Patent Application
20080141597
1. Field of the Invention
The present invention relates to flashing for preventing the ingress of moisture into a wall of a building around an installed window.
2. Description of the Related Art
In “open-stud” building construction, windows and other fenestration products are installed directly into building openings formed by framing members (e.g., wood studs) prior to the installation of water resistive barrier (“WRB”) over the framing members which form the wall cavities. Two types of flashing are known for use in open-stud construction. One type of flashing is “nail-on flashing” formed from a strip of water-impermeable film which is nailed to the wood studs before a window is installed such that, upon window installation, the edge of the flashing is covered by the window flange. A second type of flashing is “self-adhered flashing” formed from a water-impermeable film with a strip of adhesive along the edge for attachment to the window flange along the vertical jambs and the horizontal head of the window, wherein the adhesive is covered by a release liner. Self-adhered flashing can also comprise adhesive over an entire surface. Water resistive barrier is subsequently installed over the framed walls of the building such that around the window, the water resistive barrier covers the flashing at the vertical jambs and head of the window and is layered behind the flashing at the window sill.
According to conventional practice in open-stud construction, the space between the water resistive barrier and the flashing at the vertical jambs and head is not sealed, thus creating the possibility of rainwater entering between the WRB and the flashing. The purpose of the flashing is to divert such water down and eventually to the outside of the WRB at the sill. Under excessive wind forces, water that has entered the space behind the WRB can travel beyond the width of the flashing into the wall cavity which may result in moisture damage to the framing members, such as rotting of wood studs and loss of insulation.
It would be desirable to have a cost-effective means for reducing the likelihood of water penetration into wall cavities around flanged fenestration units in open-stud building construction. In particular, it would be desirable to have a flashing product that utilizes pressure-sensitive adhesive to integrate the window flange with the water resistive barrier which minimizes the amount of adhesive used.
In at least one embodiment of the invention there is a flashing for integrating a flanged fenestration unit and a water resistive barrier, the flashing comprising
an elongated flexible substrate having two major surfaces and a first lateral edge and second lateral edge defining a width of the substrate therebetween;
an elongated adhesive layer having a width less than the width of the substrate adhered to one of the major surfaces of the substrate adjacent the first lateral edge of the substrate; and
a release liner covering the adhesive layer wherein the release liner is scored or perforated along a line parallel to the first lateral edge of the substrate and located a distance from the first lateral edge that is less than the width of the adhesive layer dividing the release liner into a first release liner section adjacent the first lateral edge and a second release liner section,
and methods for installing in a building.
The invention relates to an improved flashing product for use along the vertical jambs, head, and sill of a flanged fenestration unit, such as a window, that integrates the peripheral flange of the fenestration unit with a water resistive barrier installed over the framing members of the building. The use of the improved flashing product prevents the ingress of moisture into the wall cavity surrounding the fenestration unit. It should be appreciated that when the term “window” is used, other types of fenestration units, such as doors, skylights, vents, utility supply boxes, and other items that are made to fit into openings in structures, such as buildings, are contemplated.
The flashing 10 comprises a substrate 12 having an adhesive layer 14 partially covering one surface near a lateral edge 16 of the substrate. The adhesive layer is covered by release liner 18. Advantageously, the release liner 18 is scored or perforated (as indicated by the dotted line) along a line parallel to lateral edge 16 for ease of folding the release liner and adhesive layer along the line as well as for ease of separately removing release liner sections 18a and 18b to separately expose, respectively, underlying sections 14a and 14b of the adhesive layer. If desired, film 16 is also scored to aid in folding the film along the score line.
The adhesive layer 14 integrates the window flange and the WRB in use, as adhesive layer section 14a attaches directly to the WRB and adhesive layer section 14b attaches directly to the window flange. In order to install the flashing of the invention to a window installed in a building opening in open-stud construction, the lateral edge sections of the release liner and adhesive layer (18a and 14a, respectively) and the attached lateral edge portion of substrate 12 are folded back along the scored line in the release liner 18 such that the substrate 12 is folded onto itself. Release liner section 18b is removed from the flashing and the underlying section of adhesive 14b is exposed and adhered to the window flange. Subsequently, release liner section 18a is also removed, exposing the adhesive of the adhesive layer section 14a so that it is available to be adhered to the WRB when the WRB is installed. The integration of the window flange and the WRB prevents the ingress of water into the wall cavity behind the WRB around the window.
The substrate 12 of the flashing of the invention can be a film, sheet metal, nonwoven fabric, woven fabric, paper, rigid plastic, or a combination thereof. The substrate is liquid water impermeable and can be either water vapor permeable or water vapor impermeable. The substrate can be a material that has been made water impermeable by the use of a water impermeable coating. The substrate can be a nail-sealable film such as Titanium-UDL® roof underlayment commercially available from InterWrap, Inc. of Canada. The flashing can be at least 9 inches (22.9 cm) wide if required by applicable industry standards, e.g., ASTM E 2112; otherwise it can be less than 9 inches (22.9 cm) wide.
