How to remove black mold and prevent humidty?« Back to Previous Page

Black mold on an exterior wall facing the marina is a classic sign of condensation due to the high humidity differential between our hot outdoor climate and your cooled indoor space. The wall is likely a "cold bridge," where moisture from the humid air condenses and creates the perfect damp environment for mold.

For safe removal, first address the moisture source. Then, wearing an N95 mask and gloves, scrub the area with a solution of detergent and water. Avoid bleach, as it only removes the colour and does not kill the underlying spores. For porous materials like drywall or insulation, cutting out and replacing the affected section is often necessary, as mold roots deeply penetrate.

Prevention is critical and requires managing humidity. Despite running your AC, the relative humidity inside may still be too high. Use a hygrometer to monitor levels; you want to maintain indoor humidity below 60%. Ensure your AC unit is properly sized and functioning, as an overwhelmed system will cool the air but not remove enough moisture. Consider adding a dedicated dehumidifier, especially in that room, to combat the marina's high ambient humidity. Improving air circulation around the closet by not overpacking it and occasionally using a fan can also help.

For a recurring issue on an exterior wall, a professional inspection is recommended to assess for potential insulation flaws or hidden leaks. They can also perform surface and air quality tests to identify the mold species and confirm the spore count has returned to a safe level after cleaning.