Passive slab / insulated raft costs

[Conor]

Had a search through the forums but not found anything definite.

 

What is the approx cost (supply only) per m² for passive slab / insulated raft foundation formworks? Likes of Isoquick, Kore, kingspan?

 

Also, is there a way to do it yourself by just using standard EPS100 for the floor and EPS300 for the load bearing parts? I'm assuming that would require sign off by an engineer and BC.

[Jeremy Harris]

I costed up Isoquick, Kore and Supergrund and all came out within about 10% of each other, which was about £120 to £130/m² for the design and materials (SE fees for the structural design, foam insulation, steel reinforcement, concrete) without labour.  This cost could be reduced by just buying sheet EPS and fabricating the corners etc, although you'd still need an SE to do the structural design.  The longest jobs are levelling the blinding before laying the insulation and fitting and wiring up the reinforcement.

[Alexphd1]

Connor, what ever you do you will need a engineer to design this, whether it's designed by the supplier or a independent structural engineer and shop around for material that's your call. A few people on here have used Tanner Structural Design from South Ireland but if you need a SER certificate they can't issue them now (i have been caught out here).

Nothing stopping you assembling your own L forms, Another person on here think @Triassic done exactly this very successfully.  

 

*sorry I have repeated most of what Jeremy has already said.

Edited May 28, 2019 by Alexphd1

[Alexphd1]

Quick check from a buildhub thread feb last year. 100mm deep eps300 worked out about £12m2 and eps 100 £5m2. Tbh you don't actually need a lot (depending on the load bearings of walls) of eps300 most of the floor is 300mm of eps100.