Damp occuring after a damp proof course

[HezzieB2B]

We have had a damp proof course done downstairs, waited 6 months for it to dry out, then we decided to take off the top part of the wallpaper to redecorate. As a lot of the plaster came off with the wallpaper, we got someone in to replaster the whole room. A week later its drying out downstairs and looks great, however the bedroom directly upstairs has now got little brown spots of damp all over the room!! What can I do to make this better? Dehumidifer plus dampsealing paint to cover it? Or should I be complaining to the initial damp proof contractor? Help and advice please!

Rising damp - which is what a damp proof course stops - can only rise so far, I think 1.5m. So the damp upstairs must be something different - no idea what though! Condensation??

damp is water, and there must be a source of the water. Sometimes it is wet washing draped round the house, or steamy showers; sometimes it is a leaking pipe or drain; or the roof or gutters.

Chemical injections do nothing to cure these defects.

Tell us about the damp you've experienced, and show photos please.

If we can track down the source of the excess water, we can probably find a way to cure the cause..

Thank you ... my partner thinks it's caused my having the downstairs replastered after the damp proof course being done and all the wet is coming out upstairs.
I've ordered a dehumidifier to see if that will help. And then I was going to get some ronseal mound remover and then some damp paint that seems quite good but pricey at £30 a tin!!
We have no leaks or anything. However we do use the 2ndbedroom for hanging up damp clothing, but it's not affecting that room though! I'll add a photo soon.

You need to think about where water you are releasing into you house can go. Either you need to ventilate it, really well when there is a lot of water like with drying plaster, or you need to collect it with a dehumidifier. Water vapour will condense on cold surface, usually most visible on windows, but colder external walls will attract condensation as well. Just heating won't solve a damp problem, it will just move it around, you have to get rid of the water generated by drying washing, cooking, showers stc. Damp proof paint will temporarily relieve symptoms but not cure the problem.

Here are the photos of the damp spots

can you put something in the pic to show scale

and stand back to show the whole wall, floor to ceiling.

is it an outdoor wall? a chimneybreast?

the marks look like black mildew spots to me, caused by condensation. They will probably smudge if you wipe them. Open the windows and let the moist air out. The mildew will die when it dries, then you can clean it off.

Mould spores are everywhere in the air, they do not grow unless you provide a damp surface for them.

Here are two more photos of the wall. It’s on all the indoor walls of the bedroom.
It’s a cold house, but I will open the windows to see if that helps.

is that room heated and ventilated?

how thick is the loft insulation?

condensation on internal walls is rare because they are warmer than external walls. I suspect high humidity.

in the top right corner I think I can see a damp patch which might be roof or gutter related. is it a corner with an outside wall? Can you take a pic of the outside, including the roof and gutter?