Why Nor-Cal Maintenance Is Diamond Certified
Nor-Cal Maintenance is a Diamond Certified company, which means an independent rating organization surveyed our real, randomly selected customers and confirmed we score Highest in Quality. It is one of the hardest local-business ratings to earn in the Bay Area — you cannot buy it, and you cannot fake it. Here is exactly what it took, and why it matters when you are choosing who to put on your roof.
The share of surveyed customers who said they would use us again.
The share who said we provided helpful expertise when they needed it.
The customer-satisfaction score required to qualify at all.
Our award is based on 52 random customer surveys conducted since December 2023. You can view our independent company report at dccert.org/2754.
What Diamond Certified Actually Means
Diamond Certified is awarded by American Ratings Corporation, an independent research firm that has rated Greater Bay Area companies for more than 20 years. Unlike online review sites where anyone can post, Diamond Certified ratings come only from confidential telephone surveys of a company's verified past customers. To qualify, a company must score 90 or higher on a 100-point scale for both Quality and Helpful Expertise — and most companies that apply do not make the cut.
In other words: the rating reflects what our actual clients said when an independent third party called and asked them, not what we say about ourselves.
The Rigorous 12-Step Certification Process
Earning and keeping the Diamond Certified award is an ongoing process, not a one-time badge. Here is what American Ratings Corporation requires:
Apply
The company applies to begin the rating process.
Sample
A random sample of roughly 400 past customers is pulled from the company's full customer files.
Survey
Only real, verified customers are surveyed by confidential telephone research.
Score
The company must score 90+ out of 100 on Quality and Helpful Expertise to qualify.
Credentials
Required insurances and valid state-mandated credentials are independently confirmed.
Practices
The company must perform to contract, run customer-friendly business practices, and stand behind its work.
Commitment
The company agrees to the Diamond Certified Customer Satisfaction Principles.
Award
Only companies that clear the quality, practices, and credential bars are awarded Diamond Certified.
Monitor
Ongoing surveys confirm the company keeps its satisfaction and loyalty high.
Mediate
The company agrees to participate in Diamond Certified mediation if a dispute ever arises.
Guarantee
The Diamond Certified Performance Guarantee adds assurance the company stands behind its work.
Quality
Companies that qualify and maintain the award are far more likely to deliver quality consistently.
What This Means For You
When you hire a Diamond Certified company, you get a layer of protection most contractors can't offer. If you use us, are not satisfied, and we are unable to resolve it, you can contact American Ratings Corporation within six months of your service. They will attempt to mediate a solution, and if they determine the resolution was unfair, they will refund you up to $1,000 of the purchase price.
Full terms are at diamondcertified.org/performance-guarantee.
Practically, the rating tells you three things before we ever show up: our past customers were satisfied enough to recommend us, our license and insurance have been independently verified, and we are accountable to an outside organization for the quality of every job.
About the Company Behind the Rating
Nor-Cal Maintenance is a locally owned exterior maintenance company serving Sonoma, Napa, and Marin Counties, led by owner David Stankas. We handle gutter maintenance and cleaning, gutter cover installation, pressure washing, roof cleaning and moss removal, and glass cleaning — and our Peace of Mind Program lets you schedule annual exterior care so it's handled year after year without you having to remember.
Verified by the Certification Process:
- Licensed & insuredCalifornia license #772419, with workers' compensation and liability insurance confirmed.
- Trusted materialsWe install Gutterglove, Amerimax, and Unger products.
- We stand behind our workIncluding a 30-day guarantee on gutter clogs.
- Straightforward estimatesWe gather information and prepare an honest proposal, with no pressure to buy.