VAPOR BARRIER

RELATED APPLICATIONS

[0001] This application is a non-provisional application based on provisional patent application U.S. Serial No. 62/157,171, filed May 5, 2015, the disclosure of which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

[0002] Building codes are progressively requiring improved energy efficiency. As a result, prescriptive code requirements for continuous insulation and continuous air barriers have become widespread. At the same time, buildings must be designed to effectively manage moisture from both exterior and interior sources. In addition, the assemblies must conform to structural and fire safety requirements.

[0003] The exterior walls are the most complex area to address due to the variety of assemblies and the interface with other assemblies and architectural features. Exterior wall assemblies are becoming increasingly complex in order to meet the aforementioned code and performance requirements. A typical commercial exterior wall assembly consists of interior gypsum board, steel studs with fiber insulation batts, perhaps a vapor retarder on the inside of the insulation batts, exterior gypsum sheathing, an air and water resistive barrier membrane, continuous insulation, and exterior cladding. Each of these components must be sourced and installed. Additionally, the components must work together to deliver a high-performing assembly.

[0004] To fulfill the wall assembly continuous insulation function, board foam, spray foam or semi rigid fiber batt insulation is typically used. Polyisocyanurate (polyiso) board foam insulation is becoming more popular in walls due to its high R value per inch and good burn properties.

[0005] High-density (HD) polyiso has also become popular for use as a cover board in single ply roofing assemblies. HD polyiso provides a tough, hard substrate to enhance the mechanical and puncture resistance of the overlying roof membrane. The HD polyiso offers advantages of being light weight and highly moisture resistant compared to gypsum or fiber cover board. To further reduce labor, a composite product is offered consisting of HD polyiso factory-laminated to standard polyiso insulation (HD polyiso composite board). In roofing applications, HD polyiso composite board allows quick, easy installation of insulation and cover board in a single step.

[0006] Air and water resistive barrier membranes can consist of fully-adhered sheets, liquid coatings or mechanically-attached wraps. Fully-adhered systems are favored in high-performance applications due to their enhanced level of air and water tightness.

[0007] Plastic sheet, foil or kraft paper vapor retarders are often used in colder climates to reduce winter time stud cavity condensation. Due to discontinuous application or displacement in service, the benefit provided by these products is often reduced or eliminated.

SUMMARY OF THE INVENTION

[0008] The invention provides a means of installing a vapor retarder, wall sheathing, continuous insulation, air barrier and water resistive barrier in one simple system. The factory-application and layering of the components provides an exterior board which simplifies installation and reduces the possibility of incorrect or missing components.

[0009] The invention provides a HD polyiso composite board with fully-adhered, self-sealing membrane air and water barrier membrane factory-laminated to the HD side of the composite. The composite board is installed on the exterior wall with the membrane facing the exterior. Different versions of the composite board provide appropriate hygro-thermal performance for the building's use and location. To fulfill these requirements, an aluminum foil facer (vapor retarder) or a coated glass facer (vapor permeable) may be provided on the interior side of the composite board, while a vapor permeable or vapor retarding air/water barrier membrane may be on the exterior side.

[0010] The invention provides the same simplicity and installer friendliness as the current "foam boards and tape" approach. However, the added features provided by the invention include: 1) tough, self-sealing air & water barrier membrane over hard HD polyiso substrate an 2) optimal configuration for hygrothermal performance - i.e. optional interior vapor retarder, optional permeable or non-permeable air/water barrier membrane.

[0011] The invention will be further appreciated in light of the following detailed description and drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a perspective view, partially broken away, of a wall system according to the present invention;

[0013] FIG. 2 is an exploded view of a foam board for use in the present invention;

[0014] FIG. 3 is a cross-sectional view of a wall system according to the present invention showing exterior cladding;

[0015] FIG. 4 is an exploded view of a further embodiment of the present invention;

[0016] FIG. 5 is a cross-sectional view of a wall structure partially exploded showing heat and moisture transfer through the board shown in FIG. 4;

[0017] FIG. 6 is an exploded view similar to FIG. 4;

[0018] FIG. 7 is a view similar to FIG. 5 with the wall board of FIG. 6; and

[0019] FIG. 8 is a view similar to FIG. 7.

