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I've recently bought a 1930s house and looking in the loft space there's no felt lining. You can see the backside of the tiles from the inside. What would be the best way to achieve some sort of insulation / roof protection without having to remove the roof tiles? For example is there a spray-on product that creates the same effect as felt?

I'm trying to find the simplest way of bringing the roof into the present day without having to remove the tiles.

Any advice would be wonderful!

Thank you.

Mark Lawrence

  • Where are you located? What kind of tiles are on the roof? – Jim Stewart Mar 8 '17 at 11:38
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    I'd insulate the joists not the rafters. The loft space needs to breathe. – RedGrittyBrick Mar 8 '17 at 13:43
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Wood shingle roofs in Dallas used to be nailed onto strapping (battens) without any roofing felt underneath. Then when those shingles were worn out a layer of asphalt shinges was put over that, and I don't think roofing felt was used. (I do remember heavy wood shake roofs in the 1970s were installed with felt interleaved with the courses.)

If you have a 1930s roof and the wood structure underneath is not rotted, then you should leave it alone. When the roof needs to be be replaced, then probably OSB or plywood decking will be put down, and modern water barrier on top of that.

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We had this exact same problem in our first property. Going up there in the winter was a bit of an experience. Whilst I understand wanting to resolve this situation, the important thing is that your loft floor is fully insulated. This will ensure the best protection for the rest of your home against the cold weather and drafts.

The primary issue with the resolution you might be looking for is that it could turn your loft area into a little hotbox in the summer, which will quickly accumulate mould as it won't be ventilated.

However, you could try stapling felt (or something similar) to your roof joists on the inside - instead of between joist and tiles - to give yourself a little protection without "sealing" the room. I do understand the frustration your having - in windy weather the amount of crud and random debris that can get blown in through the gaps is pretty sizable.

  • Hi Tom and Jim, thank you for your response. I think I'll look into the route of stapling felt to the roof joists on the inside and fully insulating the roof. It's currently a sort of recycled paper material and not quite up to modern standards! Many thanks. M – Mark Mar 8 '17 at 11:38
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    i would be very careful about this. the advantage of not having any underlayment and sealing (even if just roofing felt) is that if you do have moisture, it's well ventilated and thus is intrinsically mold/rot resistant. putting up any barrier on the roof side will compromise this benefit to some extent. – aaron Mar 8 '17 at 12:23
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    So the roof has worked fine (no dryrot, etc.) for 80 years and you're going to change this? I'd be careful of changing the vapor barrier and ventilation systems. – Lee Sam Mar 8 '17 at 12:46
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    Roofing felt stapled to the undersides of the rafters would be impervious to the movement of water liquid or vapour. No roof is ever installed this way. It would prevent the battens and rafters from drying to the inside and very likely lead to rot. Also it would provide an ideal collection chamber for debris getting in through holes in the tiles and a haven for rats which would be inaccessible to you. The one membrane that people in my part of the world apparently have applied to the undersides of the rafters was a radiative reflective barrier. I think it was more trouble than it was worth. – Jim Stewart Mar 8 '17 at 13:03
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    Mark, a word on terminology: Joists are horizontal framing members separating the living space below and the attic (or loft) above. Rafters are usually inclined framing members above the loft space, under and supporting the roof. Where is it that you were considering placing this roofing felt? The recycled paper you are referring to sounds like loose cellulose insulation on the top of the ceiling of the living space and the bottom of the attic or loft space. Is that right? – Jim Stewart Mar 8 '17 at 18:24

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