DIY Doctor

Drying plaster following water leak

Postby lylbf » Sat Oct 31, 2009 10:36 am

Morning everyone,

Am looking for some advice (and possibly peace of mind?) about some damp plaster in my airing cupboard and bathroom.

Returned from holiday earlier this week to find a leak from our cold water storage tank overflow pipe (the ball cock wasn't closing off properly). Plumber came out and replaced the ball cock, so no more leak. However the water stains, which run all around the airing cupboard from ground level to about a foot/foot-and-a-half up, don't seem to be drying very much (if at all), despite having a dehumidifier going and the heating on (albeit the latter isn't 24/7).

There is also a large damp patch at the head of the bath (the bathroom is beside the airing cupboard), from ground to about a foot up. Not sure whether that'd been there from the start or is more recent. There are small bubbles appearing in the paintwork on a wall in the hall in the last day or so. This wall is the other side of the damp wall in the bathroom.

The floor of the airing cupboard is still quite wet, but below the bath is bone dry. Our pipes are handily buried in a concrete floor, which is a clever design feature until they leak.

In several places there are white powdery deposits appearing on the wall; I don't know what these are - some type of mould? Salt?

I suppose my questions are as follows:

Is it likely that there is another leak, or is the water that came off the overflow pipe and leaked into the airing cupboard just spreading out?

Assuming the latter, how long should I expect it to take for the plaster to dry? Is there anything I can do to speed up this process?

At what stage do I get a plumber back and have him start tearing up the concrete floor looking for leaks?

I live in a first floor flat; to date, the downstairs neighbours haven't come charging round complaining of water leaking through their ceiling, which is what i would expect were one of the buried pipes leaking.

Grateful for any advice. I can post pictures if that would help, particularly around the layout of the flat.

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Postby stoneyboy » Sun Nov 01, 2009 7:23 pm

To be effective you need to use a de-humidifier with a re-heat option.
This time of year it may take several months for your walls to dry out fully.
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Postby rosebery » Sun Nov 01, 2009 11:06 pm

It will be at last a fortnight if it got very wet. Did the plumber check that the overflow pipe had not come apart? Did he check that you actually have one?

I suspect tyou only had one source of water. To find out if there is another leak just monitor it and if that area does not dry out in a similar timescale to the rest or just remaisn wet then yes you probably have another leak. Hoeever, if the neighbour hasn't complained yet then you probably don't have another leak.

The salts are efflorescence. Whe it is dry brush it off (under no circumstances wash it off you'll only make it worse) treat with an anti-alkaline primer and redecorate.

The bubbles on the wall in the hall are where the damp has caused the paint to come off the wall. You may find eflorescence underneath the paint. Scrape the affected paint off and treat as before.

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