An HVAC duct penetrates a roof opening framed by structural steel provided by others and a built-up leveler curb installed by the general contractor. A twenty-gauge duct support and cap flashing secures the assembly with a six-inch clearance to the transverse duct flange. Twenty-four-gauge counter flashing extends down over the curb, finished with a half-inch drip edge at forty-five degrees with a tight hem. Neoprene washer fasteners and three-eighths-inch caulk edges at forty-five degrees seal the upper connection.
4" 8" DUCT OPNG FRAMING BUILT UP LEVELER CURB (BY G.C.) 12" MINIMUM ABOVE ROOFING (BY OTHERS) 20ga. DUCT SUPPORT & CAP FLASHING DUCT FLANGE-TDF 4" 24ga. COUNTER FLASHING 3/8" CAULK EDGE @45° 1/2" DRIP EDGE @45° W/HEM TIGHT 6" NEOPRENE WASHER FASTENERS
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