First, some set up: My friends and I have been building a sort of Mancave over the last year. It's about 300 square feet, with a height of about 14 feet -- half of the place has a loft (making something like 2 floors) while the other half has tall ceilings.

We initially did not have plans to put in a bathroom -- so, we put drywall up everywhere. THEN, we decided it would be nice to have a bathroom. We ran all of the water lines from city water up into the crawlspace (passing inspection), but now are preparing to tackle the bathroom.

My question: With the drywall up, and roof shingled -- and the whole place basically ready for use.. we are putting a bathroom in. Under the loft, we have built a 2x6 dividing wall for all of the plumbing to sit inside (just the studs right now). HOWEVER -- we did not realize, being newbies, that you need a plumbing vent stack. The question is, can we possibly vent our plumbing for an entire bathroom WITHOUT penetrating the roof?

There is a somewhat tall crawlspace under the building. Could the drain just be low in the crawlspace, and have a vent that angles out through the rim joist and run the vent outside? I have read that it is possible to vent through an exterior wall -- but as this 2x6 wall is in the middle of the house, reaching an outside wall might be difficult.

What is my best option? I really appreciate any help!!

P.S. I will be making sure any plans pass inspection before doing the plumbing -- Any help I get will go toward my plans.


2 Answers 2


To vent plumbing you must either find a way to tie into an existing stack vent, go to the outside via wall (this is code depending on area and must be higher than all fixtures - what you are describing is not), or go through roof.

If the roof is available this is probably your easiest option. You drill a hole and throw a roofing vent with gasket over the hole, caulk gasket, plug pipe in bottom of vent through hole and you are done. This is a very easy, forgiving process. With materials in hand you can do this in 30 mins. So just do it right.


Depending on your local codes, one might use a studer vent at the end of a short vent pipe (higher than any sink bowls/toilet resevoirs in the basement). Such a vent isn't allowed to be within a closed off space (ie. within a wall) ...as there's be no make-up air.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.