Black shower grout: DIY cleaning or call a pro?« Back to Previous Page

The black discoloration is likely Cladosporium or Aureobasidium, two moulds common in bathrooms due to high humidity. In Dubai's climate, constant AC use creates significant condensation, especially in frequently used showers, making it a persistent issue.

For a small, surface-level patch (less than 10 sq. ft.), a DIY approach is reasonable. Use a hydrogen peroxide-based cleaner or a paste of baking soda and vinegar. Scrub the grout with a stiff brush, ensure excellent ventilation during cleaning, and use a dehumidifier or your AC’s dry mode for at least an hour after showering to remove moisture.

If the mould returns quickly despite thorough cleaning, or if the grout feels soft, crumbly, or allows water to seep through, the issue is sub-surface. This indicates the waterproofing seal has failed, and moisture is trapped behind the tiles. In this case, scrubbing the surface is ineffective and can spread spores. A professional assessment is needed to determine if a full reseal or tile replacement is necessary to prevent structural damage and potential indoor air quality issues.