Routine cleaning is an essential part of roof maintenance. The roof mold and mildew that accrue are far more than unsightly blemishes; if left intact, they decrease the lifespan of your roof substantially. Professional roof cleaning services are available for every type of roof at very reasonable prices.
Does My Roof Need Cleaning?
If you have green or black streaks on your roof, you may want to consider hiring a roof cleaning service. Such stains indicate the presence of living organisms that are eating away at your roof. Left unchecked, they can reduce a roof’s lifespan by as much as a decade. Asphalt and wood shingle roofs are especially susceptible to algae and mold due to their organic composition.
Asphalt and wood shingle roofs are highly susceptible to organic growth. Metal and stone resist algae and mold well.
Not every type of roof is afflicted by algae and molds, however. Metal, slate, and other stone tiles resist them very well. Cleaning these types of roofs is mostly done for aesthetic reasons, but is still recommended as part of routine maintenance. Once they climb atop your house, roof cleaners will be able to identify potential problems and address them before they cause significant damage.
Roof Cleaning Procedures
Cleaning a roof typically involves spraying a chemical solution (composed of water, bleach, and other household cleaners), letting it sit, and then pressure washing it off. Some companies offer eco-friendly, biodegradable cleaners that won’t harm plants or animals. If harmful chemicals are used, speak with the company beforehand about ways to protect flora and fauna.
Organisms most often grow on the north and east sides of a roof, so keep an eye on those areas. Products such as zinc strips and anti-algae growth materials can be applied to your roof to retard growth. Zinc strips are installed on the ridge and release a protective coating during precipitation.
Roof Types and Special Considerations
- Asphalt and Wood Shingles: If you have an asphalt or wood shingle roof, it’s important that the power washer is operated at reduced capacity so that it doesn’t damage these relatively soft roofing materials.
- Slate and Clay Tile Roofs: Highly resistant to mold and mildew growth, these roofs can still be stained by bird droppings and tree debris, although they wash off easily.
- Metal Roofs: A metal roof can usually be cleaned without the use of chemicals. Pressure washing alone should be sufficient.
- Flat Roofs: Care must be taken when pressure washing flat roofs to avoid puncturing the rubber membrane. Hand scrubbing with a soft-bristle brush is often used in place of a power washer.
Roof Cleaning Costs
The following roof cleaning prices are based on a 2,000 square foot roof cleaned with a solution of water and bleach and a powerwasher. Actual roof cleaning costs can vary depending on your location, the size and layout of your roof, contractor rates, and other factors.
- Cleaning an asphalt or wood shingle roof costs approximately $25 – $30 per square (100 square feet), or $500 – $600.
- For metal and slate roof cleaning, expect to pay around $15 – $20 per square, or $300 – $400.
- Flat roof cleaning costs around $10 – $20 per square, or $200 – $400. If manual scrubbing must be performed, prices can double to $400 – $800.
- Using bio-friendly cleaning solutions typically adds $50 – $100 to cleaning costs.
- Installing zinc strips on a roof ridge costs approximately $100 – $200.
- Steep slopes that require staging or other safety devices might add approximately $100 – $300 to the project cost.
- Most roof cleaning companies also offer gutter cleaning, and combining this service with roof cleaning can save you money.