How to Waterproof an Attic

Sweep your roof with a broom to clean it of any loose dirt or leaves. Rinse it with a garden hose to eliminate debris that could interfere with the waterproofing process. Wear a safety harness and helmet whenever working on a roof to prevent falling accidents. Allow the roof to dry fully.

Apply an oil-based waterproofing compound over your roof with a paint roller. The compound rolls on over your shingles to help prevent water from seeping through them and leaking into the attic. It also works on roofs without shingles.

Squirt neoprene cement around the flashing of a chimney or vent where it meets the roof with a caulk gun. This fills any gaps between the metal and the roof where leaks commonly start. Once it dries, add a layer of roofing cement over the seams with a trowel.

Paint the rafters and woodwork in the attic with a wood sealer using a paintbrush. This prevents water from penetrating into the wood fibers. Use two coats for best results with the second coat being added after the first fully dries. Follow any special instructions on the container.

Inspect the insulation in the attic to check for moisture or mold. Replace any damp or moldy insulation sheets with fresh ones.

Repair any leaky pipes in the attic or have them professionally serviced to prevent them from dripping water into the attic.

Install a dehumidifier in the attic if high humidity is a problem. A dehumidifier removes water from the air so it doesn't damage the fixtures or encourage mold growth.