How to Remove Algae from a Roof

How to Remove Algae from a Roof

Roof shingles look so bright and colorful when they’re first installed, but they can start to deteriorate and become discolored over time. Green or black streaks can form on roof shingles, especially in warm, humid environments. Tree branches hanging over your roof can provide enough shade to encourage algae growth, with leaves and other debris falling on the shingles and adding nutrients that feed the algae.

You can remove algae from the roof yourself, and there are steps to take that will discourage it from coming back.

How Algae Takes Hold

Algae growth spreads because of spores blown on the wind, and spores from one roof can migrate to adjacent ones. Taking the time to remove algae from your roof will not only make it look better, but it can protect your neighbor’s roof as well. The most common form of algae, Gleocapsa magma, is a type of blue-green algae that can form unsightly streaks on a roof. Even though it looks bad, the discoloration doesn’t damage the roof, but it certainly hurts the curb appeal of your home.

How to Remove Algae from the Roof

The simplest way to remove algae from your roof is to spray it with a solution of half water and half household bleach. Use a hose-end sprayer instead of a pressure washer because too much waterpower can degrade the shingles and shorten the lifespan of your roof.

Once you know how to remove algae from the roof, the next step is protecting your landscaping when you spray the roof with the 50/50 bleach and water solution. Follow these steps to keep your lawn and bushes from being affected from overspray and drips when you do the job.

  • Water the lawn and shrubbery around the perimeter of the house, as this helps protect the plants.
  • Next, cover them with clear plastic sheeting. You can find inexpensive rolls of it in the paint department at your local home improvement store.
  • When you’re finished cleaning the roof, spray the sheeting on top of your grass and shrubs with water, and then remove it.
  • Spray the foliage and lawn with water again to remove any traces of bleach.


How to Discourage Algae Growth

It will save a lot of time and trouble if you can prevent algae from taking hold on your roof in the first place. Here are some suggestions for keeping algae from accumulating on the roof of your house.

  • Cut back any overhanging tree branches.
  • Use a leaf blower to get rid of leaves and other debris.
  • Blow air downward to avoid getting debris under shingles.
  • Redirect any drain spouts that cause water to travel over roofing.
  • Keep roof gutters clear.

There’s another way to keep algae from coming back, and that’s adding copper or zinc strips to your roof just under the peak of the roof. Roofs with an algae problem usually have clean streaks below the chimney area. That’s because of the metal at the base of the chimney, called flashing, that directs water away from the seam between the chimney and the roof. If roof flashing is made of zinc or copper, small particles of the metal wash down the roof with every rain, and these particles are deadly to algae.

Contact Thompson Creek for Your Roofing Needs

If you decide to add zinc or copper strips, be sure and consult a professional roofer. It’s important to maintain the seal between the shingles to keep your roof from leaking. Ideally, the metal strips should be installed when the roof is put on, but an expert can add them to an existing roof without damaging the shingles.

Thompson Creek has installs top quality roofs, and our knowledgeable professionals can inspect your roof and determine the best roof replacement options . If your roof is more than 10 years old, it’s also a good idea to have it checked for wear and tear. The best time to replace your roof is before it starts leaking. Contact us today for all your roofing needs.