 using thin set mortar (not clearly shown) and/or an adhesive. The tiles 1156 can be adhered to the bonding layer 1160 using thin set mortar (not shown) and/or an adhesive.

[0098] In some embodiments, a method of constructing an exterior wall finish comprises: (1) forming or providing an exterior wall structure of a building or enclosure; (2) fastening a plurality of lightweight composite panels to an exterior side of the exterior wall structure, the lightweight composite panels each comprising: (a) a foam core (e.g., polymer or inorganic foam) having a first surface, a second surface opposite the first surface, a first edge forming a perimeter of the first surface, a second edge forming a perimeter of the second surface, and side surfaces extending between the first and second edges; (b) a first protective layer (e.g., first fiber mesh reinforced cementitious layer, thermoset polymer, or other rigid material) formed over and covering at least a portion of the first surface of the foam core; and (c) a second protective layer (e.g., second fiber mesh reinforced cementitious layer, thermoset polymer, or other rigid material) formed over and covering at least a portion of the second surface of the foam core, (d) wherein the lightweight composite panels are positioned so that one protective layer faces toward and the other protective layer faces away from the exterior wall structure of the building; and (3) applying an exterior finish to the lightweight composite panels.

[0099] In some embodiments, an exterior wall finish comprises: (1) an exterior wall structure of a building or enclosure; (2) a plurality of lightweight composite panels fastened to an exterior side of the exterior wall structure, the lightweight composite panels each comprising: (a) a foam core (e.g., polymer or inorganic foam) having a first surface, a second surface opposite the first surface, a first edge forming a perimeter of the first surface, a second edge forming a perimeter of the second surface, and side surfaces extending between the first and second edges; (b) a first protective layer (e.g., first fiber mesh reinforced cementitious layer, thermoset polymer, or other rigid material) formed over and covering at least a portion of the first surface of the foam core; and (c) a second protective layer (e.g., second fiber mesh reinforced cementitious layer, thermoset polymer, or other rigid material) formed over and covering at least a portion of the second surface of the foam core, (d) wherein the lightweight composite panels are positioned so that one protective layer faces toward and the other protective layer faces away from the exterior wall structure of the building; and (3) an exterior finish applied to the lightweight composite panels.

[0100] In some embodiments, the exterior wall structure comprises at least one of wooden studs or metal studs and sheathing fastened to the studs. The lightweight composite panels to which the exterior finish is applied can be fastened to the sheathing by screws or other mechanical fasteners. In some embodiments, the sheathing may comprise OSB panels, either traditional OSB panels or modified OSB panels that include a waterproofing layer (i.e., ZIP System panels). In other embodiments, the lightweight composite panels to which the exterior finish is applied can function as the sheathing. In such case, the lightweight composite panels will be fastened directly to the wooden or metal studs of an exterior wall frame. In yet other embodiments, an underlying layer of lightweight composite panels can be the sheathing, and lightweight composite panels to which the exterior finish is applied are fastened to the underlying layer of lightweight composite panels.

[0101] The screws or other fasteners for securing lightweight composite panels used as sheathing to a wall frame can be spaced about at predetermined intervals, such as to match spacing between studs in the x-direction and with spacing in the y-direction to securely fasten the lightweight composite panels to the wall frame and form a shear wall. Alternatively, lightweight composite panels used as sheathing can be fastened to studs or other structural elements of a wall frame using construction adhesive instead of, or in addition to, screws or other mechanical fasteners, which can improve the shear strength of the wall structure. Screws, mechanical fasteners, construction adhesives, and other fastening elements known in the art comprise means for fastening lightweight composite panels to studs or other structural elements of wall frames.

[0102] FIG. 12 illustrates the use of mesh tape 1202 that acts as a template for proper placement of screws or other mechanical fasteners when fastening lightweight composite panels 1200 to studs 1210 or other structural elements of a wall frame. Placement of screws or other mechanical fasteners through the mesh tape 1202, preferably at or near the center line of the mesh tape 1202, helps ensure that the screws or other mechanical fasteners reliably engage the studs 1210 or other structural elements rather than being driven uselessly outside the studs or other structural elements.

