Insulating up to the roof membrane
Information, help, tips and advice on cavity walls, ceilings and lofts etc....

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Rebo00
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Insulating up to the roof membrane

by Rebo00 » Tue Dec 13, 2022 7:51 pm

Hi,
I had a search on the forums but was unable to find anything specific about the use of over fascia vents with ridge vents and whether an air gap between insulation and membrane is still required.
I've been Googling away trying to understand exactly how the ventilation works and as far as I can tell the air is brought in between the membrane and roof tiles and then flows into the loft and out which leads me to believe that an air gap isn't required and the loft floor can be insulated to the edges.
If the ventilation was through the soffits then I understand why you would want to leave the air gap. The soffits have no ventilation.
If anyone can provide any advice on this it would be appreciated.
Thanks,
Andy

stoneyboy
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Re: Insulating up to the roof membrane

by stoneyboy » Wed Dec 14, 2022 10:28 pm

Hi rebo00,
If you have a breathable under-slaters felt then ventilation is not needed, if however you have a non breathable felt then ventilation is needed.
The underslaters felt should be on top of the vent strips so you should not fill in the edges, you can get folded plastic channel to fit in the eaves which would allow full fill with roof insulation.
Regards S

Rebo00
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Re: Insulating up to the roof membrane

by Rebo00 » Wed Dec 14, 2022 11:51 pm

Thanks S,
That makes sense!
I couldn't find any videos on how the over the facia vents are installed so assumed they sat between the tiles and felt but it makes more sense that they sit below the felt, just needed someone else to tell me :)
Regards,
Andy

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