VAPOR-PERMEABLE, WATER-RESISTANT SHEATHING AND METHODS THEREOF

Abstract

Embodiments of the present invention generally relate to sheathings generally used for building structures. More specifically, embodiments of the present invention relate to vapor-permeable, water-resistant, surface-treated sheathings having a drainage plane. In one embodiment a sheathing comprises a plurality of core layers, a first and second surface layer, each defining an exterior surface of the sheathing, and a plurality of adhesive layers, each disposed between each of the plurality of core layers, wherein the sheathing comprises a permeability rate of at least about 5 perms, and an absorption rate of less than about 15% water-by-weight.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to sheathings generally used for building structures. More specifically, embodiments of the present invention relate to vapor-permeable, water-resistant, surface-treated sheathings having a drainage plane.

2. Description of the Related Art

Sheathings are widely used in construction to form the exterior surface of a building or as an intermediary layer between the exterior surface and the interior framework of the building. These sheathings may typically be exposed to liquid water from outside the building, in the form of atmospheric precipitation, as well as water vapor from inside the building. The sheathings may also be exposed to liquid water from inside the building due to moisture introduced into the framework during the building process.

Much of the building industry relies upon the use of non-water-resistant sheathings with low permeability. The sheathings are fastened to the building frame and covered with construction fabric in the form of “house wrap”, to protect from water intrusion and to allow water vapor to escape. This method traps any moisture inside the wall cavity behind the sheathing regardless of its permeability. Introduction of liquid water to the internal structure may cause problems such as mold and rot which can compromise the integrity of the structure.

Additionally, if exterior cladding is installed over house wraps, to increase water-resistance, the cladding is generally fastened tightly against the house wrap surface. This provides an opportunity for water to become entrapped in localized areas. The entrapped water may thus enter the non-water-resistant sheathing either by directly passing through the house wrap or by following a path of least resistance through any fastener locations. Attempted solutions have included using apertures in- or varying the thickness of vapor-permeable but water-resistant layers, such as adhesive layers and outer resin layers, to increase the permeability. Both have failed to meet industry needs.

Thus, there is a need for an improved sheathing.

SUMMARY OF THE INVENTION

Embodiments of the present invention generally relate to sheathings generally used for building structures. More specifically, embodiments of the present invention relate to vapor-permeable, water-resistant, surface-treated sheathings having a drainage plane.

In one embodiment a sheathing comprises a plurality of core layers, a first and second surface layer, each defining an exterior surface of the sheathing, and a plurality of adhesive layers, each disposed between each of the plurality of core layers, wherein the sheathing comprises a permeability rate of at least about 5 perms, and an absorption rate of less than about 15% water-by-weight.

In another embodiment of the present invention, a sheathing comprises at least four core layers comprising a cellulosic or polymeric material, a first and second surface layer comprising a layer of clay impregnated polyvinyl alcohol adhesive, and a plurality of clay impregnated polyvinyl alcohol adhesive layers, each disposed between each of the core layers, wherein the sheathing comprises a permeability rate of at least about 5 perms, and an absorption rate of less than about 15% water-by-weight.

A method of protecting a structure, comprises providing a sheathing having a plurality of core layers, a first and second surface layer, each defining an exterior surface of the sheathing, and a plurality of adhesive layers, each disposed between each of the plurality of core layers, wherein the sheathing comprises a permeability rate of at least about 5 perms, and an absorption rate of less than about 15% water-by-weight, and adhering the sheathing to a structural member of the structure using an attachment means.

BRIEF DESCRIPTION OF THE DRAWINGS

So the manner in which the above recited features of the present invention can be understood in detail, a more particular description of embodiments of the present invention, briefly summarized above, may be had by reference to embodiments, which are illustrated in the appended drawings. It is to be noted, however, the appended drawings illustrate only typical embodiments of embodiments encompassed within the scope of the present invention, and, therefore, are not to be considered limiting, for the present invention may admit to other equally effective embodiments, wherein:

FIG. 1 depicts a cross-sectional view of a sheathing in accordance with one embodiment of the present invention;

FIG. 2 depicts a top perspective view of a sheathing in accordance with one embodiment of the present invention;

FIG. 3 depicts a flowchart illustrating an exemplary method of manufacturing one embodiment of a sheathing in accordance with the present invention; and

FIG. 4 depicts a flowchart illustrating an exemplary method of protecting a structure in accordance with one embodiment of the present invention.

