5 Costly Mistakes Homeowners Make When Cleaning Their Roofs (and How to Avoid Them)

When it comes to protecting your home, few things are more important than your roof. It shields your house from the elements, helps regulate energy costs, and boosts curb appeal. But when black streaks, moss, or algae show up, many homeowners try to clean their roof the wrong way. The result? A damaged roof, voided warranty, and thousands of dollars in repairs.

In this article, we’ll cover the five most costly mistakes homeowners make when cleaning their roofs—and why soft washing is the only safe method recommended by roofing experts.

Mistake #1: Using High-Pressure Washing

One of the biggest mistakes is using a pressure washer to “blast away” dirt and stains. While it works on driveways or decks, roofing materials are far more delicate. High-pressure water strips away the protective granules on asphalt shingles and can crack or loosen tiles.

The Asphalt Roofing Manufacturers Association (ARMA) specifically warns against pressure washing, noting that it “dislodges granules, reduces shingle life, and may void manufacturer warranties.”

• Instead: Choose soft washing, which uses low-pressure water and biodegradable cleaning solutions. This method kills algae, moss, and mold without damaging shingles or voiding your warranty.

Mistake #2: Ignoring Algae, Moss, and Lichen

Many homeowners see black streaks or green patches and assume it’s only cosmetic. In reality, algae, moss, and lichen actively eat away at your roof.

• Algae (Gloeocapsa magma) feeds on the limestone in shingles, weakening them.
• Moss holds moisture, which accelerates rot.
• Lichen digs into shingle surfaces, causing permanent damage.

The National Roofing Contractors Association (NRCA) emphasizes that roof maintenance isn’t just about looks—algae and moss “shorten the service life of shingles and wood components if left untreated.”

• Instead: Have your roof professionally soft washed every 2–3 years. The cleaning solutions penetrate and kill growth at the root level, preventing regrowth much longer than pressure washing or scrubbing.

Mistake #3: DIY Roof Cleaning Without Safety Precautions

Trying to handle roof cleaning yourself can be dangerous. Homeowners often attempt a mix of bleach and water with a garden sprayer, but this approach carries risks:

• Falls: According to the U.S. Consumer Product Safety Commission, ladder-related accidents send over 500,000 people to the ER every year. Roof cleaning is one of the riskiest tasks for DIY homeowners.
• Chemical Damage: Bleach can kill landscaping, corrode metal fixtures, and damage shingles.
• Ineffective Cleaning: Household cleaners don’t penetrate deeply enough, meaning algae returns quickly.

• Instead: A professional soft washing contractor uses commercial-grade safety equipment, harnesses, and eco-friendly solutions designed specifically for roof cleaning.

Mistake #4: Hiring the Wrong Contractor

Even when homeowners decide to hire help, many make the mistake of choosing the wrong contractor. Some roof cleaners advertise “soft washing” but still use modified pressure washers, while others don’t carry insurance.

The Better Business Bureau (BBB) advises homeowners to “verify licensing, insurance, and reputation before hiring any exterior cleaning company” to avoid scams or shoddy workmanship.

To protect yourself, ask:

• Do you use true soft washing equipment with low pressure?
• What cleaning solutions do you use, and are they safe for shingles and landscaping?
• Are you fully insured with liability and workers’ comp coverage?
• Can you provide references or before-and-after photos?

A reputable contractor will answer confidently and provide documentation without hesitation.

Mistake #5: Waiting Too Long Between Roof Cleanings

Some homeowners wait until their roof looks terrible before taking action. By then, the damage may already be underway.

• Algae spreads quickly and feeds on shingles.
• Moss growth retains water, leading to wood rot in the roof deck.
• Dirty shingles absorb heat, raising energy bills.

The International Association of Certified Home Inspectors (InterNACHI) recommends regular inspections and maintenance, noting that “cleaning and treatment of moss and algae is critical to preserving roof integrity.”

Instead: Schedule a soft wash cleaning every few years as preventive maintenance. This extends roof lifespan, lowers long-term repair costs, and keeps your home looking its best.

Why Soft Washing Is the Only Safe Roof Cleaning Method

Soft washing is the only method endorsed by roofing associations and shingle manufacturers because it:

• Uses low water pressure (similar to a garden hose)
• Relies on cleaning agents that kill growth at the root
• Preserves shingle integrity and prevents granule loss
• Keeps warranties intact while extending roof life

Unlike power washing, which treats the symptom, soft washing treats the cause.

How to Find a Trusted Soft Washing Professional

Here’s how to make sure you hire the right pro for the job:

1. Search locally for companies that list “soft washing” as a primary service.
2. Check reviews on Google, BBB, and local community boards.
3. Verify insurance and licenses before hiring.
4. Compare quotes—but don’t choose solely on price. Process and professionalism matter more.
5. Ask about guarantees: Some companies offer warranties against algae regrowth.

Following these steps ensures you’ll find a contractor who cleans your roof safely and effectively.

Final Thoughts

Your roof is one of your home’s most valuable assets. Cleaning it the wrong way—or not cleaning it at all—can cost you thousands in repairs or even a full replacement. By avoiding the five costly mistakes above and choosing professional soft washing, you’ll protect your roof, extend its life, and preserve your home’s value.

👉 Ready to restore your roof safely? Contact us today for a free soft washing estimate.