damp patches on chimney breast

21 Mar 2007
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United Kingdom
Recently had the chimney breast removed from ground floor room however rain came down the chimney onto the floor so had the cowl holes blocked up with cement. Now getting damp patches on the chimney breast at ceiling level in 1st floor bedroom. A roofer suggest that the lead flashing may need replacing. What course of action should I take?
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Inspect the lead flashing, and replace if necessary. :idea:
Redo the flaunching. That is the usual cause.
if the chimney is no longer in use,and blocked at both ends ,it will need air bricks/vents to prevent damp causing problems in future,though this is unlikley to be the cause in this instance,but,if you're going to have the flashing done,you might as well get air bricks fitted at the same time.
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the problem with a lot of chimney breasts, or indeed the masonry within, is the bricks have become saturated with soot, oil, tar, hygroscopic salts etc. etc.

there is no more room for anything else. so when a chimney breast gets blocked off with no ventilation, the already vulnerable masonry will react almost instantly.

very temperamental structures are well used chimneys!

so what i'm saying is, yes, do look out for the obvious signs first, i.e. flashing, flaunching, missing tiles etc., but don't be too surprised if these elements are sound.

read about hygroscopic salts and you will see what i mean.

Thanks every one for your advice.
Going to start with a new ventilated cowl and then the lead flashing etc.

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