Bendable 'Z' head flashing
Bendable ‘Z’ Head flashing is used in conjunction with other building materials above arched openings or components in the exterior walls of buildings to protect the building structure from water intrusion. Pre-formed notches in the vertically mounting flange allow the horizontal portion of the flashing to conform to arched or curved openings, the head of arch top window or door frames, and arched trim.
This non-provisional utility patent application claims the benefit of provisional patent application No. 60/756,646 filed Jan, 6, 2006, and disclosure document number 545447.
BACKGROUND OF THE INVENTIONThe present invention relates to architectural stock flashing material used for weatherproofing the head of arch top windows and doors, and arched trim on the exterior buildings in building construction.
In construction it is customary to install head flashing at the tops of openings in exterior walls, during the installation of windows, doors, and adjacent siding and trim. Uniform building codes require exterior openings exposed to the weather shall be flashed in such a manner to make them weatherproof. The intent is to keep moisture on the surface of building paper from wetting structural elements or entering the exterior wall cavity. Various flexible flashings, water resistant papers and sealants are utilized to seal around openings, windows or doors onto the building framing and sheathing at the building paper or primary moisture resistance surface, which is then covered by siding and trim. When a window or door has a integral nailing fin for fastening the assembly onto the building framing, flexible sheet flashing employed at the head of an opening can satisfy the building code requirement for protecting the building structure, although additional flashing can be used to provide protection to adjacent exterior siding and trim, as well as increase the weather resistance of the structure.
Where a window or door does not have an integral nail fin, specific architectural sheet stock called ‘Z’ flashing is commonly used to divert water from the surface of building paper to the outside, away from the head of the opening. This type of flashing is readily available commercially in straight lengths and in various dimensions. The ‘Z’ adjective indicates the three leg configuration of this flashing, with the legs characteristically at right angles to each other. ‘Z’ flashing has also been used in addition to flexible flashing to provide extra protection to the opening and exterior wall components. Historically ‘Z’ flashing is formed from metal. More recent, flashing has been manufactured from plastics.
With arched or curved top doors and windows, or curved siding trim, ‘Z’ flashing does not easily conform to a radius, with the legs or flanges perpendicular to the curved surface resistant to bending because of the inherent geometry. Because of the resistance to bending, the installation of head flashing along curved surfaces is difficult, if attempted at all. Some sheet metal fabricators have the capacity to custom rolled “Z’ flashing to the exact radius required, which is costly and requires planning ahead. One window manufacture provides arched top windows with an aluminum head flashing preformed to match the window head radius, to be installed directly onto the window head frame. Flashing between siding and wood trim installed above a window with this manufacturer supplied flashing would be a custom fabrication with a different radius and length. For most installations of arched top windows, doors and curved trim there is not a satisfactory solution.
Construction contractors or trades people have modified commercially available metal or vinyl ‘Z’ flashing in the field by cutting multiple slits into the vertical back leg or mounting flange of ‘Z’ flashing to allow bending, impairing the water diversion capability. It is also inefficient and difficult for field tradespersons to make closed end cuts of uniform length or spacing. Poorly made cuts tend to further lengthen along the cut or induce cracking in the flashing flange, while inaccurately spaced cuts do not permit a uniform radius. With field modified metal flashing, bending can also result in kinking or distortion in legs of the flashing. Flashing with numerous slits is sometimes repaired in the field with a covering of a self-adhering flexible sheet flashing. When a repair is made it can be labor intensive and ineffective. Slits made into the total height of the flashing back leg are difficult to properly repair with flexible sheet flashing, as the sheet material must be carefully placed into the curving corner formed between the back vertical leg and horizontal leg of the flashing, and there is insufficient lap distance between the self-adhering flexible sheet flashing and the notch made in the underlying ‘Z’ flashing.
For the reasons stated above, it would be very desirable to provide a bendable ‘Z’ flashing for weatherproofing the head of arch top windows, arched door heads, and arched trim.
