Roof Washing & Roof Cleaning in Princeton, NJ
Safe, effective roof cleaning that removes black streaks, algae, and moss while extending the life of your shingles.
Protect Your Roof With Professional Cleaning
Those dark streaks on your roof are not just cosmetic. They are caused by Gloeocapsa magma, a type of algae that feeds on the limestone in your shingles. Left untreated, algae, moss, and lichen can shorten your roof's lifespan by years and lead to costly repairs or premature replacement.
Our roof washing uses a safe, low-pressure soft wash method recommended by shingle manufacturers. We apply a specialized cleaning solution that kills algae and organic growth at the root, then gently rinse it away. No high pressure, no damage to your shingles or flashing.
A clean roof looks better, lasts longer, and can even improve your home's energy efficiency by reflecting more sunlight. We recommend roof cleaning every 2 to 3 years across central New Jersey and eastern PA.
Why You Should Never Pressure Wash a Roof
High-pressure washing strips the protective granules off your shingles, the same granules that shield your roof from UV damage and weather. Once those are gone, shingles crack, curl, and fail years early. Every major manufacturer including GAF, CertainTeed, and Owens Corning specifically warns against pressure washing. Soft washing is the only method they recommend.
How Roof Algae Affects Home Value and Insurance
Dark algae streaks make your roof look old and neglected, even if the shingles still have years of life left. Some insurance companies now flag heavily stained roofs and may require cleaning before renewing your policy. If you are selling your home in the Princeton or Hopewell area, a clean roof is one of the easiest ways to boost curb appeal.
The ARMA Recommended Cleaning Method
The Asphalt Roofing Manufacturers Association (ARMA) recommends a soft wash using a low-pressure sodium hypochlorite cleaning solution. That is exactly what we use. The solution kills algae, moss, and lichen at the root, and we apply it at safe low pressure with zero risk of shingle damage. Growth dies off over the following days and your roof returns to its original color.
Roof Washing Saves You Money
A new roof in New Jersey costs $10,000 to $25,000 or more. Roof washing costs a fraction of that and can add years to your existing roof's lifespan. Most roofs are designed to last 20 to 30 years, but algae and moss growth can cut that significantly if left untreated. Regular cleaning protects a much bigger investment.
Why Roof Cleaning Matters
Regular roof maintenance protects your biggest investment.
Extends Roof Life
Removing algae and moss prevents premature shingle deterioration and avoids early replacement.
Boosts Curb Appeal
A clean roof transforms your home's appearance and can increase property value.
Safe & Eco-Friendly
Low-pressure method with biodegradable solutions. Safe for shingles, plants, and pets.
Where We Provide Roof Washing
We serve communities across Mercer, Hunterdon, and Somerset counties in NJ and Bucks County, PA.
Other Services We Offer
Window Cleaning
Crystal-clear windows inside and out, including screens, tracks, and frames.
Soft Washing
Gentle, low-pressure cleaning for siding, roofs, and delicate surfaces.
Power Washing
High-pressure cleaning for driveways, walkways, patios, and hard surfaces.
Gutter Cleaning
Full gutter cleaning and flush to protect your foundation.
Common Questions About Roof Washing
How much does roof cleaning cost?
For most homes throughout Mercer and Bucks counties, professional roof washing starts at $450, with the average job running around $2,000. The price depends on roof size, pitch, amount of algae or moss buildup, and accessibility. A walkable ranch costs less than a steep colonial with multiple dormers. We always give free estimates so you know the exact cost before any work starts.
Can you pressure wash a roof?
No. You should never pressure wash a roof. High-pressure water strips the protective granules off your asphalt shingles, causing them to crack, curl, and fail years earlier than they should. Every major manufacturer including GAF, CertainTeed, and Owens Corning explicitly warns against it. The correct method is always a soft wash, which uses low pressure and a cleaning solution to kill algae and rinse it away safely.
What are those black streaks on my roof?
Those dark streaks are caused by Gloeocapsa magma, an algae that feeds on the limestone filler in asphalt shingles. It thrives in humid, shaded conditions, which is why north-facing sections get hit first. The algae holds moisture against your shingles, speeding up deterioration. It also spreads via airborne spores, so once one home in the neighborhood has it, others tend to follow.
