Plaster Or plasterboard?

[Maccapacca]

http://www.ultimatehandyman.co.uk/garage_conversion/walls.htm

That is quite comprehensive

 

[Cosmic182]

Reason its so cheap is cause youre not allowed to use it on new builds,extensions etc, main use is in the loft. Doubt anyone would know anyway.

 

[Threepwood]

It does matter you need 400mm of loft insulation to get the same performance of something like 150mm of Kingspan Kooltherm k3, also it'll sag into a cavity.

Yes, different type of insulation will preform differently, but that's not what I meant

Edit: But you are correct, I should have included efficiency and building regs.