ZeitGeist wrote:
Hi,

I live in a 1930s semi which has a void underneath the living room
that is about 6 foot deep. Although the wooden floor is carpeted,
would it help to insulate underneath the floor with something like
celotex between the joists?

Yes, definitely.

If so, do I need to leave a gap between
it and the floor and/or put any membrane layer somewhere? The void has
a concrete floor that has always been bone dry.

The void should be ventilated to teh outside world. it is advisable to
put a vapour barrier between the joists and the flooring above the
insulation.

What I would do is to lift the floor, nail battens to the joists to
support the insulation, at the right height to bring the celotex panels
flush with the joist tops, and then tape over the joists and panels with
celortex foil tape.


Grateful for any advice as to me the living room does not seem to heat
up to well.


The floor is less relevant than walls, typically, but easier to sort out.

TIA