[0103] In some embodiments, the screws or other fasteners used to attach lightweight composite panels to a wall frame include corresponding washers or enlarged heads, also known as pan head screws or screws with integrated washers, that are at least about 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm, or 80 mm, in diameter. This ensures sufficiently large surface contact between the screws or other fasteners and the fiber mesh reinforced cementitious (or other protective) layer so that the screws or other fasteners provide a higher pull-out force to the lightweight composite panels thus improving the structural integrity of the wall structure formed by the lightweight composite panels.

[0104] To illustrate this point, FIG. 13 illustrates a lightweight composite panel 1300 with holes 1310 formed by screws 1305 passing all the way through the exterior fiber mesh reinforced cementitious layer. Remnants of fiber mesh 1320 of the damaged fiber mesh reinforced cementitious layer can be seen. The holes 1310 were the result of screw heads being too small (i.e., having too little surface area) to prevent the screws and screw heads from perforating and penetrating all the all the way through the exterior fiber mesh reinforced cementitious layer. FIG. 13 further illustrates a screw 1305 with a washer 1330 abutting the surface of the lightweight composite panel 1300 without having passed through the exterior fiber mesh reinforced cementitious layer.

[0105] Reference is now made to FIGS. 14A-14D, which illustrate the use of specialized washers with enlarged surface areas and penetrating prongs that help fix the washers in place relative to the lightweight composite panels, prevent rotation when screws are being driven into studs or other structural elements of a wall frame, and add additional lateral strength between the washers and the lightweight composite panels. The penetrating prongs can also be designed to abut the underlying stud or other structural element and act as a stop to prevent the washers from being driven too far into the lightweight composite panel and undesirably crushing or fracturing the exterior fiber mesh reinforced cementitious (or other protective) layer, which could greatly reduce the shear strength of the exterior wall structure or roofing deck.

[0106] FIG. 14A more particularly illustrates the use of screws 1405 and specialized washers 1410 having a plurality of penetrating prongs 1420. The specialized washers 1410 can be rectangular in shape in order to overlap the end surfaces of adjacent lightweight composite panels 1400a, 1400b. The penetrating prongs 1420 penetrate through and become embedded within the lightweight composite panels 1400a, 1400b, including though the exterior fiber mesh reinforced cementitious (or other protective) layers and at least partially through the foam cores of the lightweight composite panels 1400a, 1400b. The penetrating prongs 1420 hold the specialized washers 1410 in a desired position relative to the lightweight composite panels 1400a, 1400b and prevent rotation while the screws 1405 are being driven through the lightweight composite panels 1400a, 1400b and into the underlying stud 1425 or other structural elements of a wall frame. The penetrating prongs 1420 thereby ensure that left and right wings of the specialized washers 1410 reliably overlap corresponding surfaces of the left and right lightweight composite panels 1400a, 1400b to tie them together. The penetrating prongs 1420 can also provide a load spreading/pressure spreading effect, i.e., the prongs 1420 distribute the normal and lateral pressure from the screw 1405 to the prongs. The specialized washers 1410 and penetrating prongs 1420 provide greater lateral tension of the screw and washer ensemble relative to the lightweight composite panels 1400a, 1400b, thereby increasing the overall shear strength of the wall structure. FIG. 14A also illustrates a specialized washer 1430 having a circular shape.

[0107] FIGS. 14B-14D more particularly illustrate a fastener assembly 1400 comprising a screw 1402 and specialized washer 1404 with a circular shape, enlarged surface area, and penetrating prongs 1410 for attaching a lightweight composite building panel 1420 to a stud 1450 or other structural element (e.g., OSB sheathing). The penetrating prongs 1410 help fix the washer 1304 in place relative to the lightweight composite building panel 1420 prevent rotation of the washer 1404 when the screw 1402 is being driven into the stud 1450 or other structural element of a wall or roof structure and add additional lateral strength between the washers 1404 and the lightweight composite building panel 1420. The penetrating prongs 1410 can also be designed to abut the underlying stud 1450 or other structural element and act as a stop to prevent the washer 1404 from being driven too far into the lightweight composite building panel 1420 and undesirably crushing or fracturing the exterior fiber mesh reinforced cementitious (or other protective) layer 1422, which could reduce the strength of an exterior wall structure or roofing deck.

