Ridge Flashing Purchase & Install Introduction Back to Home Page
Purchase flashing from a sheet metal fabricator, or off the shelf at lumber yards. (If purchasing a metal building frame, you may get their ridge flashing). Do a simple scale drawing that shows dimensions, angle, etc. At the edge of Type A flashing that covers the polycarbonate we suggest a 1/2" long bend (flange). Draw so that the leg(s) of the flashing are tilted down 5° from the actual pitch of your roof. This will create a small amount of pressure against the polycarbonate sheet, useful in achieving a watertight installation. On Type B flashing leading edge do a 1/2" hem and 45º bend, creating a sealant flange. Sheet metal should be a minimum of .019" aluminum or 30 gauge steel. Aluminum is easy to fasten through, easy to cut, but is a little flimsy and care is required in handling. Steel is more sturdy, harder to cut and requires pre drilling prior to fastening. Availability at your local sheet metal shop may be the limiting factor. Look in the Yellow Pages under Sheet Metal Work. Some shops, especially those that cater to glass installation contractors, will inventory medium architectural bronze and anodized sheet metal in the thickness you will be looking for. These colors will be a close match to the Trim Components we offer. In high wind areas use Big Stretch, not silicone, to bond tip of Ridge Flashing to poly.
1) The easiest method of installation is to set and screw down a section of flashing that covers the first sheet of polycarbonate (on freestanding greenhouses install sheets on both sides of the greenhouse). Set screws so flashing presses against polycarbonate, place a bead of sealant at this point { Lean-To Ridge & Freestanding Ridge } and stop there. Lay the next sheet of polycarbonate and fasten the Cap so that it butts against the edge of the flashing that comes in contact with the polycarbonate. Now screw down the flashing and place a bead of sealant along the edge of flashing that comes in contact with the polycarbonate, and also where the Cap comes in contact with the flashing. Continue installing more polycarbonate and flashing. Overlap seams in flashing a minimum of 4". This method provides a watertight installation, but care must be taken to lay a smooth bead of sealant on a cleaned surface.
2) A more difficult, but a cleaner looking and tighter installation involves installing the flashing after all sheets are set. See {Lean-To Ridge & Freestanding Ridge}. This involves acquiring access to the ridge with all polycarbonate in place. As mentioned in the Roof Access Notes, this can be tricky and is best performed by individuals accustom to working on roofs or in situations where balance and care during installation procedures is second nature. If you are working on an attached greenhouse you may be able to gain access to this detail from the roof of the adjoining structure. When installing the Type A flashing, first lay in place and mark where the flashing overlaps the Cap at sheet seams. One may notch the flange at these locations to fit the Cap. When installed, the flashing will rest flat on the polycarbonate and the Cap. It is also fine to butt Cap against tip of flashing (see Type B) and apply sealant to joint.
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