How to Vent Drain Pipes
Vent pipes are attached to sewer lines via connecting couplings. They allow both for gases to escape from the sewer line and for fresh air to enter the sewer line. The vents travel up the interior wall cavity, exiting through a hole in the roof. The vent pipes are connected together with cement (glue) and plastic couplings. Each water fixture usually has its own vent, which, according to local city code, is attached to the sewer line within a certain distance from the water fixture. Does this Spark an idea?
Things You'll Need
- Felt-tip pen
- Hacksaw
- Utility knife
- PVC primer
- PVC connecting coupling
- PVC glue
- PVC vent pipe and couplings
- Power drill
- 1/2-inch wood drill bit
- Reciprocating saw
- Vent cover
- 3 roof nails
- Hammer
Instructions
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1
Mark the existing sewer line at the point where the vent pipe needs to be attached, using a felt-tip pen. Make a second mark 2 inches along the pipe from the first mark.
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2
Cut through the sewer pipe at both marks, using a hacksaw. If there is room, use a power saw. Make the cuts straight and parallel with each other. Use a utility knife to scrape away any burrs from the cut pipe ends.
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3
Apply PVC primer around both cut pipe ends. Prime the inside ends of a PVC connecting coupling. Wait 30 seconds for the primer to dry.
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4
Apply PVC glue to all primed areas. Push the coupling between the two existing sewer pipe ends. Make sure that the coupling's side spout faces up toward the wall cavity. Hold in place for 30 seconds while the glue dries.
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5
Prime the end of a new piece of PVC vent pipe. Prime the inside end of the coupling's side spout. Wait for the primer to dry. Apply PVC glue to the primed areas, and push the pipe end into the spout. Hold in place for 30 seconds. Follow the same steps to attach new vent pipe and couplings as needed, until the roof is reached. Drill through horizontal wall studs (known as plates) for the pipe to pass through. Use a 1/2-inch wood drill bit, and make the holes no larger than 2 inches in diameter.
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6
Cut an oval hole 2 inches in diameter through the roof, using a reciprocating saw. Install the vent pipe through the hole, and prime and glue it into place. Cut off the vent pipe so that 12 inches of pipe stick out of the roof. Slip a vent cover over the top of the vent pipe. Lift up the shingles on the top and sides of the cover. Push the cover down so that it rests on the roof.
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7
Hammer three roof nails through the cover on the top side. Lower the side and top shingles back into position.
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Tips & Warnings
The vent cover is a flat piece of metal with a rubber center. The rubber center has a hole for the vent pipe to enter through.
Make sure that the vent cover is the correct size for the size of vent pipe that is being installed.
If installing ABS (black) vent pipe, no primer needs to be used. Use ABS glue to seal the couplings to the pipe.
The connecting coupling has a side spout that attaches to the vent pipe. Make sure that this side spout is the same size as the vent pipe that will be used.