DETAILED DESCRIPTION OF THE INVENTION

[0020] According to the present invention, an exterior wall system 10 includes a plurality of verticals studs 12, typically metal studs, extending from a base plate to a top plate (not shown). Fastened to the studs 12 are rigid foam boards 18. Sealing tape 22 is applied to edges of adjoining boards. As shown in FIG. 3, exterior cladding 32 can be attached using fasteners 34. Wallboard 36 can be attached to the interior of studs 12 to form the finished surface of the interior wall.

[0021] As shown in FIG. 2, the foam board 18 includes a first foam layer 40 and a second foam layer 42. The first foam layer 40 is intended to face way from the building when installed and will generally be a thinner, denser layer which provides strength and rigidity, while providing some insulation. The second foam layer 42 is less dense and thicker to optimize R-value. The first and second foam layers will generally be made from the same chemical composition, such as expanded polystyrene, polyiso or the like. Other foam boards such as phenolic foam and rigid polyurethane foam can be used in the present invention. [0022] The first layer 40 will generally have a thickness of from .25 to 1", generally .5", and a core compressive strength of at least 60 psi up to about 125 psi. Second layer 42 is thicker than layer 40, with a thickness of about 1.5 to 4.5" and a core compressive strength of at least 15 psi up to about 25 psi. Generally, the minimum physical characteristics of the combined board 18 are:

• Thermal resistance R6-R30, as per ASTM 518 according to ASTM C1289 or ASTM 578;

• Air permeance less than 0.004 CFM/ft ² at 1.57 PSF ASTM E 2178;

• Damage resistance exterior face at least 50 ASTM D1032 (Janka Ball Test);

• Water resistance: 22" water column - no leaks after 5h AATCC 217;

• Nail seal ability (outboard side) pass ASTM D1970.

[0023] Boards 18 include a self-sealing outer layer 48 so that when fasteners 20 penetrate the board 18, they do not compromise the barrier characteristics of the board 18. As described herein, membrane 48 acts as a water/air barrier and may be either vapor permeable or vapor impermeable, depending on the application as described below. If water vapor impermeable, membrane 48 should have a water vapor permeance of 0.1 perm or less, ASTM E 96A and 1.0 perm or less ASTM E96B. If vapor permeable, the permeance should be greater than 1 perm ASTM E95A and 10 perms or more ASTM 96B.

[0024] The layer 48 can be a liquid applied coating which is factory-applied to the exterior surface of the composite board and sets. The coating can also be an elastomeric-like material with a thickness of at least 20 mils. Further, it can be an asphaltic-type emulsion.

[0025] The membrane 48 can also be a sheet membrane, factory laminated to the exterior of the composite board. The sheet membrane would consist of a facing, such as a polypropylene or other polyolefinic material coated with a layer of a tacky mastic-like pressure-sensitive adhesive. The mastic-like pressure sensitive adhesive consists of rubberized asphalt, latex, acrylic or other tacky polymers and is again at least 20 mils thick. The facing simply prevents the composite boards from sticking to each other.

[0026] As shown in FIG. 1, the boards 18 of the present invention are affixed directly to the studs 12 without any intervening gypsum layer or the like, so that the interior surface 46 directly abuts the studs 12. The fasteners are then driven directly through the foam board 18 into the studs 12 with the heads 52 of fasteners 20 abutting the exterior surface 44. This fastener arrangement is also shown in FIG. 3. Since the membrane 48 is self-sealing, the penetration from the fasteners does not destroy the water/air barrier properties of the board.

[0027] As shown in FIG. 3, exterior cladding 32 is applied on wall system 10 directly over outer surface 44 of board 18 using standard attachment mechanisms, depending on the selected cladding. The exterior cladding can be stone, brick, stucco or metal, as well as other well known materials.

