Damp patches on new plaster - 8 weeks - advice needed

[bobby5000]

Hi all,

I've had rooms in my house replastered, as in skimmed. Some of the rooms are practically all dry, as in, consistent faint pink colour.

However, one of the rooms - the one that was done first 7-8 weeks ago - is still quite patchy. I think some of the reasons might be that it is an outside corner of the house exposed to this baltic weather; that the room doesn't get drafts through it like the other rooms as it is off to the side (I had windows and doors open even in the cold to dry those out up until recently and the flow of outside air through the house really took away a lot of moisture); the room has only one top opener on the window; and I've not consistently had heating on because it is so expensive.

However, perhaps there are other reasons? Most of the patches are higher up the walls if anything, especially above the window. The pointing is fine outside and there are no roof leaks. The higher up factor would seem to rule out rising damp.

I have decorators coming in about 3 weeks and I am concerned that the plaster won't be dry enough. Obviously don't want to spoil new plastering I've spent a load of money on or waste money on decorating that doesn't work out. I've been putting the heating on more plus using a dehimidifer but it doesn't seem to be shifting. I am mindful of people saying heating and dehumidifying could cause cracks.

I've attached photos. Any thoughts? Is this normal after 8 weeks in the above circumstances? Would you paint over this? Could it be that it isn't damp but salts or something?

Many thanks
Bert

 

[Wayners]

Air House by opening a window front and back or doors. Id put a fan bowing out a window or door as this will drag air out. Will go cold but get the damp air out.
Look up air house..

Then get fan on as it looks like you have.

Looking at pictures I think it's dry. Normal coloured patches in dried plaster which happens more in winter with slower drying.

No condensation on windows is a good sign all is dry

 

[bobby5000]

Hi mate, thanks for the reply.

I've been doing all you've suggested for a while now. Large parts of the walls and ceilings are very light in colour - almost white. But these darker patches persist. I cannot tell if it is to do with moisture or not, perhaps because of cold spots on the walls that moisture is being drawn to, or what. The patches look quite dark in contrast to the very light areas around them so am concerned about paint failing when decorators come if moisture is there.

What would be the reason for the dark patches if not moisture? Could it be salts or something thst I should apply salt neutraliser to? Also, if it is moisture and I need somehow get that out, what do you think about those industrial type dehumidifiers that are for hire?

Also, on a separate point, I've noticed some hair line cracks have appeared, mainly on ceilings in some isolated places and around a light switch. Is this normal and would you get the plasterer back to fix?

 

[Wayners]

Re colour
Depth of plaster
Polishing off
The way air moves with drying
Type of surface skimmed can all effect drying and then overhaul colour when finished.
I don't think that's damp. Just the colour it is.

Re cracks. Maybe less pva at that spot? It happens.
Don't know what your walls were like to start with.
With spiders web wall cracks I use 1m x100m rolls of mesh in the plaster coat but still not as popular as it should be on refurbishment jobs. Stops the 100s of hairline cracks coming back through is the idea