A Guide to Preventing Mold Growth in a Damp Attic

Mold will not grow without moisture, so the first step is to find where the dampness comes from. Check for roof leaks, especially around vents, chimneys, and flashing. Look for water stains on the roof sheathing or rafters, and inspect for gaps where rain could enter.

In a humid subtropical climate with hot summers and spring hail and thunderstorms, roofs take a beating. After a storm, check the attic for fresh stains or damp insulation. Also look at plumbing vents and exhaust fans that pass through the attic. A leak may be slow and hidden, so feel for damp spots with your hand.

• Inspect the roof after heavy rain or hail
• Look for dark stains on wood or insulation
• Check around chimneys, vents, and skylights
• Feel for dampness on rafters and joists
• Look for rusted nails or metal fasteners

If you find water in the attic, act quickly. Mold can start growing within 24 to 48 hours on wet wood or drywall. Dry wet insulation and wood with fans and dehumidifiers. Remove soaked items that cannot be fully dried, such as cardboard boxes or paper.

For large water damage, you may need professional help. Local water damage pros have industrial drying equipment and moisture meters to ensure everything is truly dry. If you attempt it yourself, keep the attic warm and air moving for several days, and check for hidden dampness.

• Use fans to circulate air over wet surfaces
• Run a dehumidifier continuously
• Remove soaked insulation and drywall
• Discard wet cardboard and paper
• Check for dampness behind stored items

Once the attic is dry and clean, take steps to keep it that way. Fix any roof issues promptly, and keep gutters clear to prevent water backing up under the roof edge. Insulate the attic floor to keep warm, moist air from the living space from reaching the cold attic.