Retro Fit Insulation to Converted attic

R

RugbyBoy

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Hi All,

Looking for suggestions how to insulate my converted attic. It was done by previous owners and there is no insulation behind the plasterboard slabs on the apex joists.

I am thinking about pulling it all down and insulating between the joists and reslabbing.

Open to suggestions on other ways of doing it. A friend suggestion pumping it in however I am worried about air flow under the tiles

Thanks
RB
 
Hi Rugbyboy. Can I presume you mean the plasterboard onto the rafters? How thick are the rafters? 100mm? 150mm? Does your roof have old style felt or a breathable membrane? If it doesn't have breathable membrane, you could have the slates/tiles removed and have the felt replaced with a breathable membrane before replacing them again. You can then fill the entire space with Rockwool, Moy Metac, Knauf Rafter Roll, etc. If you use rigid insulation, you have to leave an air gap above the insulation. If you have felt, you're supposed to have a 50mm gap. You'd probably be able to leave a smaller gap with a breathable membrane. It'd be a fairly big job and would probably be expensive too.

Alternatively, you could take the plasterboard ceiling down and, if you have good head height, you could replace it with insulated plasterboard. And you should use the thickest insulated plasterboard you can. If you're doing this, it would be very worthwhile to put some insulation between the rafters also.

To get the best fit between the rafters with rigid insulation, you should use something like Rafterloc which is concertina like. It's very difficult to cut rigid board for an exact fit between rafters without leaving gaps that will lead to cold bridging.
 
Hi Lex,

Sorry I did mean rafters. Thanks for the info I have good idea
what we need now

Cheers
RB
 
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