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condensation on concrete floor

Postby winsome » Thu Sep 01, 2011 11:17 am

hi hope someone can help. i have a 1970 semi with corner extension. i recently had cavity foam and top quality double glazing put in. we now have damp around concrete floor under rino floorcovering were it joins house. had damp company out and say damp proof coarse ok on house. black spores have appeared. we have extracter in kitchen. will fit airbrick . is there any epoxy product that would stop the damp spreading accross floor. or other solution to problem ?. thank you
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Simply Build It

Postby Perry525 » Fri Sep 02, 2011 6:56 pm

What you have done, is to exchange cold windows and walls with condensation, for a cold floor with condensation.
Water vapour always moves to the coldest surface to condense or in the case of a wall will condense into the wall, as unseen condensation.
Raising the temperature of the windows and walls moves the condensation to the next coldest surface.

When you have high levels of humidity, fitting double glazing and/or cavity wall insulation can move the coldest part of a room from the windows to the floor or ceiling.

Do you turn the heating off, or down at times? Lowering the rooms temperature causes the water vapour to drop out as condensation.

If you fit an air brick, you will no doubt solve the condensation problem by allowing the water vapour to escape to the cold outside but, will end up with a cold kitchen, that will cost a fortune in heating.

Possible solutions, use the extractor fan, when its needed to move the water vapour outside.
It may well be that the extractor fan is part of the problem, if it does not have an air tight shutter then it may be that your heat is escaping through the body of the fan causing the room to cool down.
Buy and use a dehumidifier.
Keep the kitchen at the same temperature.
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