Phil L wrote:
Ian Stirling wrote:
I have a 1600s or so scottish cottage, that's lacking in insulation.
It's some 20m*5m, with a suspended wooden floor, with no insulation
underneath. The temperature below the suspended floor is essentially
the average house temp.
During other works, the path (20*1m) along one long side of the house
has been dug up.
Is there any point at all in putting down 2-5cm of rigid insulation
under sand blinding, then membrane, and gravel, instead of just the
gravel and membrane?

How would I go about calculating the extra insulation effect?

You don't because there wouldn't be any.

Not true.

Insulation outdoors doesn't work because there's no heat to save....the
inside and outside temperatures of your wall (below ground) will differ only
slightly, maybe a degree if that, what tiny amount dissipates through the
soil under your path, you want to lay insulation on top of this soil?
You may save a degree or two if you stood the panels upright against the
wall, but you'd probably do more damage to the walls with moisture retention
and save nothing whatsoever in heating bills.


Mmm. there is a bit more difference than that...however I agree its
bareley worth bothering with.