"Christian McArdle" wrote in message .net...
1) Why isn't it possible to insulate 2 walls? How can condensation be a
problem with insulating two walls, and yet it is possible to insulate half
of a semi-detached house?

When doing half a semi, the missing wall is a warm interior one. If you miss
off a cold exterior wall, you'll get mould and condensation on it.

whys that? The interior temp and RH will be the same as before, and
the temps on the uninsulated wall will be the same as before.

Regards, NT