The present invention relates generally to houses, more particularly to studless houses, specifically to structural wall panels for studless houses where such panels are water vapor barriers as well as being structural panels, and even more specifically to such studless houses where such panels are formed of oriented strand board.
The Leslie U.S. Pat. No. 5,351,453 issued Oct. 4, 1994 and is entitled Rapidly Erectable Housing Units. The disclosure and claims of this patent generally relate to interlocking connections, such as mortise and tenon structures, between two adjoining walls of the housing unit. This patent does not teach how to make the walls of the housing unit, but some suggestions exist as to how to make the walls. For example, the vertical lines of FIG. 3 of this patent show that the outside walls of the housing unit are formed of sections, instead of being formed from one-piece. Further, the patent states that xe2x80x9cthe primary portions of the walls may be relatively thin in cross-section with additional strength being obtained through an appropriate header and if necessary base plate addition.xe2x80x9d FIGS. 1 and 2 of this patent show headers on the exterior walls. The patent also discloses that xe2x80x9csuch wall panels, headers and the like may be formed by using local material such as grasses, wood particles and various water resistant materials and even pressed to their flat condition through the use of relatively primitive practices such as positioning the material on a flat surface and thereafter covering the positioned material with another flat surface and pressing the same through any available weight. Obviously such processes may only find their applications in isolated areas and, perhaps, areas of particularly low income but this aspect is of import in considering the worth of any invention.xe2x80x9d
In contrast to the embodiment of the present invention that includes headers, baseboards and firring strips on either face of an integral structural wall panel, the Leslie U.S. Pat. No. 5,351,453 does not teach that such integral structural wall panel runs from end to end of one wall of the house and that such integral structural wall panel runs from the bottom of the wall to the top of the wall. In short, the integral structural wall panel of the present invention is the wall of the house, with the headers, baseboards and firring strips making up a support arrangement for the integral wall panel. Advantages stem from the inclusion of a wall panel that is integral from end to end and from top to bottom. For example, water vapor permeance is minimized.
The Leslie U.S. Pat. No. 5,351,453 further does not teach another embodiment of the present invention. This embodiment includes a relatively thick structural wall panel without the support arrangement of headers, baseboards and firring strips. This embodiment further minimizes water permeance because the wall panel here is, critically, at least about 1.3 inches thick. By the inclusion of a wall panel that is integral from end to end and from top to bottom, that is at least 1.3 inches thick, and that is formed of oriented strand board, a wall having a super low water vapor permeance, perhaps of at or less than about 0.1 perms, is obtained. The thickness of 1.3 inches further provides critical load functions. This embodiment includes two species: one species is formed of three layers of oriented strand board where each layer is about {fraction (7/16)}th inches thick (for a total thickness of more than 1.3 inches) and is integral from end to end and from top to bottom, and the other species is preferably only one layer at least 1.3 inches thick so as to be integral from face to face as well as being integral from end to end and from top to bottom.
Still further, the Leslie U.S. Pat. No. 5,351,453 does not teach the problems associated with conventional studded walls or associated with exterior walls which are put together in sections. Conventional, studded walls and sectioned walls are full of defects which allow heat to flow around and through insulation. Some of these defects are insulation voids, thermal bridges, air leaks, air intrusion, convective loops, and moisture.
An insulation void is an area where insulation has been left out. For example, if three percent of a wall is not covered by insulation, the R-value is purportedly reduced 17 percent. If five percent of a wall is not covered by insulation, the R-value is purportedly degraded by 25 percent. With the studless wall panel of the present invention, it is relatively easy to cover such a flat wall panel with insulation. Since it is relatively easy to cover the studless flat wall panel, it is less likely that the wall panel will have voids.
Thermal bridges are points or components that penetrate or bridge through the insulation layer. Studs act as thermal bridges, conducting heat around the insulation and through the wall. Top plates, bottom plates, corner framing, and window and door headers and frames also act as thermal bridges, but the stud is the main thermal bridge culprit.
Air intrusion is air leakage through a house. Air leakage may be infiltration or exfiltration. Air leakage is unintentional air flow. Ventilation is intentional air flow. One way to minimize air leakage is to enclose the house in a vapor barrier envelope, such as polyethylene sheeting. A house may be a xe2x80x9csuperinsulatedxe2x80x9d house where such house has an envelope of plastic sheeting which is a water vapor barrier. When such plastic sheeting is stretched between studs, and is often ripped by subcontractors and must be patched. Sectioned walls have leakage between the sections.
