Dont do this until you know the foundation details; with some houses
it
could cause major problems, even collapse.

Not so. You do it in phases. You don't dig a trench all around the
building. You dig out 1.5 meters, install insulation and backfill, and
work
your way around the house.

You have to take into account all building types when you give this
sort of advice. Thre are very old buildings with no foundations at all
which would possibly not survive this treatment.

There is a cone of compression under the wall, dig half of it out and
youer going to cause heavy subsidence at least to such buildings, since

a) the replaced soil will not be as compacted
b) the wall wasnt supported during underdig.
Dont do it if in doubt.


NT