SUMMARY OF THE INVENTIONThe present invention is an elongate vinyl plastic ‘Z’ flashing comprised of three legs, the larger back vertical attachment flange includes pre-formed notches which allow the other horizontal leg to conform to the arched radius surface of other building construction elements, such as arched head windows and doors, and arched trim.
In accordance with the invention, the bendable ‘Z’ head flashing is shaped with a flat vertical notched attachment flange, an outwardly projecting horizontal section from the bottom of the flat vertical attachment flange, and a smaller vertical drip edge section projecting downward from the outside edge of the horizontal section. The back vertical flange is installed against building sheathing or adjacent self-adhering window or door flashing. The horizontal section sits on top of a arched window or door frame, or arched trim. The smaller vertical drip edge extends down over the face of the underlying arched building component.
For the length of the bendable ‘Z’ head flashing, the back vertical mounting flange has equal spaced holes near the top free edge for fastener locations, and equal spaced notches extending from the free edge towards the horizontal section. Each notch terminates in a circular void in proximity to the horizontal section, but at a distance to provide a small section of uninterrupted vertical flange adjacent to the horizontal flange. The diameter of the circular void is larger than the width of the notch, to distribute tension stresses at the base of the flat vertical mounting flange over a larger circle circumference and reduce the possibility of cracking and buckling.
When the flashing is curved during installation, the notches will widen adjacent to the upper free edge of the vertical mounting flange, and the circular voids will deform to an oval shape. Because of the flexible composition, the horizontal portion or leg of the present invention can readily conform to a radius, and small effective dimensional areas of both vertical flanges can absorb tension and compression stress without undo deformation.
The present invention is installed in sequence with the building wall moisture barrier, arched doors, windows or adjacent arched trim, before installing exterior siding. Building structural framing, siding and trim around windows and doors is protected from rainwater or other moisture by bendable ‘Z’ head flashing in conjunction with other building materials. Bendable ‘Z’ head flashing protects the joint between dissimilar construction components and directs moisture outward away from building moisture barriers.
The present invention can be utilized in many ways. The following descriptions and graphic indications represent potential uses of the invention to characterize the idea and general usefulness, and are not intended to limit the invention to that described or depicted herein. Notation numbers used within the FIGS. correspond to the same features or components throughout the drawings.
Referring to the views contained on drawings sheets 1 through 6:
Both
Useful embodiments of the invention have been described and illustrated, including depictions of building components necessary to integrate the invention with various surrounding building materials. It is understood that the words used are descriptions rather than limitations, and the present invention is not limited to the embodiments described above, but encompass any and all embodiments within the scope of the following claims.
Claims
1. An elongated bendable ‘Z’ head flashing article used in building construction above arched exterior wall openings, said flashing comprised of:
- a first vertical member having a free edge and extending down towards the second outwardly projecting horizontal member. Said vertical member having a series of notches forming straight edges extending towards said second horizontal member and ending in a circular void.
- a second outward projecting horizontal member connected at a right angle to the first member and extending to a third vertical member.
- a third vertical member connected at a right angle to and extending down from the second member to a free edge.
2. A bendable ‘Z’ head flashing article as recited in claim 1, wherein said circular voids are in proximity to the second horizontal member.
3. A bendable ‘Z’ head flashing article as recited in claim 1, wherein said circular voids are spaced from the second horizontal member.
4. A bendable ‘Z’ head flashing article as recited in claim 1, wherein the free edge of said third vertical member has a bead of greater diameter than the adjacent material thickness of the third member.
5. A bendable ‘Z’ head flashing article as recited in claim 1, said bendable ‘Z’ head flashing article being formed of plastic material.
Type: Application
Filed: Jan 6, 2007
Publication Date: Jul 12, 2007
Inventor: Douglas S. Gawoski (San Rafael, CA)
Application Number: 11/650,915
International Classification: E04D 13/14 (20060101);