I was asked to look at a property today where they have damp patches showing through the plasterboard on the walls in the bedroom. It seems the plasterboard has been dot and dabbed and then skimmed. The exterior wall is brick built, with a flat roof above, so no overhang/eaves to divert water away from the walls.
Somebody else quoted to dot and dab the walls and then redecorate but I don't think that will solve the problem, only mask it for a few months.

I am sure some of it is just normal condensation but some looks too "wet" to be condensation.

I was thinking of stripping off the D&D and then fitting insulated plasterboard using D&D. Part of me thinks that this will prevent the damp/moisture forming on the walls (as it is now) but there will still be a possibility of damp where the walls and floor meet. Alternatively using foil backed plasterboard to act as a vapour barrier.

Rendering/cladding the outside wall is not an option as it is a block of flats.

Any ideas or suggestions?

I think it is a cavity wall, it is a flat that has been built above a shop and the estate they are in was probably built in the late sixties to mid seventies.
Without ripping the plasterboard off the inside walls I can only imagine they have a combination of condensation and damp.
The 2 bad walls are exterior walls that have no roof overhang, porous bricks and probably something bridging the cavity.

If the client was willing I would strip off the plasterboard, possibly remove a couple of bricks/blocks from the internal skin to see what is going on in the cavity.

I have inherited the job because the first guy quoted, the job was accepted and then he did not want to do it.
It is not really clear what he quoted to do? There was mention of 3 air bricks, dry lining and decorating.
Where he was planning on fitting the air bricks I have no idea?
Why you would take off dry lining only to put more up I have no idea?
The decorating is self explanatory.

My house has damp walls with foam backed plasterboard dot and dabbed on, it is not an ideal solution but it does work. It is better to fit some vents in the wall then build an insulated stud wall in front of the damp wall, but it does take a fair bit of space off the room.

On mine they have put vents right through the wall, but with only 35mm insulated plasterboard you are not going to get a lot of insulation and the wall could still be cold??

You could skim the wall with a sand cement mixed with a waterproofing additive, that is something some of the builders do round here with barn coversions. Others line the wall with a breathable membrane then batten the wall for plasterboard. You takes your pick

Thanks Jerry, you have pretty much confirmed what I was thinking.
Most of the solutions mentioned are treating the symptoms but not the cause.
It is a tricky job for me because I am way down the line...
Owner/property management company/maintenance company who then subs me. Every quote has to go all the way to the top and filter back down again. I don't know how much is added to or taken away from my quotes before they arrive on the owners desk?

I don't want to do the job unless I know I can do it properly with no come-backs.

Quote:


Jerry, with a lot of barn conversions the walls are impossible to damp proof, mine are 2ft thick with a core of soil or whatever else they could throw in. The builders fitted one of those electric dpms to keep the NHBC happy, but they are about as much use as the proverbial chocolate fireguard. The only option is to dot and dab or stud off the wall. Done properly, it works well. Mine have been done for 12 years and apart from where the builders cocked it up I have had no problems. Though of course you are right, with a modern building it is better to cure the underlying problem.

Zam, if you're that far down the 'chain' then, unless you're desperate for the work, walk away from it. Management companies are notorious for wanting the quickest job done at the lowest rate, and then you usually have to wait for your money!

Jerry's right, they'll want a cheapo job done but you'll be the patsy picking up the future comebacks.

We all know from experience that, unless you're incredibly lucky, hitting on the cause of a "damp problem" involves a lot of exhaustive work to narrow down the cause because you have to be sure. If it was a private customer with whom I was dealing direct then no problem, but a property management company? The relationship is too impersonal. No way!

Oh dear!  A cover-up job!

Nasty  

At least the cheque will have cleared by the time it reappears!