Water-damaged plaster only needs replacing if the underlying structure or lath is compromised, it has begun to sag or crumble, or mold is present. If the plaster is still firmly adhered, the moisture issue has been resolved, and it is merely stained or cracked, it can usually be patched, primed, and repainted.
Patch it up
Get some bonding agent on the wall with a roller then apply some plaster mix. Once it's all dry, sand the wall to make sure it's smooth before you start decorating.
Generally yes, the board should be removed and replaced with an equivalent Gyproc product to maintain the original performance criteria.
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.
Yes, you can plaster over existing plaster, commonly referred to as "skim coating". However, the old plaster must be structurally sound and properly prepped. If the old base is crumbling, cracked, or loose, the new plaster will fail.
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.
Look for: Permanent water stains and unsightly mold water damage markings on ceilings, walls and floors. Erosion of drywall, often causing it to be warped or changed in texture (TIP: newer water spots will feel firm to the touch, while older water damage will create a spongy, mushy feeling)
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.
Drywall ceilings
Drywall finishes on ceilings are a common alternative to plaster ceilings because they are smooth, can easily be painted, and are typically less expensive.
Cost-Effective: Drywall is less expensive in both materials and installation labour, making it a budget-friendly choice for most homeowners. Easy to Repair: If damaged, drywall is much easier and cheaper to repair than plaster, requiring fewer skills and less time.
Over time, the moisture weakens the plaster, causing it to crumble, crack, and bubble. Water stains may also become visible, further compromising the aesthetic appeal of the walls.
Drywall can recover from water damage, but there comes a point when it needs to be replaced. No matter the severity, the first step in any ceiling water damage repair is finding the moisture source and stopping it. There are a range of potential causes, including missing roof shingles, burst pipes, and clogged gutters.
Fill in holes and cracks
A joint compound or filler can work here. Fill them in to sit flush with your wall. Don't worry about putting too much filler on; you'll be sanding it down once dried. You can also purchase skim repair fillers which you roll on with a roller, which could work for larger areas.
Mold is highly likely—but not strictly guaranteed—after water damage. Microscopic mold spores naturally exist everywhere, and they can germinate and spread in as little as 24 to 48 hours if organic materials (like drywall, carpet, or wood) remain damp and unventilated.
Yes, drywall can survive getting a little wet if it dries quickly (within 24–48 hours) and does not swell, soften, or grow mold. Small, localized wet spots that remain rigid can typically be dried and repainted, but if the drywall is sagging, soft, or damaged, it should be removed to avoid structural weakness.
Moisture within and behind walls can be detected with a pinless moisture meter. A non-destructive moisture meter can accurately locate and measure elevated moisture levels without the need to break the wall's surface material.
Mold toxicity (mycotoxin illness) happens when prolonged exposure to mold spores triggers chronic inflammation and immune system activation. Symptoms are often subtle and mimic other illnesses, but common red flags include persistent allergy-like reactions, chronic fatigue, unexplained brain fog, recurring headaches, and respiratory or digestive distress.
Key Takeaways. Mold can begin to colonize on wet drywall within 24 to 48 hours. Due to its porous nature, drywall is highly susceptible to mold growth. Visible mold can appear within 2 to 4 weeks under optimal conditions.
Toxic black mold growth has a more potent and identifiable smell, like the smell of decay, wet soil, or rot. Visually, it may be greenish-black, grayish-black, slimy, or more furry than other forms of mold or mildew.
Plaster is rarely used in modern construction primarily because drywall (gypsum board) is faster, significantly cheaper, and easier to install. While plaster is highly durable and offers better soundproofing and fire resistance, traditional multi-coat plastering requires highly skilled labor and lengthy drying times, making it inefficient for modern housing demands.
Apply each layer of plaster 15-30 minutes after the previous layer. If there is not enough time to finish the project in one day, it is important to apply a thin layer of water over the plaster before applying the next layer. If a new layer is applied to plaster that is already fully dry, it will not bond.
Skim coating – also known as a level-five drywall finish – is the process of smoothing over worn or damaged drywall with a thin coat of diluted joint compound in order to improve the look of the surface. It is usually done to repair damage and improve appearance.