Bathroom · 10 min read

How to clean bathroom mould properly and stop it coming back

Practical UK bathroom mould guide: cleaning, ventilation, silicone, grout, safety and when mould is a maintenance problem.

Quick answer Clean the surface mould, dry the room properly, improve ventilation and replace failed silicone where mould has gone behind the sealant.

DifficultyBeginner

Time45 minutes to 3 hours depending on severity

DIY cost£8-£35 for cleaner, gloves and cloths

Professional costDeep bathroom cleaning commonly starts from £95 depending on condition and property size

Is this suitable for DIY?

Should you do this yourself?

Light surface mould on tiles, grout and painted areas can often be cleaned safely by a homeowner with proper ventilation and gloves.

When not to DIY

When to stop and call a professional.

Do not treat it as a simple cleaning job if mould keeps returning quickly, there is damp plaster, failed extractor, leaks, swollen wood or mould behind silicone.

Tools and materials

What you need before you start.

Required skillsSafe cleaningVentilation awarenessBasic surface inspection

ToolsGlovesEye protectionSoft brushMicrofibre clothsOld toothbrushSpray bottle

MaterialsBathroom mould cleanerWarm waterMild detergentKitchen rollReplacement silicone if sealant is stained through

Safety and UK regulations

Read this before touching the job.

Safety warningsNever mix bleach with other cleaners.Ventilate the room while cleaning.Wear gloves and avoid breathing spray mist.Persistent damp or black mould may need a property maintenance assessment.

UK regulations and professional limitsRental homes should be fit for habitation and landlords may need to address damp and mould causes.Bathrooms should have suitable ventilation under Building Regulations where relevant to works.

Step by step

How an experienced tradesperson would think through it.

Open the window or run the extractor. Remove towels, toiletries and bath mats.
Wash the area first with mild detergent to remove soap scum and body oils.
Apply mould cleaner according to the manufacturer instructions. Do not mix products.
Agitate grout lines gently with a small brush. Do not scrape away sound grout.
Rinse and dry thoroughly. Moisture left behind encourages mould to return.
Inspect silicone. If the black staining is behind or inside the silicone, cleaning will not solve it; replacement is needed.

Professional tipsMost bathroom mould is a ventilation and moisture-control problem, not just a dirty surface.After showers, leave the extractor running and wipe heavy condensation from glass and tiles.If silicone is peeling, stained through or soft, remove and replace it rather than painting over it.

Common mistakesSpraying bleach on dirty soap scum and expecting a lasting result.Closing the bathroom door after a hot shower.Ignoring a weak extractor fan.Sealing over damp silicone or grout.

Troubleshooting

If it does not go to plan.

IssueLikely causeFix

Mould returns within two weeksPoor ventilation, cold surfaces or hidden moistureCheck extractor performance, window use and possible leaks.

Black lines stay in siliconeMould behind the siliconeRemove and replace silicone after drying the joint.

Paint flakes above showerWrong paint or persistent condensationDry, prepare and repaint with suitable bathroom paint after fixing ventilation.

Questions

Frequently asked questions.

Can I just paint over bathroom mould?

No. Painting over mould traps the problem. Clean, dry and fix the moisture cause first.

Why does mould grow on silicone?

Soap residue, moisture and failed sealant allow mould to sit in or behind the silicone.

When should I call someone?

Call for help if the mould is persistent, linked to leaks, behind silicone, on plaster or caused by poor ventilation.

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