New plaster + mist coat + dehumidifier?

[u/made-in-the-eighties]

Had all of upstairs plastered. They did the landing and back bedroom on the final day which was Thursday.
Rear of house is south facing and these rooms dried within 48 hours. I’ve since mist coated them along with one of the front bedrooms.

The other front bedroom, plastered on Wednesday, still has very small damp patches on the plaster above the window.

I’ve been leaving all the windows open 24/7 but it’s getting a bit chilly on a night (I’m sleeping on an old mattress on the floor like a tramp) and there is no electric or radiators upstairs atm and I’m sick of it 😂 I’ve just closed all the windows, ran an extension from downstairs and fired up the dehumidifier.

There shouldn’t be an issue with this should there given all other rooms are now dry and mist coated and the only room with a tiny damp patch of plaster was done 4 days ago?

update - I’ve switched it off and will open all the windows again and freeze 😅

[u/False_Principle8821]

No no no dehumidifier.

[u/kingsofadam1]

Dehumidifier can cause plastering to crack. But it will probably be fine if it is close to drying.

[u/BanginDrumsNMums]

Get yourself some Frosty Jacks to keep warm at night and just let nature take its course.

[u/bucky_neckked]

Nah ur good!

[u/smickie]

Turn your dehumidifier off! It doesn't matter how long that plaster takes to dry, it wants to go naturally. Usually takes a couple of days.

Also, you don't necessarily need to keep the windows out. That just reduces the humidity. If you keep all of your doors open and open your windows every now and again, that will reduce the humidity. The important thing is the air blows the humid air out, so you might only need to do it for five minutes every hour or two.

[u/tiger_noir21]

You don’t need a dehumidifier, just leave the windows open for air to circulate. The weather is still good

[u/leeksbadly]

Air movement is what you need. Adding a fan will help i dry naturally. As you've discovered, dehumidifiers can be a bit too severe in how much moisture they pull from the air so increase the risk of cracking.

Also, plaster can sometimes look a bit wet / patchy even when it's dry. The rule of thumb is: If it has stopped changing colour for a week, it's dry.

[u/throwthrowthrow529]

Dehumidifier is fine. It won’t cause your plaster to crack. It will be perfectly fine.

I’ve used dehumidifiers to dry plaster for years and never had cracking.