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mikej460

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Not over rafters but I've used it extensively during out house renovation. We have solid stone and brick walls so I dry lined the brick walls with superquilt over battens then battened over and screwed in 50mm PIR plasterboard. Each room was noticeably warmer afterwards.

Edit: When we have our roof replaced I am seriously considering using superquilt over rafters.
 

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baldkev

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Edit: When we have our roof replaced I am seriously considering using superquilt over rafters.

Hi mike,
A properly done celotex job inbetween the rafters, with expanding foam to any gaps, even small ones, then foil tape across all timber joints and butt joints will work wonders.... but the key is to take the time to make sure its dont properly. Some people undercut the edges to get it in easier, but basically reduce the insulation value by doing so 🤷
 

mikej460

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Hi mike,
A properly done celotex job inbetween the rafters, with expanding foam to any gaps, even small ones, then foil tape across all timber joints and butt joints will work wonders.... but the key is to take the time to make sure its dont properly. Some people undercut the edges to get it in easier, but basically reduce the insulation value by doing so 🤷
absolutely agree Kev, I do exactly that on roof insulation with PIR plasterboard over it to prevent bridging. I haven't used superquilt over the rafters yet though. You can lay it under or over rafters.

YBS SuperQuilt Pitched Roof Under Rafter Application - YouTube

SuperQuilt Over Rafter Application - Bing video
 

Jones

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I've used tlx gold which is a multifoil with breather membrane over rafters . The spec was tlx over with counter battens, rockwool in between and insulated PIR plasterboard to the inside. For a workshop you could probably miss out the insulated board which may make it economical and fitting is very easy particularly if you use rafter line rockwool which won't fall out on your head.
 

Hornbeam

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Thermal performance of PIR board is about twice that of glass wool quilt so th achieve the same insulation value you only need half teh thickness, One issue with insulating between rafters is that the rafters act as thermal bridges through the insulation and significantly reduce the insulation performance
 

Molynoox

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Thermal performance of PIR board is about twice that of glass wool quilt so th achieve the same insulation value you only need half teh thickness, One issue with insulating between rafters is that the rafters act as thermal bridges through the insulation and significantly reduce the insulation performance
Yeah but presumably people are doing cold roofs because they have to, not because they think it's better than a warm roof design. But I think the point you are making is to use PIR if you have to go cold roof, which I totally agree with.
I've never really understood cheap and ineffective insulation materials, surely the cost model doesn't work because you will only lose more through heating costs I would have thought. Unless it's a very low occupancy room and hardly ever heated maybe.
Martin
 

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