Thermaclass and Wet plaster

[richo106]

Hi 

 

I am in the stages of designing exactly what insulation etc I will be having in my extension/conversion.

 

The max cavity width we can have on the extension is 100mm, I have spoken to an eco house builder and they suggested 90mm celotex thermaclass cavity insulation and then also instead of dot and dab they would use wet plaster instead to help with air tightness and thermal mass 

 

has anyone used the thermaclass insulation?

 

is wet plaster better than dot and dab and how much more expensive is it? 
 

Thanks again

[nod]

D&D can be made just as airtight as  wet plaster 
I do both and have to follow the same airtightness standard for each 

[MikeGrahamT21]

Don't risk dot and dab, one crack in the blockwork (which is highly likely with drying out) and you've had it.

[joe90]

11 hours ago, richo106 said:

The max cavity width we can have on the extension is 100mm,

Why?

[richo106]

52 minutes ago, joe90 said:

Why?

We are building on top our existing bungalow with 70mm cavity and the builder is going to step it out 15mm either way to create a 100mm cavity.

 

Many Thanks