HK1172665A - Article for controlling attic moisture - Google Patents

Description

Article for controlling attic moisture

Background

1. Field of the invention

The present invention relates to improved building construction materials for controlling attic moisture and increasing the energy efficiency of a building.

2. Background of the invention

Some types of buildings have a space called an attic that is located directly below the roof structure and above the available living space. In such houses, it is common to use rubber and beams in the attic space. Air is typically circulated from the eaves of the house to ridge vents at the highest points of the roof, using airflow to control the moisture content on the attic. Air is caused to flow by convection from open spaces along the eaves (located between the house walls and the bottom of the roofline) to open spaces along the ridge (located at the top of the roof), such as ridge vents. The air flow is capable of removing moisture from the attic before the moisture accumulates in the attic. Moisture typically enters the attic from the living space in the form of vapor. Sources of moisture in living spaces include human breath, use of bathtubs and showers, cooking, potted plants, and the like.

Typically, the attic is in communication with air flow from the living space and around the exterior eaves of the house. While this approach works well to control moisture on attics, it is not energy efficient. Because the living space is not enclosed and energy from the environmentally controlled living space can leak with the air flow through the ridge vents to the exterior of the house.

Intumescent foams have been used to insulate and seal attics. These foams are sprayed under roof boarding and into roof rubber, or onto the "floor" of the attic. While this method is effective in sealing the attic, it is not acceptable for many environments because the typical foam is air impermeable and does not allow air flow through the attic, and therefore does not prevent moisture from accumulating on the attic. A common method of providing attic ventilation is to use a vacuum formed plastic pallet having flanges attached to the top edges of the rafters. The design of these products does not allow any variation in the space between the rafters and they are made of rigid materials (such as plastic and cardboard) which are not vapor permeable. One method of controlling attic moisture using a breathable film disposed over the top of rafters is described in U.S. patent publication 2006/0260265 to Zatkulak, which is assigned to E.I. DuPont DE Nemours and company, Wilmington DE (DuPont). In order to place the film firmly above the rafters, large pieces of film must be handled by those who install the material. This work has been found to be very cumbersome. It is difficult to attach the membrane to the underside of the rafters since it is difficult to handle large sheets of membrane in the attic space, especially when trusses and their associated cross supports are used.

It would be desirable to provide a building material and method that eliminates air exchange between the living space and the attic, yet provides good control of moisture on the attic and is safe and convenient to install.

Summary of The Invention

The present invention relates to an attic tray comprising a breathable film having first and second opposing edges and top and bottom opposing edges, side supports of the breathable film adhered at the first and second opposing edges, and an upper laminate at the top edge, at least a portion of which is coated with an adhesive, and a lower laminate at the bottom edge.

Drawings

Figure 1 is a view of an assembled attic tray folded up for installation.

Figures 2A-2C show cross-sectional and side views of an installed attic tray.

Detailed Description

Definition of

The term "active air space" refers to an air space within which air is free to flow and into or out of which air is free to flow as a function of conditions affecting airflow (e.g., thermal gradients).

The term "roofing board" is used interchangeably with the term "roofing board" and refers to a structural board, such as plywood or Oriented Strand Board (OSB), on which roofing material, such as shingles, is mounted.

The term "eave" herein generally refers to the intersection between the roof and walls of a house.

The term "ridge vent" herein generally refers to the space between different planes of a roof panel along its uppermost edge, typically protected by a cover.

The term "house perimeter wrap" herein refers to the wrapping of an unfinished wall of a house with a flexible sheet material, such as a protective film.

The term rafter as used herein refers to a discrete structural load bearing member (also commonly referred to as a joist, beam or truss) forming the upper part of a house attic.

The term "rafter openings" as used herein refers to the spaces between adjacent rafters.

The present invention provides an attic tray that is capable of forming a moving air space directly under the roof deck for moving air streams into the air space at the eaves and out of the house at the ridge. As shown in fig. 2A, active air space 6 is the space between attic tray 1 and roof deck 10. The active air space removes water vapor from the attic space (as indicated by the arrows) to avoid moisture build up in the rafters 12 and wood of the roof deck 10. The present invention also seals the attic, minimizing air exchange between the living space and the attic and enabling considerable energy savings.

As shown in fig. 1, the attic plate of the present invention comprises a breathable membrane 100 having side supports 200 attached to a first opposing edge and a second opposing edge, the side supports being capable of being secured to rafters. The breathable film is generally rectangular and may be in the shape described herein, but the shape is not limited. In one embodiment, the vented membrane is approximately 20 inches wide and 44 inches long to form a loft having a width that matches the rafter opening with a 16 inch center post.

