Damp problem?

[daves1y]

I am not sure whether I have a damp problem or the remains of a former damp problem.
There are mottled patches under the paint on a couple of walls. When I scrape the paint/plaster from these spots there is a dark patch on the wall. These appear behind the door, on another internal wall and in two patches by the French windows, where the curtains would be.
The places don't appear damp, but I have no damp meter. On the wall behind the door there is a horizontal line above which are these marks and below is clean bright paint suggesting new plaster (perhaps after damp proofing).
Do I have a damp problem or the aftermath of a previous damp problem?
What is the solution, replaster or seal the wall?
Best regards,
Dave

 

[roughcaster]

As with most questions like this it's hard to say without seeing, but if you can upload 2 or 3 pics on here, it would be helpful.

 

[misterhelpful]

As roughcaster says, it's very difficult to help without seeing the problem.

It could just be the remnants of a damp problem which has been sorted, dried out and left some damage caused by salts or just some plain and simple staining. If either of these is the case, and the plaster is sound, then an alkali resistant primer may help cover the patches before re-painting with your emulsion. All loose paint will need to be removed and the area dry before using it.

If you can post some pictures and it turns out to be more significant than that, you will be in good hands with the advice the spreads will give.

 

[daves1y]

Hi All,

Posted this message a while ago but didn't get round to any pictures. I have added some pictures into my album which shows the overall view and a close up of what may be the soruce, but from what I have seen, it appears to be due to something painted on the wall perhaps due to damp from before.
Please take a look and let me know what you think
Regards,
Dave

 

[stevethespreader]

Hi All,

Posted this message a while ago but didn't get round to any pictures. I have added some pictures into my album which shows the overall view and a close up of what may be the soruce, but from what I have seen, it appears to be due to something painted on the wall perhaps due to damp from before.
Please take a look and let me know what you think
Regards,
Dave

the photos are not that good, but i would say the black stuff is bitumin paint also known as blackjack or aquaseal and it looks like someone may have painted it on to try and cure a damp problem, not sure about the other pic being damp or not

 

[daves1y]

Just added another picture, but it looks like it has been painted on the wall, unless the whole wall was black with damp and they just painted over it.
Cheers

 

[spreddie]

usually black patches indicate condensation. are there are bricks or trickle vents in the house?

 

[daves1y]

I am pretty sure this is not damp, but rather a tar bases covering used by a previous owner to stop damp.
I was recommended by a painter and decorator to use undercoat to seal the wall, but this substance is leaching through.
I would welcome suggestions, but I am now leaning to getting a plaster skim coat
Cheers to all for your help