Roof Cleaning: Is It Necessary? How To Do It And How Much It Costs

Roof cleaning is a necessary maintenance task that preserves the life of your shingles, ensures the roof is safe to walk on, and keeps it looking its best. "Even if you have algae-resistant shingles, you'll eventually need to clean your roof," says Chad Conley, CEO at Complete Roofing in Georgia. "This is especially true if you live in a southern coastal or humid climate." 

If cleaning your roof sounds scary, we're here for you. Below, we go into the task of roof cleaning, why it’s necessary, proper methods of cleaning, and how often. 

Project Overview 

Total Time: Half-day	Skill Level: Professional
Estimated Cost: $459 to $850	Yield: Improved curb appeal

Does my roof need cleaning?

Just because your roof looks clean doesn't mean that it is. Algae growth on your roof can continue for years before you notice its tell-tale black streaks. According to Conley, algae left unchecked continues to grow and damage the roofing material. Regular cleaning removes the algae, but you don't have to do it yearly. Conley suggests roof cleaning every five to seven years.

Average cost to clean a roof

The average cost for a professional roof cleaning is $.27 to $.50 per square foot, depending on the type of roof and your location.

The average cost to clean your own roof is $22 to $50 per gallon for the cleaner, plus any equipment you may need.

Average cost of professional roof cleaning based on square footage

Roof size	Cost range
500 square feet	$135 to $250
1,000 square feet	$270 to $500
1,500 square feet	$405 to $750
2,000 square feet	$540 to $1,000
2,500 square feet	$675 to $1,250
3,000 square feet	$810 to $1,500

When you hire a professional roof cleaning service, approximately 98 percent of the total cost is labor. It takes about six hours to clean 1,000 square feet of roof, and the average labor charge is $42 to $77 per hour.

Commercial roof formulas and their costs

The cost of the commercial formulas used to clean a roof averages $22 to $50 per gallon, depending on the product, the quantity purchased, and the retailer. Here are a few highly-rated, bleach-free roof cleaning solutions to compare.

Cleaning formula	Rating	Cost	User information
Wet & Forget Moss, Mold, Mildew, & Algae Stain Remover Multi-Surface Outdoor Cleaner Concentrate	4.4 stars of 9,089 ratings	$32.93/gallon	One gallon of concentrate covers 750 to 2,250 s.f., depending on the material and amount of staining. No pressure, brushing, or rinsing is necessary May require repeat application in one to two months for stubborn stains For easier use, it also comes in a hose-end bottle
Oxy Solve House and Siding Pressure Washer Cleaner Concentrate	4.2 stars of 5,278 ratings	$21.99/gallon	One gallon cleans up to 6,300 sq. ft., depending on the material and amount of staining. Requires scrubbing and rinsing with a garden hose on high-pressure
Spray & Forget Revolutionary Roof Cleaner Concentrate	4.2 stars of 1,394 ratings	$37.99/gallon	One gallon of concentrate covers 1,000 to 2,000 square feet, depending on the material and amount of staining. No pressure, brushing, or rinsing is necessary Green stains disappear in one to three days Black stains disappear in three to six months May require repeat application in one month for stubborn stains

DIY vs. professional roof cleaning

Since most of the cost of a professional roof cleaning is labor, you're probably tempted to do it yourself. But, if cleaning your roof requires you to walk on it or navigate around solar panels, we highly discourage a DIY operation. "Algae on the roof makes it like walking on ice," says Conley. "Especially when it's wet."  

Also, DIY-ing a roof cleaning may not be as cheap as it sounds if you need to buy all the equipment. Here's a list of all the necessary tools and materials to clean an average 1,700-square-foot roof. Take a look and see if it's worth the risk of falling.

Tools and materials needed to clean a roof with costs

Necessary tools	Average cost
Cleaning agent	$22
Tank sprayer	$23
Hose extension wand	$27
Brush for extension wand	$34
Extension ladder	$200
Ladder stabilizer	$69
Safety harness	$100
Anti-fog eye protection	$10
Waterproof work gloves	$9
Cost for DIY equipment	$494
Fall risk: Cost of a broken leg	$7,500
Possible total cost to DIY a roof cleaning	$7,994
Average cost to hire a pro	$655

How to stay safe while cleaning a roof

If you've reviewed the numbers and still feel confident that DIYing a roof cleaning is on your agenda, let’s be safe about it. Here are some basic precautions to follow, no matter what you climb on a roof to do. 

• Have a spotter nearby. Never climb on the roof when you're home alone. 

• Never climb on a roof if you feel unsafe. If you’re afraid of heights, get dizzy spells, or are uncoordinated, please stay on the ground.

• Always use personal protective equipment like a safety harness and ladder stabilizer.

• Wear shoes with non-slip soles.

How to clean a roof–step-by-step

We know die-hard DIY homeowners will still try cleaning their own roofs. So, let’s talk about a few roof cleaning methods. Avoid power washing at all costs. A soft wash using a spray-and-forget-it solution is always preferred. The goal is to preserve the life of your roof by preventing algae damage but with as little force as possible. Otherwise, you may end up needing to make roof repairs down the line. 

So, remember that walking on any roof causes damage. The weight of a 150 to 200-pound human can break a clay or slate tile roof, dent metal roofs, and tear hot asphalt roof shingles. Therefore, do it after the dew has dried on a clear day and before it gets too hot.

Step-by-step roof cleaning process

• Use a dry brush to scrub away any buildup of moss or lichen and a leaf blower to remove all the remaining debris.

• Clean out the gutters and ensure that water flows freely through the downspouts.

• Protect your landscaping by covering plants or wetting thoroughly, according to directions on the cleaning product you use.

• Follow the manufacturer's directions to mix and apply the roofing cleaner concentrate. Always use low pressure.

• If the directions require scrubbing, use a soft-bristle brush and a light touch. Take special care not to dislodge the granules on asphalt shingles.

What to avoid when roof cleaning

• Pressure washing on a high setting or holding a spray nozzle too close to the surface.

• Acidic cleaners. Always check with the roofing manufacturer for best practices and products to use.

How to maintain your roof

Even though Conley says cleaning your roof isn't necessary every year, other tasks are. Routine roof maintenance includes things like removing debris, gutter cleaning, and taking a look-see for any storm damage. Here is a list of items to do more regularly than cleaning.

Routine roof maintenance tasks

Task	Frequency
Inspect the attic for signs of moisture.	Whenever you're up there or twice a year.
Check the attic vents for anything blocking the airflow, like insulation.	Whenever you're up there or twice a year.
Remove debris from the gutters.	Weekly in the fall. Monthly for the rest of the year.
Remove twigs and leaves from the roof.	Whenever you notice them.

Frequently asked questions

If your roof is covered in algae-resistant shingles that are still under warranty, call the manufacturer. The warranty could cover a professional roof cleaning. If so, the shingle company will send a partnering contractor. Otherwise, professional house cleaners or pressure washers offer roof cleaning services.

At most, five to seven years, according to our experts. More frequent cleaning compromised the integrity of asphalt shingles.

Many shingle manufacturers offer algae-resistant shingles. Some with a 25-year warranty period. However, if you live in a coastal or other humid environment, you may still find your roof needs to be cleaned. Contact your roofing contractor if you have any questions regarding your roofing materials.

Yes. According to Conley, algae will grow on all roofing materials, including metal, wood, slate, and clay.