Insulating single skin external wall

[Fridge03]

Hi all,

I've got to insulate an external wall in our former outbuilding. It's single skin brick.

The issue is, I've only got 50mm depth to play with due to the wooden beam along the top of the wall that we want to and need to leave exposed.

Originally, I was thinking of dot and dabbing insulated PB (something like Kingspan Koolterm or Gyproc Thermaline Super which have an VCL layer built in) straight onto the wall. However, I've not done this before (but I'd give it a go) and people have suggested that it's best to avoid D&B to an external wall.

So the other option is 25x50mm battens on the wall, with 25mm celotex between the battens and then foil backed 12.5mm plasterboard straight over. Would the foil backed PB provide the vapour control barrier I need?
I'm guessing if possible, I want the celotex to not sit against the brick? So I could possibly use 34mm thick wood, meaning I could keep the insulation off the wall?

I would put a DPC between the batten and the brickwork.

Is there anything else to consider?

Cheers all

 

[^woody^]

Insulation flush against the wall, with a DPM sandwiched between.

Battens fixed to wall, insulation between and across the battens, tape the joints, then plasterboard.

 

[Fridge03]

Insulation flush against the wall, with a DPM sandwiched between.

Battens fixed to wall, insulation between and across the battens, tape the joints, then plasterboard.

I don't have the depth for this. I can only come out a max of 50mm.

 

[^woody^]

You select the appropriate thickness of insulation for the depth available, but the principle remains the same.

 

[Captain Nemesis]

Is there anything else to consider?

Building regs?