floor insulation - query

theGrinch

We are undertaking a small extension and need floor insulation. The builder has sent me the spec - Insulation for floor 100 mmx1200mm x 2440 mm TD3080z and a price of £750 for 15 sheets. another place quoted £1020. I thought it was a bit expensive.

I have been browsing online for comparable prices but I am a little unsure if "special" insulation is required for new build floors.

Are any of the following suitable?

http://www.builderdepot.co.uk/building/insulation/polystyrene-70-grade-2400mm-x-1200mm-x-100mm.html http://www.builderdepot.co.uk/building/insulation/claylite-2400mm-x-1200mm-x-100mm.html
http://www.less2build.com/insulation/kingspan-celotex-xtratherm/kingspan-celotex-xtratherm-insulation-100mm

many thanks

warmhands.coldheart

Stick to the last link, Kingspan/Celotex/xtratherm 100mm High Performance Rigid Insulation. As it says it's suitable for under slab. I've just done my entire ground floors with the 100mm Xtratherm (Kingspan/Celotex/xtratherm are all much of a muchness, just different brands)