How to Vent a Toilet Drain

What You'll Need
3 or 4 inch PVC Pipe
PVC T-Connectors
PVC Couplers
Sloped PVC elbow connector
Toilet flange
Hack saw
Sand paper
PVC primer
PVC glue
Drill with bit
Measuring tape

If you are installing a toilet in a new location, you will need to know how to properly install and vent the toilet drain. While plumbing codes for the installation of a toilet vent pipe system vary slightly (depending on the building code in your area), most are very similar, and the steps to install the pipe vent are generally the same. Therefore, you can use this how-to guide as a reference to help you when installing the drain and vent system for your new toilet.

Step 1 - Determine Type of Pipe Needed

First, you will need to determine what size of PVC pipe you will need for the vent pipe that will tie into your home's existing vent "stack", so go into the basement or crawl space beneath your home and measure the diameter of the pipe that is used. Also, measure the distance from the new toilet location to the closest point in the vent stack pipe. You should try to keep the distance to the stack vent pipe as short as possible.

Step 2 - Mark and Saw for New Toilet

Select a installation point for the toilet drain. Most areas require that the drain be about 12 inches from the rear wall and about 15 inches from any side obstructions such as a cabinet or wall. Once you select the location for the drain, take a pencil and draw a circle that is slightly larger than the base of the drain flange. Then, take a drill to make a pilot hole inside the circle and use your jigsaw to cut out the circle. Make sure that you cut through any subflooring that may be under the floor as well.

Step 3 - Install Flange

Take the drain flange and insert it into the hole. Secure the toilet flange with self tapping wood screws that should be included in the flange kit. When installing the drain flange, make sure that it extends all the way through any subflooring. If it does not, you'll need to add an extension to the flange with PVC primer and glue.

Step 4 - Connect Sloped Elbow to Flange

Clean the inside of the sloped elbow and flange extension with PVC primer. Then, use PVC glue to connect the two pieces.

Step 5 - Install T-Connector on Current Vent Stack

Choose the location will you be tying into the current vent stack pipe. Then, cut a piece of the pipe out where you can install that the T-connector fitting. Sand the edges of the pipe with sandpaper and apply primer and glue to the pieces of pipe and the insides of the T-connector coupler. Affix the T-coupler to the two pipe sections.

Step 6 - Measure for Vent Tie-In Connection

Measure the distance between the sloped elbow connector and the T-connector where you'll be tying into the vent stack pipe. Then, cut a piece of PVC pipe that will run from the elbow to the T-connector. Sand away any rough edges on the cut piece of pipe with sandpaper.

Step 7 - Tie Into Existing Vent Pipe

Use PVC pipe on the elbow connector and the connector couplers. Also, apply PVC primer on the ends of the piece of pipe that you just cut. Apply glue to all fixture points and install the new vent pipe.