Is every dark patch “black mould”?

No. Several kinds of mould can appear dark or black, and colour alone cannot reliably identify the species. The name Stachybotrys chartarum refers to one particular fungus, not every dark stain found in a bathroom. Do not assume the health impact or the appropriate treatment from appearance alone.

Why does mould grow in bathrooms?

• Condensation: Warm humid air from bathing meets cooler ceilings, windows or external walls.
• Poor extraction: An ineffective fan or blocked airflow allows moist air to linger.
• Leaks: Failed seals, leaking pipes or damaged waterproofing can keep hidden materials damp.
• Cold surfaces: Insulation or heating problems may increase condensation.
• Organic deposits: Dust and soap residue can contribute to surface contamination.

How can bathroom mould affect health?

Exposure to damp and mould can aggravate respiratory symptoms and affect some people’s eyes and skin. Children and people with asthma or other respiratory conditions may be particularly vulnerable. The UK government’s damp and mould guidance explains the risks and stresses the importance of tackling underlying moisture.

How to reduce the risk

Improve ventilation

Use a suitable extractor while showering and allow it to run afterwards in accordance with its controls. Keep vents clear. Opening a window can help where safe, but it is not always a substitute for appropriate mechanical extraction.

Control persistent dampness

Dry frequently wet surfaces where practical and report leaks as soon as they appear. If condensation repeatedly returns despite reasonable ventilation, investigate insulation, heating and the extraction system.

Maintain joints and seals

Inspect the silicone around baths and showers. Split or detached sealant should be replaced appropriately. In tiled wet areas, a working waterproofing system behind the surface is just as important as the appearance of the grout.

When should you seek professional advice?

If mould is extensive, keeps returning, appears within wall materials or follows a significant leak, it may need a specialist assessment. People with health concerns should obtain advice from a healthcare professional. In a rented home, notify the landlord or managing agent promptly and explain the moisture problem in writing.

Can a bathroom renovation help?

Where repeated mould is linked to failed waterproofing, inadequate extraction or a damaged background, renovation may address those building defects. A cosmetic repaint alone does not solve an unresolved moisture source. For a bathroom assessment, send ARDECO details of your project.