Venting of basement plumbing fixtures

david.plymouth · 01-17-2010, 06:50 AM

I am currently finishing my basement and plan to have a full bathroom and a wet bar with a small sink. The house is 12 years old and the builder pre-plumbed the basement for a full bathroom and there are 3 waste outlets in the floor. I have a couple of questions:

1. Do I have to vent the bathroom fixtures, if so how can I do this as I don't see a way of connecting into the upper level vent pipe?

2. Can I use one of the existing waste outlets for both the wet bar sink and the bathroom wash basin or will I have to dig up the floor and add an additional waste for the wet bar sink?

Any advice would be appreciated

David

adpanko · 01-17-2010, 08:21 AM

In short, yes, you need to vent every fixture. ALL plumbing fixtures require venting. The sizing and location of the vents is determined on the specifics of your layout. So without seeing detailed drawings, I can't say. But everything will need to be vented. Check if your local code allows mechanical vents. They are either known as Air Admittance Valves or Automatic Air Vents. They are little one way air valves that you essentially attach along the drain line and don't require you to run vents up and out of your house. Most national codes allow them, but certain town overrule and don't allow them. My town is one example. My town uses the 2006 National Standard Plumbing Code, which allows such vents, but my town doesn't allow the vents...go figure.

willowgirl · 01-18-2010, 12:45 AM

If the contractor already had the plumbing in the design layout they may be vented as that would be part of what needs to be done for the plumbing of a bathroom. Are you able to check with that contractor, or if you have the design's it should show. You just may not be able to see it. Or the vent lines may have been run to somewhere you can easily tie into it since they new it was part of the design.

david.plymouth · 01-18-2010, 06:46 PM

All of the main level fixtures connect into one soil stack in the basement (see attached). The rough plumbing for the basement bathroom consist of 3 PVC pipes sticking out of the concrete floor of the basement, two 2" and one 4". These three pipes are in one corner of the basement about 15-20' from the soil stack.