Black/green wall splotches: DIY clean or call a pro?« Back to Previous Page

Those black and green splotches are a strong indicator of active mold growth. In Dubai's climate, this is most often caused by condensation from an AC unit or a hidden water leak.

For a small patch (under one square foot), you can attempt DIY cleaning. A mix of 1 part household bleach to 4 parts water can be effective for non-porous surfaces. However, if the mold is on drywall or has penetrated the paint, bleach will only remove surface discoloration, not the root structure. It will return. The location behind the wardrobe is a major concern; it suggests a persistent moisture source that needs to be identified and fixed, or the problem will recur.

Given that the AC unit is on the other side of the wall, this is a strong sign of a more serious issue. The problem is likely not the wall itself but the AC's condensate drain line being blocked or the insulation around the unit failing, creating constant dampness inside your wall cavity. This requires a professional assessment to locate the moisture source.

I would recommend a professional inspection in this case. They can use moisture meters and thermal cameras to see inside the wall without destructive drilling, confirming if the AC unit is the culprit. A proper remediation will involve fixing the moisture source at the AC, then addressing the mold growth. Simply cleaning the visible spot without solving the hidden cause is a temporary fix.