Beginning to question whether your shingles will ever seal? We explain why you shouldn't.


Do dark roofs really affect cooling costs?



If you have a light-colored roof, you may have noticed dark or even black streaks developing on the shingles and wondered whether this is dirt, moss, or fungus and if the accumulation is causing damage to your roof. Most often, these black streaks are caused by a blue-green algae and typically, the growth will not cause damage to your roof.


Algae are plant-like bacteria that easily spread from rooftop to rooftop because their spores are carried through the air. Algae is most likely to grow in hot, humid climates (similar to Midwest summers) and feeds on the limestone granules that are added to many shingles. The most common type of algae that grows on roofs is called gloeocapsa magma. To protect itself from the harmful UV rays that bare down on it, the algae produces a dark pigmented coat. This pigmentation is what causes you to notice the dark discoloration on your roofs.


Typically, algae growth does not harm the roof, but very extensive growth can cause damage if algae and fungus grow together to form lichen which further feeds on the granules of the shingles.


To prevent algae growth, many shingle manufactures are now adding copper or zinc granules to the shingles. These copper or zinc granules are lethal to algae and can prevent their growth. Nevertheless, in especially hot and humid climates, or on roofs without algae-resistant shingles, algae is likely to accumulate and become noticeable on light-colored roofs. If the streaks bother you, the algae should be dealt with appropriately by a roofing professional. Using a pressure washer, excessive scrubbing, or applying harsh chemicals will damage the surface of the shingle, which not only makes your roof more susceptible to leaks, but may also void the manufacturer’s warranty.


To keep algae growth on your roof under control, the following recommendations should be followed:

  • Trim tree limbs that hang over the roof to let sunlight reach the roof
  • Regularly clean your gutters (read how to here) so that water can drain freely from the roof
  • Regularly remove debris from your roof using a leaf blower

Copyright All Rights Reserved © 2018 Apple Roofing | Designed by PSW Digital

Call: 1.866.APPLE88​

Corporate Office (Lincoln, NE):

4833 N 32nd St

Lincoln, NE 68504

Email: info@appleroofingllc.com  

Tel: 402.475.0098

Omaha, NE Office:

2770 S 129th Ave

Omaha, NE 68103

Email: info@appleroofingllc.com 

Tel: 402.475.0098

Kearney, NE Office:

1312 2nd Ave

Kearney, NE 68847

Email: info@appleroofingllc.com 

Tel: 308.224.0750

Kansas City, MO Office:

5251 W 116th Pl, Ste 200

Leawood, KS 66211

Email: info@appleroofingllc.com 

Tel: 913.730.6109



This field is required.

Thank You!

The form has been successfully sent.


This field is required.


This field is required.


This field is required.

Street, City, State, Zipcode:

This field is required.

Have a question you need to ask, or need to schedule a a FREE estimate? Call or come by one of our offices. We will be happy to assist.​

contact us

Des Moines, IA Office:

6165 NW 86th St, 1st & 2nd Floor Johnston, IA 50131

Email: info@appleroofingllc.com 

Tel: 515.229.6927

Denver, CO Office:

15660 E Hindsdale Dr, Ste 201

Centennial, CO  80112

Email: info@appleroofingllc.com 

Tel: 303.219.0957