The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include”, “including”, and “includes” mean including but not limited to. To facilitate understanding, like reference numerals have been used, where possible, to designate like elements common to the drawings.

DETAILED DESCRIPTION

Embodiments of the present invention generally relate to sheathings generally used for building structures. More specifically, embodiments of the present invention relate to vapor-permeable, water-resistant, surface-treated sheathings having a drainage plane.

FIG. 1 depicts a cross-sectional view of a sheathing 100 in accordance with one embodiment of the present invention. The sheathing 100 generally comprises a plurality of core layers 110, at least one adhesive layer 120, and a pair of surface layers 130. Optionally, the surface layers 130 comprise a drainage plane for assisting in the drainage of water away from the sheathing 100 or structure, as discussed below. In one embodiment, the sheathing has a total thickness between about 0.050 inch to about 0.625 inch.

The plurality of core layers 110 may comprise as few as two or as many as twelve layers, yet more or few layers are contemplated by embodiments of the present invention. In one embodiment of the present invention, four core layers 110 are provided. In any embodiment of the present invention, two core layers will be the outermost core layers 110 in a sheathing 100. Each of the outermost core layers comprise a surface facing away from the center of the sheathing 100, and are termed the exterior surfaces 130 of the respective core layers 110.

The core layers 110 generally comprise a cellulosic or polymer material provided such material is suitable for embodiments of the present invention. In one embodiment of the present invention, the core layers 110 are comprised of a paperboard.

The term “paperboard,” as it is used herein, comprises all forms of paper and paper-like materials, having a cellulosic composition, useful and suitable for the sheathing industry. Suitable exemplary paperboard materials include, but are not limited to, kraft paper, kraft liner board, recycled kraft or chip board, or the like, which materials are made primarily from or originate from pine wood by digestion with a mixture of caustic soda, sodium sulfate, sodium carbonate, and sodium sulfide. Suitable paperboard may additionally comprise conventional paper.

The core layers 110 may vary in thickness from about 0.003 inch to about 0.200 inch. In one embodiment of the present invention, kraft paper having a thickness of about 0.028 inch is utilized. One exemplary paperboard is commercially available under the name Recycled High Sized Chip from Covalence Specialty Coatings, LLC d/b/a Berry Plastics Tapes and Coatings Division of Constantine, Mich.

The core layers 110 may be adhered to each other by adhesive layers 120 therebetween. The number of adhesive layers 120 is directly correlated to the number of core layers 110 in an embodiment. In one embodiment, where four core layers 110 exist in the sheathing 100, at least three adhesive layers 120 are provided.

The adhesive layers 120 may consist of similar or different materials, including but not limited to any known adhesive composition suitable for embodiments of the present invention. Exemplary adhesive materials include: polyvinyl alcohols, acrylics, thermoplastic hot melts, urea or melamine formaldehyde resins, phenolics, and the like, as well as blends and copolymers thereof. In one embodiment, the adhesive layers 120 comprise at least a clay impregnated polyvinyl alcohol. The thickness of the individual adhesive layers 120 may range from between about 0.0001 inch to about 0.1 inch. In one embodiment, the adhesive layers 120 have a thickness of about 0.001 inch.

A pair of surface layers 140 are provided on the respective exterior surfaces 130 of the outermost core layers 110 of a sheathing 100. Generally, the surface layers 140 comprise any suitable material for embodiments of the present invention. Exemplary materials comprise: polyesters, polyurethanes, acrylic polymers, polyethers, ester-ether copolymers, and the like, as well as blends and copolymers thereof. In one embodiment, a commercially available material suitable for the outer layers 140 comprises an Estane polymer from Lubrizol Advanced Materials, Inc. of Cleveland, Ohio, under the name “TPU (Thermoplastic Polyurethane).”

