Plasterboarding inside of garage

[CaptainJack88]

We have a tandum garage, and the back half of it was converted to a room by the previous owners. The garage is I believe a single skin brick wall, with breeze block support columns every X meters

Unfortunately, the previous job of plasterboarding was to say the least...terrible. Walls aren't straight, wasn't skimming or taped etc, however I believe they have framed the wall between the breeze blocks to add insulation. They have left the breeze blocks exposed though:

What my plan was, is to rip out all the plasterboard, and then bring it forwards so that it covers the breeze blocks.

My concern here though is the cold, damp, water ingress etc. What sort of a gap would I need to leave between the breeze block and the plasterboard? Would 3cm suffice if packed with some insulation behind it?

I don't plan on fixing the new plasterboard to the breeze block, as will add studs either side of the breeze blocks and fix the plasterboard to that

 

[JohnD]

I'd go for Celotex or Kingspan behind the plasterboard. It can be screwed to the walls, no battens needed. An airgap might be useful in case of damp.

the board have about twice the insulating power of mineral wool the same thickness.

 

[CaptainJack88]

I'd go for Celotex or Kingspan behind the plasterboard. It can be screwed to the walls, no battens needed. An airgap might be useful in case of damp.

the board have about twice the insulating power of mineral wool the same thickness.

I've just measured the depth of the breeze blocks, they're about 118mm deep.

Are you suggesting that I do something like:

Brick Wall -> 70mm Battons -> 50mm Celotex -> 12mm Plasterboard -> Skim

This will bring the plasterboard over the breeze blocks, although there would only be an air gap behind that part.

 

[Happyplumber]

Dot and and dab it with insulation lined plasterboard which will save you all the hassle of battening out and you can get perfectly plumb walls