On Thu, 05 May 2005 21:45:22 +0100, Peter Parry
wrote:

On Thu, 5 May 2005 18:37:25 +0100, "Andrew Barnes"
wrote:

I have a cellar which has damp wall, not wet, just damp. The existing white
paint is coming off in places and there is a white powdery deposit.

I would like to make it into a pleasant room, so need to tank the cellar.

It may need nothing more than some proper ventilation. The wall
temperature will be lower than the rest of the house and damp air
will pool there causing condensation. Try running a dehumidifier in
it for a month - if that works almost certainly improving the
ventilation will work.

A celler had been converted to a washroom by a basic tanking method of
adding sika1 waterproofer to the render mix. It was then just
rendered around and the floor screeded all using the water proofing
additive. there is also a manhole in the same room. The manhole
hasn't got the correct cover on it. The room was ventilated via
several air bricks. The room was dry but always smelled damp.Anyways a
few years after this was done a water leak developed from the out side
mains, leaking into the cellar wall. The waterboard supplied a
dehumidifier which was the size of 3 drawer office cabinet (on its
side). this had what must have been a 10 gallon drum underneath. This
filled up in about 3/4 days. It was there for about 6 weeks. It wasn't
emptied regularly and would spill over hence taking longer to dryout
the room. From then on the room hasn't smelt of damp.
so a dehumidifier might just work but you could also consider
rendering with something like sika1 ( it was the architects suggestion
to use that product).