WINDOW SILL FLASHING
This application claims the benefit of U.S. Provisional Application No. 60/487,343, filed Jul. 15, 2003, the entire contents of which are herein incorporated by reference. The present invention generally relates to building materials and more particularly relates to window sill flashing for a window frame to prevent the ingress of water. Typical wall construction techniques include forming a rough opening from framing members such that a window opening is formed. The bottom portion of the window opening (called the sill) is susceptible to rotting if water is not prevented from penetrating from around the window perimeter. Additionally, adjacent ceilings, plastered walls, and the like are susceptible to damage if rain-water infiltrates under the window sill. Many systems are used to solve the problem of water intrusion. One method includes providing a means to collect and control the water that does infiltrate the window perimeter. Alternatively, surface sealing agents, such as caulk, expanding foam, and the like are used as filling agents to fill openings between the periphery of the window and the adjacent, wall surfaces. However, over time, the filling agents have a tendency to dry, crack and shrink, thereby exposing gaps which provide a passageway for water to infiltrate the window perimeter. The present invention is directed towards a window sill flashing comprising a base having a substantially rectangular shape. A front flange projects perpendicularly downward from a front edge of the base and at least one side flange extends vertically from a side edge of the base. The side flange includes a front surface. The window sill flashing is made from a vacuum formed, rigid homopolymer vinyl film. Referring to The flashing 10 of the present invention is preferably manufactured from sheets of thermoforming film, such as a rigid homopolymer vinyl film, or polyvinyl chloride (PVC), or the like. The preferable material properties for flashing 10 are listed in the table below: Flashing 10 is preferably fabricated using vacuum forming techniques. Vacuum forming flashing 10 from thin gage material allows the first and second side flanges 18, 20 to be substantially perpendicular to base 16. The material properties, including the material thickness, provides flexibility to flashing 10, thus allowing the vacuum forming dies to separate from the flashing 10 once the vacuum forming process is completed. Additionally, vacuum forming flashing 10 allows the material to have a minimum thickness (as thin as 7.5 mm). Therefore, when portions of flashing 10 overlap, the resultant gap under the flashing 10 is minimal and does not allow water intrusions. Due to the geometry and thinness of flashing 10, flashing 10 cannot he manufactured using an injection molding process. if flashing 10 were to be manufactured by injection molding, the minimum thickness feasible for flashing 10 is 40 mm, significantly higher than the practical thickness of flashing 10 formed by the vacuum forming process. Moreover, to maintain the perpendicularity of surfaces 16, 18, 20 and 22 over the depth of base 16, flashing 10 would require ribs, or support struts, to be molded into base 16. These ribs would detract from the functionality of flashing 10. Furthermore, it would be necessary to include ports along base 16 to ensure that sufficient material flows across and covers the entire base 16. These ports would give rise to dimples, or other imperfections in the surface of base 16. The imperfections could create gaps or openings along the window sill, thereby comprising the water impermeability of flashing 10. Even with the use of ports along base 16, obtaining complete flow coverage of injected material is problematic because the preferred depth of base 1 is in the range of 1 inches to 3¼ inches. The embodiments disclosed herein have been discussed for the purpose of familiarizing the reader with novel aspects of the invention. Although preferred embodiments of the invention have been shown and described, many changes, modifications and substitutions may be made by one having ordinary skill in the art without necessarily departing from the spirit and scope of the invention as described in the following claims. The present invention is directed towards a window sill flashing comprising a base having a substantially rectangular shape. A front flange projects perpendicularly downward from a front edge of the base and at least one side flange extends vertically from a side edge of the base. The side flange includes a front surface. The window sill flashing is made from a rigid homopolymer vinyl film. 1-14. (canceled) 15. A window sill flashing, comprising:
a base having a substantially rectangular shape; a front flange projecting perpendicularly downward from a front edge of the base; at least one side flange extending vertically from a side edge of the base, the at least one side flange including a front surface; and a front flange that extends perpendicularly downward from the front edge of the base and integrally adjoins the front surface; wherein said window sill flashing is made from a sheet of thermoforming film; wherein each of the flanges, the base portion and the front surface of the window sill flashing define a continuous shaped structure; and wherein the flashing is adapted to be cut to size in the field to accommodate any width of window opening. 16. The window sill flashing of 17. The window sill flashing of 18. The window sill flashing of 19. A method of forming a window frame assembly for a building, the method including the steps of:
forming an opening in a wall for receiving a window assembly, the opening being defined to include left and right opposing bottom corners located at opposite sides of the opening; providing a first one piece sill flashing that includes:
i. a base having a substantially rectangular shape; ii. a front flange projecting perpendicularly downward from a front edge of the base; iii. at least one side flange extending vertically from a side edge of he base, the at least one side flange including a front surface; iv. a front flange that extends perpendicularly downward from the front edge of the base and integrally adjoins the front surface; wherein the first window sill flashing is made from a common sheet of thermoforming film; providing a second one piece sill flashing that includes:
i. a base having a substantially rectangular shape; ii. a front flange projecting perpendicularly downward from a front edge of the base; iii. at least one side flange extending vertically from a side edge of he base, the at least one side flange including a front surface; and iv. a front flange that extends perpendicularly downward from the front edge of the base and integrally adjoins the front surface; wherein the second window sill flashing is made from a common sheet of thermoforming film; wherein the first one piece sill flashing is configured to fit in the left bottom corner of the opening, and the second one piece sill flashing is configured to fit in a right bottom corner of the opening; cutting to size in the field at least one of the first or second one piece sill flashings; placing the first one piece sill flashing in the left bottom corner of the opening; placing the second one piece sill flashing in the right bottom corner of the opening; optionally covering any resulting gap between the first one piece sill flashing and the second one piece sill flashing; wherein each of the first and second one piece sill flashings is sufficiently thin that the members cannot be manufactured using an injection molding process. 20. The method of 21. The method of 22. The method of 23. The method of 24. The method of 25. The method of 26. The method of 27. A method of making a window sill flashing, comprising:
forming from a common sheet of a thermoforming film a thin one piece plastic sill flashing that includes:
i. a base having a substantially rectangular shape; ii. a front flange projecting perpendicularly downward from a front edge of the base; iii at least one side flange extending vertically from a side edge of the base, the at least one side flange including a front surface; and a front flange that extends perpendicularly downward from the front edge of the base and integrally adjoins the front surface. 28. The method of 29. The method of 30. The flashing of 31. The method of 32. The method of 33. The method of 34. The method of RELATED APPLICATIONS
TECHNICAL FIELD
BACKGROUND OF THE INVENTION
SUMMARY OF THE INVENTION
BRIEF DESCRIPTION OF THE DRAWINGS
DETAILED DESCRIPTION
Gauge Range Mils 7.5-35 Gauge Tolerance % ±5 Specific Gravity — 1.33 Material Yield (Nominal) in.2/lb. 2770 (7.5 mil) 2080 (10.0 mil) 1390 (15.0 mil) 1040 (20.0 mil) Tensile Strength (Yield) lb./in.2 6600 Elongation (Break) % 180 Tensile Impact Strength ft-lb./in.2 275 Cold Break Temperature ° C. −30 Heat Deflection Temperature at 264 psi ° F. 162 Gloss % 115
It can be appreciated that the flashing 10 may be covered with a silicone coating for ease of manufacturing and separation of the flashing 10 and for ease in installation of window assembly 13.









