Rear extension ------------Hollow block construction

[Clonback]

My engineer has specified that our 25sq.m. extension should be built using hollow blocks.Would like views on the current thinking on this type of construction

 

[Jetblue]

Can you give some more details? What kind of insulation and how much of it?

 

[Clonback]

Renderwill be mixed with a waterproof solution plus an exterior paint that also has a waterproofing solution.
80mminternal insulation on exterior walls.

 

[kceire]

80mm insulation is not enough.
Hollow block is not a problem. It’s quicker to lay and as long as
Your engineer is happy then that’s all good. It still complied with the same EN standards for solid blocks etc

I would ensure the following from the outside In :

external render as mentioned.
hollow block. (If no other choice).
coat the inside face with a sand/cement layer for air tightness.
then the insulation but I’d want 100mm minimum.