"Andrew Mawson" wrote in message
...
"Geoff Pearson" wrote in message ...


"Geoff Pearson" wrote in message
...
I am thinking of improving the floor insulation of my house. Under the
ground floor of my 1897 stone-built house in Edinburgh I have a space
about 1.6m high under all the rooms so access for work is very good. My
energy bills (gas+electricity) are about £2800 a year.

The floor is a standard Edinburgh floor: 11 inch joists with the space
between filled with ash and covered in plaster, supported on riven
wooden strips, themselves supported on battens along the joists. This
deafening (as it is called here) is about 3-4" thick. The floor is
standard 1 1/8 inch tongued and grooved boards. The space below the
riven timber strips to the lower edge of the joists is about 6".

So there is space to add insulation below the deafening and access is
easy.

First question: is it worth doing? With deafening in place that
provides quite a thick layer - but then in more modern houses cavity
walls do get insulated so maybe the deafening is not a good thermal
insulator (although good for sound). Insulation is cheap enough and it
is bound to reduce my costs - more importantly it might make the place
warmer.

Second question: how to do it? I can put mineral wool rolls in the
space and hold it in place with netting. Or should it be slabs of
something? Do I need vapour barrier - I think not?



Just to finish the story: The Energy Savings Trust arranged for Carillion
to do the work, paid for by Edinburgh Council/Scottish Government, for no
cost to me in April. All complete in two hours - now I have to work out
if it makes a difference.

When we did our house re-furb we insulated the suspended ground floor by
loosely stretching nylon mesh (*) across the joists, and placing cavity
wall insulation batts between the joists supported by the mesh. Mesh was
stapled to stop it moving, then we laid the flooring on top. Worked very
well and kept a ventilated space below.

(* the sort used for fruit cages)

AWEM

That is pretty much what I have as a result of this free work: 150mm of
fibreglass suspended between the joists. I had a void of 1.5 metres below
the ground floor so it was easy.