Roof Cleaning

Roof Cleaning: Frequently Asked Questions



Roof Cleaning

Before and after algae treatment by J. Blank Construction.


What are the ugly, dark spots on my roof?

Any black stains on your fiberglass shingles are probably caused by Gloeocapsa magma. More commonly known as roof algae, this cyanobacteria feeds on moisture and the limestone fillers in shingles. Once the black stains become noticeable, they will continue to worsen. This is harmful to your roof because the growth holds moisture in the shingles, which in turn causes premature aging, rotting, and granule loss.

Could these stains be costing me money?

Besides reducing your home's curb appeal, these stains could be costing you money! If your roof has algae, studies indicate that the temperatures under your roof become higher, increasing your monthly air conditioning costs and possibly even shortening the lifespan of your air conditioning unit. Also, the same studies suggest that the lifespan of your roof is shortened by the increased granule loss, resulting in premature roof replacement.

How do I know if I should replace my roof or have it cleaned?

I do not recommend cleaning your roof if the shingles are not in good condition. Some signs that your roof cannot be cleaned are: brittle, crumbling, wavy, loose, or curling shingles. Also, excess loose or missing granules are a sign of a worn roof. Shingles that are "lifting" are sometimes a sign of age, but often are caused by nails “popping” out of the roof deck. This can be fixed easily before your roof cleaning.

If your shingles are still in good shape but have roof algae on them, having your roof cleaned will allow you to get the full life out of your shingles. This can save you thousands of dollars.

What does my shingle manufacturer recommend?

Companies like Owens Corning and GAF, as well as the Asphalt Roofing Manufacturers Association, recommend a low pressure chemical application using certain cleaners to restore shingles suffering from roof algae, followed by a low pressure rinse. We use the cleaners and methods recommended by these companies, for a safe and damage-free roof cleaning.

How do you clean my roof?

  1. We take precautions to protect your landscaping and property.
  2. We inspect your roof for damage and potential leaks.
  3. As a free service we clean gutters before any chemicals are applied.
  4. We apply manufacture-recommended chemicals with low pressure, letting the chemicals sit a predetermined amount of time.
  5. We lightly rinse and reapply chemicals if necessary.

What makes J. Blank Construction unique?

I am a professional roofer, with more than 16 years of experience. I carefully inspect every roof and inform you of its condition and potential problems. We do not use a high pressure washer on your roof, as this could cause excess granule loss.