The thickness of the individual surface layers 140 may range from about 0.0001 inch to about 0.01 inch. In one embodiment, the thickness of each outer layer 140 is about 0.001 inch. In some embodiments, it may be advantageous for each of the surface layers 140 to be comprised of similar or different materials and have similar or different thickness.

In many embodiments, surface layers 140 comprise a drainage plane 220 for assisting in the drainage of water from the sheathing 100. The drainage plane 220 may comprise any chemical, mechanical or structural composition, provided such composition assists in the drainage of water away from the sheathing, as understood by those of ordinary skill in the art. FIG. 2 depicts a top perspective view of the top surface 200 of a sheathing 100 in accordance with one embodiment of the present invention. In one embodiment, a plurality of channels 150 create a drainage plane 220 on a top surface 200 of the sheathing 100. In several embodiments, the channels 150 are multidirectional, and in one embodiment, form a substantially diamond-shaped pattern. In another embodiment, the channels 150 are substantially parallel to one another. The channels 150 generally comprise a depth between about 0.010 inch to about 0.100 inch. Particular embodiments of the present invention may comprise channels in a uniform or random shape, depth or pattern.

Optionally, the sheathing 100 may comprise perforations through its structure in connection with at least or more embodiments, as disclosed above. As understood by embodiments of the present invention, additional treatments may be performed on the sheathing, or individual layers of the sheathing, to accomplish the characteristics set forth by embodiments of the present invention.

Collectively, in many embodiments, the sheathing 100 comprises advantageous vapor-permeability, water-resistance protection, optionally enhanced by a drainage plane 220. Some experimental embodiments of the present invention have demonstrated a water vapor-permeability of at least 5 perms or greater when tested under the ASTM E96, Desiccant Method. The ASTM E96, Desiccant Method, is conducted in a controlled environment, whereby samples are edge sealed all around the surface of a container holding anhydrous chloride. Weight measurement reading is taken until a consistent linear gain is recognized to determine the materials ability to pass water vapor.

Additional experimental embodiments of the present invention have demonstrated about a 15% water-by-weight absorption rate after immersion in de-ionized water for 24 hours. Such sheathings 100 have also met or exceeded water-resistance test criteria such as the “Canadian Pond Test”, wherein a sample of the material is clamped between two annular rings that are 7.8 inches (200 mm) in diameter with a rubber type gasket. Water is then poured into the top ring to a height of 1 inch (25.4 mm). The assembly is raised 10 inches (250 mm) and monitored for two hours. A desirous result would one in which no leakage shall occur through the specimen during the two hour period.

Additional experimental embodiments of the present invention, have also demonstrated at least about a 90% drainage rate when tested using standards such as, for example, ASTM E2273. Testing using the ASTM E2273 standard comprises constructing a full wall, 4 feet in length and 8 feet in height, using a sheathing 100 in accordance with embodiments of the present invention to be tested. The sheathing 100 is covered with a solid foam or plastic sheet that covers the entire surface. A 2 inch by 24 inch slot is cut through the foam plastic cover sheet and 106 cc/min is sprayed into the slot for 75 minutes. The water that drains through the space between the foam/plastic and the sheathing is collected in a collection trough at the wall bottom. The water is allowed to drain for 60 minutes after the 75-minute spray is ended. The collected water is measured.

FIG. 3 depicts a flowchart illustrating an exemplary method of manufacturing one embodiment of a sheathing in accordance with the present invention. The method 300 begins at step 310, and at step 320, core layers 110 are provided. Two of the core layers 110 are selected as outermost core layers, and a surface treatment step 330 (i.e., adding the surface layers) is applied to the exterior surface of the outermost core layers.

At step 340, each of the core layers are adhered to one another, using at least one or more adhesive layers 120. Optionally, this may occur through an extrusion or lamination process. At step 350, the multiple layers are compressed to form a sheathing 100. Any channels 150 may be embossed in the top surface 200 of the sheathing 100 at step 360. Optionally, at step 370, the sheathing is cut and stacked for ease of application as exterior building components. The method 300 ends at step 380.

