How to Clean Mildew From Rafters

Fill a basin with 3/4 of a cup of bleach and a gallon of water. Mix thoroughly using a paint mixing stick

Fill another bucket with warm, clean water.

Put on rubber gloves, and dip a sponge into the bleach solution taking care not to get the solution on your skin or near your eyes or hair.

Scrub the wooden rafters with the sponge until the mildew stains are gone.

Immediately rinse the rafters with the warm water in the other bucket, taking special care to remove all of the bleach solution. Any remaining bleach can be a breeding ground for mold spores so be very careful to make sure that the bleach has been completely rinsed.

Dry the rafters thoroughly with a soft cloth, getting all moisture off of them to avoid causing any damage to rafters.

Fill a spray bottle with vinegar and spray liberally over the surface of the rafters. There is no need to dry the vinegar, it will evaporate on its own and act as a deodorant and a disinfectant, inhibiting the future growth of mold and mildew.