A convective loop defect is a channel or bypass that carries air from relatively warm to relatively cold locations. One type of convective loop is caused by the stud. The conventional way to install foil-backed fiberglass insulation is to staple it to the sides of the studs, creating an air space between the foil and the inner wall surface. This creates a channel through which air can flow up and circulate around the insulation, carrying heat with it. The present studless home therefore eliminates a common convective loop.
Moisture is problematic for at least two reasons. First, when any insulation becomes wet, it becomes less effective thermally. Second, wood and other materials, including insulation, may be damaged even after the wood, other material, or insulation dries out. Convection, a defect caused mainly by studs, in turn causes most moisture problems. Warm interior air leaks through the walls of a house, then cools and condenses when it reaches a relatively cool portion of the house. Convection is reduced or eliminated by a vapor barrier. One such vapor barrier is the wall panel of the present invention with or without a conventional vapor barrier such as polyethylene sheeting. The embodiment of the present invention having one wall panel of about {fraction (7/16)} inch in thickness and having the support network of headers, baseboards and firring strips includes a permeance value of about 1.95 perms. The embodiment of the present invention represented by the sandwich panel having three panels of a {fraction (7/16)} inch thickness (for a total thickness of about 1.3 inches) is projected to have a permeance value of about 0.5 perms. The embodiment of the present invention represented by the integral wall panel that has a thickness of at least 1.3 inches is projected to have a permeance value of about polyethylene sheeting, i.e. at or less than 0.1 perms. Any material with a permeance of less than 0.1 perms is considered to be a vapor retarder or vapor barrier effective for a superinsulated house.
It should be noted that the embodiment of the present invention represented by the wall panel having the support network of headers, baseboards and firring strips in practice attains a permeance value at or better than polyethylene sheeting even though such wall panel may be only about {fraction (7/16)} inch thick. This is because polyethylene is easily torn or punctured by subcontractors and, subsequently, by the home owner who most probably is not aware of such a feature in the wall. Oriented strand board (or another material that consists essentially of one material, is formed or an organic matter, is capable of transmitting loads between a base and a roof, and is capable of receiving and holding pin connectors such as nails and screws) is not easily torn.
Oriented strand board is a mat-formed panel made of strands sliced in the long direction from small diameter, fast growing round wood logs and bonded with an exterior-type binder under heat and pressure. The fast growing trees include aspen poplar, southern yellow pin. The basic steps for making oriented strand board include a) slicing the logs into strands along the direction of the grain, b) drying and sorting the strands, c) mixing the dried and sorted strands with wax and a waterproof exterior-type binder such as phenolic or isocyanate resin binder, d) orienting the strands by electrical alignment or mechanical alignment, with each layer of strands being laid down separately along a conveyor belt to result in a xe2x80x9cmatxe2x80x9d which is loosely held together and has no strength, e) sawing the loose mat into lengths and running the loose through a prepress to remove some air and vapor to escape, f) pressing and heating the mat to a specified thickness to cause the resin to cure and to cause an interweaving or tangling of the strands, and g) permitting the pressed mat to cool. The strength of the oriented strand board product is a result of the uninterrupted fiber, interweaving of the strands, and the orientation of the strands.
Oriented strand board is a wood product and hence reacts to moisture or to changes in moisture. At the same time, oriented strand board includes a waterproof and boilproof binder that is preferably a thermosetting adhesive binder which when fully cured is not softened by moisture or heat. These binders, such as phenol formaldehyde and isocyanate binders, are insoluble heat-resistant polymers that resist aging, moisture and chemical degradation. Permeability of a panel of oriented strand board, or the rate that moisture passes through the panel under stated conditions of moisture vapor pressure, is proportional to the density, degree of orientation and thickness of the panel. According to the pamphlet xe2x80x9cOSB Performance By Design,xe2x80x9d copyright 1996 by the Structural Board Association, printed in Canada, the vapor permeance (in perms) of oriented strand board with nominal panel thicknesses of xe2x85x9c inches, {fraction (7/16)} inches, xc2xd inches and ⅝ inches is 2.55, 1.95, 1.55 and 1.1, respectively. This pamphlet further states that panel thicknesses of greater than ⅝ inches were not tested, but that it can be assumed that panels having a thickness greater than ⅝ inches, such as xc2xe inches, provide a permeability resistance equal to or better than that of ⅝ inch panels.
