Internal insulation no-fines wall

[Lfcsixtimes]

Installing insulation on no-fines wall which is neither plumb or level due to the softness of the block. I originally intended to foam celotex foil backed onto it, finishing with 12.5 normal plasterboard and twistfix through both layers into the block.

The room is very small box room so studding out isn't ideal and no cavity so d&d is out as well. What would be the recommendation? Fill and straighten beforehand or adhesive foam, straighten/plumb and fill gaps behind with more foam?

 

[oldbutnotdead]

Why can't you dot and dab? You'll not get damp or thermal bridging from the dots through PIR....

 

[Lfcsixtimes]

I thought the general consensus was never to dab on an external wall (where there is no cavity). My blocks are extremely aerated so the dabs sucking above normal levels of moisture into the internal leaf is entirely possible

 

[oldbutnotdead]

You don't have an internal leaf if you have solid walls. D&D plasterboard on solid walls is bad news- you can end up with the dots being visible through the pb and skim (due to dampness and cold bridging).
Foil isn't porous, not is PIR.

 

[Lfcsixtimes]

Sorry, I did mean internal side not leaf. Surely the moisture sucked by dabs has to go somewhere in the small void between the block and PIR foil?