Mix together a cleaning solution of 1 part bleach and 9 parts water.
Use a stiff cleaning brush to scrub your brick with the bleach solution. You need to remove all mold and mildew before you seal your brick house.
Rinse the brick with plain water, and allow at least a day for the bricks to dry thoroughly.
Apply a water-repellent brick sealer once your house is completely dry, using a hand-pump sprayer.
Add a second coat of brick sealer once the first coat is dry if the sealer instructions recommend it.