A stain on a ceiling is water coming from above, so start with what is directly over it. Then find out whether it is still active.
A damp patch or brown stain on a ceiling is almost always water coming from above. What sits above it narrows the cause down quickly: a bathroom or toilet, heating or water pipes, a tank in the loft, the roof, a flat roof or a chimney. Water can also run along a joist or pipe and show up some distance from where it got in.
The brown colour is usually dirt and minerals carried out of the ceiling as the water dries, which is why a stain can stay long after the leak has stopped.
A failed seal round the shower tray or bath, a leaking waste, a toilet seal, or water getting behind tiles. Often worse straight after a shower.
A roof leak, a cold water tank or pipe, or condensation in a poorly ventilated loft dripping on to the ceiling. Check after heavy rain and on a cold morning.
Extension and dormer ceilings stain when the roof covering or the edge detail fails. Water can travel a long way under a flat roof before it shows.
A stain near the chimney breast on a top floor ceiling often points to flashing, the stack or the pot letting rain in.
A slow drip from a joint or radiator valve in the floor above. Often a small stain that grows steadily regardless of the weather.
If you live in a flat, the source may be in your neighbour's bathroom or kitchen. Speak to them, or to the managing agent or landlord.
If nothing above it seems to be leaking, the usual explanations are:
Thermal imaging is good at showing where a ceiling is wetter or colder than it should be, often well beyond the visible stain.
Wait until the source is fixed and the ceiling is fully dry, then use a stain blocking primer. Water stains bleed straight through ordinary emulsion. If you repaint over an active leak, you lose the best clue you had about where it was coming from.
Vigilant Surveys is an independent damp and mould surveying practice covering East Anglia, North London and the West Midlands. We carry out no remedial work, sell no products and take no commission from anyone who does the repairs, so there is nothing to sell you afterwards.
Every survey includes thermal imaging, moisture readings against a dry control and hygrometer readings, and you get a clear written report within 24 hours of the visit. £350 for the problem areas, £450 for the whole property, fixed prices, no payment to book.
There usually is a leak, just not an obvious one. Water can travel along a joist or pipe from a source further away, only show in wind driven rain from one direction, or come from condensation on cold pipes or in the loft. A stain can also be left from an old leak that has since been fixed.
Most often a failed seal round the shower tray or bath, water getting behind tiles or grout, a leaking waste pipe or a toilet seal. If the patch grows straight after a shower or bath, that is a strong clue.
Look at the roof and the loft: a slipped or broken tile, flashing round a chimney, a valley, a tank or pipe, or condensation in a loft without enough ventilation. Check whether it gets worse after rain or on cold mornings.
It may be an old leak that has stopped. Mark the edge and check it through a few weeks of mixed weather before repainting. If it stays dry and does not grow, seal it with a stain blocking primer and redecorate.
If you can see the source, call the trade that fixes it. If you cannot tell where the water is coming from, or a repair has not stopped it, an independent survey traces the source first.
No payment to book. Tell me what you are seeing and I will call you straight back, usually within a couple of hours, to arrange a visit and confirm the fixed price.
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