Hi all, 

 

We've a 1960s mass concrete terrace, and are looking taking out the current suspended floors and replacing with an concrete slab.

 

We're not going the UFH route, so what are peoples thoughts on the following build up to convert the approx 550m void. 

 

Mot type 1 compacted in 100mm layers

Sand binding and DPM

200mm PIR 

Another DPM

100mm concrete

 

Asking as I'm seeing some people going concrete, insulation, then a screed on top.

 

 

Think the general consensus is rather than use expensive PIR, use double the amount in EPS, and minimise the amount of hardcore underneath and concrete on top will save you a small fortune and likely give a better result overall in terms of insulation.

 

plenty have done it on here, so sure someone will be along shortly to advise.

I agree with Mike. I'm in the process of building up my floor (same with insulation below the concrete slab) and in half the house I have only enough space for 100mm PIR and in the other half I more space so used a bigger build up of eps. Got better insulation values and saved a whole bunch of money. Plus building up with eps is much easier and less heavy work than hardcore

Interesting, I've a lot of space to work with so EPS would make sense. Coll659, what depth of concrete are you going with?

100mm concrete

 

I'm doing the following: 

 

Sand blind (only to level) 

30mm EPA

Dpm

Insulation

Underfloor heating foil

Underfloor heating stapled to insulation and 4mm composite rebar on 50mm chairs

100mm concrete

 

Though please note I'm a joiner and not a professional on this stuff so don't blindly follow me 😅