Black mold in damp closet: DIY or call management?« Back to Previous Page

That damp patch behind clothes in an exterior wall closet is a classic symptom of thermal bridging and condensation, very common here due to the high humidity and constant AC use. The cold from your AC-chilled room meets the hot, humid air seeping through the exterior wall, causing moisture to condense and mold to grow.

For a small patch (under one square foot), you can handle it yourself. Wear a mask and gloves. Mix a solution of one part white vinegar to four parts water or a diluted bleach solution (ensure good ventilation). Scrub the area thoroughly, not just the surface. Dry it completely with a fan; simply wiping it away will not address the moisture source. However, this only fixes the visible growth, not the underlying cause.

The dampness on the wall indicates an ongoing moisture issue. This is where involving building management is often necessary, especially as you're in an apartment. The problem could be a breach in the building's external waterproofing (a common issue in older towers), faulty insulation within the wall cavity, or even a leaking pipe. These are structural concerns the property owner is responsible for fixing.

Before you call them, document everything with photos and notes. When you do contact management, frame it as a potential building integrity and moisture intrusion issue, not just a cleaning request. They should send a maintenance team to investigate the wall from both inside and out.

If the mold returns quickly after your cleaning or the patch is large, a professional inspection is wise. They can use moisture meters to pinpoint the exact source of water and take air or tape-lift samples for lab analysis to confirm the mold type, which helps in planning the correct remediation strategy.