Top commercial roofing contractors in California, ranked by ChatGPT answers

Places ChatGPT showed

• Central Roofing · 4.3★ · Roofing contractor
• Red Pointe Roofing · 5.0★ · Roofing Service
• Kodiak Roofing & Waterproofing · 4.7★ · Roofing contractor
• Enterprise Roofing Service, Inc. · 4.8★ · Roofing contractor
• Watson Companies Inc · 4.0★ · Roofing contractor
• Peterson Roofing Co, Inc · 3.4★ · Roofing contractor
• OneRoof Solution Commercial Roofing · 4.6★ · Roofing contractor
• Specialty Roofing of CA - Modesto Commercial Roofing · 5.0★ · Roofing contractor

If you mean commercial/industrial roofing rather than residential, California has a large field of strong contractors. I wouldn’t treat any statewide list as an objective “best-to-worst” ranking; the right contractor depends heavily on location, roof system, building size, and whether you need repair, restoration, or replacement.

Here are several contractors worth putting on an RFP list based on their commercial focus, geographic coverage, industry credentials, and available business information:

• Central Roofing — Gardena/Southern California. Commercial low-slope roofing, repairs, replacement and emergency leak response. Their stated service area includes Los Angeles and Orange County.
• Red Pointe Roofing — Orange/Southern California. Commercial-focused contractor with GAF PlatinumElite Commercial Contractor credentials and an emphasis on larger commercial projects.
• Kodiak Roofing & Waterproofing — Roseville/Northern California. Commercial roofing and building-envelope work, including waterproofing and metal roofing.
• Enterprise Roofing Service, Inc. — Concord/Bay Area. Commercial and industrial roofing and waterproofing; the company lists NRCA, WSRCA and Roofing Contractors Association of California affiliations.
• Watson Companies Inc — Sacramento/Central California. Commercial/industrial roofing, reroofing, maintenance, coatings, TPO, built-up and modified-bitumen systems.
• Peterson Roofing Co, Inc — Modesto/Central & Northern California. Commercial and industrial roofing with TPO, PVC, EPDM, modified bitumen, metal and coating systems.
• OneRoof Solution Commercial Roofing — Visalia/Central Valley, with Northern California operations as well. Commercial/industrial replacement, coatings, metal roofing and solar-roof coordination.
• Specialty Roofing of CA - Modesto Commercial Roofing — Central Valley. Commercial replacement, maintenance, repairs and leak work.

For an additional independent screening source, Diamond Certified's 2026 Bay Area commercial-roofing directory reports customer-survey data and identifies companies such as All Seasons Roofing & Waterproofing.

How I'd screen them

For a serious commercial project, I would get 3–5 bids and compare more than price. The National Roofing Contractors Association specifically recommends prequalifying commercial roofing contractors and considering experience, qualifications and references.

Check:

• California CSLB license: verify the contractor's current license and classification directly through the state's database.
• Commercial references: ideally several comparable roofs completed within the last 2–3 years.
• Manufacturer credentials: GAF, Carlisle, Johns Manville, Elevate, Tremco, Garland, etc., depending on the specified system.
• Roof-system expertise: TPO, PVC, EPDM, modified bitumen, BUR, coatings, metal, etc.
• Warranty: distinguish manufacturer material/system warranties from the contractor's workmanship warranty.
• Maintenance capability: particularly important for warehouses, retail centers, multifamily portfolios and industrial buildings.
• Safety and insurance: request current workers' compensation and liability certificates.
• Leak history: for an existing roof, require a documented inspection rather than accepting a replacement recommendation at face value.

If you tell me the California city/region, building type (warehouse, apartment, office, retail, industrial, etc.), approximate roof size, and whether this is repair/restoration/replacement, I can narrow this to a 5-company shortlist specifically for your project and compare their commercial specialties and credentials.