Side supports 200 hold the vented membrane in place, the primary purpose of which is to provide stiffeners for the vented membrane to allow installers to handle the attic floor without the attic floor falling too hard. The side supports may be made of a rigid or semi-rigid material, as a material with some flexibility aids in the positioning of the loft. Some suitable materials include corrugated plastics, such as Coroplast(available from Coroplast, Inc. (Dallas TX)), cardboard, plastic, and wood. A preferred material is corrugated plastic. There is no limitation on the size of the support, but a support sheet 2.75 inches wide and 44 inches long is suitable. As shown in fig. 1, the side support may optionally be provided with perforations 210 to enable a portion of the side support to be bent to form a flange 212. The flange will form an excellent surface to attach the loft panel to the horizontal surface of the rafter. The large perforations allow the side supports to be bent inwardly or outwardly to form the loft floor in a manner that allows installation from below the loft space or from above the roof, as shown in figures 2C and 2B, respectively.

Optionally, the position of the side support bends may be fixed using a dead-fold reinforcement 400 as shown in FIG. 1. Any material that can be folded and that maintains the folded state without rebounding, i.e. forming so-called dead folds, can be used as dead fold reinforcement. Suitable materials include metal wire, metal sheet, biaxially oriented polyester and HDPE sheet. The preferred dead-fold reinforcement is made of wire. The dead-fold reinforcement may be passed across the joint of the side support or the perforation of the support or both to pass through the side support. The optional hook shape 400a as shown in fig. 1 prevents the wire from unraveling when the wire is used as a dead-fold reinforcement.

Optionally, a support 300, as shown in FIG. 1, may be provided that passes along one edge of the side support to the other to provide greater rigidity to the vented membrane during installation and to prevent sagging of the vented membrane after installation. The cross brace may be approximately 2 inches wide and 14.5 inches long.

The attic pallet of the present invention is formed from adhesive support members and a breathable membrane, as shown in figure 1. Any adhesive capable of bonding the nonwoven fabric may be used, such as hot melt adhesives and acrylic adhesives. A preferred adhesive is a hot melt adhesive, such as the Duro-Tak 4233 hot melt adhesive supplied by Nacan Products Limited (Brampton, Ontario, Canada). The side supports and optional cross braces may be of unitary construction cut from a single piece of material or may be constructed from multiple pieces of material. When forming a single construction attic tray, perforations allowing bending are provided in the folds between the side supports and the cross-brace, and stiffeners are optionally provided to maintain the folded position. When the side support and the cross support are formed from the assembled sheet, the cross support is butted against the side support. When forming the side supports and cross braces from the assembled sheet material, dead-fold reinforcements are preferably used at the joints between the side supports and the cross braces.

In order for each attic pallet to form a continuous air permeable membrane with the other attic floors mounted in the rafter openings and the walls below them, a sealing process must be used to join them. It has been found that a length of the vented membrane extending from each end of the vented membrane portion made of the support provides a suitable method of stacking one pallet on another. Figure 1 shows an assembled attic pallet with a lower stack 130 at the bottom of the membrane and an upper stack 120 at the top of the membrane. At least a portion of the upper laminate is coated with an adhesive 110, which may be covered by a release paper (not shown). Any adhesive known to bond nonwoven materials may be used.

The installation method of the attic supporting plate comprises the following steps: the folding pallet is placed at the rafter opening and fixed, and the joint is sealed with all the attic pallets or wall surfaces adjacent to the folding pallet. Attic trays are typically placed during the roofing process, along one of the eaves of the building, and then subsequent attic trays are all mounted in a row above it. The release paper (if present) is stripped away to expose the adhesive tape and the lower stack 130 of upper loft floors is pressed onto the upper stack 120 of lower loft floors, thereby sealing the upper loft floors from the lower loft floors. When there is no place at the end of the first loft tray where the second loft panel meets, the overlap will seal with the house perimeter wrap. Typical roofing materials (e.g., roofing shingles and asphalt roofing shingles) are then used to construct the roof panels. It has been found to be very useful to use the shade after each attic tray is installed. The installer can use the mask as a work platform during subsequent loft pallet installation, making the installation process safer. Attic pallets may also be secured to the bottom of the rafters. Mounting the attic pallet at the bottom of the rafters allows workers to work from the attic and avoids any risk of the roof material falling off.

In another embodiment of the invention, the attic tray is formed into a roll. The roll formed is stapled and sealed to the ceiling and rolled out over the eaves to form a continuous attic tray.

