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Missing bathroom plumbing vent stack

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Craig says:
September 29, 2011 at 9:44 pm
The previous owners of our house replaced a downstairs closet with a small bathroom. This bathroom is at the back end of the house, where the main vent stack is at the front of the house. 
When you flush the toilet, it sucks the trap in the sink dry, couple of hours needless to say it smells of sewage. So I’m assuming that since the vent stack is at the front of the house were the main bathroom is, the downstairs bathroom isn’t vented right.
HOWEVER, the original kitchen sink along with an original sewer line is right on the other side of the bathroom. So the toilet and bathroom sink are tapped into an original sewer line where the sink is tapped in. Let me add, the kitchen sink is also sucking water out of the bathroom sink.
I’m thinking this is a new issue since the house and the kitchen sewer line are original with the 90 year old house. Regardless I have a venting issue. My question it would be really difficult and costly to run a new vent outside, is there another solution? Thanks in advance.
asked in Plumbing by darekrudy (21,730 points)
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1 Answer

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Hello Craig,
    Difficulty would be in getting inside the wall / floor to install and tie vent pipes to the existing plumbing fixtures drain lines, connect them to a single vent stack, and running it through the house floors and the roof. PVC pipes (if you can use them in your area) aren’t expensive but there might be a lot of labor involved in this entire operation.
    There’s another option which is using AAV (air admittance valves) but it might be forbidden in your jurisdiction so you have to check with the building department. You’d still have to gain access to the pipes to install AAV’s. Some examples of the air admittance valves: http://www.plumbingmall.com/studor.htm
answered by darekrudy (21,730 points)