Patent Application
20060156654
This Invention relates generally to fenestration and more particularly to prevention or reduction of leaks at the bottom corners of a clad window frame.
Fenestration units such as window frames often are waterproofed and protected from weathering by cladding them with formed sheets of material resistant to weathering and water penetration. Typical cladding materials include, for example, plastics, such as polyvinyl chloride (PVC), and aluminum. Cladding components may be produced by molding, extruding, bending, or otherwise forming the cladding material into pieces having shapes that conform to the profiles of at least the exterior portions of underlying window frame elements, such as jambs, sills, and headers, which often are made of wood. The formed cladding is then fitted and attached to the wooden elements of the frame to cover the wood and protect it from moisture and attendant rot and decay. Cladding components typically are held in place on their underlying wooden frame elements by adhesives or mechanical fastening mechanisms. It often is useful to incorporate snap-fitting tongues or other self attaching devices into cladding components that mate with corresponding slots milled in frame elements to simplify assembly and avoid leaks that otherwise might result from holes required for screws, rivets, and similar fasteners.
Because window cladding is formed in separate pieces that are attached to the corresponding elements of a window frame, such as the jambs and sill, joints between cladding components result where the separate pieces of cladding meet. One such joint that historically has been particularly troublesome is the joint between the cladding that covers a window sill and the jamb liners that cover the inside faces of the window jambs. These joints occur at the bottom corners of the window frame and, unless properly sealed, can result in water leakage to underlying wooden window frame elements. In order to seal cladding joints, sealants such as silicone RTV historically has been used. While such sealants can produce adequate sealing, particularly in the short term, it has been found that considerable skill and patience may be required during application to avoid sealing defects, a limitation that may be incompatible with manufacturing requirements because of the likelihood of immediate or eventual leaks. Even where sealing is applied precisely according to requirements, the sealed joints can, over time, develop leaks due to a number of factors including, for instance, thermal expansion and contraction of cladding components, movement and settlement, and physical damage.
Accordingly, a need exists for a solution that eliminates or at least greatly reduces instances of leaks at joints between cladding components in clad windows, and particularly at the bottom corners of a window unit. Such a solution should be installable during window assembly-with a minimum of required skill level yet still provide superior and virtually fool-proof sealing against water penetration. Further, the sealing characteristics should be permanent and should not degrade over time due to thermal or mechanical influences. It is to the provision of such a solution that the present invention is primarily directed.
Briefly described, the present invention, in one preferred embodiment thereof, comprises an improved and enhanced cladding system for clad windows that substantially eliminates leaks at the bottom corners of windows and also eliminates or at least reduces the criticality of traditional sealants applied in these locations. The invention includes a sill cladding that is shaped to define a barrier pan having upwardly extending end walls configured to project upwardly a short distance beneath the vertical jamb liners of the window. An upturned or upwardly extending interior edge wall extends along the inside edge of the barrier pan between the upwardly extending end walls. The barrier pan with its upwardly extending end and edge walls thus forms a sill cladding that captures any moisture that may leak through the joint between the sill cladding and jamb liners and prevents the moisture from penetrating through to underlying wooden elements of the window frame. While sealant still can, and likely should, be used at critical cladding joints, the criticality of this sealant and its application is greatly reduced because the consequences of leakage are virtually eliminated by the unique barrier pan of the present invention.
According to a preferred embodiment, the barrier pan is formed of thermoplastic polymeric material such as PVC by traditionally known fabrication methods such as injection molding or thermoforming. Other materials, such as aluminum, also can be used. Further, the barrier pan can be formed of multiple assembled components such as, for instance, a pan portion to provide the barrier function and a cover portion to provide suitable appearance and weatherability. During window unit assembly, the barrier pan cladding is installed covering the sill of a window with its end walls extending partially up the vertical side jambs. Jamb liners are then installed, with the bottoms of the jamb liners overlapping the end walls of the barrier pan. Other cladding components also may be attached to the frame. Assembly may include the application of a sealant at the junction of the jamb liners and barrier pan to reduce the likelihood of leakage; however, such a sealant may not be required at all because any leakage that occurs is captured by the upwardly extending end walls and inside edge wall of the barrier pan and directed outward to the edge of the sill, where it can drain away from the window in the usual way.
Thus, a window cladding system is now provided that virtually eliminates leakage at the bottom corners of the window where leakage has traditionally been a primary concern. At the same time, the cladding system is simple and efficient to install during window unit assembly, does not involve the elevated skill level required in the past for sealant application, and is not likely to develop leaks over time. These and other objects, features, and advantages of the window cladding system of this invention will become more apparent upon review of the detailed description set forth below, when taken in conjunction with the accompanying drawing figures, which are briefly described as follows.
