Step 1
Clean the roof surface with a long-handle scrub brush and soapy water. Rinse the soapy residue away with a hose. Towel off any puddled water. While you're on the roof, examine its condition. Nail down or replace any lifted or rusted flashing, rusted sections of metal, or missing roof tiles. Roof sealant is meant to seal small fissures and pores, not large holes or rusted out areas. Wait until the roof is repaired and dry before moving on to the next step.
Step 2
Apply one even coat of the sealant to the roof with a spray painter, long-handle paint roller or paint brush. Follow the sealant's instructions for application methods and amounts. Let the first coat dry for the manufacturer-recommended amount of time. Most sealants dry to the touch in 20 minutes to 1 hour, or sooner during warm weather.
Step 3
Apply two to three more coats of sealant. Allow each coat to dry before applying the next.