Martin Bonner wrote:
On Oct 31, 1:45 pm, The Natural Philosopher wrote:
Martin Bonner wrote:
On Oct 31, 11:03 am, The Natural Philosopher wrote:
wrote:
The Natural Philosopher wrote:
nightjar cpb@ wrote:
"Chris Styles" wrote in message
...
Hi,
A friend is looking to buy a Victorian Terraced house, and it doesn't have
a
damp course.
After spinning her an elaborate story about having the entire house sliced
out of the terrace and lifted up on blocks while a damp course is fitted,
I
promised to ask around to find out how much she should expect to pay to
have
a chemical DPC done.
I seem to recall someone else having the chemical DPC, and it requiring a
certain amount of replastering to be done after, because the plaster had
to
be stripped back at the bottom of the wall. Is this normal (or even
anything
to do with the DPC?)
Any hints, tips gratefully received.
The Building Research Establishment did extensive tests, to try to detect
rising damp, by standing various building materials in water for prolonged
periods. They concluded that damp does not rise more than, at most, a few
inches, which implies that the DPC is entirely superfluous. Good ventilation
is far more important for avoiding damp problems.
Well it made about a foot in my old house up 18th century porous brick.
Be interesting to hear how you determined that the water rose up
the wall, rather than being lateral penetration or condensation.
Because there was no way other than that it could get up what was
essentially a pillar in the middle of the house.
****.
There was no 'outside wall' idiot.
THEY were dry - THEY had been injected. It was only the INTERIOR walls.
Not taking sides here, but how do you know it wasn't condensation?
Elsethread you refer to this being the chimney - it sounds possible to
me that warm(ish), moist, internal air could rise up the chimney,
cool, and condense - leaving the chimney wet. (I am assuming the
fireplace wasn't in use of course).
Sigh. Because it happened a day *after* it *rained heavily*. Without
fail.
Fair enough!

Using the chimneys helped a lot.
Of course. (Althogh that's not diagnostic of where the water was
coming from)

Also on one spine wall, it appeared UNDER a layer of plastic bags the
previous owner had placed UNDER the carpet. To prevent it discolouring.

Total lift up from the soggy clay underneath would have been about a
foot or so.
It is difficult to see how it could be anything other than rising damp
doesn't it. I wonder why the BRE results were so different. Two
options spring to mind:
1. They weren't, and are being (innocently) misremembered
2. They tested modern bricks and/or modern mortar.

I think that is fairly relevant actually.

I know fom my own bricklayng experimens that tudor/17th century bricks
are soft and friable, and soak up water out of mortar like nothing.
Cheaper modern bricks are similar, bu good quality modern bricsk are `
heap different.

Likewise teh fact that peoel use string portlanmd cement mortars to
'tank' up wdamp walls sows that that is also a relevant factor. Indeed
the proponents of lime mortar argue that its 'breathable' porous nature
is what makes it so good: In the context of rising damp IMHO its a
fecking disaster.

Damp arguments aways devolve to whether its better to help it get out,
or stop it getting in.

My logic says as long as it gets out faster than it gets in and via a
place where it won't rot wood or screw up plaster, all is well and good.

It is vital to establish how its getting in tho: tanking up the outside
of a wall with rising damp under the impression its penetrating damp
will make things worse, forcing moisture to the inside of the house.

Ive got a little bit of it myself. I have a loose slate in the wetroom
floor and patch f wall in te corridor shows efflorescence about 6"
above floor level..Must fix hat..theres a stud wall nearby.