Cold roof to warm roof interface...

[MattChan]

I've got a lean-to style roof along the front of the house part of which is over the garage and the other part is over the hall and WC.

The part over the WC is being changed from a cold roof to a warm roof and the ceiling is being changed to a vaulted style.

The ceiling in the garage has 300mm rockwool quilt insulation and the ceiling in the hall will have around 130mm of celotex.

The wall inbetween the hall and garage is a double skin of 100mm thermolite blocks with no cavity. So obviously the top of this wall will be in the hall on one side and in the cold roof area on the other side. Is the best plan to clad the cold roof side of the wall in celotex? Or am I somewhat wide of the mark?

 

[^woody^]

What about the rest of the house walls with one side in the warm and the other outside in the cold?

 

[MattChan]

I guessed that as these are cavity they would provide a higher value of insulation than the double thermolite with no cavity? Or is the difference so minimal its not worth worrying about?