[0028] The board 18 is formed by known processes. Generally, the first and second layers are formed and bonded together, along with the barrier 48 and, if desired, an interior barrier layer. The interior face 50 of board 18 can be one of a variety of different material, depending on the desired characteristics of the finished board as discussed below. Interior face 50 can either be water vapor permeable or water vapor impermeable, depending on the desired application. If it is intended to be water vapor permeable, it can be, for example, a coated glass face with a water vapor permeance of 5 perms or more ASTM 96A. If it is intended to be impermeable, it can be an aluminum foil face with a permeance of 0.1 perm or less ASTM E96A. The face can also be a polymeric film or the like, provided it has the requisite permeance.

[0029] The embodiment of board 18 shown in FIG. 2 is but one basic embodiment of the present invention. The present invention can be modified to accomplish a number of desired end results, although all embodiments will include a self-sealing water barrier layer 48. In particular, the present invention can be modified for optimal use in cold climates, moderate climates and in warm humid climates.

[0030] In particular, the board 72 shown in FIGS. 4 and 5 is particularly suitable for use in colder climates. In this embodiment, the outboard side 74 of the board 72 includes the self-sealing membrane 48. In this embodiment, membrane 48 is vapor permeable. Membrane 48 is attached to a dense polyiso board layer 76 which is approximately 1/2 inch thick, 100 PSI, and includes first and second coated glass facers 78, 80 laminated to either side of the polyiso foam core board 76. The facer boards enhance the toughness of the outboard facing membrane by providing a high compressive strength substrate. In turn, a laminating adhesive layer 82 bonds the dense polyiso foam core layer 76 to the thicker, less dense polyiso core layer 84. This layer 84 generally has a thickness of 1-4.5 inches and a density of around 20-40 PSI. Between the adhesive layer 82 and the foam core layer 84 is a coated glass facer 86. Finally, there is an aluminum foil facer 88 on the inboard side of the board 72. [0031] FIG. 5 shows how the board 72 functions in a colder environment. The interior surface of the wall system 91 is gypsum 90 attached to, for example, steel studs 92, to which the board 72 is attached. With more heating inside than cooling, there is a vapor drive as indicated by arrows 94 which would impinge and be blocked by the foil facer 88. In turn, due to the fact that the self- sealing membrane 48 is vapor permeable, there is drying potential as indicated by arrows 96 from the polyiso cores to the exterior of the building (through cladding 98), which is preferred when the exterior is typically colder than the interior.

[0032] Composite board 100 shown in FIG. 6 is designed for use in a moderate climate. Board 100 allows vapor permeation in either direction. In this embodiment, self-sealing membrane 48 is vapor permeable and is bonded to the thin, dense polyiso core 102, which is laminated to two glass facers 104, 106 and adhered to a thicker 20 PSI polyiso foam core 108, also laminated to two coated glass facers 110, 112, with an adhesive layer 114 bonding the two layers together. As shown in FIG. 7, this embodiment allows for vapor drive represented by arrows 116 and 118, as well as drying potential as indicated by arrows 120, 122, to go in either direction. This will minimize moisture formation on the surface and maximize the R-value of the insulation.

[0033] Composite board 124 shown in FIG. 8 is useful for warm, humid climates where the cooler, drier air would typically be on the inside of the building. This embodiment again has a self- sealing membrane 48 but, in this embodiment, it is formed as a vapor impermeable membrane. Otherwise, this composite board is the same as that shown in FIG. 6.

[0034] As further shown in FIG. 8, the vapor impermeable membrane 48 prevents the outside vapor (as represented by arrow 126) from passing through the board 124 and further allows moisture (as represented by arrow 128) to be drawn from the foam core into the building.

[0035] In any of the embodiments shown in FIGS. 1-8, the high density polyiso board (40 in FIGS. 2 and 3, or 76 in FIG. 4, 102 in FIG. 6) can be replaced with a 5/8" plywood or OSB board, although generally plywood is preferred. Such a board would provide all of the advantages of the present invention, however, it would also provide a structure to nail, for example, siding directly to the cover board of the present invention. It will still have the same vapor permeability and moisture impermeability as the various embodiments shown herein. It will also retain the self- sealing features provided by membrane 48. Basically any high density nail-receiving material, such as plywood or OSB board, can function in this embodiment. [0036] This has been a description the present invention, along with the preferred method of practicing the present invention, however, the invention itself should only be defined by the appended claims, wherein we claim: