How much does Algae removal cost?

If you have black or greenish streaks on your roof or windows, you may be surprised to learn that they could be algae. But algae growth on homes is a common problem, especially in areas that are damp or heavily shaded.  

Like algae blooms—where millions of individual alga collect in a body of water, harming aquatic life and contributing to climate change—similar thing can occur on your roof to a lesser degree. Algal spores travel through the air, carried by wind currents or birds. When they land on a spot that provides moisture, heat, and a food source (such as limestone in asphalt roof shingles), they settle in and produce new blooms. 

Blue-green algae can appear seemingly out of nowhere, or spread through entire neighborhoods. The growth starts out looking like black streaks on shingles and windows, but can eventually develop into blue-green spots. 

This algae growth (also called “algal growth”) on roofs and windows not only makes your house look dirty, it can damage building materials. When algae spores feed on the limestone in roofing, they weaken the structure of the shingles. Algae buildup can also clog gutters. And because the microorganisms absorb, rather than reflect, the sun’s heat, a large growth can make the house warmer, increasing cooling bills. 

Removing algae involves working on roofs, climbing ladders, and using specialized equipment, work that’s best done by an experienced roof cleaning service or window washing company. A pro can examine your algae growth and recommend the best course of treatment.  

In this guide, you’ll learn about the typical costs of removing algae growth from your roof or windows. 

The typical cost of professional algae removal from roofs runs $375–600, with a nationwide average of $490. 

Professional roof-cleaning companies typically charge $0.20–0.75 per square foot, depending on the technique used. On a large home, you could spend as much as $3,000.

To remove algae growth from windows, expect to spend $10–20 per window. 

There are 3 methods of roof algae removal. The treatment you choose will affect your cost estimate.

Chemical treatment. A chemical wash is the most common treatment for microalgae removal, and it’s often the most cost-effective remediation method. The professional will spray a strong chemical cleaning agent on the algae, and allow it to sit for some time before rinsing it off. Average cost: $0.20–0.30 per square foot.

High-pressure or power washing. Pressure washing is the easiest way to remove microalgae from a roof. But it can’t be used on delicate building materials, and must be done correctly to prevent damage. The price can vary depending on equipment used, severity of toxic algae growth, and accessibility of the area. Average cost: $0.20–0.70 per square foot. 

Soft washing (low-pressure wash). With this method, a detergent or bleach solution is applied to loosen or kill algae spots, then removed with a low-pressure rinse. It’s best for homeowners who are concerned about protecting materials such as composition shingles, wood shingles, asphalt shingles, or slate roof tiles. Average cost: $0.30–0.70 per square foot. 

Roof cleaning costs can vary according to the kind of shingles or tiles you have. Here’s what you’ll typically pay to remove algae from different roofing types.

Metal. Average cost: $0.20–0.70 per square foot. 

Slate shingles. Average cost: $0.30–0.70 per square foot. 

Asphalt shingles. Average cost: $0.30–0.75 per square foot. 

Concrete tile. Average cost: $0.30–0.75 per square foot. 

Wood shakes or shingles. Average cost: $0.20–0.30 per square foot. 

Clay tile. Average cost: $0.30–0.75 per square foot. 

There are a number of considerations that may affect the cost of algae removal.

How much does it cost to remove algae from the roof?
You’ll typically pay $0.20–0.75 per square foot to have algae professionally removed. The cost can vary depending on method used and size of treated area. 

How much does roof cleaning cost?
Roof cleaning costs vary based on size, kind of roof, and extent of algae buildup. Prices typically range from $0.20–0.30 per square foot for wood shingles to $0.30–0.75 per square foot for asphalt shingles or clay tiles.

How do I get green algae off my roof?
The easiest way to remove blue-green algae from a roof is to hire a professional, for a nationwide average cost of $490. They’ll use a chemical treatment, high-pressure wash, or low-pressure wash to treat the algae growth.

Find a roof cleaner or algae removal professional in your area.