Everywhere something penetrates the roof structure, leaks can happen. Pipe vents are a common place for leaks to appear. To prevent leaking in the first place, the roofer will use a flexible boot around the base of the vent where it comes through the roof. The boot fits tightly around the diameter of the pipe and its base goes under the roof shingles around.
The flexible boot will last many years after insulation. However, with time, the sun’s UV rays, along with heating, cooling, and weathering, will deteriorate the boot causing it to crack and fail. That is often when the first droplets begin to get into the attic. Eventually, you will look up and find a water stain on the ceiling or wall. That is when you learn how to repair a roof vent leak.
How to Find if a Boot is Leaking
When you have dripping water or a water stain, the first priority is to find out where the water is coming in through the roof. Go up into the attic and find where the water is hitting the ceiling or wall. Look straight up. That is often where dripping water will release from the rafters or deck and hit the surface below. However, it may not be the place where water is penetrating the roof deck.
Water takes the path of least resistance and it often travels from a spot higher in the roof, down the rafter or deck, before hitting a spot where it releases. Start working your way up the roof deck to find the place of penetration. At the other end, you may very well find a pipe vent going through the roof.
A good way to tell if a boot is leaking is to look up into the hole. If you can see anything that resembles daylight, you have a failed boot. A brand new, flexible boot properly installed around the vent, under shingles, will not allow any light penetration.
Now, even if you do not see daylight, there is still a possibility that the boot has failed. You will need to get up on the roof and look around the base of the boot. Gently lift the shingles sitting above the vent. The edge of the boot sits under this layer. When you lift it up, you may find a hole or crack. The overlying shingles do not allow light penetration, but water will always find those little holes. You need to learn how to repair a roof vent leak.
You Have a Failed Boot, Now What?
The repair is actually pretty simple.
Take out the nails holding the old boot in place.
Gently lift the shingles above.
Lift the old boot off the vent.
Put the new boot over the vent.
Place the upward part of the boot under the shingles above.
Using roofing nails, secure the new boot to the roof deck.
Dab roofing sealant over the nail heads and under the bottom edge of the boot over the downhill shingles.
You have just learned how to repair a roof vent leak. Most homeowners can do the job, start to finish, in a half an hour or less.
If you see any signs that the roof surrounding the pipe vent is rotting and deteriorating, you need to bring in the professionals. Water can do damage to a roof quite quickly. If you have a major repair job, a professional roofer is the answer. They can assess the extent of the damage, do the work and get your roof back into shape quickly.