Q: I have a stain on my bathroom ceiling that is in the middle of the first floor of my house. The room above does not have any plumbing and nothing has been spilled up there. What can cause a problem like this, and how can it be fixed?
A: During a home inspection, I always look at the ceiling above a bathroom because there is a large pipe inside one of the bathroom’s walls.
The pipe extends all the way through the house and attic and finally above the roof. The pipe is a plumbing vent used to vent sewer gases and to allow air to enter the plumbing sewer pipes so they can drain efficiently.
A rubber boot is slipped snugly over the pipe where the pipe penetrates the roofing, creating a water seal. Over time, the rubber will degrade, leaving an opening where rain can run down the pipe to the ceiling below.
Sometimes I have found stains on the ceilings of other rooms in a home where the water ran down the vent pipe and followed a horizontal path along the pipe until a drip formed at a fitting on the pipe. If the fitting is above a living room, bedroom or kitchen, the stain will appear there.
When you contact a repairman, he may simply caulk the rubber boot as a temporary fix. No matter how much caulking is used, it is “temporary.”
A new rubber boot can be slipped down and over the vent pipe and left until the home requires a new roof covering, flashings and boots.
C. Dwight Barnett is a certified master inspector with the American Society of Home Inspectors. Send questions to C. Dwight Barnett, Evansville Courier & Press, P.O. Box 286, Evansville, Ind. 47702 or e-mail him at d.Barnettinsightbb.com.