The substrate 12 should be dimensionally stable and durable under the conditions of temperature and humidity experienced by the flashing in use. The substrate should not shrink or curl which could result in delamination of the flashing or separation of the flashing from the framing member or window flange. Such separation could create channels through which water could migrate into the wall cavity surrounding the window flange. For ease of installation of the flashing of the invention, the substrate should have sufficient stiffness so it does not easily fold over on itself at the upper corners of the window. The substrate is advantageously tear resistant.
The substrate 12 should not react with the adhesive layer 14 in a manner detrimental to the structural integrity and dimensional stability of the substrate. In the case of a polymeric substrate, the substrate is made of a polymer having a sufficiently high softening temperature. Suitable polymers include polyethylene, polypropylene, polyethylene terephthalate, polyamide, or a blend or copolymer thereof. The substrate can include optional additives such as UV stabilizers, antioxidants, antimicrobial agents, pigments, etc. The substrate 12 can optionally be translucent if it is desirable for the framing elements 20 to be visible behind the installed flashing 10.
For enhanced adhesion with the adhesive layer 14, the substrate 12 can be subjected to a surface treatment, such as corona treatment or micro-embossing. The substrate can also be subjected to corona treatment for improved ink adhesion.
The adhesive used in adhesive layer 14 has good adhesion to the material of the substrate 12 as well as to a wide variety of construction materials, e.g., wood, aluminum, vinyl, and commonly used water resistive barriers such as DuPont® Tyvek® HomeWrap available from E. I. du Pont de Nemours & Co., Wilmington, Del. (DuPont). The adhesive is stable under conditions of heat and moisture over an extended period of time. Suitable adhesives for use in the flashing of the invention include butyl rubber adhesive, bituminous adhesive, acrylic, or combinations thereof (layers and blends). Additionally, the adhesive can be neoprene, a polymer based on EPDM (ethylene propylene diene monomer), or other pressure sensitive adhesives generally used in construction applications.
The release liner 18 can optionally be provided with some level of water and UV resistance for protection in limited outdoor exposure during building construction. The outer surface of the release liner can be coated with a water resistant resin such as linear low density polyethylene, so that the adhesive bonds well to the outer surface of the release liner at locations where one piece of flashing crosses over another piece having the release liner covering the outer adhesive surface still in place during use, such as at the upper corners of a window. It is desirable for this release liner to be removed so that adhesive-to-adhesive contact occurs at these crossover locations. It is desirable for the release liner to be thin and flexible so that it will wind without excessive buckling when the flashing is wound onto a roll with the outer release liner on the inside of the roll. The flashing according to this embodiment of the invention is cost effective since an adhesive layer is needed only on one side of the flashing.
The invention also relates to a method for integrating WRB with the peripheral flange of a fenestration unit installed in a rough opening in a wall, in order to prevent the ingress of moisture into a wall cavity around the fenestration unit. A method for installing the above-described flashing of the invention is described as follows. A fenestration unit such as a window is first installed in a rough opening such that the peripheral flange overlaps the adjacent framing members. The flange is advantageously secured to the underlying framing members via screws, nails etc. As shown in
According to another embodiment of the invention, as illustrated in
Alternatively, another flashing embodiment 120 can be made as illustrated in
A method for installing the above-described embodiment of the flashing of the invention in order to integrate WRB with the peripheral flange of a fenestration unit installed in a rough opening in a wall to prevent the ingress of moisture into the wall around the fenestration unit, is described as follows. A fenestration unit such as a window is first installed in a rough opening such that the peripheral flange overlaps the adjacent framing members. The flange is advantageously secured to the underlying framing members via screws, nails etc. A portion of the release liner is removed to expose the adhesive layer adjacent the lateral edge on one surface of the substrate; the exposed adhesive is then adhered to the window flange. Subsequently, the remaining release liner is removed, exposing the underlying adhesive layer adjacent the lateral edge on the opposite surface of the substrate. Finally, WRB is installed over the wall surrounding the window and adhered to the exposed adhesive layer of the flashing along the sides and uppermost portion of the window. The WRB is advantageously covered by the substrate of the flashing at the lowermost portion of fenestration unit in a shingling fashion as described above.
Alternatively, the flashing of the invention can be installed by removing a portion of the release liner and adhering the flashing to the flange of the fenestration unit prior to installing the fenestration unit in the rough opening in the building wall. Thereafter, the remaining release liner can be removed and WRB is adhered to the exposed adhesive layer as described above.
Another embodiment of the invention is shown in
