Roofing · A closer look at leaks
Why does my roof leak around a vent pipe when it rains?
If water shows up near a plumbing vent during rain, the seal around the pipe or the flashing at its base may have failed. Water can also enter higher on the slope and run along the wood before it drips. The stain inside tells a roofer where to start looking.
What to note before you call ↓
Two places to look around a vent pipe
- Where the flashing meets the pipe
- A plumbing vent passes through a hole in the roof. The fitting around it is often called a pipe boot. Some boots have a flexible collar that hugs the pipe. If that collar splits or pulls away, rain can run down the outside of the pipe into the opening.
- Where the flashing meets the shingles
- Look at the metal lip in John’s photo. Water coming down the slope needs a continuous path over that lip and onto the shingles below. A lifted edge, damaged flashing or a poorly fitted shingle above it can let water get underneath, even when the collar looks sound.
Bremerton roof replacement
What disappears when the last shingle goes on?
On this job, John wrapped the pipe openings with Titanium® PSU30 ice-and-water protection beneath the shingles. At the surface, he fitted the metal flashing into the shingle courses. You can see the exposed apron in the close-up above. The membrane underneath is already hidden.
See the layers on John’s Bremerton roof ↗What to note before you call
A few observations from inside the house help John trace the problem. Leave the roof inspection to him.
- When did it start? A drip that begins during steady rain is a different clue from dampness that also appears on dry mornings. Note whether wind or a particular storm direction seems to matter.
- Where does it show up? Name the room and the nearest wall or fixture. Take one wide photo for location and one close-up of the stain. If water is tracking down the outside of a pipe where you can safely see it, mention that too.
- Is it changing? Record whether the stain is spreading, the spot dries between storms, or water is actively dripping. Keep clear of a sagging ceiling or a wet electrical fixture.
Does a leaking vent pipe mean I need a new roof?
A worn boot on an otherwise sound roof may need only a local repair. The inspection should also cover the shingles uphill of the pipe and the wood around the opening. If the wood is damaged, ask to see the affected area and how it changes the repair. See what a decking repair looks like.
Seeing a fresh stain after rain in Tacoma, Lakewood or the Kitsap area? Tell John when it appeared and request a free initial roof inspection.
Further reading: GAF’s guide to vent pipe collars, flashing and leaks.