Dave Starling wrote:
On Oct 20, 8:55 am, The Natural Philosopher wrote:
I am intrigued by annas solution to using rockwool. I suppose it would
work, but the slightly more orthodox way would be to wedge celotex
between the joists,

I was thinking the rockwool solution would end up with bouncy floor
but I suppose once its all screwed down it would be ok. One snag would
be laying the insulation down carefully enough whilst relaying the
floor - If you put your foot through it.... Also the effective
insulation wouldnt be as effective as filling in the joist as the
rockwool is compressed to almost nothing at the joist so you would end
up with strips of colder floor.

That happens anyway. Its cold bridging par excellence, but fitting slabs
between reduces joist heatloss to the bottom area of them only..

And you can improve matters slightly by laying e.g. insulation board
over the joists before screwing the floor back down.