Integral garage wall insulation

[PI build]

Our renovation has a 50mm cavity wall between the house and garage. We would like to fit insulation on the garage side of the wall. Our plans have plasterboard coated PIR for this. I do not like the idea of plasterboard on the garage walls as this is an unheated space and would prefer something less hygroscopic. Some external wall insulation systems look over the top  - What would be the simplest way of achieving this?

[tonyshouse]

Sheet insulation covered with Glassrock board, mechanically fixed through the insulation with wafer screws 

[nod]

You can dot and fab the insulated plasterboard directly to the masonry 

But you will need to mechanically fix it also Usually a simply knock in 16 per board 

[PI build]

Glassrock board is a new one to me. A quick search implies that it is fitted similar to plasterboard but is stronger and moisture resistant - is this correct?

[tonyshouse]

Yes , fireproof too and can fixed to 

Edited May 8, 2021 by tonyshouse

[nod]

I use a lot of glass rock muti board for fireproofing beans While it’s great for FP It will offer little for insulation 

Insulated pb is prone to damp issues like PB