Places ChatGPT showed

• Red Pointe Roofing · 5.0★ · Roofing Service
• Peterson Roofing Co, Inc · 3.4★ · Roofing contractor
• Kodiak Roofing & Waterproofing · 4.7★ · Roofing contractor
• Watson Companies Inc · 4.0★ · Roofing contractor
• Enterprise Roofing Service, Inc. · 4.8★ · Roofing contractor
• Central Roofing · 4.3★ · Roofing contractor
• Sadler Roofing Inc. · 3.9★ · Roofing contractor
• OneRoof Solution Commercial Roofing · 4.6★ · Roofing contractor
• Wedge Roofing Inc · Roofing contractor

For warehouses and industrial buildings, I’d focus less on general “best roofer” lists and more on contractors with demonstrated commercial/industrial experience, large low-slope roofs, single-ply systems (TPO/PVC/EPDM), coatings, metal work, maintenance programs, and manufacturer-backed warranties.

Here are several California contractors worth putting on an RFP list:

• Red Pointe Roofing — Southern California. GAF lists Red Pointe as a PlatinumElite Commercial Contractor, which is a particularly relevant credential for large commercial roofs. GAF says PlatinumElite contractors can offer its Diamond Pledge NDL guarantee for up to 35 years on qualifying systems.
• Peterson Roofing Co, Inc — Central Valley / Northern California. Particularly relevant to warehouses and industrial properties; its commercial work includes reroofing and maintenance, and its customer/project information specifically includes warehouse reroofing.
• Kodiak Roofing & Waterproofing — Northern California. Commercial roofing plus waterproofing and building-envelope work, making it a useful candidate for industrial facilities where roof penetrations, walls, decks, and waterproofing details are important.
• Watson Companies Inc — Sacramento / Northern California. Commercial and industrial roofing with TPO, built-up, modified bitumen, coatings, sheet metal and preventative maintenance capabilities.
• Enterprise Roofing Service, Inc. — Bay Area / Northern California. Focused on commercial/industrial roofing and waterproofing, with union affiliations and several industry associations.
• Central Roofing — Los Angeles / Orange County. Commercial roofing contractor with a substantial focus on low-slope commercial roofs, repairs and ongoing service.
• Sadler Roofing Inc. — Orange County / Southern California. Commercial contractor with stated experience serving industrial, warehouse and multi-property customers.
• OneRoof Solution Commercial Roofing — Central Valley and statewide coverage. Commercial/industrial focus with operations in Visalia and Northern California, plus broad California service coverage.

One credential I'd pay particular attention to

For a large warehouse, manufacturer certification matters, but it shouldn't be the only criterion. For example, GAF's current commercial program has Certified, GoldElite and PlatinumElite tiers. GoldElite can offer qualifying Diamond Pledge guarantees up to 25 years, while PlatinumElite can offer them up to 35 years. GAF says its commercial certifications are reviewed annually and considers factors such as inspection ratings, claims history, responsiveness and reputation.

There are also contractors with credentials from multiple major membrane manufacturers. For example, Wedge Roofing says it is a GAF Master Elite Commercial contractor, CertainTeed Gold Star Commercial contractor, Firestone Master Contractor and Carlisle approved installer.

How I'd screen them for a warehouse

For a 50,000–500,000+ sq. ft. warehouse, I'd ask each bidder for:

1. Three comparable warehouse/industrial projects — ideally similar square footage and roof system.
2. Manufacturer certifications for the proposed system (GAF, Carlisle, Johns Manville, Sika, Firestone/GenFlex, etc.).
3. Proposed roof assembly — membrane, insulation thickness/R-value, attachment method, cover board and vapor retarder.
4. Roof warranty — distinguish the manufacturer's NDL/system warranty from the contractor's workmanship warranty.
5. Maintenance program — inspection frequency, leak response and documentation.
6. Safety record and insurance — especially important for occupied industrial facilities.
7. Solar compatibility if rooftop solar is planned.
8. Drainage design — ponding water is a particularly important issue on large low-slope warehouse roofs.
9. Sheet-metal/penetration detailing — often where industrial roof leaks originate.
10. References from facility owners/property managers, rather than only residential customers.

If you tell me where in California the warehouse is (e.g. Inland Empire, LA, Bay Area, Sacramento, Central Valley, San Diego) and approximately how many square feet, I can narrow this to 5–8 contractors specifically suited to that market and roof size, with their licenses, certifications, project experience and contact information.

