Discover effective Algae and Moss Prevention methods to maintain the longevity and appearance of your asphalt roof, ensuring a well-maintained and appealing home.

Algae and Moss Prevention for Asphalt Roofing Systems


Algae and moss can significantly impact the longevity and appearance of asphalt roofing systems. If left untreated, these growths diminish curb appeal and can lead to structural damage. This guide explores practical methods for Algae and Moss Prevention. 

Understanding Algae and Moss Growth

In order to understand the important of Algae and Moss Prevention, we first my look at what it is:

Causes of Growth

Algae and moss thrive in moist, shaded environments. Algae appear as dark streaks on roofs, often in areas with less sunlight. Conversely, moss can grow into a thick, green mat that retains moisture and can damage shingle.

Impact on Roofs

Algae can cause discoloration, while moss can lead to more severe issues such as shingle lifting and water retention. This moisture can eventually seep into the roofing structure, causing leaks and wood rot.

Prevention Methods

Install Zinc or Copper Strips

Installing zinc or copper strips along the roof ridge can prevent the growth of algae and Moss. Rainwater will carry traces of these metals down the roof, creating an environment hostile to these organisms.

Trim Overhanging Branches

Reducing shade by trimming overhanging branches allows more sunlight to reach the roof, inhibiting the growth of algae and moss. This also improves airflow, helping the roof dry more quickly after rain.

Clean Gutters Regularly

Keeping gutters clean ensures proper water drainage from the roof. Clogged gutters can lead to water backup, creating ideal moss and algae growth conditions.

Use Algae-Resistant Shingles

Consider installing algae-resistant shingles that are treated with copper granules. These shingles can effectively resist algae growth for several years.

Cleaning Methods

Safety Precautions

Before beginning any cleaning process, ensure you have the necessary safety equipment, including non-slip shoes, a safety harness, and gloves. It is also advisable to work with a partner for added safety.

Cleaning Solution

Equal parts water and bleach can make a simple and effective cleaning solution. This solution kills algae and moss without damaging the asphalt shingles.


  • 1 part water
  • 1 part bleach

Application Process

  1. Prepare the Solution: Mix water and bleach in a large bucket.
  2. Apply the Solution: Using a garden sprayer, apply the solution generously to the affected roof areas. Ensure that you cover all areas where algae and moss are present.
  3. Let It Sit: Allow the solution to sit on the roof for 15-20 minutes. This will give it time to kill the algae and moss.
  4. Rinse Thoroughly: Rinse the roof thoroughly with low-pressure water. High-pressure washing can damage the shingles, so a gentle spray is essential.

Manual Removal

For thicker moss, you may need to manually remove it after applying the cleaning solution. Use a long-handled brush to scrub away the Moss gently. Avoid using too much force to prevent shingle damage.

Professional Cleaning

If you have extensive algae or moss growth or are unsure about cleaning safely, it is best to hire professional roofing services. Professionals have the expertise and equipment to clean the roof effectively without causing damage.


Preventing and cleaning algae and Moss from asphalt roofing systems is essential for maintaining the roof’s integrity and appearance. Regular maintenance, such as installing metal strips, trimming branches, and cleaning gutters, can significantly reduce the likelihood of growth; for homeowners in Edmonton, Alberta, Fair and Square Roofing specializes in providing high-quality roofing services, including algae and moss prevention and cleaning. By following these methods, you can ensure your roof remains in excellent condition for years.