In one embodiment of the present invention, the method 300 utilizes continuous lamination or extrusion techniques to uniformly apply and/or create each of the respective layers. Alternatively, each of the layers, particularly the outermost core layers and/or adhesive layers may be “printed” onto the core layers using an engraved transfer roll to apply non-uniform layers. In some embodiments, a sheathing may be manufactured using a continuous lamination process utilizing uninterrupted running webs of paperboard, permeable resin and adhesive application methods as described hereinabove, and as understood by those of ordinary skill in the art.

FIG. 4 depicts a flowchart illustrating an exemplary method of protecting a structure in accordance with one embodiment of the present invention. The method 400 begins at step 410, wherein an embodiment of a sheathing 100 is manufactured and provided 420. At step 430, the sheathing 100 is attached to a structural member of the structure using an attachment means. An attachment means may comprise any means known in the industry for putting sheathing on an exterior surface. Exemplary attachment means comprise nails, screws, staples, glue, adhesive, pins, or the like. The method 400 concludes at step 440.

While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof.

Claims

1. A sheathing comprising:

a plurality of core layers;

a first and second surface layer, each defining an exterior surface of the sheathing; and

a plurality of adhesive layers, each disposed between each of the plurality of core layers;

wherein the sheathing comprises a permeability rate of at least about 5 perms, and an absorption rate of less than about 15% water-by-weight.

2. The sheathing of claim 1, having a thickness ranging from about 0.050 inch to about 0.625 inch.

3. The sheathing of claim 1, wherein each of the plurality of core layers comprise at least one of a cellulosic or polymer material.

4. The sheathing of claim 3, wherein each of the plurality of core layers comprise paperboard.

5. The sheathing of claim 1, further comprising at least four core layers.

6. The sheathing of claim 1, wherein the at least an adhesive layer comprises at least one of polyvinyl alcohol, acrylic, thermoplastic hot melt, urea or melamine formaldehyde resin, phenolic, or blends or copolymers thereof.

7. The sheathing of claim 6, wherein the at least an adhesive layer comprises clay impregnated polyvinyl alcohol.

8. The sheathing of claim 1, wherein the first and second surface layers each comprise at least one of a polymer layer or an adhesive layer.

9. The sheathing of claim 8, wherein both the first and second surface layer each comprise a layer of clay impregnated polyvinyl alcohol.

10. The sheathing of claim 1, wherein the first and second surface layers each comprise a drainage plane.

11. The sheathing of claim 10, wherein the drainage plane comprises a plurality of mechanically deformed channels.

12. The sheathing of claim 10, wherein the channels comprise a depth of between about 0.020 inch to about 0.080 inch.

13. A sheathing comprising:

at least four core layers comprising a cellulosic or polymeric material;

a first and second surface layer comprising a layer of clay impregnated polyvinyl alcohol; and

a plurality of polyvinyl alcohol adhesive layers, each disposed between each of the core layers;

wherein the sheathing comprises a permeability rate of at least about 5 perms, and an absorption rate of less than about 15% water-by-weight.

14. The sheathing of claim 13, wherein the sheathing comprises a total thickness of between about 0.050 inch to about 0.625 inch.

15. The sheathing of claim 13, wherein the first and second surface layers each comprise a plurality of mechanically deformed channels, defining a drainage plane.

16. The sheathing of claim 15, wherein the channels of the drainage plane are uniformly diamond-shaped.

17. The sheathing of claim 16, wherein the channels comprise a depth of between about 0.020 inch to about 0.080 inch.

18. The sheathing of claim 13, wherein the sheathing comprises a drainage rate of about 90% drainage.

19. A method of protecting a structure, comprising:

providing a sheathing comprising: a plurality of core layers; a first and second surface layer, each defining an exterior surface of the sheathing; and a plurality of adhesive layers, each disposed between each of the plurality of core layers; wherein the sheathing comprises a permeability rate of at least about 5 perms, and an absorption rate of less than about 15% water-by-weight; and

adhering the sheathing to a structural member of the structure using an attachment means.

20. The method of protecting a structure in claim 19, wherein the first and second surface layers of the sheathing each comprise a plurality of mechanically deformed channels, defining a drainage plane.