Water stain on the ceiling: causes and what to do

What the stain is telling you

The brown or yellow ring is left behind by water that soaked into the ceiling and dried, carrying dust, tannins and minerals to the edge of the wet patch. One ring means one event. Several rings, one inside another, mean it has happened repeatedly.

The stain marks where the water came through, which is not always directly below where it got in. Water runs along the top of the ceiling, along joists and pipes, before it finds a seam or a fixture.

Likely sources, by where the stain is

Below a bathroom. A leaking supply line or drain, a failed toilet seal, a shower surround that lets water behind the tile, or water splashed over the edge of a tub.

Below the attic or roof. Missing or damaged shingles, failed flashing around a chimney, vent or skylight, or an ice dam in winter.

Near an outside wall in winter. An ice dam, or condensation in the attic dripping onto the ceiling.

Around a ceiling fan or bathroom exhaust. Condensation in an uninsulated duct running back down.

Below an air conditioner or furnace in the attic. A blocked condensate line or overflowing drip pan.

In the middle of a room with plumbing above. A pinhole leak or failed fitting.

Is it urgent?

Treat it as urgent if:

• The stain is wet, growing or dripping
• The ceiling is sagging or bulging
• It is near a light fitting or other electrics
• There is a musty smell or visible mold

A sagging ceiling can come down. Keep people away from under it. Switch off the power to that room at the breaker panel, because water collects around light fittings. Then, if a bulge is holding water and you can reach it safely, a small hole at the lowest point releases the water in a controlled way.

An old, dry stain that has not changed is not an emergency, but it still needs explaining.

Finding the source

1. Note when it appears: after rain, after a shower, in a thaw, or all the time.
2. Look directly above, then uphill along the framing.
3. In the attic, look for wet insulation, dark trails on the wood and daylight around penetrations.
4. For plumbing, run each fixture above in turn and watch.
5. A moisture meter shows whether the ceiling is still wet and how far.

Why you should not just paint it

Paint covers the mark and leaves three problems: the leak, which will recur; wet insulation and drywall above, which can grow mold; and the stain itself, which bleeds back through ordinary paint within weeks.

Proper repair

1. Stop the source.
2. Check the cavity above. Remove wet insulation.
3. Dry the ceiling and framing.
4. Replace drywall that is soft, sagging or moldy. Sound, dry board can stay.
5. Seal the stain with a stain-blocking primer.
6. Repaint the whole ceiling for an even finish.

Insurance

Sudden leaks, such as a burst pipe or storm damage, are commonly covered. Slow leaks over time and wear-and-tear on an old roof often are not. Photograph the stain and the source before repairs.

Old stain or active leak?

A stain that is dry, hard and unchanged for months is probably historical. To check, outline the edge lightly in pencil and date it. If the stain grows past the line, or feels damp or soft, the leak is still active.

Other signs of an active leak:

• The centre is darker than the edge
• The paint is bubbling or peeling
• The drywall is soft when pressed gently
• There is a drip, however occasional
• A musty smell near the stain

In a condo or apartment

A ceiling stain usually means water from the unit above or from common plumbing. Report it to the property manager or landlord straight away, in writing, with photos. Do not open the ceiling yourself. Finding the source and repairing the building is the corporation’s or the landlord’s responsibility, and your own policy covers your belongings and any improvements you own.

More: water damage restoration.