Plastering damp proofed walls
 

We have a few remaining problems with damp in a house that we bought that
had been damp proofed with a chemical treatment. The Damp Proofing company
claims that the type of plaster used after their treatment was not the right
plaster.

Could this be true? Is there a type of plaster that can better resist damp?

--


Regards

John




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In message , John
writes
We have a few remaining problems with damp in a house that we bought that
had been damp proofed with a chemical treatment. The Damp Proofing company
claims that the type of plaster used after their treatment was not the right
plaster.

Could this be true? Is there a type of plaster that can better resist damp?


Strong chance. I remember having some dampproofing done, getting the
wall plastered by someone else, then calling the damp proof firm back
when the wall got a bit mouldy.

They quickly pointed me to their advice and specification for the
plaster mix on the back of their guarantee - clear as day!! Did I feel
like a prat?? g



--
Richard Faulkner

"Richard Faulkner" wrote in message
...
In message , John
writes
We have a few remaining problems with damp in a house that we bought that
had been damp proofed with a chemical treatment. The Damp Proofing
company
claims that the type of plaster used after their treatment was not the
right
plaster.

Could this be true? Is there a type of plaster that can better resist
damp?


Strong chance. I remember having some dampproofing done, getting the
wall plastered by someone else, then calling the damp proof firm back
when the wall got a bit mouldy.

They quickly pointed me to their advice and specification for the
plaster mix on the back of their guarantee - clear as day!! Did I feel
like a prat?? g


I seem to remember it is some kind of cement mix with waterproofing
additives (lets water vapour out, but not water), then plaster on top for
the final skim.

Never had it properly explained why this is necessary if their damp proof
course was any good... It is called damp *proof*, not damp resistant
course.

Bob

In article ,
"John" writes:
We have a few remaining problems with damp in a house that we bought that
had been damp proofed with a chemical treatment. The Damp Proofing company
claims that the type of plaster used after their treatment was not the right
plaster.

Could this be true?

There were some special plasters for damp walls, but I'm not sure if they
exist anymore. The company's guarantee will stipulate the type of plaster
required. If it doesn't, they're pulling a fast one.

Most chemical damp companies are a scam anyway. They misdiagnose the
cause of the damp in the first place, so the treatment doesn't fix it.

Is there a type of plaster that can better resist damp?

Scratch (base) coat of sand and cement (and lime for a lime mortar building)
with waterproofer (and plasticiser if you like).

You can use a normal plaster finish coat on this, but avoid getting any
of the finish coat bridging across the waterproof scratch coat (e.g. at the
bottom edge).

--
Andrew Gabriel

Bob Smith (UK) wrote:

I seem to remember it is some kind of cement mix with waterproofing
additives (lets water vapour out, but not water), then plaster on top for
the final skim.

Never had it properly explained why this is necessary if their damp proof
course was any good... It is called damp *proof*, not damp resistant
course.

Sovereign rendermix is the stuff:
http://www.esecure.co.uk/sovchem/sho...odid=479605705

--
Andy

In article , "John"
says...
We have a few remaining problems with damp in a house that we bought that
had been damp proofed with a chemical treatment. The Damp Proofing company
claims that the type of plaster used after their treatment was not the right
plaster.

What was the initial cause of the damp?

Rob Morley wrote in message ...
In article , "John"
says...
We have a few remaining problems with damp in a house that we bought that
had been damp proofed with a chemical treatment. The Damp Proofing
company
claims that the type of plaster used after their treatment was not the
right
plaster.
Hm. I've often wondered whether it's the new render that stops the damp,
rather than the dpc injection.
IMO cement boards are an easier d-i-y option. They bond to brick well with
plaster adhesive and there's no drying time. You can stick a few long screws
in to be on the safe side, or maybe use mortar as the adhesive.

Could this be true? Is there a type of plaster that can better resist
damp?

Most damp proofing companies seem to insist on doing the plastering
themselves to ensure that the correct stuff is used. There are all sorts of
plaster and they will have chosen something very specific as part of the
treatment.

Christian.

"John" wrote in message ...
We have a few remaining problems with damp in a house that we bought that
had been damp proofed with a chemical treatment. The Damp Proofing company
claims that the type of plaster used after their treatment was not the right
plaster.

Could this be true? Is there a type of plaster that can better resist damp?

--


Regards

John

Few more facts please: Was the work done when you bought the house?
What did the remedial company specify for re-plastering? Was this
specification adhered to or was the work 'dual-responsibility' with
the dpc company doing the (presumably) injection and someone else
doing the re-plastering?

An injection dpc is not a cure for rising damp. It is part of a
system which also involves replastering. The new plaster not only
prevents moisture and salts from migrating to the surface, it also
ensures residual hygroscopic salts are removed. If these are'nt
removed then you will forever have damp patches.

There are many kinds of base coat which will work, the one recommended
by BRE (defect action sheet 86) is 1:3 cement sand). There are other
proprietary mixes of course which may have been recommended by the dpc
company. What will not work are light weight gypsum plasters such as
Carlite browning, weaker sand cement mixes and those with lime in
them. These all make for a more porous mix.

If you have one of the former then the dpc system should work, if you
have one of the latter, it won't.

To find out for sure you'll have to get the plaster analysed. If you
don't, you're never going to find out the truth. If you want to do
this, email me directly.

(IANAL)

As for the legalities if you get into an argument: if you have a base
coat which is normally acceptable but it isn't the one the dpc company
have specified, you may still have a case for asking them to re visit.
I would guess however that you'll be flogging the dead horse because
BS6576 (dpc installers credo) says it (re-plastering) should be to the
installers specification.

Dual responsibility is a recipe for disaster whereas employing a
remedial treatments company in the first place was simply a dreadful
mistake!!!

HTH

Xav