On 12 Nov 2004 17:42:45 -0800, (N. Thornton) wrote:

(Jake) wrote in message ...
On 11 Nov 2004 04:58:06 -0800, (N. Thornton) wrote:

Whether its enough on its own, who knows, only one way to see, but
certainly it'll help. IIRC your walls are covered on the interior with
some kind of waterproof paint or something, this wants removing
really. Gypsum plaster and emulsion all considerably reduce
evaporation, thus increasing damp in the wall. The standard proper fix
is to remove plaster and replaster in lime. Lime is porous, and
greatly improves the drying.

But it's very absorbent too - so that is sort of contrary to the usual
advice about plastering with sand & cement mortar to block the flow of
moisture to the interior wall surface, yes?

Its contradictory to that popular poor advice, obviously. The idea is
to dry the wall out, not trap the water in it. If you seal the 2 sides
of the wall, the wall will simply head for the level of damp of the
ground it sits on, which will be more wet than damp.

The plaster that's already on the walls inside, seems about as
absorbent as lime plaster. There's a party wall, perpendicular to the
damp side of the house which divides the lounge from the hall. In the
hall, the plaster is lime plaster, but in the lounge, the plaster is
some modern but similarly absorbent plaster. Both felt equally damp to
the touch.

I appreciate your comment about the rendering going down to the ground
outside preventing evaporation. It may be difficult to emove that, but
it would be easy to install absorbent air bricks, say every six feet,
close to ground level. But drying out the exterior skin of the cavity
wall isn't really going to cure the rising damp in the inside skin, is
it?

I could install some absorbent airbricks in the inside skin, below the
level of the suspended floor. I'm not sue how many to install.... one
every four feet or so perhaps. When the holes for the air bricks are
cut, I can also clear out any debris in the cavity hopefully. A lot of
air bricks will obviously detract from the thermal insulation of the
cavities, but if it cures the damp, I'd be likely to go for it...

Jake