Having a new garage next week and will be framing and lining the walls and ceiling.

What board would you line it with? Plywood or plasterboard?

Plasterboard would be cheaper and easier to paint. Plyboard would be harder wearing and easier to screw stuff to.

Whadya reckon?

Depends what you are using it for. For a workshop or storage then being able to screw stuff to the walls is very useful. I’d go for OSB.

I would like a ‘nice’ finish so I wasn’t really thinking of OSB.

I suppose I could ply the walls and plasterboard the ceiling…

Is it single skin brick, if so it will not be waterproof! I’m just finishing boarding out my garage extension. I’ve used polythene to line the wall first (the stuff that goes under concrete) held on with 50mm batons with sheet insulation between and then finished with 9mm ply (6mm is a bit floppy). I used OSB in the original garage which worked well but didn’t look that good painted, was great for screwing stuff to though. I did toy with the idea of using plasterboard as it’s a lot cheaper but I wanted the ease of attaching stuff. I’m renovating the old garage next, the polythene/insulation/worked well keeping stuff dry, just going to reskin it with 6mm ply to tidy it up.

9mm is enough?

Was looking at 12, that makes the ply option more viable… It’s a pretty big garage, 12mm ply everywhere would bankrupt me!

It’s a new concrete sectional garage going up, so I’d like to think it would be waterproof!

If it is single skin brick you don’t need to line the walls – you don’t with a cavity wall – as the structure still needs to breathe. I would build a timber frame wall within, creating a 50mm cavity, with a breather membrane and vapour control layer. The studwork can be lined with ply and then plasterboard to provide a nice finish and secure fixing. Just remember to install a cavity tray at the bottom, linked to the dpc, to collect any water that does get in.