Is it OK to Power Wash Roofing?

How to Keep Your Roof Clean: A Roofing Q&A

Many people ask us how to keep their roof clean and free of debris. In this post, we'll address some of the most common questions we encounter about roof cleaning. If you have questions or concerns, call us anytime for a roofing consultation.

Will Moss Hurt My Roof?

Moss is generally harmless. You should only worry if your roof is sprouting fungi, algae or mold. These organisms can lead to a dangerous condition called roof rot.

What Is Roof Rot?

Roof rot happens when you leave mildew, fungi or lichen growing on your roof. Over time, this plant growth can break through a weak spot in your roof. This leads to severe mold growth all over your roof and your home. That can be a dangerous condition that's costly to fix.

If you live in a damp climate, you need to take steps to prevent roof rot.

  • Keep your roof free of lichen, algae and mold growth.

  • Keep your gutters clean to keep water off your roof.

  • Get your roof professionally inspected and cleaned twice a year.

How Do I Know if I Have Roof Rot?

The only way to be certain is with a professional roof inspection. You should have your roof checked twice a year to prevent roof rot and other problems. It's also a good idea to have your roof checked after a major storm.

How Do I Clean My Roof?

There are various methods you can use to clean debris, moss and algae from your roof. You can use a soft-bristled brush, a leaf blower or a hose with low pressure.

The first rule is to be careful. Roofing falls are the number one cause of construction-related deaths and injuries. Don't do this while the roof is wet and slippery. Use sturdy shoes with gripping soles. If you're at all worried about your safety, call a professional roofing contractor.

Can I Power Wash My Roof?

Power washing a roof is not a good idea. We don't recommend power washing, jet washing or any other high-pressure cleaning method. 

Most roofing materials won't stand up to the high pressure of a power washer. Power washing can destroy the protective layer on top of the shingles. Spraying a power washer directly onto tiles can gouge holes in them. 

Power washing can also damage roof elements like your fascia, windows and gables. 

What If My Roof Has Algae, Lichen or Mold Growing on the Surface?

If you have unwanted plant life on your roof, it's not going to come off with a simple hosing. There are only three ways to get rid of it:

  • You can use a safe, organic mold killer.

  • You can scrape it off by hand.

  • You can use low-pressure power washing.

This is one of the only times that we recommend power washing your roof. Follow these tips for the best results.

  • Set your power washer to its lowest pressure setting. If your washer doesn't have variable settings, don't use it.

  • Don't add bleach or harsh chemical cleaners to the power washer tank. These will degrade your roofing tiles, damage your power washer and dump toxins into your soil. Use an environmentally safe cleaner designed to kill mold and algae.

  • Let the cleaning solution sit on the roof for 10 to 15 minutes and then rinse thoroughly.

  • Wash your roof from the top down. 

Note that power washing won't work on a flat roof. It will leave puddles on your roof that just make the problem worse.

Get Expert Help for All Your Roofing Needs

Roofing work can be dangerous and complicated. To keep your roof in the best shape possible, always work with an experienced, knowledgeable roofing contractor. Last Call Exteriors can help clean, repair and maintain your roof. Give us a call today.