How Do I Vent My Plumbing?

Under most plumbing codes, every plumbing fixture must have a vent. There are many ways to vent a plumbing fixture, but the most common is with an individual vent that runs a vent stack or outside air. Vents must rise at least six inches above the flood-level rim of a fixture before being run horizontally.

In some cases, a kind plumbing inspector may allow the use of a mechanical vent. These vents screw into a one-and-one-half-inch female adapter and provide air for a fixture to drain better. In remodeling job, these vents are sometimes allowed in lieu of running a vent all the way to the roof. However, if you are installing a toilet or a sewer sump, plan on running a two-inch vent to the outside air or to an approved connection point with another vent.

When you have to get a vent from your basement to your attic, look for closets to run the vent in. Consider building a small box-chase in a corner to allow the installation of the pipe. The routing of the vent from a basement is often the hardest part of the job.

Can I run my vent up the outside of my house?
Some plumbing codes do allow side-wall vents. These vents must be protected from freezing, in cold climates, and they must not terminate under a soffit vent. There are restrictions pertaining to the proximity of the vent to windows, doors, and even properly boundaries. Check with your local code officer for details on side-wall vents.

My drain goes out at floor level, what can I do?
If you position your bathroom or plumbing near the existing drain, you may be able to build up the new floor, with a sleeper system, to allow height for your new drains. Check your ceiling height requirements before raising the finished floor level.

Can I tie into the pipe for my floor drain?
Most floor drains will be connected to a pipe of at least two inches in diameter. In fact, the minimum pipe size for pipes running under concrete is usually two inches. The floor drain could be connected to a three- or four-inch drain.

As long as you vent your new fixtures, there shouldn't be any problem with tying into the same drain used by your floor drain. The plumbing code does set requirements for the number of fixture-units placed on a pipe, so check with your local requirements before making such a connection. For example, you would not be able to install a toilet and have its drain tie into a two-inch pipe. The minimum pipe size for a toilet drain is three inches.