Technical Details: Vents - Two Pieces are Better than One
Vents are installed through the roof to relieve vapor pressure — in the form of water or gas — from the interior of the building into the atmosphere. Because this is required in all types of buildings, vents and tubular penetrations are typically standard details on any roof system.
Although common, installing roofing around vents and tubular penetrations can provide a challenge to the roofing contractor. The challenges exist in completing and tying in the sheet metal work with the roofing work. Typically, sheet metal workers install metal components. However, roofing mechanics work with the metal flanges for vents and tubular penetrations because the roof flashing and flanges have to be installed at the same time. In this procedure, the existing penetration is waterproofed in accordance with proper roofing procedures. The sheet metal flange is applied over the waterproofed penetration. Finally, the sheet metal flange is flashed or tied into the roof system.