Roof Vent Leak: Where Is the Water Really Coming In?

Updated 2026-10-24 · Sources checked

"I had my roof replaced earlier this year. During heavy rain I’m seeing a stream of water come from this vent on my patio overhang."

A homeowner who started a thread on r/HomeMaintenance wrote that.

A leak at a roof vent can come from the seal around the pipe, but the stain can sit well away from where the water gets in. Leaks are rarely directly above the stain1, and valleys and penetrations are vulnerable spots for water intrusion2 too. Before you pay for any repair, find the source of the leak from the ground and the attic.

Quick answer:

  • Look at the vent with binoculars from the ground, because you should not risk serious injury trying to inspect or repair a roof1.
  • Check the attic for a drip trail or a spot of light coming through1.
  • Photograph the stain with the date, and dry wet areas and items within 24-48 hours3.
  • Get written estimates4 before you agree to a bigger job than the problem needs.
On this page

Is it the vent, a valley, or the humidity in your home?

It can be any of the three, and the stain alone will not tell you which. A pipe through the roof is sealed by boot or collar flashing5, the flashing ring where the pipe meets the shingles. Flashing around vents can corrode, pull loose or crack6. Valleys and other roof penetrations are vulnerable too, and moisture made inside the house can look like a roof leak.

How to look without going on the roof

Here is what to look for:

If the flashing at the vent looks cracked, is sealing it enough? How to decide between repairing and replacing flashing.

Can a fan or dryer make the attic wet without a roof leak?

Yes. Kitchen ranges, bathroom exhaust fans and dryers that vent their moist air into the attic rather than outside7 can leave it damp with nothing wrong on the roof. A commenter in a roofing thread put the doubt this way: "it could be the roof, but it also could be condensation building up inside".

Checking a duct is attic work, so look only. If you find one, write it down for your roofer.

The order that works when you don't know the cause yet

  1. Find where the water comes in, using the signs above, and note any fan or dryer duct in the attic. If water is coming in now, put a bucket under it and move belongings away first.
  2. If you may file a claim, check your policy's deductible8, the amount you pay first, since a loss lower than it may not be worth the claims process. Ask your insurer how it treats a slow leak compared with sudden damage.
  3. Call a roofer you choose, with what you found.

What decides whether insurance pays for a leak like this one? Will insurance pay for a roof leak.

If the roofer can't come today

A commenter on r/HomeMaintenance asked, "How are you supposed to find the source of the leak when it is no longer leaking?" If the leak stops with the weather, be ready for the next rain:

Who do you call for what you found?

Could a plumbing leak be behind the stain if none of these fit? Who to call for a roof leak.

What to get in writing before you sign

In New York, contact at least three contractors and get written estimates4. Compare them for the same scope, and you can see whether one is selling a bigger job. Ask each roofer to show you a photo of every problem they find, and to put the vent work in writing. You can send this:

Please write in your estimate what you would replace at the vent and why. If you find hidden damage underneath, please tell me and get my signed approval before doing that work.

If a roofer won't put this in writing, that is an answer too: weigh it against the bids that do.

Have these ready for the call:

Quick questions

Can a dryer vent go straight up through the roof? Avoid ending the dryer duct at the roof10. Ask the installer what your area requires before anything is moved.

How do I repair a roof valley leak? A valley repair is roof-top work, and you should not risk serious injury trying to repair a roof1. What you can do is note in the attic whether the drip trail or light lines up with the valley, and tell the roofer.

How much does it cost to replace a roof vent? It depends on what the roofer finds around the vent, and no honest figure is possible before someone has found where the water enters. Ask what exactly would be replaced, only the seal around the pipe or more.

Does homeowners insurance pay for a leaky roof? Your policy and the cause decide. An insurance policy will not cover damage due to lack of maintenance11. Ask what applies to a slow leak from a worn seal.

Sources

1. University of Wisconsin-Extension: Assessing and Repairing Leaky Roofs: Safely Fixing a Watery Problem

2. Pacific Northwest National Laboratory (U.S. DOE), Building America Solution Center: Roof Valleys and Penetrations Sealed

3. U.S. Environmental Protection Agency: A Brief Guide to Mold, Moisture and Your Home

4. New York State Attorney General: Hiring a home-improvement contractor

5. Pacific Northwest National Laboratory (U.S. DOE), Building America Solution Center: Look for Missing Roof and Wall Flashing

6. IBHS: Extend the Life of Your Roof Through Routine Maintenance

7. U.S. Department of Energy: Guide to Durable Attics

8. Triple-I: How to file a homeowners claim

9. Texas Department of Insurance: When are water damage and mold covered by insurance?

10. Pacific Northwest National Laboratory (U.S. DOE), Building America Solution Center: Proper Clothes Dryer Venting

11. Triple-I: Which disasters are covered by homeowners insurance?

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