Insulated plasterboard

[bluebaron]

hi all following on from my sizing post has anyone got any advice on insulated plasterboard?

Basically it's to cover a timber frame which is already insulated (between studs). My understanding is a need to insulate across the studs and then PB to avoid ghosting. I will probably add a skim coat after that.

Main concern is cost as insulated boards 27mm (10mm insulation 12.5mm PB) are around £28 a board. I could use normal board with a separate 10mm insulation? Any problems likely with this aside from having to fix twice?

Thanks and Merry Christmas all.

 

[Malc]

That's presumably plasterboard with celotex or similar on the back. Boards with polystyrene on the back are half the price. Polystyrene is 0.040 W/mk where as celotex is 0.021 so you need ~20mm or polystyrene to match 10mm of celotex. Polystyrene isn't a vapour barrier I believe but if you skim then I think skim is.