I have an house constructed from old farm buildings. We have
persistant damp problems in one or two areas of the house.
Its generally a plastered wall, we have had back the guy who
did the damp proofing a few times. He tested the wall and
stated the wall got damper higher up. We called in the roofer
who found nothing.

I than ran into somebody who said it was salt within the wall
migrating to the surface of the wall. The salt was such that
it attracted mosture out of the air causing the damp patches.
Internally the wall is day, its only the surfaec that is damp.

Has anybody else run into this?

Also; what do I do about it? I was told to strip the plaster
and replaster with some special kind of plaster that blocks
the salt migration. What kind of plaster do I need to use?
How well does it work?

I have been given quite a bit of duff advice from "experts"
over the years, so I want to hear what the group thinks.

--
Fergus McMenemie .
Unix/Mac/Intranets Analyst Programmer

Fergus McMenemie wrote:
I have an house constructed from old farm buildings. We have
persistant damp problems in one or two areas of the house.
Its generally a plastered wall, we have had back the guy who
did the damp proofing a few times. He tested the wall and
stated the wall got damper higher up. We called in the roofer
who found nothing.

I than ran into somebody who said it was salt within the wall
migrating to the surface of the wall. The salt was such that
it attracted mosture out of the air causing the damp patches.
Internally the wall is day, its only the surfaec that is damp.

Has anybody else run into this?

Also; what do I do about it? I was told to strip the plaster
and replaster with some special kind of plaster that blocks
the salt migration. What kind of plaster do I need to use?
How well does it work?

I have been given quite a bit of duff advice from "experts"
over the years, so I want to hear what the group thinks.

search string: efflorescence : http://tinyurl.com/3qlwh


hth


RT

Fergus McMenemie wrote:
I have an house constructed from old farm buildings. We have
persistant damp problems in one or two areas of the house.
Its generally a plastered wall, we have had back the guy who
did the damp proofing a few times. He tested the wall and
stated the wall got damper higher up. We called in the roofer
who found nothing.

Do bear in mind that it's a fact of life that no damp-proofing
contractor will ever, ever tell you that a recurrent damp problem is due
to problems with the work they did and that in the entire history of
mankind, no DPC guarantee has ever been honoured (Clarkson mode off)

David

Do bear in mind that it's a fact of life that no damp-proofing
contractor will ever, ever tell you that a recurrent damp problem is due
to problems with the work they did and that in the entire history of
mankind, no DPC guarantee has ever been honoured (Clarkson mode off)

David

Snap. There are people who say there is no such thing as rising damp. Where
I live (old limestone house, built straight on the limestone, at the bottom
of a hill) I sometimes think if I set a tap into the wall, I could use it as
a spring.

Newshound wrote:

Do bear in mind that it's a fact of life that no damp-proofing
contractor will ever, ever tell you that a recurrent damp problem is due
to problems with the work they did and that in the entire history of
mankind, no DPC guarantee has ever been honoured (Clarkson mode off)

David


Snap. There are people who say there is no such thing as rising damp. Where
I live (old limestone house, built straight on the limestone, at the bottom
of a hill) I sometimes think if I set a tap into the wall, I could use it as
a spring.


Indeed. Rising damp is a total fact. but in general it gets dealt with
one way or teh other or the house doesn';t last.

BTW the salts don't cause the damp, the damp causes the salts...(to migrate)

Dlast hih up a wall indicates either high level damp getting in, or low
level damp that has had to go that far up to get out...due to
waterproofing on the wall surface below.

Fergus McMenemie typed:

I have an house constructed from old farm buildings. We have
persistant damp problems in one or two areas of the house.
Its generally a plastered wall,
snip

Also; what do I do about it? I was told to strip the plaster
and replaster with some special kind of plaster that blocks
the salt migration. What kind of plaster do I need to use?
How well does it work?

Well ignoring the varied views on damp remedies

but to answer your question.
All the wall plaster should be removed back to brick, the walls should then
be treated with a salt inhibitor (acetic acid), the walls should then have
one coat of plaster at 3 sand 1 cement with the appropriate water proofing
add-mixture when this has set but is *still green*(Important ) another coat
of plaster at 5-1 sand cement mixed with clean water should be applied.
After this has dried completely you can the finish with ordinary gypsum
plaster.

How well does it work?
Well it does work, but when if does fail it's a bar-steward to fix the
second time around.
--
Mark§

" Well ignoring the varied views on damp remedies

but to answer your question.
All the wall plaster should be removed back to brick, the walls should
then
be treated with a salt inhibitor (acetic acid), the walls should then have
one coat of plaster at 3 sand 1 cement with the appropriate water proofing
add-mixture when this has set but is *still green*(Important ) another
coat
of plaster at 5-1 sand cement mixed with clean water should be applied.
After this has dried completely you can the finish with ordinary gypsum
plaster.
Or use aquapanels. More expensive in materials but, if it's a smallish area
and/or your plastering skills aren't up to much, and/or you don't want to
wait for it to set, then they're a viable option. Pretty easy to bond to the
brickwork with sand/cement/pva and maybe a couple of screws per board.

"Mark" wrote in message ...
Fergus McMenemie typed:

I have an house constructed from old farm buildings. We have
persistant damp problems in one or two areas of the house.
Its generally a plastered wall,
snip

Also; what do I do about it? I was told to strip the plaster
and replaster with some special kind of plaster that blocks
the salt migration. What kind of plaster do I need to use?
How well does it work?

Well ignoring the varied views on damp remedies

but to answer your question.
All the wall plaster should be removed back to brick, the walls should then
be treated with a salt inhibitor (acetic acid), the walls should then have
one coat of plaster at 3 sand 1 cement with the appropriate water proofing
add-mixture when this has set but is *still green*(Important ) another coat
of plaster at 5-1 sand cement mixed with clean water should be applied.
After this has dried completely you can the finish with ordinary gypsum
plaster.

How well does it work?
Well it does work, but when if does fail it's a bar-steward to fix the
second time around.

Barn conversions are notoriously difficult to treat for rising damp.
They are often made of difficult materials - e.g. earth-retaining
walls, or even mud. Furthermore, there tends to be a high
concentration of salts (caused by many years of animals urinating, I'm
afraid to say!). For this reason, special plaster membranes are now
commonly used to cover up the damp rather than actually stop it rising
up the wall (for an example, see
http://www.safeguardchem.com/Drybase...erMembrane.htm ). A
further advantage of this type of solution is that it is easier to
reverse than putting a hard render on the wall, making it easier to
meet the requirements of listed buildings officers.