On 30/12/2011 23:11, Dave Liquorice wrote:
On Fri, 30 Dec 2011 08:16:35 -0800 (PST), harry wrote:

Sounds like a pointing problem.

The OP said it was rendered... I suspect that has failed and is now
trapping water against the outer skin. How that is getting across the
cavity is problematical. What form does the cavity insulation take?
Blown fibre, injected foam? The only real way to find out is to make
some holes and see what is going on in the cavity.

I'm the OP.

Everybody who has looked at the rendering - and there have been many
- say the rendering is fine. However, I think they are wrong and that
this is the cause of my upper storey problems. Is it possible for render
to look good yet still be defective? It's been there for at least 40
years and may even have been there for all 80 years of the house's life.
How long does render last?

Rising damp, how far up the wall does it go? Assuming there is a damp
course make sure that isn't bridges by plants/soil etc and is at
least 4" above ground level (6" would be better).

It goes up about 2 feet.
There are some concrete flags up against the house in the area affected
which are only 3 inches below the DP course. Is it worth removing them?

Condensation has been mentioned, don't rule that out.

I'd like it to be condensation but I'm almost certain it isn't.

Another Dave