June 10, 2008
Steep-Slope Vent DetailMost steep-slope applications require the installation of exhaust and intake vents. The correct detailing of the shingle installation around these penetrations is critical due to the fact that improper termination can contribute to moisture infiltration.
• Shingles: Asphalt or glass-fiber reinforced roofing shingles.
• Nails: 11– or 12-gauge hotdip galvanized roofing nails with deformed shanks.
• Roof and flashing cement: Asphalt roof cement (asphalt-based plastic cement), ASTM D 4586: Type II.
• Vent: Prefabricated vent such as the Duraflo Weatherpro Turbo, manufactured by Duraflo.
Apply shingles up to the vent pipe and cut an opening in the shingle that is set over the pipe. Set the shingle in an approved asphalt cement. Set the vent flange over the pipe - flat on the roof - in asphalt cement that has been evenly applied over the bottom shingle. Resume shingle application and set the successive courses around the pipe. Upper and side shingles that overlap the vent should be set in asphalt cement. The asphalt cement should be applied in an even application and used in moderation. Do not apply asphalt-based cement over the top of the shingle. Excessive asphalt cement application may cause blistering.