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Chimneys & Fireplaces

Mysterious damp patches - who has seen this before??

We have damp patches on a ceiling upstairs around a fireplace, on the front of the same fireplace lower down and in the room below around the fireplace. Roof redone & dry underneath when rechecked, chimney pots rebedded & flaunching redone - no imprevement. Our roofer/builder suspect it is due to condensation, however, the problems gets so much worse when it rains! No idea what could be the cause of the leak. Can you help?

Steffi

3 Answers from MyBuilder Chimney & Fireplace Specialists

When your roof and pots we done, did they fit rain guard cowls with vents, also if the fire places are blocked up, you need vents fitted, as there needs to be a good ciculation of air.

2011-11-07T12:30:01+00:00

Answered 7th Nov 2011

Hello, this sounds like penetrating damp, ceiling unusual, but possible, is the chimney, faced brick or rendered? I suspect that it is facework and requires repointing. But if it's rendered...I'd recommend having it sprayed with a mastic paint like Andura(25yr Guarantee) I am expecting it is a building close to 100yrs old with lime mortar(which is very pourus.) and the patches are darker the day after rain. If you have over insulated the loft, with no airflow for drying, this would cause condensation, but not explain the worsening after rain. other possibility is if the felt has been lapped under the lead/zinc flashing, was this removed when checked?

Regards Simon

2011-11-07T12:30:01+00:00

Answered 7th Nov 2011

are the chimney pots open or capped ?

2011-11-07T12:30:01+00:00

Answered 7th Nov 2011

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