[0108] FIG. 14B more particularly illustrates the use of a specialized fastener assembly 1400 comprising a screw 1402 and specialized washer 1404 having a body 1406 of enlarged diameter, a concave interior portion 1408, and a plurality of penetrating prongs 1410 extending laterally from the washer body 1406. Although the specialized washer 1404 in this embodiment is illustrated as having a circular washer body 1406, other embodiments of specialized washers may include enlarged rectangular-shaped washer bodies (not shown) designed to more completely overlap and adjoin adjacent lightweight composite panels during installation.

[0109] The penetrating prongs 1410 are designed to penetrate through and become embedded within a lightweight composite panel 1420, including though the exterior fiber mesh reinforced layer 1422, at least partially through the foam core 1424, and optionally through the interior fiber mesh reinforced layer 1426 and drainage layer (not shown) so as to make abutment with a stud 1450 or other structural element of a wall or roof frame. The penetrating prongs 1410 help retain the specialized washers 1404 in a desired position relative to the lightweight composite panel 1420 and prevent rotation while the screw 1402 is being driven through the lightweight composite panel 1420 and into the underlying stud 1450 or other structural element of a wall or roof structure. The penetrating prongs 1410 can also provide a load spreading/pressure spreading effect to distribute normal and lateral pressure from the screw 1402 and washer body 1406 to the prongs 1410. The specialized washer 1404 and penetrating prongs 1410 provide greater lateral tension of the screw and washer assembly 1400 relative to the lightweight composite building panel 1420, thereby increasing the overall shear strength of a wall or roof structure.

[0110] FIG. 14C is a bottom perspective view and FIG. 14D is a top perspective view of the specialized washer 1404, which more particularly illustrate features of the specialized washer 1404. The washer body 1406 can have an enlarged diameter in order to provide higher surface area and increase contact between the specialized washer 1404 and an adjacent fiber reinforced cementitious (or other protective) layer of a lightweight composite panel 1420. The washer body 1406 can have a concave interior portion 1408, which permits an outer rim 1412 to become substantially flush with, and the concave interior portion 1408 to advance below, the adjacent fiber reinforced cementitious (or other protective) layer when used to attach a lightweight composite building panel 1420 to a wall or roof structure, as shown in FIG. 14B. This allows the concave interior portion 1408 to partially compress the interior foam core 1424 and exterior fiber reinforced cementitious (or other protective) layer 1422 of the lightweight composite panel 1420 to provide firm and reliable attachment of the panel 1420 to the wall or roof structure. The washer body 1406 can include a countersink 1414 that accommodates the head 1403 of the screw 1402 so that the screw head 1403 does not protrude beyond the surface of the washer body 1406 when driven into a stud 1450 or other structural element of a wall or roof frame.

[0111] The length of the penetrating prongs 1410 can be selected to determine and limit how far the concave interior portion 1408 of the washer body 1406 is able to advance into and compress the lightweight composite panel 1420, forming a depression therein. The penetrating prongs 1410 can advantageously have a length in order to penetrate all the way through the lightweight composite panel 1420 and make contact with the stud 1450 or other structural element. In this way the penetrating prongs 1410 can act as a stop that limits how far the specialized washer 1304 can be driven toward and into the lightweight composite panel 1420. Providing a stop prevents the specialized washer 1304 from being driven too far into the lightweight composite panel 1420, thereby preserving the structural integrity and strength of the exterior fiber mesh reinforced cementitious (or other protective) layer 1422 adjacent to the specialized washer 1404. This preserves and maximizes the overall strength, including shear strength, of the wall structure.

