I know the vent pipe travels vertically for about 7 feet through the attic and out the roof. One common cause of sewer gas leaks comes from damage to your sewer or septic pipes. That will tell you for sure. The first place to check for a leak in your vent stack is around the base of the vent stack. 1. Do you have small water stains appearing on your ceiling? Steps for Fixing a Leaking Rooftop Vent Pipe: Use a pocketknife to scrape rough edges and sharp points from upper end of plastic vent pipe. Your pipes could be leaking from rust, corrosion, a blockage, or holes along the pipes or pipe joints. Please see attached pic of a 4-way in the pipe vent (stack vent), the one that is used to prevent vacuum forming in drainage lines. One of the most common, if not the most common problem I find with inspecting roofs, is a leaking flashing boot around the plumbing vent pipe. It isn't full on "leaking" but there is a drop of water that seems to always be around the rim. Usually the roof flange leaks and it travels down the outside of the pipe.It only looks like the pipe is faulty. Those vent pipes provide fresh air to all the plumbing fixtures so that the system can efficiently move water through the drainage pipes each time a sink is drained, or a toilet is flushed. The 3" (larger one) goes through the roof and open. (See below for a shopping list and tools. Another option would be to dry the area, build a dam of some sort, and pour epoxy glue to encapsulate the leaky joint. Use the knife blade to scrape the pipe clean and smooth. Our Tampa plumbing experts want to point out that if the smell coming from your leak smells like sewer gas, it could be dangerous and unsanitary to do a home repair. So any water in the sewer pipes runs downhill out of the house through to the main sewer line which is connected to the city’s system or a septic tank. Plumbing vent pipes are always located away from windows and HVAC units so that fumes dissipate easily without contaminating those air sources. When these fail, water gets in to places … This Old House general contractor Tom Silva shows how to create a watertight seal around a vent pipe. Common blockages tend to be caused by tree roots, grease, and items that … If you are convinced that the water is coming from inside the pipe through a bad joint, you could try a Leak-B-Gone PVC Repair Ring, or replace the tee. However, with hot showers being taken a little more regularly we have noticed water … I am having a leak on the roof repaired so I will just make sure it is nice and caulked from the roof. If no water then spray around the flange to see what happens. This is the most obvious to spot and the easiest to repair. Sewer or Septic Pipe Leaks. Now that the weather has gotten nice and cold - we have a slight problem with water vapor collecting on the inside of our vent pipe leading to a fan leading to one of our top floor bathrooms. I am going to just cut and lower the pipe (with a t-trap). When it rains, rain water collected by it trickles down the inside wall of the pipe and leaks out at the joint as shown in the pic. To test for leaks, we take a rubber, inflatable test ball that is connected to an air hose and insert it into the sewer pipe at the main line cleanout . Apply a thick bead of lap-seal caulk around the seam between the vent pipe and … I think taking the pressure off of the vent and redoing the pipe may … Your best bet to be sure its the pipe is to put a hose in the vent and run water down there. Cut away the old caulk from around the vent pipe. The problem is likely the flashing around your plumbing vents.