Roof Cleaning 101

By Kathleen McCoy | Advertiser Disclosure

Are leaves, pine needles, algae, ash, or moss and lichen on your roof affecting your home’s curb appeal? The roof is one of the most highly visible exterior surfaces of your home, and one of the most challenging surfaces to keep clean. If roof cleaning isn’t on your annual home maintenance checklist, it should be.

For example, if you have tree limbs hanging over your home, leaves and pine needles may collect and begin to rot. The rotting of organic matter can cause staining and even permanent damage to the surface of your roof as the mold, mildew, and fungi begin to feed on the roofing material. Of course, if you have trees around your home, you also need to learn how to safely clean your gutters to ensure proper drainage.  

In this article, we’re going to dive into roof cleaning costs, the best roof cleaners for each roofing type and each type of debris, as well as how to keep your roof clean.

How much does roof cleaning cost?

Like most home maintenance projects, the cost of roof cleaning depends on a variety of factors. Generally speaking, the price of a thorough, eco-friendly roof cleaning service completed by a licensed company can vary from $350 to over $750. Here are nine of the factors contractors use to give you a roof cleaning quote:

  1. The size of the roof
  2. The type of roofing material
  3. The slope of the roof
  4. The height of the roof
  5. The number of roof sections
  6. The nature and the amount of debris, dirt, fungi, bacteria, or moss growths
  7. The presence of visible stains
  8. Accessibility
  9. Geographic location

Taking the above into consideration, if your home has a large roof with a steep pitch and multiple roof sections, the price will be higher than a roof with a gentler slope. The amount of debris, type of debris, and the presence of staining may require specialized cleaning techniques and significantly increase the amount of skilled time required.

Roof cleaning techniques

You can determine if roof cleaning will be a DIY task based on what’s on your roof, the type of roof material, and whether or not you can safely reach all the nooks and crannies.

If your roof has a steep pitch that reaches more than 30 feet above the ground, you may want to hire a licensed and insured contractor. On the other hand, if your home is a ranch-style or two-story home, you may be able to safely clean your roof from the ground—depending on the technique you choose to employ.

Before you choose a cleaning method, it’s important to understand the unique cleaning needs of each type of roofing.

Painted metal roofing

Metal roofs are long-lasting, durable, and an excellent material for areas prone to wildfires. However, unlike tile or asphalt shingle roofs, a light hand is required during roof cleaning to keep the roof looking its best. If the metal roof has dust, pollen, or dirt on the surface, spray the roof with clean water from your garden hose—not a high-pressure washer.

To remove algae, mildew, fungi, or mold, you may want to try one of the eco-friendly solutions mentioned below, but be sure to read the label carefully to make sure the product is safe for painted metal roofs.

Wooden shingles/shakes

Cedar shingle roofs are common in many areas of the country because of their durability, visual appeal, and natural resistance to rotting and insects. To stay fresh and beautiful, they need regular cleaning.

If you’re comfortable working on your roof, you can spray down areas affected by algae and moss with your garden hose. For any stubborn build-up, scrubbing with a bristle brush may do the trick. You can use plain water, or a citrus-based solution formulated for wood shingle cleaning and rehydration.

Clay tile roof

Clay tile roofs are elegant, durable, and have a natural resistance to fire embers. Tile roofs can be cleaned similar to painted metal roofing materials. Use a gentle, eco-friendly, non-caustic formula that can help maintain the look and health of the clay tile.

Performing regular maintenance with your garden hose can also help prevent the growth of mildew and mold spores. If organic material persists, you may want to discuss resealing the tiles with a licensed roofing company in your area.

Now that you’re aware of different types of roofing and their cleaning needs, here are the most popular roof cleaning techniques and methods used today:

1. Pressure washing

If your roof has algae, lichen, or moss, you may be tempted to turn on your pressure washer to hose it off. While this is an eco-friendly option, pressure washing may void your roof’s warranty. High-pressure washing can cause significant “fall” of the texture of asphalt shingles, and the process could damage clay tiles and even metal roofs. If you want to try pressure washing, check your roof warranty and find a licensed contractor in your area that can complete this task.

2. Chemical cleaning

You can walk into any home improvement or hardware store and find a chemical cleaning solution formulated to remove bacteria, moss, and algae from roofs. Using these roof cleaning products on your house is known as “soft washing.” However, the formula may contain controversial compounds like phosphates, chlorine bleach, and other chemicals that can damage your roof, kill plants, and potentially pollute waterways. It’s vital to read any warning labels carefully and to follow directions precisely for safe application.

3. Eco-friendly cleaning solutions

Fungicides and other natural compounds are used to create eco-friendly formulas that effectively kill moss, algae, and fungi growing on the surface of the roof. These products, including Wet & Forget and Spray & Forget, are non-acidic and safe to use around landscaping. Manufacturers have made these products easy to use with an attached spray that can cover most roofs, up to 30 feet in height, without requiring a ladder or standing on your roof.

Preventative maintenance to keep your roof clean

For a roof to remain sturdy, free of damage, and healthy, it’s important to keep them clean and clear of organic matter. 

Here are six tips for maintaining the roof over your head: 

  1. Remove leaves and pine needles as they fall—don’t allow them to build up on the surface of the roof. 
  2. Clean algae, mold, and mildew off of the roof when you first notice it developing to prevent a widespread infestation.
  3. Install moss and mildew prevention strips made from zinc or copper to kill algae before it takes hold.
  4. Repair any worn or damaged roofing shingles or tiles. 
  5. Remove tree limbs that hang over the roof.
  6. Visually inspect the roof annually and after severe hail, rain, or wind storms.

Roof cleaning FAQs

How often should I clean my roof?

In general, you should get your roof cleaned professionally at least once a year.

How do I know my roof needs to be cleaned?

If you live in a humid climate, organic growth is quite common. When you see moss or other staining on your roof, it’s time for a thorough cleaning. Your roof should also be cleaned when debris, dust, pollen, ash, mildew, or algae are visible.

How do I remove moss, mildew, and algae from my roof?

Moss and other organic growth can be removed with water. However, to kill the underlying algae or mold, you may need to employ an eco-friendly fungicide or chemical compound to kill it and keep it from spreading.

What are some eco-friendly solutions for roof cleaning?

Plain water is an excellent choice for removing dust, pollen, ash, and dirt from your roof. For algae, mold, and mildew, there are other natural roof-cleaning products with fungicides that will kill the organic matter and prevent further spread.

Is it safe to power wash a roof?

Generally, no. A high-pressure hose can void the roof’s warranty and damage your roof. 

Is roof cleaning worth the money and the effort?

Yes. A clean roof is visually appealing and the absence of organic matter can extend the life of your roof. 

Remember, even the best roofing materials need some tender love and care from time to time. Keep an eye on your roof and contact a licensed roofing company for an inspection if you see damaged or lifting shingles. If you are comfortable on your roof, or if the top peak is less than 30 feet from the ground, you can keep it clean with water or an eco-friendly roof cleaner.

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