It might be tempting to use a dehumidifier to dry plaster, but do-it-yourselfers should stop and think this through before rushing to do it. Nevertheless, you can dry plaster with a dehumidifier, but it will be hard work, and the solution is not without problems.
The fact of the matter is, if you are using a dehumidifier to speed dry your plaster walls, then chances are, you might be doing it wrong.
This article will be detailed about why people choose to use a dehumidifier in their drying phase and explain some of the pitfalls with the process.
Make Plaster Dry Faster (Using a Dehumidifier)
How Long Does Plaster Take To Harden?
The first point here is that plaster takes a long time to dry. If you are using a dehumidifier, and have great ventilation, then your plaster may be dry in 3-4 days after it has gone off the forms. However, for average conditions (ventilation), it can take anywhere between 5-10 days to dry completely.
Plaster takes longer to set in corners and edges, so if possible, it is best if you try to ensure that your plasterer has relatively smoothened the finish by using a trowel. Also, drying will take longer if your home is warm or damp (as most people do not have an air conditioning system) and if your walls are thick (3-4" painting plaster will take longer to dry than 1.5").
Does Cold Air Dry Plaster?
Plaster absorbs water by evaporation; therefore, the hotter and more humid your conditions are, the slower it will dry. Therefore for the plaster to dry faster, you want a cold surface temperature and low humidity.
With a dehumidifier, it cools the air surrounding your walls which makes them drier. This is good and means that your plaster should be dry in a few days. However, the plaster has also been exposed to cold temperatures, and this will cause it to start contracting.
How Long Does Plaster Take to Dry in a Cold Living Room?
The plaster will take longer to dry in a cold living room than it would if you left the ambient (room) temperature alone. Therefore, if you are solely using a dehumidifier, your painting plaster will take longer than necessary to dry.
How Do You Make the Plaster Mold Dry Faster?
The dehumidifier will cause the temperature of the walls and plaster to increase when it is used. Therefore if you use a dehumidifier, you have just increased the risk that there could be some water damage or plaster mold.
If you have to use a dehumidifier and not leave the windows open after plastering, then you should try to ensure that the temperature of your house does not get too warm (and always ventilate your home regularly).
It is best if you can fully ventilate your house (windows open for long periods) if you do not have AC, as this will allow the plaster to dry naturally.
Related Article: Does a dehumidifier help with mold? (mildew)
Why Does Plaster Crack as It Dries?
The dehumidifier has cooled the air around your walls, and this will cause them to contract faster, which means that more contraction is occurring as the plaster tries to dry in an already cold room/conditioner. If you are solely using a dehumidifier to speed along the process to dry the painting plaster, then it will often crack.
You can dramatically reduce cracking by leaving your windows open for long periods after you plaster and ventilate your home regularly. Cracking is more common when people use their dehumidifiers in damp conditions or keep them running for too long before the plaster.
Dehumidifier as the Best Way to Dry Out New Plaster
Do Dehumidifiers Use a Lot of Electricity?
If you have chosen to dry your plaster using dehumidifiers, then be prepared to keep it running for at least three days after you plaster. Ensure that you are not drying your plaster in a cold, damp room (or use an air conditioner instead), and do not be tempted to close all of your doors or windows after you have plastered because the dehumidifier will work best when it has free access to air.
If your house is cool, then this should not cause any problems; however, if the temperature is warm, then you will need to ensure that your home is ventilated by leaving windows open for long periods.
Sleep in a Room That Has Just Been Plastered and Dehumidified?
If you use a dehumidifier to speed dry your plaster, it is better if you do not sleep in the room which has just been plastered. As well as being cold and dusty, it will be tacky and sticky after the drying process of the room. Also, because of the cold temperatures in your new plaster, any condensation on the walls or ceiling will not evaporate overnight. So you will have condensation on your walls in the morning.
Dehumidifier and Opening Windows to Let the Plaster Dry
Should You Let the Plaster Dry Naturally?
If you can, then yes! Unless you are really in a hurry to dry the plaster.
If you have chosen to dry your plaster by using a dehumidifier and opening the windows to let it dry naturally, then make sure that you leave them open for several days. If possible, continue to ventilate your home after you have plastered, as this will allow the plaster to harden on its own (without any risk of mold growth or damage) fully.
If you do not ventilate your home and you use a dehumidifier to dry out new plaster, then the walls will only dry from the surface. This will mean that there is wet wallpaper behind your plaster, which can lead to mold growth and water-damaged walls.
Dehumidifier to Dry Plaster FAQ
What Setting Should a Dehumidifier Be On Drying Plaster?
Before you plaster, it is advisable to set your dehumidifier at the highest setting. What you need to do after you plaster is to slowly reduce the Air Circulation setting (to 1) and then increase it again once your room has dried out (usually in two days).
Reducing the Air Circulation setting allows the air around the walls to warm up, balance the humidity level, and some of the air moisture within the plaster will evaporate, which can dry out plaster better.
Can a Dehumidifier Be Used With a Fan?
Yes, a dehumidifier is made to remove moisture from the air. This means that when you use it with a fan, you will get a much faster drying process rate than if you just use your dehumidifier on its own.
But you should open the windows in your room that have just been plastered. This will allow moisture to evaporate from your walls, and it will also help to circulate fresh air within the room. After the plaster paints process, you can close the window (so that it remains warm).
Summary
So after reading all of these points, do you think that using a dehumidifier to dry out your plaster is the best way? Well, if you have time and patience, then it can be.
A dehumidifier can be used to dry out new plaster; however, the long-term results depend on what you have done to ventilate your room after you plastered. If you allow air moisture within the walls of your home to evaporate naturally, then it is likely that your home will remain mold-free, and water-damaged areas will be avoided.