Places ChatGPT showed

• Central Roofing · 4.3★ · Roofing contractor
• Stone Roofing Company, Inc · 2.4★ · Roofing contractor
• Andy's Roofing Company, Inc. · 4.1★ · Roofing contractor
• Enterprise Roofing Service, Inc. · 4.8★ · Roofing contractor
• Peterson Roofing Co, Inc · 3.4★ · Roofing contractor
• Specialty Roofing of CA - Modesto Commercial Roofing · 5.0★ · Roofing contractor

If you’re looking for commercial TPO and flat roof replacement contractors in California, the “best” choice depends heavily on your region (Bay Area vs. Los Angeles vs. Inland Empire vs. Central Valley), roof size, and whether you need a full tear-off, retrofit, warranty-backed system, or maintenance program. Here are several established contractors to consider and compare.

Commercial roofing contractors to consider in California

Additional Southern California firms that specifically market TPO and flat-roof replacement work include Frontline Roofing, TopCal Roofing, and PWC Roofing. They advertise TPO installation/replacement, low-slope systems, and commercial reroofing services.

What I would look for before hiring a TPO contractor

For a commercial TPO replacement, ask each bidder:

• Manufacturer certification: Are they certified by the membrane manufacturer (for example, GAF, Carlisle, Johns Manville, Elevate/Firestone, or similar)?
• Warranty: Is the quote including a manufacturer-backed No Dollar Limit (NDL) warranty, and for how many years?
• Roof assembly details: Get the exact specification:
• TPO thickness (45 mil, 60 mil, 80 mil, etc.)
• Fully adhered vs. mechanically attached
• Insulation type and thickness
• Cover board requirements
• Drain and flashing details
• Moisture survey: Will they test wet insulation/deck areas before replacing?
• Commercial references: Ask for projects similar in size and use (warehouse, office, retail, industrial, multifamily).

A practical shortlist by project type

• Large warehouse / industrial building: Look for contractors with documented commercial portfolios and maintenance programs (for example, Enterprise Roofing, Stone Roofing, Central Roofing).
• Bay Area low-slope replacement: Consider firms experienced with single-ply membranes and local code requirements.
• Southern California TPO reroof: Compare several bids from contractors specializing in heat-welded TPO systems and Title 24 considerations.

If you tell me the city in California, building type (warehouse/office/retail/etc.), approximate roof square footage, and whether it’s a tear-off or overlay, I can narrow this to the most relevant contractors.

Places ChatGPT showed

• Central Roofing · 4.3★ · Roofing contractor
• Bigham Taylor Roofing · 3.4★ · Roofing contractor
• Just Leaks Inc · 5.0★ · Roofing contractor
• Restco Roofing · 5.0★ · Roofing contractor

Yes. I found several California contractors that explicitly advertise 24/7 emergency commercial roof/leak response. Coverage varies, so confirm that they service your specific city before dispatching.

• Central Roofing — Gardena / Southern California
  Advertises 24/7 emergency leak response for commercial properties, particularly flat and low-slope roofs.
• Bigham Taylor Roofing — Hayward / Northern California
  Commercial roofing and waterproofing contractor advertising 24/7 emergency response, including leak investigation, temporary stabilization, and repairs.
• Just Leaks Inc — San Jose / Bay Area
  Focuses on commercial and industrial roofs and advertises 24-hour emergency leak repair.
• Restco Roofing — Lake Forest / Southern California
  Explicitly offers 24/7 emergency response for active commercial roof leaks, storm damage and structural failures throughout Southern California.
• Maximus Roofing — Sacramento / Northern California
  Advertises 24/7/365 commercial emergency service, including active leak repair, temporary protection and storm damage response. It states that its emergency teams cover Northern California.
• Stone Roofing Company — Azusa / Los Angeles & Southern California
  Advertises 24/7/365 emergency commercial roof repair and rapid dispatch across Los Angeles, Orange, Riverside, San Bernardino and San Diego counties.
• Rite-Way Roof Corp. — Fontana / Southern California
  Advertises 24/7 emergency service for commercial roofing, including active leak containment and temporary repairs.
• ADCO Roofing — Southern California
  Offers 24/7 emergency commercial roof repair, including leak containment, temporary dry-ins, tarping and storm-damage assessment.

