I was speaking with a "damp specialist" on the phone and he informed
me that putting a membrane around the walls is the option to go for in
a stone house.
He said the drill/injection method is not usually used (or maybe he
it's not effective - can't recall) in stone houses. Anyone know if
this is true?
Also, if a membrane is placed around the wall, then wouldn't this mean
that the damp is still coming up the wall but it's just not
noticeable? If so, does this mean it could rot at the stonework (if
it's still coming up)?
Does the membrane method remove the dampness from the air in the
house? I would imagine the drill/injection method would prevent damp
air as it stops the damp coming up the wall in the first place.
IME *rising* damp is rare, certainly in brick built houses. The whole wall
is usually porous, so you can take your pick as to where it's coming in.
The membrane method seemed a little expensive when I checked it out. The
plastic itself isn't cheap and it has to be screwed every few inches, making
it very labour intensive. I think the method plasterers use is to batten the
wall, fix a wire mesh to the battens, and render the mesh. This allows air
to travel behind the new surface and achieves the same result as the dimpled
I would talk to a few plasterers rather than a damp "expert".
I'm not by any means an expert, but I live in a stone house which used
to be damp (still is in places).
injection won't work at all - it works (maybe) on brick walls because
you drill a hole into the brick, and inject the liquid which then
penetrates through the porous brick. Your stone isn't porous.
As for tanking (lining with a membrane on the inside), this can give you
dry walls on the inside, but can also lead to the mortar degrading.
My approach was to eliminate as many of the sources of damp as possible
(new gutters, fix render etc.), then make sure that all the rooms are
adequately heated and ventilated. This has worked very well, except for
a couple of odd spots.
On 25 Jan 2004 18:16:00 -0800, firstname.lastname@example.org (SuzySue)
Funny the way these "specialists" only suggest "cures" they sell.
neither would be particularly effective. The solution is to
reinstate the system the house was probably built with and which has
been removed or filled over time - the French Ditch.
"Dig a deep ditch around and then away from the building. Dig it as
deep as you can without endangering the building. Then lay in a large
vented drain pipe, and cover it with large clean stones to within 6"
of the ground surface. Then lay a slate cover, like a roof, draining
away from the footings, and turf over it. In this way any water in
the ground will drain away leaving the cottage standing upon a dry
island. Any water running down the wall will be drawn away from the
footings and will enter the rubble fill and drain into the ditch.
This technique is called a French ditch. When used properly, it
cannot fail. Dont be tempted to leave the stone fill as an uncovered
No. In older stone houses you need to keep an eye on condensation
more than damp - they were built to be used with a lot of air
exchange through chimneys with open fires and windows that leaked.
Making them warm often means stopping air flow and you need to
consider how to restore controlled but adequate ventilation.
I would imagine the drill/injection method would prevent damp
It has no effect on stone (or much else for that matter - but zero on
Water doesn't come up the wall, "rising" damp doesn't - it does come
through the wall though and can look as if it is wicking up. The
French Ditch works (always) and is relatively simple.
Thanks for all the information and links Peter! I handn't heard of
this technique before.
Is this French Ditch technique useable for a house which is a terraced
house, or is it useable just with detached houses? As an "island" has
to be built around the house.
On 27 Jan 2004 03:29:14 -0800, email@example.com (SuzySue)
It will almost certainly have been used on the building originally in
some form or another. It can be perfectly effective on terraced
houses - ideally all houses would have such drainage but even if only
your house is done it will significantly reduce the problem (and if
your neighbours have similar issues might persuade them to do the
If you are in a terrace you may well find that the stone drain at the
foot of the wall has been blocked by a neighbour installing some service
into his house, or simply filling the drain because he didn't know what
it was for. In our terrace someone decided to build a sauna in the back
of the cellar, and promptly flooded the upstream neighbour.
Then line the excavation with a geotextile - see Cormaic's pavingexpert
site for the details. This will stop your drain from filling with silt.
However there is often a stone drain at the bottom of stone walls, you
just need to flush the silt out of it and you may find your damp
problems go away. In many houses I have seen there is a stone drain both
inside and outside the foot of the wall.
I take it from this he means something like NewLath (or the older
In a rubble filled cavity the injection fluid just runs down in the
Indeed, and as there is little ventilation the damp is trapped in there.
A wall sat on damp soil is going to be cooler than its surroundings, and
much of what is labelled as "rising damp" is condensation on these
cooler surfaces. I've lived in a house with two cellars one beneath the
other, both backing onto soil, and even the lowest one dried out with a
little heat and plenty of ventilation.
I also have a stone built house which has not been lived in for nearly 150
years, we have looked at this problem also, we have had many opinions
experts and companies looking at the house. The census of opinion seems to
be the walls that are below ground level have tanked with the membrane you
mention, but around the house instead of any conventional DPC the most
favoured method for stone seems to be, not sure of the technical name, but
it is a wire that runs around the walls with a very low electrical current
running through it, "don`t ask me how it works".
That's because it doesn't. The trick is the oldest in the
dampfmeisters (very thick) book of tricks. In order to install the
magic wire you have to clear all the rubbish from around the house,
dig a trench and fill it with rubble (sound familiar?). If you
simply stop at this stage the problem is solved - but to justify a
vastly inflated fee you drape a bit of wire around the place.
Injection does not work in certain types of stone.
You have to keep the water out, which you can do by keeping the water away from your
house with a french drain (not that this always works). Keep the water away from the
bottom of the walls and it can't soak up.
I suggest you find an expert, check his refences, this is a nighmare,
and easy to spend piles of cash for no effect.
On 25 Jan 2004 18:16:00 -0800, firstname.lastname@example.org (SuzySue) wrote:
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