On 30/12/2017 22:13, Andrew Gabriel wrote:
In article ,
Brian Reay writes:
On 30/12/17 14:53, Roger Hayter wrote:
There are allegedly some dramatic damp problems due to fitting it in the
wrong sort of situation, or with the wrong sort of householder. In
Merthyr Tydfyl and points south especially, for some reason. I don't
know the truth of the matter.


Depends on the house etc.

Some houses, including ours, were build with it as standard. We've not
had a problem.

When it's installed during the build, it's normally held against
the inner skin, leaving an air gap against the outer skin, and
that prevents moisture wicking through.

You can do a new-build with full-fill rockwool cavity batts but
that requires the brickie to be careful not to allow mortar to
lie on top of a line of batts before the next row is added.

It is treated to repel water, so nothing should cross the cavity,
though I wouldn't be happy with full-fill if I lived on the South
Coast, or West coast of Wales or Cumbria and parts of Western
Scotland.

A new build with a 100mm cavity, with 50mm celotex, where the slabs
are carefully cut, butted and taped and held firmly to the inner leaf
with special round clips on the wall ties should be weather proof
even in the most severe locations.