"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