Toilet venting is an important aspect of your home’s sewer system.
Installing drain and vent lines in your bathroom is a home project that can be completed in a weekend.
You might find that a joist is in the way of a toilet bend, for example.
Credit: Emily Followill
If so, remove as much flooring as necessary to get at the framing.
Cut the joist, install a blocking piece, and attach 2x4 cleats around the opening.
The horizontal vent pipe runs right next to the closet bend.
You might need another elbow (of any degree) to position the vertical vent where you want it.
The fittings can be pointed straight at the wall or at an angle, as needed.
You might be able to cut it to the exact length after it has been installed.
Insert the Assembly
Insert the assembly down through the wall plates and temporarily anchor it.
double-check the Y-fitting is low enough to allow for installation of the other drain lines.
Once you are sure of the configuration, pull up the assembly and prime and glue the pieces.
Place and Secure
Place the assembly back into the hole.
Secure the low-heel vent fitting to the framing with pipe strap.
Secure the pipe from below as well.
Check that the pipe slopes 18 to 14 inch down to the fitting.
Once you are sure the toilet drain setup is correct, mark the alignment of the fittings and disassemble.
Prime and glue the pieces.
Support the closet bend with a strap.
All fittings should be Ys or drain elbows so wastewater can flow easily.
Assemble Fittings
If the existingpipe is cast-iron, take care to support it securely before cutting.
Once you are sure the fittings are correct and the horizontal pipe slopes correctly, make alignment marks.
Have a helper hold the pipes plumb as you mark the plate below for notching.
Cut notches about an inch wider than the pipe to accommodate a fitting.
You might need to move the hole over a few inches.
The top plate can be doubled, meaning you have to drill through 3 inches.
You mightneed to drillwith a hole saw first from below (shown), then from above.
(A 3-inch horizontal pipe is shown, but your inspector might permit a 2-inch pipe.)
Insert a street elbow into the Y and hold the other pieces in place to mark for cutting.
ensure the horizontal pipe slopes at a rate of 18 to 14 inch per running foot.
Study the directions for the tub to determine precisely where the trap should be located.
Hold the trap-and-pipe assembly in place and mark it for a cut.
Dry-fit and check that the horizontal pipe slopes correctly.
Once all the parts are accurately assembled, draw alignment marks and prime and glue the pieces together.
Use a carpenter’s level to mark the studs for drilling holes.
Drill holes, cut pipes, and connect them in a dry run using drain fittings.
Install a Sanitary Tee
Install a sanitary tee facing into the room for the sink trap.
Cement a 114-inch trap adapter into the tee.
Install a piece of 1x6 blocking and anchor the pipe with a strap.
Connect to Other Pipes
In the attic, tap into a conveniently located vent pipe.
Cut the pipe and connect a reducer tee fitting.
Use no-hub fittings to connect a PVC fitting to cast-iron or ABS pipe.
Check for Leaks
fire off the new vent line over to the tee fitting.
The pipes should slope gently away from the existing vent pipe so water can travel downward.
Pour water into it until all the drain and vent pipes are filled with water.
Allow the water to sit for a day tomake sure there are no leaks.
Check Codes
Check local codes for the correct way to install aroof jack.
In most areas, you will need to install a 4-inch pipe.
Purchase a roof jack with a rubber flange that will seal a 4-inch pipe.
Mark for the hole, which will be oval.
Cut the hole using a drill and areciprocating saw.
Anchor Jack
You might need to cut some roofing shingles back.
Poke the vent pipe up through the rubber flange.
To anchor the jack, lift up some shingles and drive roofing nails.
If any nails are not covered by shingles, cover the heads with roofing cement.
This assures waste and water flowing through pipes will drain out of your house.
Drain-waste-vent (DWV) pipescarry waste and water out of the house without noise or odors.
To do this, there needs to be an air passageway behind the water.
Vents extend from the drains up through the roof to provide that passage.
According to the 2021 International Residence Code,a house only needs one vent line.
Drain lines that aren’t properly vented won’t be able to move waste out of your home effectively.
In addition, your pipes could begin to dry out and crack.
Plumbing lines don’t have to go through the roof.
However, they must extend at least one foot above the roof if installed through walls.
The toilet could still flush with a clogged vent, but the drain will be sluggish.
Chapter 31, Vents.International Residence Code.
