DIY Doctor

Damp Loft - Advice Required

Postby Wiema » Mon Dec 15, 2008 5:43 pm

Hi All, thanks in advance for your help. I have a damp loft. Ventilation is poor to non-existinent and currently I have about 150mm of insulation. As a result of the above two factors the lining between the roof tiles and rafters is wet and slowing dripping to dampen the existing insulation. Question is what is the next practical step?

- Leave existing damp insulation (only damp for first inch or so) and cross lay another 150 of space blanket?
- Remover all insulation and lay new up to 270mm even though the lining is dripping?
- Clear existing blocked up vents first? Will this dry out the lining?

Any advice much appreciated :D

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Simply Build It

Postby stoneyboy » Tue Dec 16, 2008 11:43 am

you need to cross ventilate the roof space either by adding new vents or unblocking the ones you refer to.
In time this will dry out the existing insulation but don't add any extra insulation until this has happened.
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Postby welsh brickie » Tue Dec 16, 2008 2:16 pm

you need a roofer to fit a tile vent ,Basicly its a tile with a vent that will let air in to dry out the moisture,Its not that hard to fit but seek proffesional help.
Also make sure the insulation is a foot away from the edge of the rafters this will also help and clear all vents where you can
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Postby Perry525 » Tue Dec 16, 2008 5:47 pm

The is only one main reason for a damp loft!
The condensation of water vapour from inside the home!
The water vapour you are making in your home is rising into the loft and condensing on the cold roof.
The culprit is usually the trapdoor into the loft.
Aided and abetted by holes in the upstairs ceilings.
The passing wind sucks the moisture up into the loft.
The other possibility is a badly place exhaust vent from your boiler, where the wind sucks the moisture up into the loft.

Check, are the upstairs windows running with condensation when it is cold?
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Postby Wiema » Tue Dec 16, 2008 8:17 pm

Thanks chaps, air vent option sounds ideal given the old age of the house and given I dont really fancy another trip into the lofts deep recesses!
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