[0112] In some embodiments, it may be desirable for the length of the penetrating prongs 1410 to be slightly less than the cross-sectional thickness of the lightweight composite panel 1420 in order to superficially compress, but not damage, the exterior fiber mesh reinforced cementitious (or other protective) layer 1422 toward the polymer foam core 1424 to thereby increase the compressive force of the washer 1404 bearing against the lightweight composite sheathing panel 1420. This can increase the overall fixation strength of the fastening assembly 1400.

[0113] In some embodiments, sealing one or more joints or seams between adjacent lightweight composite panels includes applying waterproof tape, metal flashing, polyurethane foam, fiber mesh tape and an appropriate seam coat (e.g., thin set mortar or fine sanded stucco), or other sealing means known in the over the joints or seams, including joints or seams in the wall face and corners. In addition, joints, seams, openings, or gaps between lightweight composite panels and other structural elements, such as wooden or metal beams or posts, vent pipes in roofs, fixtures, and the like, can be filled using sealing means known in the art, such as polyurethane foam, metal flashing, or tar.

[0114] In some embodiments, an appropriate seam coat can be applied over at least a portion of the exterior facing fiber mesh reinforced cementitious (or other protective) layer, including over any exposed screws, washers, or other mechanical fasteners used to attach the lightweight composite panels to the exterior wall structure, and over any joints or seams, fiber mesh tape, polyurethane, or other exposed sealants on or in the exterior wall structure.

[0115] To illustrate the significant improvements provided by the methods and systems for constructing exterior wall finishes, the following comparisons are made between stucco systems made using lightweight composite panels and either a traditional hardcoat stucco system or an exterior insulation and finish system (EIFS). Advantages include streamlined and simplified methods and systems that reduce steps, labor, and material requirements while maintaining fire rating and structural integrity.

[0116] A traditional 3-coat system, also known as a hard coat system, requires the following steps: [0117] 1. Install some type of house wrap (1 or 2 layers); [0118] 2. Attach wire mesh/lath; [0119] 3. Apply scratch coat (first cement layer for bonding) over the lath; [0120] 4. Apply brown coat (second cement layer for smoothness) over the scratch coat; [0121] 5. Apply primer if acrylic stucco is used; and [0122] 6. Apply finish stucco coat.
In a modified process, the scratch and brown coats can be combined in a single thicker layer (e.g., ( inch to inch thick)

[0123] By comparison, applying an exterior stucco finish according to the disclosure includes the following steps: [0124] 1. Fasten lightweight composite panels directly to sheathing (e.g., OSB) or studs using proprietary screws (19.8 mm heads) or screws with washers or adhesive; [0125] 2. Apply 4 inch fiberglass mesh on corners and seams; [0126] 3. Apply bond coat to cover screws/washers, seams, and corners to create a surface for the final stucco coat and prevent cracking; no mesh is required to cover screws but is optional; [0127] 4. Directly apply the exterior finish (stucco or other finishes); no primer is required but is optional.

[0128] The following is a summary of improvements of the disclosed methods and systems for constructing an exterior wall finish compared to traditional hard coat stucco system: [0129] Eliminates wire mesh, scratch coat, primer (if acrylic-based stucco), and brown coat across large wall areas (only a seam coat is needed for seams and screwheads). [0130] Results in reduced labor, shorter scaffolding rental, safer working conditions (removes cement spraying on large commercial jobs and less mobilization of premixed concrete materials), and cleaner installation. [0131] Lightweight composite panels support other exterior finishes, including but not exclusive to synthetic, acrylic, brick veneer, stone and masonry, and porcelain slabs. [0132] Eliminates up to 4 steps.

[0133] An EIFS system for applying stucco requires the following steps: [0134] 1. Install some type of weather resistant barrier (WRB) over sheathing; [0135] 2. Apply some type of rain screen (drainage plane); [0136] 3. Install foam insulation board over WRB and rainscreen (drainage plane) with fasteners or adhesive; [0137] 4. Apply base coat to stick mesh; [0138] 5. Apply reinforcing mesh to the surface of the foam board on the wet base coat; [0139] 6. Apply one or two base coats to cover the mesh; [0140] 7. Apply a primer for finish coat; and [0141] 8. Apply the finish coat (typically acrylic-based).

