Brown stains with defined edges that appear or grow after rain usually point to a roof leak or plumbing leak, while black spotty mould spread across a cold area of ceiling, often near external walls, points to condensation. Checking the loft above usually settles it.
A mark on the ceiling causes a lot of worry, and the first thing to work out is whether water is coming in from above or forming on the surface from the room below. They look different if you know what to look for.
Signs of a leak
- Brown, yellow or tea-coloured staining, often with a darker ring at the edge.
- A patch that appears or grows after rain, or after using a bath, shower or toilet upstairs.
- Bubbling or sagging plaster or plasterboard. Don’t ignore a sagging ceiling; it can come down.
- Damp near a chimney stack, roof valley, skylight, flat roof edge or soil stack.
Signs of condensation
- Black, spotty mould rather than brown staining.
- Spread across the coldest parts of the ceiling: in corners, along external walls, and in bedrooms and bathrooms.
- Worse in cold weather, regardless of whether it’s been raining.
- Sometimes a pattern of lines where the ceiling joists are, or a patch where loft insulation is missing above.
Check the loft
Get up there safely with a torch.
- For a roof leak, look for daylight, damp or stained timbers, wet insulation, and slipped or broken tiles and slates, especially after rain. Look around the chimney and any vents or pipes through the roof.
- For plumbing, check the cold water tank, pipes and any loft-mounted equipment for drips.
- For condensation, look at the insulation over the mouldy area. Gaps, especially at the eaves and in corners, leave a cold patch of ceiling. Also look for condensation or mould on the underside of the roof felt or timbers, which can mean the loft itself is poorly ventilated.
What to do
- Leaks: fix the roof or plumbing, let the ceiling dry, and repair or replace any damaged plaster. Stain block before painting.
- Condensation: fill gaps in the loft insulation without blocking eaves ventilation, improve room ventilation and heating, and clean the mould.
- Loft condensation: make sure the eaves and roof vents are clear, don’t vent bathroom fans into the loft, and seal around the loft hatch.
When to call a specialist
If you can't tell where the water's coming from, or the stain keeps returning after repairs, get a survey to trace the source. Book a survey with All Dry on 01226 287181 or email info@alldrydampproofing.com.
Frequently asked questions
Does a brown stain on the ceiling mean a leak?
Usually, especially if it has defined edges or appears after rain or using water upstairs.
Why is there mould on my bedroom ceiling?
Often condensation on a cold area, sometimes where loft insulation is missing.
Can the loft get condensation?
Yes, poorly ventilated lofts can have condensation on the underside of the roof.