How to Pressure-Wash a Roof

Remove mildew and mold from a roof with a pressure washer.

Many homeowners have an issue with mold and mildew on their roof. This is caused by moisture, and occurs most commonly on the north- and west-facing sections of the roof. This growth can cause water to collect on the roof, which can lead to damage on the exterior and interior of the home. A pressure washer will help you remove this buildup.

Things You'll Need

• 25-degree pressure washer tip
• Ladder

Instructions

1. Turn the pressure washer to 1,000 lbs. per square inch and attach a 25-degree tip. This will work on almost any type of shingle, from clay to metal.

2. Climb up the ladder and onto the side of the roof that has the most dirt, moss or mold growth. Walk up the side of the roof that does not have this growth as the affected side can be slippery.

3. Point the pressure washer 6 inches away from the roof and spray one shingle to ensure that no damage occurs. If you see damage, consider turning down the PSI.

4. Spray the entire roof. Keep the pressure washer pointed downward so the debris and buildup are washed away and so that no water travels underneath the shingles.

5. Inspect the entire roof, both the sides that were not exposed to the moss or mildew and the area just cleaned. Check for any small patches you may have missed.

Tips & Warnings

• Avoid pressure-washing the roof while standing on a ladder. The force of the water may throw you off the ladder.

• Consult a professional if you do not feel comfortable climbing onto the roof or using the pressure washer.

References

• Ask the Builder: Roof Cleaning
• Amazing Machinery: How to Pressure Wash a Roof