Insulated plasterboard - avoiding insulation gaps

soldsold

Todays question:

I have some insulated plasterboard that I bought to insulate my attic before I changed plans and took the roof off and thickened the rafters.

I might as well use the boards somewhere on the new extension, but as the plasterboard overhangs the insulation all around, there will be a 20mm gap between the insulation around each board.

Should I:

1) fill the gaps with expanding foam (and hope it doesnt expand too much
2) cut a sliver off the plasterboard all around so the insulation sticks out a couple of mm and fill the gap in the plasterboard with skim coat
3) Cut the board on one side so the insulation sticks out 10mm and fit the boards in a tongue and groove fit?

Cheers!

beyondpassive

Another option is to leave a 10mm gap and fill with the airtight expandable foam, recommend the one that sounds something like Hill and tea and its equivalent cheaper version. Then use reinforcing tape and skim.

Poor Uncle Tom

beyondpassive wrote: »

.....recommend the one that sounds something like Hill and tea......

PM, ftw, instead of written charades...;)

soldsold

That particular brand of tea is three times the normal foamy one. Also concerned that expanding normal foam might get behind the boards and start to lift them off the wall. Ive heard from a guy whose soffitts and fascia started to rise when he tries to put expanding foam in around this area to fill gaps...

I'm thinking now how thin strips of EPS cut from one board might work, ie strips the full length of the board, and thick enough to cover the gap between the recessed insulation. Fit a board, then a strip of insulation tucked in behind, then the next board. Should be quick and easy if I made up a timber template/ scriber

For anyone who doesn't follow where the gap I'm on about its where the insulation backing all insulated plasterboards isn't as wide as the plasterboard...


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