Is roof cleaning worth it?
Absolutely. A new roof costs $10,000 to $25,000 or more. A professional roof cleaning costs a fraction of that and lets your shingles last their full 20 to 30 year lifespan. On top of that, a clean roof improves curb appeal, keeps energy bills lower by reflecting more sunlight, and avoids potential insurance issues. It is one of the best returns on investment for home maintenance.
How often should you wash your roof?
For most homes from Lawrenceville to Yardley, every 2 to 3 years is the sweet spot. Homes surrounded by trees or with heavy shade may need cleaning every 1 to 2 years. Homes with more sun exposure can usually stretch closer to 3 years. If you are seeing dark streaks or green patches, it is time. We are happy to do a free visual assessment.
Can roof algae come back after cleaning?
Yes. Algae spores are airborne and will eventually land on your roof again. A professional soft wash kills all existing growth, but it is not a permanent shield. Most homeowners see their roof stay clean for 2 to 3 years after a wash. Heavy tree canopy, north-facing slopes, and high humidity speed up regrowth. Regular cleaning keeps the problem manageable and protects your shingles.
Does a dirty roof affect home value?
It definitely can. A roof covered in dark algae streaks makes the whole house look older and poorly maintained, even if the rest of the home is in great shape. Appraisers and home inspectors notice it too, and a stained roof can lead to lower appraisals. A clean roof signals to buyers that the home has been well cared for. If you are getting ready to sell, roof washing is one of the most cost-effective improvements you can make.
Roof Washing FAQ
What causes the black streaks on my roof?
Those dark streaks are caused by Gloeocapsa magma, a type of algae that feeds on the limestone filler in asphalt shingles. It thrives in humid climates and shaded areas. Left untreated, it spreads across the roof and can shorten shingle lifespan by years.
Will roof washing damage my shingles?
No. We use a low-pressure soft wash method that is recommended by major shingle manufacturers including GAF and CertainTeed. High-pressure washing can damage shingles, which is why we never use it on roofs. Our method relies on a specialized cleaning solution applied at safe, low pressure.
How often should I have my roof cleaned?
In the Delaware Valley climate, we recommend roof cleaning every 2 to 3 years. Homes with heavy tree cover, north-facing roofs, or roofs that stay shaded for much of the day may need cleaning more frequently. A clean roof lasts longer and keeps your home looking its best.
Can a dirty roof affect my energy bills?
Yes. Dark algae staining absorbs more heat from sunlight, which can raise attic temperatures and make your air conditioning work harder during summer months. A clean, lighter-colored roof reflects more sunlight and can help reduce cooling costs.
Do you clean tile, metal, and slate roofs, or just asphalt shingles?
We clean all types of roofing materials, including asphalt shingles, concrete and clay tile, slate, metal, and cedar shake. Each material gets treated differently. We adjust our cleaning solution concentration and technique to match the specific roof type so it gets cleaned safely and effectively.
How long does a roof washing take?
Most residential roof washes take between 2 and 4 hours depending on the size of the roof and the amount of buildup. Larger homes or roofs with heavy moss growth may take a bit longer. We handle everything in a single visit and you do not need to be home while we work.
Will the cleaning solution hurt my landscaping or pets?
We take plant and pet safety seriously. Before we start, we wet down all landscaping around the perimeter of the home to dilute any runoff. We use biodegradable cleaning solutions and rinse everything thoroughly when the job is done. We recommend keeping pets inside during the cleaning and for about an hour afterward until the rinse is complete.
Can I wait until I see streaks to schedule a cleaning?
You can, but by the time streaks are visible, the algae has usually been growing for a while. The organisms start out microscopic and gradually build up. Waiting until you can see them means they have had more time to break down your shingles. A proactive approach with cleaning every 2 to 3 years helps prevent visible staining from ever getting that far.
Ready for a cleaner home?
Get a free, no-obligation quote. We'll respond same day and get you on the schedule fast.