Unlike drywall, plaster walls do not always need to be removed after a flood. Because plaster is made of cementitious materials, it usually retains its strength when wet, making it possible to dry out and save. However, the wall may still require partial removal depending on the extent of the damage.
Additional Repair Works
These will possibly be carried out after the property has substantially dried out. However if plaster walls and partitions have been affected badly and do not dry out in a sound condition the plaster and boards affected will have to be removed, walls dried out and re-plastered.
Key Takeaways. Drywall with visible signs of water damage will need replacement. Walls or ceilings that feel wet to the touch are likely candidates for replacement. Hidden leaks can cause unnoticed damage; look for signs like small floods under carpets or behind baseboards.
In general, if the wall material is wallboard or drywall, it should be discarded because it acts like a sponge, drawing water up past the flood level when wet. If the wall material is plaster or paneling, it can often be saved by drying it out properly.
Plaster is less porous than drywall but can still support mold if moisture is present. Common causes include leaks, high humidity, and poor ventilation. Prompt moisture control and professional remediation are essential.
Lath and plaster was a skilled craft and a time-consuming technique and the advent of cheaper, mass produced, pre-manufactured plasterboard meant lath and plaster largely fell out of favour by the 1930s and 1940s. Plasterboard was simply faster and less expensive to install.
Plaster itself is inorganic and non-porous, making it highly resistant to mold. However, mold can and frequently does grow on painted plaster surfaces when dirt, organic debris, or condensation are present. Mold also often grows on the organic backing materials (like wood lath) hidden behind the plaster.
Mold can begin colonizing damp drywall in as little as 24 to 48 hours. However, "black mold" (Stachybotrys chartarum) specifically requires prolonged moisture and usually takes 8 to 12 days of continuous dampness to form visible colonies.
Safely remove flood water by first ensuring the electricity is turned off to avoid shock. If the water is deep, wear protective gear and evacuate if necessary. Once safe, use heavy-duty water pumps or wet/dry shop vacs, followed by industrial air movers and dehumidifiers to thoroughly dry the structure.
In some instances, this can take weeks or months. One way to accelerate this process is by installing a membrane system. This gets affixed to the masonry walls and can be re-plastered immediately. A membrane system allows the wall behind to dry out on its own accord, and ensures your re-entry as quickly as possible.
Mold begins to grow rapidly within 24 to 48 hours of water exposure. Airborne mold spores are naturally present, and once they land on damp, organic materials—such as drywall, wood, or carpet—they will germinate and spread quickly if the area remains wet.
And when you have a flooded house, the repair process can be long and expensive. Cleaning and repairing a flooded house takes time. Learn the crucial steps and coping mechanisms that can help when repairing your flooded home.
Not always, but the risk is extremely high. Mold is not strictly guaranteed if you dry out the wall extremely fast, but because drywall is highly porous and features a paper facing, it acts as a perfect breeding ground for mold spores.
Plastering Cost per Square Metre
The average plastering cost per m² in 2025 is around £15–£80, depending on the work type and finish. A basic skim coat over existing plasterboard usually costs £15–£25 per m², while a full two-coat replaster ranges from £30–£50 per m².
Drywall is an absorbent material that contains gypsum and a cardboard-like paper on both sides. Drywall can wick water up to 30 inches! The water will be present on both sides of the wall. Often, however, it's higher on the inside due to restricted evaporation on that side of the drywall.
Paint and water are insoluble and an easy way to identify if plaster is water damaged is looking for flaking paint or air bubbles that burst and flake. Unlike flaking plaster, paint will flake with minimal exposure to water, while plaster often needs to get wet and re-dry before flaking occurs.
To kill mold from water damage, use either white vinegar for porous materials (like wood and drywall), or a bleach-and-water solution for hard, non-porous surfaces. Always address the root leak and thoroughly dry the area with fans and dehumidifiers first.
Direct warm air at small damp patches to lift off surface moisture and condensation. Run a dehumidifier to remove excess moisture and address the issue of moist air. Improve ventilation by opening windows so that you have plenty of fresh air.
Your washing machine might work after a flood, but it depends on how high the water rose. If the water reached electrical components, the motor, or the control board, it is likely ruined. Never plug in or attempt to run a wet washing machine, as doing so poses severe risks of shock, fire, and permanent damage.
Mold toxicity (or mycotoxin illness) occurs when you are exposed to mold spores that produce toxic byproducts. These symptoms can mimic other conditions and often range from mild respiratory irritation to severe neurological and immune responses.
According to the Florida Department of Health and Forbes, the signs indicating mold may be in your drywall or finished walls are:
In A Nutshell: Misconceptions About Mold
Your home can be 100% mold-free: No, there are always mold spores in the air. Anyone can effectively remove mold: No, you need professional services for that.
To treat mold on plaster walls, first fix the underlying moisture issue. Then, don personal protective equipment (gloves, goggles, mask), spray the wall with a commercial mold remover or a mixture of 111 part bleach to 333 parts water, let it sit for 10−15 minutes, wipe clean, and allow to fully dry.
Mold is generally at its worst from early spring through early fall (specifically July through October), peaking during the warmest and most humid months. Mold thrives in warm temperatures (60∘F to 80∘F) combined with relative humidity levels above 60%.
The Japanese practice of hanging futons and pillows outside to “air out” isn't just traditional — it kills mold and mites that love humid bedding. Wipe down bathrooms after every use. Exhaust fans during showers, wipe tiles and mirrors, keep surfaces dry. Bathrooms are ground zero for household mold.