Critique my dry lining

Refurbie

Hi

I’m intending to dry line an existing block cavity wall as follows, which I hope to be airtight and avoid interstitial condensation.

Block
Battens, with PIR / PUR insulation slabs (probably 70mm) between.
Polythene layer
Plasterboard (without foil)
Skim

I intend to lap the polythene between the battens and the plasterboard, but also use double sided tape to attach it to the PIR / PUR insulation around the perimeter of each slab. The idea being that if someone (eg me) puts a nail into the wall in future that punctures the polythene, then as long as it’s not on the perimeter of a slab and doesn’t penetrate all the way through the insulation, the wall will remain airtight, because the PIR / PUR slab is airtight and sealed to the polythene at the perimeter.

I’m using battens rather than dot and dab mainly because it’s a kitchen and I’ll need to hang units on the battens. I’ll notch v’s into the insulation on the warm side in which to run services and run the polythene behind these services so I don’t have to worry about them going through the polythene too much.

I considered using a parge coat and foil backed plasterboard without polythene, but this seems to lead to one of two outcomes: parge coat more air & vapour tight than foil backed plasterboard, in which case condensation on the parge coat could be a problem; or parge coat equal or less airtight than foil backed plasterboard, in which case there’s no point in the parge coat?

Any thoughts or ideas for improvements much appreciated!

Refurbie

BryanF

would you stick with the regular font in future please, thanks

Refurbie wrote: »

the wall will remain airtight, because the PIR / PUR slab is airtight

I dont believe you

considered using a parge coat and foil backed plasterboard without polythene, but this seems to lead to one of two outcomes: parge coat more air & vapour tight than foil backed plasterboard, in which case condensation on the parge coat could be a problem; or parge coat equal or less airtight than foil backed plasterboard, in which case there’s no point in the parge coat?

? a parge coat on the block will limit air leakage, that's not a bad thing. id reduce the insulation

id probably go with just 50mm PIR?PUR


or go use a breathable system (which would be more expensive like woodfibre board or calcium silicate board)

teepee

Complete a condensation risk analysis of the wall build up that you may be considering as the there is a high risk of due point when using foil backed products as none of these products are diffusible . Risk of mould growth can be high and many not be detected for years , mould growth in a dwelling is a serious risk to your health {Asma & respiratory problems} .