Soil stack, plumbing vent, vent boot, pipe boot jack, PVF.
At Real Good Roofing, we refer to them as ‘soil pipes’. The soil pipe is one of the least understood sections of the plumbing / roofing systems.
A soil stack allows water to drain freely out of a house waste system. The soil stack performs three functions.
- It allows air in front of the water rushing through the waste pipe to be pushed out of the way.
- It allows air to be reintroduced to the waste piping after the water has gone by.
- It allows sewer gases to escape outside through a vent stack, reducing odorsVent pipes may be cast iron, copper, galvanized steel or plastic (pvc).
If the soil stack terminates in the attic, odors can find their way into the house. Also, in cold weather, this can add very moist warm air into the attic, leading to condensation and frost damage to the underside of the roof.
Inadequate venting makes a siphoning or gurgling noise when water drains. A sewer odor at a fixture usually indicates a venting problem.
Soil stacks should terminate at least 3 feet above and 10 feet in any other direction from all doors and windows. Vents should extend at least 6 inches above the roof and be at least 12 inches away from a wall. The vent should extend no more than 12 inches above the roof line. Vents which are very long may be subject to frost in the winter. The warm moist air passes up through the vent, and the air is cooled as it contacts the cold walls of the outdoor section of the vent pipe. The moisture in the air condenses and freezes on the walls of the vent pipe. In a prolonged spell of cold weather, this frost can build up to a point where it closes off the top of the vent.
Soil pipes should be at least 3 inches in diameter where they penetrate the roof system in order to avoid frost closure in extremely cold regions.
