On 22/05/2019 17:14, Steve Walker wrote:

Well it's not directly stated, but as the first post referred to "a
draughty, uneven floor" and a later one to "I can see the danger of
heating the space under the house", I assumed that it was a suspended
floor. I could be wrong though.

Bingo.

I didn't like to be pedantic but as you've pointed it out