Referring now in more detail to the drawing figures, wherein like reference numerals indicate, where appropriate, like parts throughout the several views,
A left end wall 33 is an integrally formed part of the barrier pan 31 and extends upwardly from the end portion 45 of the floor 32. In the illustrated embodiment, the upwardly extending end wall 33 is formed with a pair of recesses configured to fit within corresponding recesses 39 along the vertical jamb of a window frame when the barrier pan 31 is installed on the window sill, as detailed below. Similarly, an upwardly extending right end wall 34 is an integrally formed part of the barrier pan 31 and extends upwardly from the opposite end portion 50 of the floor 32. The upwardly extending end wall 34 likewise is formed with a pair of recesses 41 shaped to fit within corresponding recesses along the opposite vertical jamb of a window frame when the barrier pan 31 is installed on the window sill.
An inside edge wall 36 extends along the inside edge portion 40 of the floor 32 and, like the end walls 33 and 34, preferably is an integrally formed part of the barrier pan 31. The inside edge wall 36 extends between and connects the opposed end walls 33 and 34 and has an upwardly extending portion 37 that projects upwardly from the floor 32. Optionally, a depending portion 38 that projects downwardly from the floor 32 (as perhaps best seen in
In
As discussed above, the barrier pan of this invention preferably is formed of a unitary piece of molded or thermoformed plastic so that there are no joints that might leak at, for instance, the ends and edges of the pan floor. It is within the scope of the invention, however, that the barrier pan be formed from two or more separate pieces that are joined together in any known watertight manner to prevent leaks. Further, the barrier pan may be referred to as being formed of “thin walled” material, meaning that all wall thicknesses are significantly less than other dimensions of the barrier pan. Subject to this general limitation, wall thickness for the barrier pan are not particularly limited, although very thin materials may not be sufficiently durable and may be too fragile to be handled easily during window assembly while very thick materials may be needlessly heavy, expensive, and difficult to fabricate. Generally, suitable wall thickness depends on the particular material used, fabrication methods, and the severity of service the window is expected to withstand. It has been found, for example, that a suitable wall thickness when using PVC for the barrier pan is between about 0.020 inches and 0.100 inches, and most preferably about 0.060 inches.
The end walls of the barrier pan extend upwardly from the ends of the pan floor a distance that is predetermined to insure that water cannot, under normal weather conditions, seep or be blown over the top of the end walls and onto the wooden window components beneath. More specifically, in order for water to rise over the top of an end wall (or the inside edge wall) the water must be under pressure, measured in inches of water, greater then the height of the end wall, measured in inches. Pressure can be created at the bottom corners of a window in a blowing rainstorm. The height of the end walls is predetermined so that even the maximum expected pressures are less than the height of the end walls to insure no leakage over the end walls.
Specific wall height requirements can be determined by the required water resistance test pressure. Water resistance test pressures for various performance classes are found in published performance standards such as 101/I.S. 2/A440, SPECIFICATIONS FOR WINDOWS, DOORS, AND UNIT SKYLIGHTS, available from the American Architectural Manufacturers Association, and the Window and Door Manufacturers Association, and available online at nwwda.org-files-public-specifications.pdf. These standards list a range of performance classes, along with the required minimum water resistance test pressures for each performance class. Water resistance test pressure is measured according to ASTM E 331-00, for constant pressure, and E 547-00 for cycled pressure. Exemplary performance requirements are shown in Table 1. Wall heights that are at least as great as the minimum water resistance pressure, measured in inches of water, shown in Table 1, satisfy the criteria set forth hereinabove.
It will be appreciated that while the end walls and inside edge walls are generally portrayed as being of the same height, as shown for example in
While the end walls of the barrier pan are effective as dams to block water from seeping to underlying window frame components, it may be desirable in some cases also to apply sealants or gasket materials to joints and overlapping surfaces between jamb liners and the barrier pan to reduce further the probability of leaks. Suitable sealants and/or gaskets include compliant tapes, as well as sealants, such as silicone-based sealants, applied as liquids to the surface and cured to a compliant layer. The area of overlap between the end walls and jamb liners in combination with the pressure exerted by the jamb liners on the end walls provides highly favorable conditions for sealing. Sealing of the jamb liners against the end walls is enhanced when the bottom sash of the window is closed since, in this position, the sash presses against the jamb liners to urge them against the end walls.
The invention has been described herein in terms of preferred embodiments and methodologies considered by the inventors to be the best mode of carrying out the invention. It will be understood, however, that various additions, deletions, and modifications might be made to the illustrated embodiments within the scope of the invention. For instance, as previously mentioned, the invention is equally applicable to window units with highly complex jamb liners and other cladding components. While plastic such as vinyl is the preferred material for the barrier pan of this invention, other materials, aluminum for instance, might be selected in appropriate applications. Finally, while the invention has been illustrated in the context of clad windows, other applications of the invention, such as certain doors, also may be possible. These and other modifications, changes, and additions to the preferred embodiments illustrated herein might be made by those of skill in the art without departing from the spirit and scope of the invention as set forth in the claims.
