Dot & dab or baton system for masonry wall?

[nmh]

We've had to remove some old internal render on external masonry walls. Less than 50% of each room but I'm trying to keep as much room space as possible while making sure the new internal walls behave themselves from an insulation point of view. I read I might need an air gap (25mm?) between the masonry wall (solid Victorian construction @230mm thick) and any insulated plasterboard to protect from moisture (and avoid condensation). The masonry wall itself is in good condition and I can't see any evidence of water damage etc.

 

So can we just dob and dab something like Kingspan K118 onto these walls and the space between the dot and dab serves as an air gap? Or should we install something like a Gyplynr baton system and mount something like Gyproc Thermaline PIR onto this to achieve a new wall thermal rating around u0.3?

 

Any thoughts or advise much appreciated. 

[Redbeard]

Not just an air gap, but a *ventilated void* (which I would take to be served by 4 air-bricks in diag opp corners on a rectangular wall) according to BEIS https://www.gov.uk/government/publications/retrofit-internal-wall-insulation-best-practice

 

Obviously then air-tightness becomes even more important than it is anyway, or else you just feed cold air into the room via leaks at perimeters.

[nmh]

Would one of these do the trick? https://rts.vents.co.uk/blog/product-details/aac125hp-rytons-super-acoustic-controllable-lookryt-aircore/ 

[nod]

Insulated board dabbed on would be ideal Pink backed for dot and dab

[nmh]

Thanks for this. Hard to see the wood for the trees! Retrofitting for these scenarios is odd. Looking at timber sashes with various U values etc and then building control insist on a dirty great trickle vent in window units. Hard to see how insulated and breathable go hand in hand??!!

 

[Dave Jones]

neither, megastick.

[Iceverge]

You could use a breathable insulant like woodfiber and screw it directly to the wall and lime plaster over the top. 

[Dave Jones]

drop one of these in 

 

https://www.bpcventilation.com/bsk-zephyr-single-room-heat-recovery-unit