The present invention employs a breathable membrane 100. The breathable film can be any vapor permeable material, preferably a material having a moisture vapor transmission rate of at least about 20US perms as measured according to ASTM E96 method A. The breathable membrane allows moisture to diffuse through the membrane from the attic space into the active air space where it is carried by the flowing air through the ridge vents to the exterior. It has been found that the chimney effect created by the active air space helps to accelerate the removal of moisture from the attic space. Preferably, the breathable film is made of a durable and ultraviolet-proof material. A preferred film has a machine direction tensile strength (based onASTM test method D828 measured) is at least about 34lb/in (59N/cm) and a tensile strength in the transverse direction of about 30lb/in (52N/cm). Preferably, the film did not lose strength after 25 accelerated aging (aging procedure: drying in an oven at 120 ℃ F. for 3 hours), 3 hours immersion in water at room temperature and 18 hours drying in air at room temperature (73 ℃ F.). It is also preferred that the film is exposed to ultraviolet radiation (emissivity of 5.0 watts/m)²Wavelength 315-400nm) was exposed for 210 hours (10 hours/day for 21 days), the strength of the film did not decrease. During exposure, the film was one meter from the UV source and the film temperature was 140 ℃ F.

One example of a suitable breathable film is a two-layer composite sheet material, such as TyvekHigh density polyethylene (available from dupont) was used as the inner layer and a durable spunbonded polypropylene sheet was used as the outer layer. The two layers may be joined together with an adhesive to produce a composite sheet, which is then subjected to a thermal calendering process. The temperature of the calendering process should be sufficient to melt the binder and the nip pressure should be sufficient to cause the molten binder around the fibers of the two layers to mechanically lock the two layers and ensure a composite sheet with high delamination strength.

Other examples of materials suitable for the breathable film of the present invention are spunbond polyolefin nonwoven sheets comprising, for example, three layers of spunbond polyolefin fibers, such as those sold under the trade name rofshield(available from a.proctor Group, Ltd. (UK)). Other materials suitable for breathable films are nonwoven sheets, including sheath-core bicomponent melt-spun fibers, such as the sheets described in U.S. Pat. No. 5,885,909, incorporated herein by reference; and composite sheets comprising multiple layers of sheath-core bicomponent meltspun fibers and side-by-side bicomponent meltspun fibers, such as the sheets described in U.S. Pat. Nos. 6,548,431, 6,797,655 and 6,831,025, which are incorporated herein by reference. For example, bicomponent melt spun fibers may have a polyethylene sheath and a polyAn ester core. If a composite sheet comprising multiple layers is used, the bicomponent meltblown fibers may have a polyethylene component and a polyester component and are arranged side-by-side along their length. In a multilayer arrangement, side-by-side and sheath/core bicomponent fibers are typically separate layers.

Description of a typical installation procedure for attic trays

1. Cross braces are used to bend the attic flat along the line of juncture of the side braces to form a pallet.

2. The side support is folded along the perforation to form a flange.

3. And placing the attic supporting plate at the opening of the roof rafter from one end of the eave.

4. Staples are driven through the flanges and into the top surface of the roof rubber.

5. Staples are driven through the side supports into the inner wall of each roof rafter.

6. The bottom laminate was wrapped around the eave and laminated to the housewrap and sealed with Tyvek tape.

7. Repeating the first step to the sixth step for all rafter spaces along the same row of eave.

8. Standard nailing methods were used to install roof plywood onto attic pallets.

9. Plywood is used as a working platform, and other attic supporting plates are arranged on the same row of attic supporting plates arranged on the front edge of the eave.

10. The release tape is removed from the top stack of the previously installed attic tray and sealed to the bottom stack of the attic tray on which it is installed.

11. Repeating steps 8-10 for all remaining rafter openings.

Claims (9)

1. A loft tray, comprising:

a breathable film having first and second opposing edges and top and bottom opposing edges, and side supports adhered at the first and second opposing edges, and an upper laminate at the top edge, at least a portion of which is coated with an adhesive, and a lower laminate at the bottom edge.

2. The attic tray of claim 1, comprising one or more cross braces extending from a side brace on the first edge to a side brace on the second edge and adhered to the vented membrane.

3. The attic tray of claim 2, comprising perforations in the side supports.

4. A loft tray according to claim 3, comprising dead-fold reinforcements on the perforations.

5. The attic tray of claim 4, wherein the breathable film is a three-layer spunbond polypropylene fabric.

6. The attic tray of claim 4, wherein the breathable film is a two-layer composite sheet of flash spun high density polyethylene sheet and spunbond polypropylene sheet.

7. The attic tray of claim 4, wherein the breathable film is a flash spun high density polyethylene sheet.

8. The attic tray of claim 4, wherein the breathable film is a nonwoven sheet of sheath-core bicomponent melt-spun fibers, wherein the sheath is polyethylene and the core is polyester.

9. The attic tray of claim 4, wherein the breathable film is a composite of a layer of sheath/core bicomponent meltspun fibers and a layer of side-by-side meltblown fibers, wherein the bicomponent are polyethylene and polyester, and in the sheath/core bicomponent, the sheath is polyethylene and the core is polyester.