In article . com,
wrote:
I'm renovating an old office and I'm intending to lay 22mm T&G
chipboard over the existing floorboards as they are very old, a little
uneven, and unsuitable for carpet tiles. I was wondering whether it
would be helpful to put 10mm-25mm of expanded polystyrene under the new
chipboard to take up some of the bumps and lumps of old nails, damaged
boards etc as well as possibly improving the sound insulation between
floors. Is there any possibility that the polystrene and the chipboard
could react over time? Would a wood pulp sheet material be more
suitable.

This is how the ground floor of a mate's house is constructed, but over
concrete rather than floorboards. So there's no reaction between the poly
and chipboard. I doubt it will help much with sound insulation to you, but
might help the transmission of footsteps downwards. It should help with
heat insulation, though.

--
*I wonder how much deeper the ocean would be without sponges.

Dave Plowman London SW
To e-mail, change noise into sound.