[0142] By comparison, applying an exterior stucco finish according to the disclosure includes the following steps: [0143] 1. Fasten lightweight composite panels directly to sheathing (e.g., OSB or underlying layer of lightweight composite panels) with integrated drainage layer using proprietary screws (19.8 mm heads) or screws with washers or adhesives; [0144] 2. Apply 4 inch fiberglass mesh on corners and seams; [0145] 3. Apply bond coat to cover screws/washers, seams, and corners to create a surface for the final stucco coat and prevent cracking; no mesh required to cover screws but is optional; [0146] 4. Directly apply the exterior finish (stucco or other finishes); no primer is required but is optional. [0147] 5. Eliminates up to 5 steps.

[0148] The following is a summary of improvements of the disclosed methods and systems for constructing an exterior wall finish compared to EIFS: [0149] 1. Simplified Installation: [0150] Use of lightweight composite panels as substrates replaces the multiple layers required by EIFS (insulation board, base coat, mesh, base coat) with a single panel; [0151] Adds increased strength because fiber mesh reinforced cementitious layer coat is on both sides; [0152] Reduces the number of materials, installation steps, and potential errors. [0153] 2. Improved Moisture Management: [0154] Use of lightweight composite panels as substrates can employ a drainage layer as integrated parts of the system for water drainage, further minimizing installation steps while supporting sound moisture management (an area where EIFS is known to require careful detailing to prevent failure). [0155] 3. Labor and Cost Savings: [0156] Use of lightweight composite panels is a two-layer approach that eliminates labor-intensive steps, such as applying mesh, adhesive, base coat, and primer; [0157] Fewer steps translate to faster installation and lower scaffolding rental costs. [0158] 4. Versatile Finish Options: [0159] Use of lightweight composite panels accommodates a variety of exterior finishes, including synthetic stucco, acrylics, and brick veneer, stone and masonry, offering comparable design flexibility to EIFS. [0160] 5. Summary: [0161] While EIFS provides good insulation and finish flexibility, use of lightweight composite panels simplifies the installation process, offers superior moisture control and fire resistance, and reduces labor and project costs. [0162] It delivers these benefits without sacrificing design versatility, making it a robust alternative to traditional EIFS systems.

[0163] Use of lightweight composite panels as sheathing instead of OSB panels to form exterior wall structures and roofing decks has the following advantages over exterior wall structures and roofing decks made using conventional or modified OSB panels. [0164] lightweight composite panels can replace traditional OSB sheathing; [0165] they can be applied directly to various substrates or framing (wood/metal studs) using either mechanical fasteners or adhesives; [0166] this system reduces the number of layers required between the internal structure and the final exterior finish, offering improved waterproofing, insulation, vapor permeability, and mold resistance.

[0167] A traditional OSB process typically requires the following steps: [0168] 1. Install OSB sheathing over the exterior wall frame (e.g., studs); [0169] 2. Apply a polymer house wrap (such as Tyvek) over the OSB sheathing for weather protection; [0170] 3. Use sealants or flashing around joints and openings to prevent water intrusion; and [0171] 4. Apply exterior finish cladding (siding, stucco system, or other) over the wrapped OSB units.

[0172] By comparison, the use of lightweight composite panels as exterior sheathing involves the following simplified steps: [0173] 1. Install lightweight composite panels over the wall or roof frame (e.g., studs); [0174] 2. Use polyurethane or other sealing foam around joints and fenestration openings to prevent water intrusion; and [0175] 3. Apply an exterior finish (siding, stucco system, thin bricks, stones, tiles, or other finishes) directly to the exterior surfaces of the lightweight composite panels.

