Floor insulation

[Fluffster]

Hi Guys
I am laying the floor in my kitchen extension and have a question on the insulation.
My spec says 80mm celotex fast r ff3000.

Can I use the normal white polystyrene floor insulation as an equivalent at 100mm as it is a lot cheaper.

Also will this stuff take the load of concrete/screed/tiles on top of it?
Thanks
Pete

 

[noseall]

Hi Guys
Can I use the normal white polystyrene floor insulation as an equivalent at 100mm as it is a lot cheaper.

Also will this stuff take the load of concrete/screed/tiles on top of it?
Thanks
Pete

yes and yes.

you will still need adequate compacted sulphate free hard core below.

also here in staffs, b.c require a layer of dpm below and on top of the polystyrene, though not all floor insulating material requires this,

 

[Fluffster]

Thank you yes it states the dpm under and above the insulation in my specs.
Cheers
Pete

 

[jeds]

As long as you are appreciate that 100mm standard polystyrene is nowhere near the thermal value of 80mm Celotex. And if your BI asks you to justify the change you might be struggling.

 

[Bradleybuild]

duff info from the previous
The thickness of Polystyrene is calclated by the floor area so it maybe that 100mm will suffice, check with BCO
you only need one layer of dpm for polystyrene (underneath it as it is unaffected by water.
celotex needs to be sandwiched between as it is affected.
dont foget to have upstands of insulation around the perimeter of your pour
cheers

 

[noseall]

latest b'regs are asking for 125mm jablite or polystyrene insulation.

 

[ali68]

 

[jono_h]

And my BCO has never asked for damp-proof membrane under the celtox, only on top.

Just goes to show that they all work differently!