cheap foam Insulation slabs

[Skeff]

Can anyone tell me the cheapest route when I am buying floor and wall insulation for my 21m2 floor extension to side of house and 30m2 walls
Whether I can use jablite 100mm or does it have to be kingspan, celotex etc

 

[Doggit]

Have a look on ebay for a company called seconds and co. I think Jablite is graphite EPS, so not as efficient as kingspan etc.

 

[oldbutnotdead]

Can't remember the Jablite equivalence, typically you need 100mm of Kingspan in the floor (or similar) to satisfy building regs on a refurb or 200mm of rockwool. Have a look at the Jablite website here https://www.jablite.co.uk/calculator/, they've got a cute calculator that will save you some effort, and check the Approved Docs to see what level of efficiency you have to achieve

 

[endecotp]

Polystyrene e.g. jablite is fine in floors as long as you have enough depth for lots of it, and it is nice and cheap.
Making enough space may mean more digging and of course that is not free, so you need to do some calculations.

 

[tomfe]

You'll probably need around 150mm of eps.
In my opinion it's actually a better suited product for slabs than PIR.

 

[^woody^]

The cheapest route is to ring up a supplier and get a discount.