Signs of a Leaking Roof: What to Check Inside and Out
"I noticed a small leak out of a can light today and am trying to determine whether to call plumber or roofer."
A homeowner who started a thread on r/HomeMaintenance wrote that.
A ceiling stain is the obvious sign, but not the only one. Indoors, cracked paint, discolored plasterboard and peeling wallpaper1 can point to damaged roof areas. In the attic, discolored rafters or damp insulation2 show moisture. Either way, the leak is rarely directly above the stain3, and some stains come from plumbing or moist air, so check before you call anyone.
Quick answer:
- Look at ceilings and walls for cracked paint, discolored plasterboard or peeling wallpaper1.
- Check the attic for discolored rafters, stains on the floor or damp insulation2.
- Scan the roof from the ground with binoculars, and don't risk serious injury trying to inspect or repair it3.
- Rule out plumbing and condensation: a water meter that moves while nothing runs for two hours probably means a plumbing leak4, and attic frost points to warm, moist air condensing5.
On this page
What does a leaking roof look like from inside?
Mostly stains and dampness. Plasterboard is the drywall of your ceiling and walls, so a discolored patch there is worth noting. In the attic, wet or damp insulation points to a leaky roof5, though moist house air can also dampen it, as the list below shows.
Brown mark on the ceiling and unsure if it is a leak yet? What a water stain on the ceiling means.
Signs you can see from the ground
Stand back from the house and use binoculars. Look for cracked, warped or missing shingles, deteriorated flashing, and granules collecting in gutters or downspouts1. Flashing is the metal that seals joints around chimneys and vents. Granules are the gritty coating that wears off shingles.
These are signs the roof is in trouble, not proof that water is getting in.
Why isn't the stain under the hole?
Because leaks are rarely located directly above the water spot on the ceiling3. One reply in a r/Roofing thread put it this way: "It may be leaking further up the roof than what you originally think."
So the stain tells you something is wet, not where the water gets in. Checking the attic for a drip trail3 is the next step, and how to find a roof leak walks through tracing it. You can take the steps below even if you can't find the leak yet.
Roof, plumbing or condensation?
Three causes look alike: the roof, the plumbing and moist air inside the house. A reply in a r/HomeMaintenance thread asked, "How are you supposed to find the source of the leak when it is no longer leaking?" Write down when the stain appears or grows. These checks work without a drip:
- The water meter reads different after two hours with no water used: you probably have a leak in the plumbing4. Call a plumber. An unchanged reading doesn't clear the roof.
- Frost on attic insulation in cold weather, or water staining in the same spots in warmer weather: warm, moist air condensing5. Ask an insulation or air-sealing contractor.
- A bathroom fan, kitchen range or dryer that vents into the attic: that moist air can be the source6, so the fix may be the vent, not the roof.
- Stains or damp insulation that appear or grow after rain, or ceiling stains from a leaking ice dam in cold climates7: call a roofer you choose.
Steps to take while you wait for a roofer
- Check the attic, the ground and the meter as above, and note when the stain appears or grows.
- Protect and document: photograph or videotape the damage, then take reasonable steps to protect your property from further damage8. A bucket and towels count.
- Sort the cause with the list above, then call the trade it points to.
If the roofer can't come today, keep protecting your property from further damage8:
- Catch drips in a bucket, move belongings away, and dry water-damaged areas and items within 24-48 hours9 to prevent mold growth.
- If you may file a claim, keep damaged items if possible and save receipts for what you spend8. A few pieces of anything that came off show the roofer what happened.
- Look again after the next rain, from the ground and in the attic for a drip trail3.
Does the attic smell damp, and could mold already be starting? Mold in the attic: how serious it is.
If your checks still point to the roof
Ask the roofer to show you a photo of each problem found. Then ask for each problem as its own line in the quote, with the repair and its cost, and for your signed approval before any extra work. You can send this:
Please list each problem you find as its own line, with the repair and its cost, and tell me in writing before adding any work.
If a roofer won't put this in writing, or pushes you to sign today, that is an answer too: weigh it against the other quotes.
Have these ready before you call:
- Your photos.
- When the stain showed up or grew: after rain, in a cold spell, or neither.
- What the attic and meter checks showed.
Quick questions
Can a roof leak cause mold? Yes, if the wet materials stay wet: if they are dried 24-48 hours after a leak, in most cases mold will not grow9. In cold climates, a leaking ice dam can lead to water stains on the ceiling, structural damage and mold growth7. Drying wet areas fast, as above, is the part you control.
What if the stain looks dry now? A dry stain tells you something was wet. Trace its edge in pencil with the date, and see whether it grows after the next rain or cold spell. If it does, use the steps above.
Should I read my insurance policy? If you think you may file a claim, read your policy to see exactly what your responsibilities are8. Jot down the questions you want to ask.
Is there a 25% rule for roofing? In Florida, there is a rule for a roof or roof section built, repaired or replaced to the 2007 Florida Building Code or later10. When 25 percent or more of it is being repaired, replaced or recovered, only that portion must meet the code10. Wherever you live, ask the roofer and your local building department which rules apply to your roof.
Sources
1. National Roofing Contractors Association, Roofing Resources
2. NC State Extension, Inspecting a House
4. U.S. EPA WaterSense, Take the 10 Minute WaterSense Challenge
5. ENERGY STAR (U.S. EPA / DOE), Attic Air Sealing Project
6. U.S. Department of Energy, Guide to Durable Attics
7. North Dakota State University Extension, Reduce ice dam and icicle damage
8. Triple-I, How to file a homeowners claim
9. U.S. EPA, A Brief Guide to Mold, Moisture and Your Home
10. Florida Legislature, Florida Statutes 553.844
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