On 21 Dec, 06:07, Mike Tomlinson wrote:

Celotex is a foil-backed insulation mat, about an inch thick. *

That's a bit misleading. There is more than one Celotex product, but
the most common is a rigid foam board, usually foil backed, that comes
in sizes from one inch up to - actually I don't know, but certainly
more than seven inches. It's not a mat that you can lay on top of
floorboards and fix carpet to.

Cheers
Richard