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Damp and Mould in Loft After Installing Loft Insulation

Postby Listless » Mon Jan 20, 2020 5:51 pm


Don’t know who else to ask so hoping someone can advise as I’m at a loss as to what to do.

I live in a 1970s end terrace house. Roof is original roman tile made of concrete with original felt lining. A couple of years back we cleared out all the old insulation and topped it up to 300mm - the new industry standard. Since then I believe the problem has started although it could have been an issue before then. One roofer on inspection thought the ridge tiles may be letting in water and did a repair but suspect this was not the case. Looking at websites and videos from fixmyroof we conclude it was condensation being trapped up there. As such we fitted lap vents from amazon and tried to avoid excess moisture rising by using dehumidifier for laundry in spare room.

Over the last few months it’s returned and I’ve noticed mould and mildew on items stored in loft. The smell is such that they can’t be used anymore. Further the wooden supports and laths are wet and have white mould growing on them particularly north facing roof. A few weeks back I had another roofer fit 4 tile vents to roof and put extractor up there for a week. Turned it off over the weekend and came back yesterday to find it wet up there still with water running down felt. Tile vents don’t appear to have made any difference.

Now I’m at a loss as to what to do. Short of removing all the insulation and freezing my butt off I don’t know what else we can do.
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