How to paint bathroom walls and ceilings to resist mould

🎨 Bathroom Walls and Ceilings: Mould-Resistant Painting Guide for Australian Bathrooms

Why is mould-resistant paint essential for Australian bathrooms?

Painting bathroom walls and ceilings to resist mould is all about controlling moisture, preparing the surface properly, and using the right bathroom-specific coating system. In humid Australian conditions, especially in coastal areas and tropical QLD, a quality mould-resistant primer and topcoat can significantly improve durability, washability, and long-term appearance.

This is a very achievable DIY project for homeowners, but success depends heavily on preparation, ventilation, and choosing the correct low-sheen or ceiling paint designed for wet areas. 💡 Pro tip: Surface prep is always 80% of the job.

What skill level is required for painting mould-resistant bathrooms?

What specific tools are needed for mould-resistant bathroom painting?

Which materials are crucial for effective mould-resistant bathroom painting?

Safety Requirements

Step-by-Step Guide

Step 1: Inspect the bathroom and identify moisture issues

1️⃣ Check the cause before painting

Inspect the ceiling above the shower, wall corners, around windows, and behind the vanity for black spotting, peeling paint, soft plaster, or persistent staining. If there is a roof leak, plumbing leak, failed grout, or no working exhaust fan, fix that first or the new coating will fail.

Look for:

If the substrate is sound and only surface mould is present, repainting is suitable. If plasterboard is swollen or crumbly, replacement may be needed.

Step 2: Remove mould and clean all surfaces

2️⃣ Clean thoroughly before any sanding or painting

Spray affected areas with a dedicated mould treatment such as Dulux PRECISION Mould Killer or 30 Seconds Mould Off. Follow the dwell time on the label, then wipe clean with disposable cloths or rinse if required by the product instructions.

Wash all walls and ceilings with sugar soap to remove soap residue, hairspray, body oils, and general contamination. Bathrooms often fail due to invisible residue rather than paint quality.

Allow surfaces to dry fully before moving on. In a typical bathroom, this may take several hours with good airflow.

💡 Pro tip: Do not use heavy bleach mixes as your only solution. Bleach can lighten mould staining, but dedicated mould removers and proper prep are more reliable for paint adhesion.

Step 3: Scrape loose paint, fill defects, and seal gaps

3️⃣ Repair the surface so moisture can’t get behind the coating

Scrape away any loose, peeling, or blistered paint with a paint scraper. Sand the edges smooth using 120-180 grit paper so there are no visible ridges telegraphing through the finish.

Fill dents, minor cracks, and surface imperfections with a suitable interior filler. Once dry, sand smooth. Apply paintable acrylic gap sealant to small movement gaps at:

Do not caulk large wet joints that require sanitary silicone instead. Silicone is for wet junctions like basins and showers, but it is not paintable.

💡 Pro tip: A smooth repaired surface makes low sheen finishes look cleaner and more washable.

Step 4: Sand and dust off

4️⃣ Create a sound key for the new coating

Lightly sand all previously painted surfaces to dull the sheen and improve mechanical adhesion. This is especially important if the existing paint is semi-gloss or has years of bathroom residue on it.

Vacuum or wipe down all dust thoroughly. Paint applied over sanding dust can develop poor adhesion and a gritty finish.

For glossy old enamel trim in the bathroom, a stronger degloss and dedicated primer may be needed, but for standard plaster walls and ceilings, a light sand is usually enough.

Step 5: Prime problem areas or full surfaces if needed

5️⃣ Prime for adhesion, stain blocking, and mould resistance

Apply primer to:

Recommended products include:

Spot priming may be enough for sound existing paint, but full priming gives more even porosity and a more uniform finish in small bathrooms. Typical coverage is 10-12m²/L depending on porosity.

Allow the primer to dry as per label, typically 1-2 hours touch dry and 2-4 hours before topcoat, but always confirm on the tin.

Step 6: Cut in the ceiling and paint it first

6️⃣ Always start high and work down

Cut in around cornices, exhaust fans, light fittings, and ceiling edges using a 50mm synthetic brush. Then roll the ceiling using a 10-12mm nap microfibre roller.

Use a mould-resistant bathroom ceiling paint such as:

Apply 2 coats at the manufacturer’s spread rate, typically 12-14m²/L. Recoat times are commonly 2-4 hours recoat under normal conditions.

Roll in manageable sections and maintain a wet edge to reduce lap marks. Final roll in one consistent direction for a uniform appearance.

💡 Pro tip: Bathroom ceilings above showers cop a lot of condensation, so don’t substitute standard bargain ceiling paint if you want long-term mould resistance.

Step 7: Cut in and paint the walls

7️⃣ Use a washable, mould-resistant low sheen finish

Cut in around tiles, windows, door frames, vanities, switches, and corners. Then roll the walls with a microfibre 10-12mm nap sleeve.

Best bathroom wall paints in Australia include:

Apply 2 coats for durability and washability. Typical coverage is 12-16m²/L depending on colour and substrate. Recoat generally after 2-4 hours.

A low sheen finish is usually the best balance for bathroom walls:

If painting very small bathrooms with poor airflow, extend drying times between coats.

Step 8: Check ventilation and allow proper curing

8️⃣ Drying is not the same as curing

Once painting is complete, remove masking tape carefully before the paint fully hardens. Run the exhaust fan and keep windows open if weather permits.

Most bathroom paints are dry to touch within hours, but full cure can take 7-14 days. During this period:

If the bathroom has no effective exhaust fan, consider upgrading it. Paint alone will not solve chronic condensation.

Step 9: Maintain the finish to prevent mould returning

9️⃣ Good maintenance extends the life of the coating

Clean painted surfaces periodically with a mild detergent and soft cloth. Avoid harsh abrasives that can wear the mould-resistant film.

To reduce future mould growth:

In high-humidity regions, maintenance and ventilation are just as important as paint selection.

Common Mistakes to Avoid

Pro Tips

Recommended Tools