On Friday, 12 February 2016 01:24:02 UTC+1, Rod Speed wrote:
"harry" wrote in message
...
Modern houses do not have suspended timber floors

Plenty of them do

Not, I think you will find, in the UK. At least, not on the ground
floor (where the gas pipes are most likely to be). Suspended timber makes
it hard to meet the insulation requirements. (Obviously, it's *possible*,
but there are cheaper and easier ways to do it.)