Wall construction

[Gary Martin]

Could I build a new house with 50 mm uninsulated cavity block walls, with, say, 100 mm of celotex/ kingspan fixed to the inside walls, then service battens,vapour barrier, plasterboard and skim.

would it pass building regs ?

[G and J]

No. 
 

[Redbeard]

Internal insulation (IWI) carries the biggest risk of interstitial condensation - vapour condensing on the masonry surface of the wall behind the insulation, since the insulation make the wall cold by isolating it from the heat source. It may be a good compromise solution for existing buildings but not new-build, in my view. How about building solid block with EWI (thickness depending on material)? Why are you thinking of a cavity. What is it doing, in your view?

[Gary Martin]

Cavity for weather protection. Surely if insulation is held tighter against internal skin, there is no gap to slow condensation, also the celotex acts as a secondary vapour barrier to supplement a fully sealed one.

any moisture in the blocks could dry out via the ventilated cavity. ?

ps MVHR system will also be fitted.

 

thanks for your comments

 

gary

[Gary Martin]

Thanks G&J. Could you expand please?

 

I’m new to self building and keen to learn.

 

thanks

[Conor]

From the collective experience and wisdom here, the consensus is stick to standard, proven methods of construction. You have to take account of the what most builders and trades are used to working with. Start doing something unusual, and somebody down the line will cock something up.

[G and J]

7 hours ago, Gary Martin said:

Thanks G&J. Could you expand please?

 

I’m new to self building and keen to learn.

 

thanks

I would suggest posing the question from a different angle.   What exactly are you planning to build and what factors are you focussed on?

 

Overall cost?

Wall thickness (or thin-ness)?

DIY-ability?

etc….