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Damp in fireplace

Postby maz333 » Tue Jul 17, 2007 11:48 am

There seems to be dampness in the firsplace in one of the bedrooms in my flat - a builder has told me that it is down to condensation rather than rising damp. It seems to have not got any worse since I started using a dehumidifier and airing the room better, but I am still left with blistered and flaking paint and discolouration in the fireplace. Is there an easy way to improve the look of the fireplace, ie can I simply strip off the paint and paint a new coat over it, or do I need to take more drastic action? I am complete diy novice by the way.
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Simply Build It

Postby Perry525 » Thu Jul 19, 2007 5:53 pm

Lets deal with this sensibly. First do you have condensing damp?
Condensation forms when the humidity in the air drops out due to a drop in temperature.
It always forms on the coldest smooth surface.
Such as a window. Or window frame, or cold water pipe.
Are your windows running with water because you turn the heating off?
If they are not and you do not - you do not have condensing humidity.
Of course, you may have double or treble which event, the windows may not be the coldest spot.
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Postby maz333 » Fri Jul 20, 2007 9:48 am

Thanks for your response. I do have double glazing in the room - the windows don't seem to get much condensation. Also would the fireplace not be the coldest point in the room as the brickwork is thinnest there, so therefore nearest to the cold outside air? I have been told by two separate builders that the damp is condensing rather than rising, so have been going on what they have told me.
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Postby dcmoore » Sun Jul 22, 2007 7:58 pm

Chimney breasts can become damp for many reasons;

1. Open pots at the top - no ventilated caps or cowls

2. Poor pointing in the chimney stack

3. Poor flashings around the chimney

4. Same as above but coming from next door's chimneys

5. Salts and chemicals from burning coal and wood over many, many years 'leaching' out into the plaster - these attract moisture from the air.

6. Old back boiler and plumbing leaking water

7. Chimney never cleaned - full of soot

8. Neighbours house at a higher ground level - rising damp affects the party wall and chimney back

9. Fireplaces closed up and not ventilated

10. Water leak on either side of the party wall

11. Water leak in the roof - check also water tanks
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