[0176] The use of lightweight composite panels as exterior sheathing provides the following benefits compared to traditional OSB building systems: [0177] 1. Simplified layering: [0178] lightweight composite panels eliminate the need for both OSB panels and house wrap, serving as both structural sheathing and waterproof barrier; [0179] This reduction in layers results in faster installation and fewer materials. [0180] 2. Waterproofing at joints: [0181] while OSB relies on house wrap and careful sealing at joints, the disclosed systems incorporate waterproof tape to seal joints directly, enhancing moisture resistance with fewer steps. [0182] 3. Fire resistance: [0183] standard OSB panels lack fire resistance, whereas lightweight composite panels offer built-in fire rating compliance without additional coatings or treatments. [0184] 4. Mold and moisture protection: [0185] OSB is susceptible to mold and swelling if exposed to moisture; [0186] the moisture-resistant core of the disclosed lightweight composite panels eliminates these risks, improving durability in wet environments. [0187] 5. Labor and cost savings: [0188] by reducing the number of layers (no need for OSB panels, house wrap, or additional waterproofing steps), use of the disclosed lightweight composite panels saves labor time and lowers material costs.

[0189] The use of lightweight composite panels as exterior sheathing provides the following benefits compared to modified OSB systems, such as ZIP System. The ZIP System process: [0190] combines OSB sheathing with an integrated weather-resistant barrier, eliminating the need for traditional house wrap; [0191] joints are sealed with proprietary ZIP tape to ensure air and moisture resistance. [0192] install ZIP system sheathing over the structure (e.g., studs).

[0193] In contrast, the following is a comparison of the use of lightweight composite panels as exterior sheathing compared to the ZIP System: [0194] 1. Integrated waterproofing: [0195] similar to the ZIP system, the disclosed method and system uses waterproof tape to seal joints between adjacent lightweight composite panels, ensuring effective moisture management; [0196] however, the lightweight composite panels used in the disclosed method and system combines sheathing with a bonding surface for stucco and other finishes, reducing layers and materials. [0197] 2. Enhanced fire resistance: [0198] The ZIP system sheathing provides weather resistance but does not offer inherent fire protection (i.e., the OSB core panel is still made from wood and can burn similar to standard OSB panels; [0199] lightweight composite panels integrate fire resistance, streamlining compliance with building codes. [0200] 3. Design flexibility: [0201] While the ZIP system is mainly intended for use under standard siding or cladding, lightweight composite panels support multiple exterior finishes, including stucco, acrylic coatings, brick veneer, stone and masonry, tiles, and the like, enhancing architectural options.

Additional Terms & Definitions

[0202] While certain embodiments of the present disclosure have been described in detail, with reference to specific configurations, parameters, components, elements, etcetera, the descriptions are illustrative and are not to be construed as limiting the scope of the claimed invention.

[0203] Furthermore, it should be understood that for any given element of component of a described embodiment, any of the possible alternatives listed for that element or component may generally be used individually or in combination with one another, unless implicitly or explicitly stated otherwise.

[0204] In addition, unless otherwise indicated, numbers expressing quantities, constituents, distances, or other measurements used in the specification and claims are to be understood as optionally being modified by the term about or its synonyms. When the terms about, approximately, substantially, or the like are used in conjunction with a stated amount, value, or condition, it may be taken to mean an amount, value or condition that deviates by less than 20%, less than 10%, less than 5%, less than 1%, less than 0.1%, or less than 0.01% of the stated amount, value, or condition. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0205] Any headings and subheadings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims.

[0206] It will also be noted that, as used in this specification and the appended claims, the singular forms a, an and the do not exclude plural referents unless the context clearly dictates otherwise. Thus, for example, an embodiment referencing a singular referent (e.g., widget) may also include two or more such referents.

[0207] It will also be appreciated that embodiments described herein may also include properties and/or features (e.g., ingredients, components, members, elements, parts, and/or portions) described in one or more separate embodiments and are not necessarily limited strictly to the features expressly described for that particular embodiment. Accordingly, the various features of a given embodiment can be combined with and/or incorporated into other embodiments of the present disclosure. Thus, disclosure of certain features relative to a specific embodiment of the present disclosure should not be construed as limiting application or inclusion of said features to the specific embodiment. Rather, it will be appreciated that other embodiments can also include such features.