Short answer: If a ceiling stain appears or grows after rain, the roof is the most likely source, often at flashing, vents, chimneys or valleys. If it grows in dry weather, look at plumbing above the ceiling, such as a bathroom, or at condensation from ducts or an attic air handler. Find the source before you paint.
How to tell where the water is coming from
| Clue | Likely source |
|---|---|
| Stain appears or spreads after rain or snowmelt | Roof, flashing, skylight or chimney |
| Stain under a bathroom, toilet or tub | Plumbing leak or failed seal |
| Stain near an AC vent or below an attic air handler, worse in summer | Condensation or a clogged condensate drain |
| Stain along an exterior wall after wind-driven rain | Siding, window flashing or overflowing gutters |
| Stain near the roof edge in winter | Ice dam pushing water under the shingles |
What to do right now
- Put a bucket under any drip. If the ceiling is bulging with water, poke a small hole in the center of the bulge so it drains into the bucket, which relieves pressure on the drywall.
- Move furniture and electronics away, and switch off any light or fan on that ceiling if water is near the fixture.
- Photograph the stain and, if it is safe, the attic above it during or right after rain.
- Check the attic with a flashlight for wet insulation, dark streaks on the roof decking, or daylight around vents and the chimney.
- Dry the area. The EPA advises drying wet materials within 24 to 48 hours to prevent mold.
Talk to a local pro
Thinking about a new roof, gutters or siding?
Call to be connected with an independent roofing or exterior contractor that serves your area. Calls are answered by the provider or their scheduling team.
For homeowners who need new service. Have ready: your address, the type of roof or siding you have now, and photos of any damage.
Common roof leak spots
- Flashing around chimneys, skylights and walls
- Plumbing vent boots, whose rubber collars crack with age
- Valleys, where two roof slopes meet
- Missing, cracked or lifted shingles after wind
- Clogged gutters that back water up under the roof edge; see gutters overflowing
Can you just paint over the stain?
Not until the leak is fixed and the drywall is completely dry. The EPA advises against painting or caulking over damp or moldy surfaces. Once the source is repaired, a stain-blocking primer keeps the mark from bleeding through the new paint. Drywall that sags or feels soft should be replaced.
Frequently asked questions
Is a small ceiling stain an emergency?
Usually not, but it is a warning. Small leaks rot decking and insulation and can lead to mold, so have the source found within days, not months.
Who should I call about a ceiling stain?
A roofer if the stain grows after rain, a plumber if it sits below a bathroom or pipes, and an HVAC technician if it is near an air handler or vent.