For a small patch (under one square foot), you can clean it yourself while waiting for their response. Wear an N95 mask and gloves. Scrub the area with a mixture of water and detergent. Avoid using bleach, as it doesn’t prevent regrowth and can damage paint. Dry the area thoroughly with a fan immediately after cleaning.

However, since the mold is caused by an active water leak and is spreading, DIY cleaning is only a temporary fix. The high humidity here means it will return unless the moisture source is permanently repaired. A professional inspection can identify the exact mold species and the full extent of the problem, which often spreads inside walls. They use moisture meters and thermal cameras to find hidden dampness that isn’t visible. For a situation involving a leak and spreading growth, a professional assessment is the most reliable path to a permanent solution.