Best EWI material.

[K78]

I plan to externally insulate behind timber cladding. I was thinking of using PIR, but the recent thread regarding off gassing and shrinkage has made me think again. 
 

Im thinking graphite eps is probably the best, cost effective alternative as it doesn’t shrink?

 

interested to see what others think. 
 

Thanks. 

Edited February 12, 2020 by K78

[Ed Davies]

I like EPS for that sort of thing but mabe some thought needs to be given to EPS with respect to spread of fire depending on the proximity of other buildings, boundaries, etc. Obviously it's used in standard EWI but that's not with timber cladding over it.

[Gone West]

15 hours ago, K78 said:

interested to see what others think. 

We used Rockwool RW6 batts for it's good thermal and acoustic qualities, as well being fireproof.

 

https://www.rockwool.co.uk/product-overview/slab-products/rw6-en-gb/?selectedCat=downloads

 

PS

Just remembered you're building with concrete so maybe your idea of graphite EPS would be better.

Edited February 13, 2020 by PeterStarck

[MarkyP]

I used graphite EPS for my bungalow renovation but that was rendered over. Works really well, annedotal but even having not yet insulated the rooms in the roof (see my other thread) we barely use the heating in winter. I think EPS is considered somewhat vapour open (if that matters) and is dimensionally stable (if using proper EWI EPS cut from aged blocks - I bought EWI grade KayCel for this reason, lots of no-brand stuff out there which I was dubious about).