Ridge Flashing Installation Polycarbonate

Purchase custom flashing from sheet metal shop, or standard shapes at lumber yards. For custom flashing do scale drawing showing dimensions, angle, etc. At edge of Type A flashing we suggest a 1/2″ long bend. Draw so that leg(s) of flashing are tilted down 5° from pitch of your roof. On Type B flashing leading edge do a 1/2″ hem and 45º bend, creating a sealant flange. Sheet metal a minimum of .019″ aluminum or 30 gauge steel. Aluminum easy to fasten, easy to cut, but is a little flimsy, care in handling. Steel more sturdy, harder to cut and requires pre-drilling prior to fastening.  In high wind areas use Sikaflex 295 UV, not silicone, to bond tip of Ridge Flashing to poly.

1) Easiest method of install is to set and screw down a section of flashing that covers the 1st sheet of poly (on freestanding greenhouses install sheets on both sides of the greenhouse). Set screws so flashing presses against poly, place bead of sealant at this point { Lean-To Ridge & Freestanding Ridge } and stop there. Lay next sheet of poly and fasten Cap so that it butts against the edge of the flashing that comes in contact with the poly. Now screw down flashing and place a bead of sealant along the edge of flashing that comes in contact with poly, and also where Cap comes in contact with flashing. Continue installing more poly 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 cleaner looking and tighter installation involves installing flashing after all sheets are set. See { Lean-To Ridge & Freestanding Ridge }. This involves acquiring access to the ridge with all poly in place. This can be tricky, best performed by those accustom to working on roofs. 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.

Top Detail A – Below B

Polycarbonate Greenhouse and Sunroom Building Supplies