Plaster not drying out

[Wardley121]

Hi,

I am currently refurbing a Victorian terrace. Plasterer skimmed the middle floor bedrooms on 25/11 (now over 6 weeks ago) and it still hasn't fully dried out- see pics. It's a mixture of. External and internal walls which aren't drying.

Property is unoccupied while I'm refurbing and the central heating is drained down to comply with the insurance. So the property is cold. I have tried using dehumidifiers and fan heaters to assist but I'm only there weekends/ weeknights as I'm doing the project around the day job, so it is cold at night/ most days. The cost of the fan heaters/ dehumidifiers is now becoming prohibitive.

I need to get this to a position where it can be painted as it is now holding up me finishing off the project- any ideas welcomed.

As I see it, either need a way to get the plaster dry OR a solution that lets me paint onto it with it still partly damp. I've had conflicting advice on the second part- plasterer has said to just paint it but a builder is telling me it will just flake off

Thanks in advance for your advice

 

[Deleted member 292770]

Are some of them dry-lined walls?
ventilation and heat.
You can’t paint it until it’s dry.
https://www.anglianpumping.com/prod...MIsIDAzeii9QIVAbTtCh3pzQtQEAQYFiABEgIV_vD_BwE
I use one of these in this situation , this time of year.

 

[JohnD]

you can use a porous, breathing, non-vinyl paint which is designed for plaster that is not yet fully dry, and allows it to continue drying.

The best-known is Dulux Trade Supermatt (and not anything with a "similar" name)

Having no vinyl, it is not very durable and will not withstand scrubbing, but it will look decent and you can decorate over it once drying has finished.

use two mist coats

open the windows whenever you can

I would not paint over any plaster that is still chocolate brown (very wet) as it will not dry.

Other paint manufacturers make similar products, labelled "paint for new plaster" but read the description and instructions carefully to make sure.

have you insulated the loft?

you can speed up drying by setting ordinary desk or room fans (not fan heaters) to blow on the walls, but you will have to ventilate away the water vapour that evaporates off. It is lighter than air so will rise through the house and escape through the loft hatch if you leave it open.

The evaporation will make the house (even) colder until it has finished. You will know, because the windows will stop misting up at night.

The damp will make timber, especially doors, warp and crack.

Do not put glue on the walls.

 

[Wayners]

Grab a fan and put on. Will rapidly dry it out with air movement and better than heat.
Just a standard summer fan. Can put on timer if you want but I would leave on all the time. People don't believe me then are shocked at the rate of drying.
Dehumidifiers are best but the cost can be high

 

[Wardley121]

Thanks all- some very useful advice.

In response to a couple of the questions:

- no walls are not drylined.
- loft is converted into another two dorma bedrooms, don't think it's insulated (rest of the house isnt so I highly doubt it)

I will go with the desk fans and open window for as long as I can and then if still not dry I'll give the paint recommended by JohnD a try.

Thanks again!

 

[mrrusty]

This time of year is difficult. A few days of really cold weather and the fabric of the house gets cold. Some warm wet weather then comes along and you get condensation everywhere inside and out because it takes a little while for the building fabric to catch up temperature wise. It will dry out given some warmer weather and/or heat in the house. When it's wet weather, the walls need to be above ambient temperature for any drying by evaporation to happen.

Bear in mind that if it is raining at say 10 degrees, the humidity is close to 100%, so that moisture laden air hitting anything under 10 degrees is going to condense

This, BTW is why insulating an unheated garage can be challenging - the insulation actually stops the building fabric warming up quickly to ambient and stays colder/below dew point for longer.