eps on timber frame

[claremont]

Hi,
we have a site of two timber framed houses which have a specification of 150mm eps and thin coat finish . Externally the frame has a sheathing board and roofing membrane at the moment,
Can we fix eps directly to the above substrate or does there need to be a cavity created between the two?
Thanks

 

[zolco]

Most on here reckon you have to have a cavity, which in my eyes beats the whole idea having ewi at all, I'd just do it without a cavity, but what do I know

 

[vfr12]

@johniosaif