Yes, damp plaster can dry out, but the drying time depends on several factors, such as the extent of the dampness, the type of plaster, the temperature and humidity levels, and the amount of air circulation in the affected area. Sometimes, damp plaster may take several weeks or even months to fully dry.
A little splash of water isn't an issue – you can wipe it off right away. But, in storm season, if water leaks through to your plaster board, then you have some substantial problems on your hands. Firstly, the water softens the plaster, and it begins to loosen up.
Once the source of moisture has been dealt with consideration may need to be given to the replacement of the wall plaster, either in a like material or by selection of an appropriate remedial system. It is also worth remembering that Damp Plaster can be hiding problems beneath, especially in older buildings.
The most effective and economical way to treat rising damp is with a damp proofing injection cream. You can choose between complete kits or individual cartridges of PermaSEAL PRO DPC Injection Creams. The cream is injected or hand-pumped into specially-positioned holes in the mortar course.
Painting on wet plaster is not recommended. If the plaster is not fully dry, painting over it will trap moisture between the plaster and the paint, eventually causing the paint to flake and peel off.
Increase airflow
Good airflow will help to encourage your plaster to dry more quickly. If it's not too cold, it can help to keep windows and doors open. Similarly, a fan can help as long as you keep it on a low setting so that it doesn't cool down the room too much.
Yes, mold can grow on plaster. Just like other types of building materials, plaster that has been painted, is dirty, or has been damaged is prime for mold growth. If you find mold growth on your plaster walls, what can you do about it?
If you're using a regular plaster it should be changed daily for hygiene reasons - plasters can pick up a lot of dirt and bacteria throughout the day and you don't want to risk this getting into the wound. You should also change your plaster if the blood soaks through or if it gets very wet.
If your plaster was ruined because of damp, any new plaster you apply to the walls will also be ruined by the same damp. So, once the damp proofing measures have been put in place and are protecting your property against a resurgence, you will want to consider replastering your walls.
Use desiccants to absorb moisture in closed areas.
If you're trying to dry out a small, enclosed area like a closet, normal drying techniques may not work. Instead, try placing moisture absorbent materials, or desiccants, near the wall to suck out some of the excess water vapor.
The stained drywall or plaster needs to be dry for two reasons: a) if it's wet, then it means the water damage is very recent (or still happening), and b) you can't paint onto a wet wall or ceiling. You can help the drying process by using a dehumidifier in the room.
If you are suffering from rising damp then damp will have left tidemarks and other visible damp damage on the plaster. It is important to remove this contaminated plaster before injecting a DPC.
A minor amount of water, from wet clothing or a spill, isn't detrimental to a plaster wall. Simply wipe off the wall with a dry cloth quickly, and your wall will remain solid and intact. To ensure all moisture is dry, aim a fan at the affected area to speed up the drying process.
Plasterboard walls
As plasterboard is constructed of layers, using bleach or even a mould wash will only remove the surface mould. The main issue is active mould growing throughout the plasterboard. Unfortunately, the only way to get rid of mould for good is to replace the plasterboard.
Musty Smell
If you don't see signs of mold, but you can smell it, it may be hidden in your walls. A musty smell indicates that mold is growing in your home. The smell of mold feels earthy, like rotting leaves or decaying wood in a dense, damp forest.
Drying studies of various materials show that increasing air speed over plaster casts reduces drying time. An air speed of 15 fps (ft. per sec.) is recommended, and speeds up to about 30 fps are desirable.
Open windows and doors to help speed up the drying process. Use fans to move air around the damp walls. Also use dehumidifiers, which can help remove moisture from the air and walls. Professionals use tools like moisture meters, infrared imaging devices, dehumidifiers and heavy-duty fans.
Polar damp seal paint is a great choice for DIYers looking to damp proof their interior walls. It can be used on a range of indoor surfaces, from brick to concrete and plaster, making it an incredibly useful multi-purpose paint.
1 coat of Zinsser Gardz is generally all you need. It binds loose material and creates a moisture-proof film that can act as a barrier coat between a problem substrate and new decorating materials. This is slightly different to Zinsser Peel Stop, which also acts as a stabiliser, but remains breathable and flexible.