How to Remove Algae from a Roof in 9 Simple Steps

If you aren’t afraid of heights, you can tackle this task on your own

Fragment of luxury house with nice landscape
Photo: karamysh / Adobe Stock
Fragment of luxury house with nice landscape
Photo: karamysh / Adobe Stock
SKILL LEVEL
Intermediate
COMPLETION TIME
3 hours
COST
$500–$1,000
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What you'll need:
TOOLS
  • Pressure washer
  • Extension ladder
  • Safety harness
  • Soft-bristle brush
  • Garden hose
SUPPLIES
  • Algae/moss cleaner solution
  • Protective gloves
  • Water
  • Vinegar
  • Bucket

Algae growth on rooftops isn’t just an eyesore, it can also cause damage if left unchecked. Fortunately, removing algae from your roof can be a manageable task with the right tools and a bit of effort—as long as you aren’t afraid of heights. If you don’t like the idea of climbing on your roof, you can always hire a professional roof moss remover near you. In this guide, we’ll explore the steps you can follow to safely and effectively remove algae from a roof.

Prepping to Remove Algae From a Roof

Because you will be climbing on a roof with slippery algae on it, you need to take safety seriously. Before kicking off this project, equip yourself with the essential safety gear, such as a well-fitted safety harness, impact-resistant goggles, and sturdy, slip-resistant footwear.

  1. Algae Cleaner Preparation

    First, get your cleaning product ready. Follow the specific instructions provided by the manufacturer to prepare the algae or moss cleaner solution. Alternatively, if opting for a DIY solution, blend water and vinegar in the recommended proportions in a sturdy bucket for application.

  2. Clear Debris

    Before commencing the cleaning process, meticulously clear the roof of any loose debris, such as leaves, twigs, or larger fragments using a soft-bristled brush or a reliable leaf blower. This step leads to an unobstructed cleaning process which will save you time later, and help you do a better job.

  3. Apply Cleaner

    Once you have a clear roof, you can apply the cleaner. Use a sprayer or a soft-bristled brush to uniformly distribute the prepared cleaner across the roof’s surface. It’s a good idea to initiate from the lower sections and work upwards to prevent streaking or uneven distribution.

  4. Allow Dwell Time

    Allow the applied cleaner to sit on the roof for the specified duration outlined in the product instructions. This waiting period gives the solution a chance to effectively permeate and loosen the algae, facilitating easier removal.

  5. Gentle Cleaning

    Employ a soft-bristled brush or, if using a pressure washer, adjust it to a low-pressure setting to delicately scrub or rinse the roof. Always maintain a downward motion during cleaning to avoid dislodging or damaging shingles.

  6. Rinse Thoroughly

    Post-cleaning, thoroughly rinse the roof using a garden hose to eliminate any remaining cleaner residue or dislodged algae. You need complete removal to prevent potential streaking or future growth.

  7. Inspect and Repeat

    Once you are done, conduct a thorough inspection of the roof surface for any missed spots or persistent algae patches. If needed, repeat the cleaning process, exercising caution to avoid overly vigorous scrubbing that could compromise the roof’s integrity.

  8. Take Preventive Measures

    Since you’re already on the roof, consider applying a protective treatment or strategically installing zinc strips along the roof's ridges to impede future algae growth. Additionally, trim nearby trees to reduce excessive shade and moisture accumulation on the roof.

  9. Clean-Up and Disposal

    Dispose of any used cleaning materials responsibly, ensuring they don’t pose a threat to surrounding vegetation or the environment. Leave the area clean and tidy upon completion of the project.

DIY vs. Hiring a Pro 

When considering removing algae from your roof, the DIY approach presents advantages in cost-effectiveness and control over the process. Undertaking the task yourself means potential savings on labor costs, as you'll primarily incur expenses for tools, supplies, and cleaning solutions. However, opting for the DIY route demands a significant investment of time, physical effort, and careful adherence to safety precautions, as working on a roof can pose risks if proper measures aren’t followed. 

You can expect to spend about $500 to $1,000 on this project with the bulk of that expense coming from a pressure washer. If you already own, can borrow, or can rent a pressure washer, this DIY is actually really affordable. 

On the other hand, hiring a professional for algae removal offers distinct advantages. Professionals bring expertise, specialized equipment, and a depth of experience to the task. While the upfront costs are higher due to labor charges and service fees, this approach ensures a more efficient and often quicker result. 

You can expect to spend between $295 and $621 to hire a professional. Professionals also minimize risks associated with the task, ensuring safety and potentially extending the longevity of your roof. It not only saves you time and physical effort but also provides peace of mind knowing that the job is handled by experts.

Frequently Asked Questions

Ideally, you will tackle removing algae from your roof during spring or summer when the weather is drier and warmer. Because algae tends to grow during the colder and wetter months, you want to tackle this project before the temperature drops to hopefully keep it from coming back at all.

While spotting a bit of algae on your roof may not bother you at first glance, it is certainly bothering your roof shingles. The presence of algae can cause decay and shorten the lifespan of your roof’s shingles, which can lead to much bigger problems down the road. While this issue may seem cosmetic at first glance, it goes much deeper than that.

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