On Thu, 17 Apr 2008 14:41:51 +0100, a particular chimpanzee, Danny
Monaghan randomly hit the keyboard and
produced:

I'm going to tank our damp but not wet cellar using a membrane. I've
been told that you leave the top on the membrane open at joist level to
allow the wall to breath, so I assume that I will need to add plenty of
ventilation at joist level (just above ground level in effect) to allow
the damp to get away, but is there a better way to do it than adding a
few air bricks round the house? Currently there are only three points
the cellar can breath, and one of those is the coal chute so is not
properly open because it has a cover on it.

BTW, I'm not talking about the ventilation for the rooms that the cellar
will have after tanking - I was planning on using a humidistat
controlled fan to vent those to keep any damp down.

The house is a 1902 9" solid brick wall built one.

If you are you creating rooms down there, then you will need a proper
tanking system (ie, one with a BBA certificate). A membrane won't do
anything but trap the moisture on the inside of the wall with nowhere
to go. You'll also need insulation to the walls and floors to comply
with the Building Regulations.

There are essentially two ways of tanking a basement:
1. Preventing any moisture from penetrating the walls and floor.
Waterproof material is added to the walls and floor, such as Vandex or
Synthaprufe.
2. Allowing any water coming through the structure to drain away
before it reaches the inner surfaces. A raised membrane (rather like
an egg tray) is attached to the walls and floor allowing drainage
behind, with a sump at low level to collect the water. This may need
a pump to drain away.
--
Hugo Nebula
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just how far from the pack have you strayed?"