Roof curbs are used for mounting mechanical equipment used in exhaust, air conditioning, ventilation, and other equipment such as skylights onto a roof opening. Curb construction includes fully welded corners, factory installed wooden nailers, and 1.5” x 3 lb. rigid fiberglass insulation. Custom sizes and heights may also be manufactured, as well as a pitched roof style. Other custom features include pipe and duct sleeve caps, and a damper shelf. The three main styles of roof curbs include: