1653 Vent Too Tall - Plumbing - Venting Systems -

Image Text: If the plumbing vent extends too far above the roof, frost closure can become a problem > cross section > frost closure > vent pipe > sewer gases cannot escape > cold outside air > plumbing vent should extend no more than 12 inches above the roof > plumbing vent > stack flashing > roof rafter > ceiling joist > Note: on flat roofs, the vent should extend at least 6 inches above the high water level