Anti-Mould Paint for London Bathrooms in 2026: Products, Preparation, and Prevention

Why London Bathrooms Are Prone to Mould

Mould in bathrooms is not a failure of cleanliness — it is a consequence of moisture, warmth, and inadequate ventilation. London properties are particularly susceptible because so many of them were built before mechanical ventilation was standard, and because the mild, damp climate provides ideal conditions for mould spores to colonise painted surfaces.

In period properties across Belgravia, Chelsea, Pimlico, and Kensington, the problem is compounded by solid walls that hold moisture, original single-glazed sash windows that create condensation, and bathrooms that were often converted from bedrooms without proper extraction being installed. Even in modern London apartments, internal bathrooms with no window rely entirely on extractor fans — and when those fans are undersized, poorly maintained, or switched off by residents bothered by the noise, mould follows.

The solution is not simply to paint over mould with standard emulsion and hope for the best. That approach fails reliably within months. A proper anti-mould bathroom painting strategy involves treating existing mould, preparing the surface correctly, applying the right products, and addressing the underlying ventilation issues that allowed the mould to establish in the first place.

Treating Existing Mould Before Painting

Painting over active mould is pointless. The mould continues to grow beneath the new paint film, and within weeks the dark patches reappear — often worse than before, because the paint has trapped moisture against the wall.

Step one: fungicidal wash. Apply a proprietary fungicidal wash such as HG Mould Spray or Barrettine Mould Cure to all affected areas. These products contain biocides that kill mould spores and the mycelium (root structure) embedded in the paint and plaster. Spray generously, allow the product to work for the time specified on the label (usually 15 to 30 minutes), then wipe away the residue with a damp cloth.

Step two: allow to dry. After treating, the wall must dry thoroughly. In a London bathroom with poor ventilation, this may take 24 to 48 hours. Use a dehumidifier to accelerate drying if needed.

Step three: sand lightly. Once dry, sand the treated areas with 120-grit sandpaper to remove any remaining surface mould staining and to key the surface for primer.

Step four: stain block. Mould staining that persists after treatment needs sealing with a shellac-based stain blocker (Zinsser B-I-N is the industry standard). This prevents residual discolouration bleeding through the topcoat.

Choosing the Right Anti-Mould Paint

Not all bathroom paints are equal, and the term "bathroom paint" on a tin does not necessarily mean it contains meaningful anti-mould technology. Here are the products we recommend and use:

Zinsser Perma-White Interior. This is our first choice for London bathrooms with a history of mould problems. It contains a built-in biocide (an EPA-registered antimicrobial) that actively resists mould and mildew growth on the paint film for the warranted life of the coating — typically five years. It is available in matt and satin finishes, is moisture-resistant, and can be applied directly over properly prepared surfaces. It also has excellent coverage and a self-priming formulation.

Dulux Trade Mouldshield. A fungicidal matt emulsion designed for use in damp or poorly ventilated environments. It contains fungicide that protects the paint film against mould growth. It is a good option for ceilings in bathrooms where condensation rises and settles.

Ronseal Anti Mould Paint. A more budget-conscious option that provides six years of mould protection according to the manufacturer. Available in white matt and magnolia. Suitable for areas with moderate moisture exposure.

Tikkurila Luja. A semi-matt paint with excellent moisture and mould resistance, popular among professional decorators. Its washability is particularly high, making it practical for bathroom walls that need regular cleaning.

Application Method

Priming. On previously mould-affected surfaces, apply Zinsser Perma-White as a combined primer and topcoat, or use Zinsser B-I-N primer followed by your chosen topcoat. On bare plaster, a mist coat followed by two full coats of anti-mould paint is the standard approach.

Number of coats. Two full coats minimum. Anti-mould paints rely on a sufficient film build to deliver their biocidal protection — a single thin coat does not contain enough active ingredient to be effective over time.

Ventilation during application. Ensure the bathroom is well ventilated during and after painting. Open windows where possible and run extraction fans. This accelerates drying and prevents the fresh paint from being exposed to excessive humidity before it has cured.

Addressing the Root Cause: Ventilation

Anti-mould paint is a treatment, not a cure. If the underlying moisture problem is not addressed, even the best anti-mould coating will eventually be overwhelmed. In London bathrooms, the ventilation improvements that make the most difference are:

Extractor fans. Building Regulations require mechanical ventilation in bathrooms at a minimum extraction rate of 15 litres per second. Many older installations fall short of this. Upgrading to a modern, quiet extractor fan with a humidistat (which runs automatically when humidity rises) is one of the most effective anti-mould measures available. Models from Vent-Axia and Envirovent are widely used in London properties.

Opening windows. Simple but effective — opening a bathroom window for 15 minutes after bathing allows moist air to escape. In period London properties with original sash windows, the top sash can be dropped slightly to allow ventilation without creating a draught.

Heated towel rails. These reduce moisture in the room by drying towels faster and providing gentle background heat that raises the surface temperature of walls, making condensation less likely.

Addressing cold spots. Mould typically appears first on the coldest surfaces — external walls, around windows, and in corners where air circulation is poor. In London properties with solid walls, internal wall insulation can raise surface temperatures enough to eliminate condensation points.

Ceilings Deserve Special Attention

Bathroom ceilings are where mould appears first and most aggressively, because warm, moist air rises and condensation forms on the ceiling surface. Apply anti-mould paint to the ceiling as well as the walls, and consider using a dedicated ceiling product with high opacity and anti-mould properties.

In bathrooms with downlighters, mould often appears around the light fittings where warm air meets the cold ceiling void above. Ensuring these fittings are properly sealed and that the ceiling void has adequate insulation reduces this risk.

Maintenance After Painting

Anti-mould paint is not permanent. To maximise its effective life:

• Wipe down bathroom walls and ceilings monthly with a mild cleaning solution to remove soap scum and moisture deposits.
• Run the extractor fan during and for at least 20 minutes after every bath or shower.
• Inspect for early signs of mould (small dark spots in corners or around silicone sealant) and treat immediately with fungicidal spray before the problem spreads.

We paint bathrooms across London regularly and understand the specific challenges that London properties present. If your bathroom has a persistent mould problem and you want it resolved properly — treatment, preparation, the right products, and ventilation advice — get in touch for a consultation.