Sweep the roof with a soft-bristle broom. Gently sweep away all loose dirt and debris.
Mop the roof with a cotton mop. Soak the mop in water and swab the roof completely. Allow to stand wet for at least 20 minutes to allow caked-on dirt or grime to soak. Rinse the mop well, then go over the roof again thoroughly a second time.
Spray the roof with water from a garden hose to rinse the majority of remaining dirt away.
Apply trisodium phosphate to remaining areas of grime, grease, ground-in dirt, algae or mold. Mix with water according to the manufacturer's directions and apply with a cotton mop.
Rinse the roof thoroughly with water.
Things You Will Need
- Soft-bristle broom
- Cotton mop
- Garden hose
- Trisodium phosphate
- If black mold or excessive amounts of green or blue mold are found, consult with a roof-cleaning professional to determine the best way to eradicate the molds.