Has my damp proofer cocked up?

[nickjones87]

Can anybody explain this on?

Old plaster off, dryzone injected, plasterboard on and skimmed.
10 days later these damp spots are appearing in the same place they were in before they came in to 'fix' the issue !

Notes:
1a) Wall is internal (between 2 reception rooms, solid brick)
1b) Damp spots only appear to be where dot and dab is (checked by tapping)
2) After replastering, damp spots came back within 10 days.
3) I got a huge dehumidifier in for 4 hours and could barely notice the damp spots, came back within hours after turning off.
4) Rooms have average of 60-70% humidity
5) House has barely any ventilation
6) Notice in one pic, the damp spot ends where the skirting board is, I took it off for this photograph. (Condensation , not damp?)

They want to come back and redo it but with a membrane between the brick and plaster, but I'm hesitant because they don't appear to know much about condensation and they never even brought condensation up when quoting, I was told it was rising damp.
After doing research, I'm entirely convinced I would have been better off installing ventilation and perhaps positive air ventilation (fan in loft pushing fresh air in to the house).

Can anyone give me their thoughts?

 

[vinn]

Whats happening, or has happened, on the other side of that wall?
Is that floor solid or suspended? What about the floor in the other room?
Is there an old mechanical DPC (slate, bitumen) in that wall?
Is there a chimney breast on either side of the wall?
What signs of damp did you have before calling in the Damp Company?

Dot & Dab of any kind, in any sort of arrangement, is the last thing you need on a damp wall - its a fundamentally bad, technically ignorant practice.
It sounds like you have damp penetrating the dabs of adhesive. Some p/b adhesives claim to be damp proof but will fail eventually.
There may be condensation in the room - and condensation will be attracted to damp conditions.

As you seem to know - heat and ventilation are the best preventatives against condensation.

 

[nickjones87]

Whats happening, or has happened, on the other side of that wall?
Is that floor solid or suspended? What about the floor in the other room?
Is there an old mechanical DPC (slate, bitumen) in that wall?
Is there a chimney breast on either side of the wall?
What signs of damp did you have before calling in the Damp Company?

Hi Vinn,
Wall is internal on both sides.
Photo 1 and 2 - Each photo shows the same wall but different sides
Photo 3 - Next to above wall, I had a box of tiles propped against this wall at a 45 degree angle so only barely touching the wall but perhaps this pulled in so much more moisture to this wall due to coldness of the tiles??
Photo 4 - Shows photo 3 but with some plaster chiseled out (to inspect behind)
The brick feels dry!

Both floors are solid, I've seen a membrane with my own eyes in one room but can't be sure about the other.

There is an (apparently) failed injected DPC in the wall,
Adjacent to both walls are blocked up chimney breasts - No ventilation.

Before I called the damp company, I had damp circles/spots on one side of the wall, and spots / waves of damp in corners and across the wall on the other side.
I've never seen crystals or mould on these walls in 3 years of having damp.

Hope this helps? Thanks.

 

[vinn]

Knocking off plaster behind the skirting will reveal any DPM flopping up the wall.
You have rising damp, and any Mickey Mouse DPC injections are more miss than hit.

There might be a tie-in with salts from the chimney breasts flues or even rising damp from an old hearth area.

I'd suggest that you knock off all affected D&D and any other affected plaster or render, and re-render with a 3:1 sand & lime mix with a remedial finish.

Where the skirting is off I can see what looks like water damage to the wood flooring?

Condensation mould in unventilated areas usually is black spotted & very obvious.

All flues must be swept & ventilated top & bottom.

 

[roy c]

Where does the pipe to the rad come in? Is it buried in the floor? If so it may be leaking and tracking back up the wall. Feel around both valves on rad and see if there is any moisture there. Just a thought!!

 

[Big.Wayne]

Hello nickjones87,

I'm only a beginner but the photos you posted look very similar to the ones on this salt damp page:

http://www.britpres.co.uk/services/damp/salt-damp.html