The above-noted pamphlet xe2x80x9cOSB Performance By Designxe2x80x9d indicates that the most common thicknesses of oriented strand board panels are xc2xc inches, xe2x85x9c inches, {fraction (7/16)} inches, {fraction (15/32)} inches, xc2xd inches, {fraction (19/32)} inches, and {fraction (23/32)} inches and that other panel thicknesses include xe2x85x9e inches, 1 and xe2x85x9 inches, and 1 and xc2xc inches. The pamphlet states that the Structural Board Association discourages the use of nailed in place ordinary oriented strand board wall sheathing alone in load bearing rim joist applications. The pamphlet does not teach using an integral panel of oriented strand board as a wall panel where the wall panel is used as the stud or in place of a plurality of studs and where such panel includes a support network or arrangement of headers, baseboards and firring strips. Nor does the pamphlet teach using an integral panel of oriented strand board as a wall panel where the wall panel is, critically, at least 1.3 inches such that the support network of headers, baseboards and firring strips is eliminated.
A feature of the present invention is a house having an integral wall panel running from end to end and from top to bottom of each of the exterior walls. Since the wall panel is integral, air and water vapor leakage is minimized.
Another feature of the present invention is that such integral wall panel is structural. Since the wall panel is structural, the use of studs is eliminated or minimized. Since the wall panel is structural, the never-ending search for xe2x80x9ccentersxe2x80x9d is eliminated. Implements and interior walls may be affixed to almost anyplace, if not every place, on the integral structural wall panel.
Another feature of the present invention is that the wall panel is formed of essentially only one material from end to end and from top to bottom.
Another feature of the present invention is that the one material is, preferably, oriented strand board.
Another feature of the present invention is a support network of baseboards, headers, and firring strips added to each of the faces of the integral structural wall panel.
Another feature of the present invention is an oriented strand board wall panel that eliminates the support network of headers, baseboards and firring strips and that includes a critical thickness of at least about 1.3 inches. Two embodiments spring from this feature. One embodiment includes a sandwich wall panel formed of three layers of oriented strand board, with each layer being about {fraction (7/16)} inch thick. Another embodiment is integral from face to face as well as being integral from end to end and from top to bottom. These two embodiments, especially the second embodiment where the 1.3 inch thick panel is one-piece, provide a super low permeance to air and water vapor.
An advantage of the present invention is that the labor cost of building a home is minimized. Steps that are eliminated include the step of manufacturing the wall sections, the step of teaching others how to join the wall sections on site, the actual step of joining the wall sections on site, and the step of sealing the joints between the wall sections.
Another advantage of the present invention is that a house having the oriented strand board wall panels may be built quickly and easily at low cost. For example, entire walls (not merely wall sections) may be formed in the factory, with doors and windows being cut out at the factory or at the building site.
Another advantage is that the house having the oriented strand board wall panels may be built free of studs. The oriented strand board wall panels themselves act as the studs, with the oriented strand board wall panels supporting the roof structure.
Another advantage is that thermal defects, such as insulation voids, thermal bridges, air leaks, air intrusion, convective loops, and moisture defects, are minimized. Features contributing to this advantage include the wall panel being one-piece and integral so as to minimize wall section joints and further include the wall having a low permeance value.
Another advantage is that the house having the oriented strand board wall panels is strong and exceeds the strength of conventional homes having studs of dimensional lumber.
Another advantage is that the house having the oriented strand board wall panels minimizes or eliminates the need for plastic sheeting or metallic sheeting to keep out moisture. Whether the wall panel is {fraction (7/16)}th inches thick with a support network of headers, baseboards and firring strips or whether the wall panel is 1.3 inches thick, such wall panels have an extremely low permeance to water vapor.
Another advantage is that the house having the oriented strand board wall panels complements the plastic or metallic water vapor barrier. These water vapor barriers are extremely thin and are thus easily torn and punctured, defeating the purpose of the water vapor barrier envelope. Oriented strand board 0.5 or 1.3 inches thick is not inadvertently punctured.
These and further objects and advantages of the present invention will become clearer in light of the following detailed description of the illustrative embodiments of this invention described in connection with the drawings.
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