Leaks & sources
Ceiling water stain: what it means and what to do
Updated
Short answer
A ceiling water stain means water reached the drywall from above: a roof leak, an AC condensate overflow, a swamp cooler, an attic water line or water heater, or a bathroom upstairs. Find and fix the source, confirm the drywall and insulation are dry, then prime and repaint.
Where the water is coming from
- Stain appears after rain: roof or flashing
- Near an AC vent or hallway: condensate overflow
- Near the cooler vent: evaporative cooler
- Anytime, growing: attic water line or water heater
- Below a bathroom: toilet, tub or shower leak
Check it
- Mark the stain's edge with a pencil and see if it grows.
- Look in the attic (safely) for wet insulation or drips.
- Press gently: soft drywall is still wet.
- Watch for sagging — that's urgent.
Repair
Once the source is fixed and a moisture meter shows the drywall is dry, a small stain can be sealed with stain-blocking primer and painted. Soft, sagging or moldy drywall is replaced, and wet insulation above it too.
Questions
Is an old, dry stain a problem?
Not usually, if the source was fixed. Check with a meter and repaint with stain-blocking primer.
Why does the stain keep coming back?
The source isn't fixed, or the drywall wasn't dry before painting.
Should I poke a hole in a bulging ceiling?
It's safer to call for help. If you must, turn off power, stand to the side, and have a bucket ready.
Editorial note: this guide is general information for Arizona homeowners, not professional, legal or insurance advice. For your situation, talk to a licensed contractor and your insurer.