This is the BEST choice for polycarbonate - B7533
Remains flexible. Mildew resistant. Weatherproof. Indoor/Outdoor.
100% silicone rubber sealant that withstands the damaging effects of weather. Ideal for greenhouses, gutters/downspouts, pipes/plumbing, chimney flashings, air conditioners, skylights/windows, door frames! Provides a watertight seal indoors or out. Withstands temperatures from -80º F (-62º C) to 350º F (176º C).
This sealant adheres to polycarbonate, fiberglass, masonry, painted aluminum, painted steel, glass*, and wood.
TIP: Use 1/16" bead of silicone sealant where polycarbonate panel meets the polycarbonate end cap (as pictured).
Application temperature range: 40° F to 105° F (5° C to 40° C). Apply to dry material. Cures in 24 hours. Standard 10 oz. Cartridge (296 ml) with tip.
* 1 cartridge does about 60 ft of small bead (1/16") of sealant.
* For glass application, see clear Lexel Clear Sealant B7538