On Fri, 17 Oct 2003 18:42:51 +0100, John Rumm
wrote:

Witchy wrote:

I think the core sample refered to in not taken from the ground as such,
but a core sample from a wall - i.e. drill a hole and collect the
brick/plaster dust. You can then analyse that for moisture content. This
give a much better indication of the actual moisture content of the
whole wall thickness rather than just testing the surface for moisture
content (or testing your wallpaper for electrical conductivity as most
"damp proofing" companies would ;-).


By the time you've done all that work you could just as easily have
done the visual checks - I've not heard of 'hidden' damp before

Not sure about hidden damp ;-) it is perhaps more useful in detecting
"surface dampness" i.e. the wall visually appears to be damp - but in
actuality most of it is dry.

This would often be the case where the dampness is due to internally
generated moisture not being able to escape and instead condensing on a
cold wall. Fixing would be a case of adding ventilation or heating
rather than doing anything about the wall necessarily.

More often than not that sort of dampness manifests itself higher than
skirting board level though, so it's a bit more obvious that it's not
rising damp. In that instance you know it can only be condensation or
a breach in the external wall. We looked at a house recently that had
a damp patch at first floor level 2 feet off the floor and nowhere
near a window - there was nobody living in the house and no furniture
so a look outside revealed the street sign fastened to the wall
exactly where the damp area was......

Another time a tenant said his bedroom wall was damp at bed level,
again not under a window and again on the first floor. No visual
breaches outside, and once we found out he showered with the bathroom
and bedroom doors open it turned out the steam was condensing on the
wall in the bedroom and was being absorbed by the quilt on the bed
which was in contact with the wall! Shows you how often he moved his
quilt too
--
cheers,

witchy/binarydinosaurs