How to Remove Roof Stains

Remove roof stains that erode shingles and diminish appearance. The black mold and mildew buildup that is spreading over your shingle roof is an algae that thrives by consuming the limestone in asphalt shingles. Household chemicals will kill the algae, remove stains and restore the reflective quality of shingle granules that prevent heat buildup. Roof cleaning does more than remove mildew and stains; it saves the shingles.

Difficulty: Moderate

Instructions

Things You'll Need:

• Bleach
• Liquid laundry detergent or trisodium phosphate (TSP)
• Pump sprayer
• Hose with sprayer
• Extension ladder
• Paint goggles
• Long-sleeve shirt
• Long pants
• Rubber-sole shoes

1. Prepare for the job. Wet the roof generously with a sprayer attachment on a hose. Spray the roof from the ground. Spray nearby plants and let the runoff wet the ground and saturate downspout drainage areas. Put on paint goggles, long sleeves and long pants with rubber-sole shoes for grip.

2. Mix a chemical cleaning solution. Pour 2 gallons of bleach into a 5-gallon bucket with 2 gallons of water. Add a cup of liquid laundry detergent. The industrial version uses 1 gallon of liquid chlorine or pool shock with a cup of trisodium phosphate in 4 gallons of water.

3. Spray the cleaning solution onto the roof with low pressure. Lean an extension ladder against the roof with the third rung on the eave. Fill a garden pump sprayer with solution and carry it up the ladder. Spray on enough solution to soak the entire rooftop. Leave on for 10 minutes.

4. Rinse the roof thoroughly with the hose and sprayer from ground level. The surface does not need direct high pressure spraying, only rinsing. Let the water run for several minutes to rinse the ground foliage. Rinse the sprayer by running clean water through the sprayer nozzle and tank.

Tips & Warnings

• Set an extension ladder at a safe angle by resting the bottom one-quarter the distance of the height away from the point it contacts the roof. Walk up the ladder facing forward with your hips between the rails. Avoid walking on areas of the roof that have been sprayed with cleaning solution. This presents a severe slip hazard. Avoid eye and skin contact with bleach, trisodium phosphate and laundry detergent. Mix the solution outdoors, and avoid inhaling vapors directly.

References

• Roof cleaning described by Danny Lipford