Harringay, Haringey - So Good they Spelt it Twice!
Damp patch on wall in bathroom - advice?
Hello
We had our bathroom done recently (by Chris, who is very highly recommended here on HoL). After the plaster on one of the external walls had dried, we noticed a patch that stayed damp, right in the middle of the wall. It dries a little, but then seems to look damp again after it's rained or even when condensation builds up in the room. The patch is about a foot in diameter.
We had a roofer over and there doesn't seem to be a problem with the roof above it. Sometimes I can see what looks like a thin drip stain on the outside wall roughly above where I think the patch is, but sometimes this disappears. it's driving me crazy! We want to get the wall painting finished so the room is done. I called a damp specialist recommended here but they deal only with rising damp - he said it didn't sound like damp anyway.
Any ideas for what it might be or any recommendations for someone who might be able to help?
Thanks in advance!
Tags for Forum Posts: damp-proofing
Replies to This Discussion
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Permalink Reply by Hugh on
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From my experience, damp diagnosis, seems a little like a medical one. Expert opinions differ. If you ask a couple of general builder types (many recommended on HoL), you may find that a consensus emerges.
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Permalink Reply by Philip on
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definitely a concern, but since the roof is fine, the roofer wouldn't be interested. the plaster should definitely dry out and the patch is either drawing moisture in, or there is ingress from the exterior. Since it's new plaster, it shouldn't be absorbing moisture to that extent so the next step would be to get a good look at the exterior next time it rains. (shouldn't be long!) You may find a blockage at some point is causing an overflow at that place or there is a leaking gutter joint.
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Thanks Philip. When you say 'you may find a blockage at some point' where do you mean, please?
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A blockage may not be immediately evident(you can't see it at the point of overflow) Blockages usually take place at inside corners of a building where the gutters lead into the downpipe. These can be blocked with debris/old birds nests/or typically, a tennis ball(which fits perfectly) Then the water backs up and overflows somewhere else. Also, a leaking joint can only be detected when water is present, but just a drip drip on the wall will give problems. A dripping WC overflow can also cause this problem, but it doesn't sound like that is the situation here.
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It could be plaster efflorescence. We had similar patches and after taking to the builder thought it was discolouration of the plaster. We went ahead and painted, this was a mistake the paint is now peeling off in those areas. It seems the only remedy is to apply vinegar to the walls to neutralise the salt. We still haven't sorted this out, it's very frustrating!
http://www.harringayonline.com/forum/topics/plaster-efflorescence?x...
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We didn't have any crystals either to begin with just areas of plaster that were a different colour, damp looking. On the advice of our builder we drew round the areas with pencil, if they were damp patches they would grow or shrink. The areas didn't grow or shrink so we wrongly concluded it was just discolouration. The crystals only formed once the wall had been painted, I presume the paint created a seal and made the efflorescence worse...I'd have expected my very experienced builder to have known about it...clearly not, it's very annoying!
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Permalink Reply by pamish on
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Pointing? Missing mortar between some bricks? It does only last about 50 years (if you're lucky). Could explain the limited damp spot - one chunk has fallen out.
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Hi there - we have exactly the same problem - have you found anyone to help? It's driving me crazy too.
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