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Home/Roofing/Cracked plumbing vent boot

Roofing · Often DIY

Cracked rubber boot around a plumbing vent

One of the most common roof leaks there is, and among the cheapest to fix. The rubber collar around vent pipes splits from UV long before the shingles fail. You can often see it from the ground.

More on 1940 to 1980 roofs
Quick answerOne of the most common roof leaks there is, and among the cheapest to fix. The rubber collar around vent pipes hardens and splits from UV in roughly ten to fifteen years, long before the shingles fail. You can often see the split from the ground with binoculars. You can handle this one yourself. No call needed: on a single-story, walkable roof, replacing the boot is a short job.

This is most common in homes built roughly 1940 to 1980. Every plumbing vent that comes through the roof is sealed with a metal or plastic flange and a rubber collar that hugs the pipe. The flange lasts. The rubber doesn’t.

1Why it happens

  • UV. Sunlight hardens the rubber until it cracks, usually on the side that faces the sun.
  • Heat and cold. Years of expansion and contraction open the cracks wider.
  • Reused at a reroof. If the boots weren’t replaced with the last roof, they are older than the shingles.

2How to check

  1. Look from the ground with binocularsA gap or crack between the rubber and the pipe, or rubber that looks split or shrunken, is the sign.
  2. Check the attic below the pipeFollow the vent pipe up in the attic. Stains or damp wood around it confirm the leak.
  3. Check the ceiling belowA stain below a bathroom or near a plumbing wall, appearing after rain, often traces to the boot.

3Fixing it

Do it yourself

  • Single-story roof with a low, walkable pitch
  • Replace the boot with one sized to your pipe
  • Slide the upper shingles back over the flange
  • Seal exposed nail heads as the boot’s instructions say

Leave it to a roofer

  • Steep or second-story roof
  • Shingles around the pipe are brittle or damaged
  • The deck around the pipe is soft
  • You’re already planning a reroof

Caulking the crack is a stopgap. Replacing the boot is the fix, and it’s cheap. Measure your pipe size before you buy.

Roof safety

Only work on a roof you can walk comfortably, in dry weather, with a properly secured ladder and someone with you. If the roof is steep or high, don’t do it yourself.

4What drives the cost

The boot itself is inexpensive. What moves the price is roof access, pitch and height, how many vents there are, and whether shingles or deck around the pipe need repair. If you’re reroofing, new boots should be included.

Roofing cost

5Questions

How long do pipe boots last?

The rubber typically hardens and splits in roughly ten to fifteen years, often well before the shingles.

Can I just put sealant on the crack?

It may hold for a while, but the rubber keeps aging. Replacing the boot is the real fix.

Should a new roof include new boots?

Yes. Ask for it in writing so old boots aren’t reused under new shingles.

Written by Jaylan Jones. I Like To Exterior Services earns a referral fee when a call connects to a contractor. See our business-model disclosure.