If you tell me the California city or ZIP code

I can narrow this to 5–10 contractors that actually cover your property, including their emergency phone numbers, commercial-roof specialties, California license information, and whether they handle TPO, EPDM, PVC, modified bitumen, BUR, or metal roofs.

Places ChatGPT showed

• Red Pointe Roofing · 5.0★ · Roofing Service
• Central Roofing · 4.3★ · Roofing contractor
• Sadler Roofing Inc. · 3.9★ · Roofing contractor
• HP Roofing Pro · 4.7★ · Roofing contractor
• TWM Roofing · 4.7★ · Roofing

If by “reliable” you mean established commercial specialists with strong manufacturer credentials, licensing/insurance indicators, and a meaningful Southern California service footprint, I’d put these on the shortlist to interview. I’m not ranking them because reliability is highly project-specific.

• Red Pointe Roofing — Orange/Chatsworth. Commercial-focused and listed by GAF as a PlatinumElite Commercial Contractor, which is a relatively high manufacturer credential. Good candidate for large reroofing and warranty-oriented projects.
• Central Roofing — Gardena. Longstanding Southern California commercial operator with a focus on flat/low-slope roofs, repairs, reroofing and emergency leak response.
• C.I. Services, Inc. — Anaheim. Full-service commercial contractor serving Orange County, LA County, the Inland Empire and San Diego, including industrial, retail, municipal and managed properties.
• Sadler Roofing Inc. — Orange. Family-owned commercial roofer serving Southern California; handles inspections, repairs, reroofing and multiple membrane/roofing systems.
• HP Roofing Pro — Alhambra/San Bernardino. Commercial-focused, with an emphasis on leak diagnosis, maintenance, restoration/coatings and documented inspections.
• TWM Roofing — Oceanside. Particularly worth considering if your project is in San Diego County; it has a substantial review history and commercial/flat-roof capabilities.
• Tecta America Southern California — Santa Ana. A particularly interesting choice for larger commercial/industrial work. GAF lists it as a GoldElite Commercial Contractor and CoatingsPro contractor, with single-ply and liquid-applied roofing capabilities.
• OC Custom Roofing — Lake Forest. GAF GoldElite and certified with GAF, Carlisle, CertainTeed and Fiberlite; CSLB license #1042433. Its stated service territory covers much of Orange County and portions of LA County.

How I'd vet them

For a commercial property, I wouldn't choose based on Google/BBB stars alone. I'd ask each bidder for:

1. Current CSLB license number and verify it directly with the California Contractors State License Board.
2. Certificate of insurance — including general liability and workers' compensation.
3. At least 3 comparable commercial references from the last 2–3 years.
4. Examples of roofs using the same system you're considering (TPO, PVC, modified bitumen, BUR, metal, coating, etc.).
5. Manufacturer certification and the exact warranty offered—not merely “20-year warranty.”
6. Whether they use their own crews or subcontractors and who will actually supervise the job.
7. A detailed scope covering tear-off, insulation, drains/scuppers, penetrations, flashing, curbs, edge metal and cleanup.
8. A written maintenance/warranty-response procedure after completion.

One useful signal is manufacturer certification: for example, GAF says its GoldElite commercial contractors must meet licensing/insurance requirements and can qualify to offer enhanced system guarantees, although GAF also makes clear that these contractors are independent businesses.

If you tell me the city (e.g., Los Angeles, Orange County, Inland Empire, or San Diego), approximate roof size, and whether this is a warehouse/industrial, office, retail, apartment, or other property, I can narrow this to 5–7 contractors and compare their licensing, manufacturer certifications, reviews, service area, and commercial specialties.

Places ChatGPT showed

• Environmental Roofing & Waterproofing, Inc. · 5.0★ · Roofing contractor
• California Roofing Company. . · Roofing
• Peterson Roofing Co, Inc · 3.4★ · Roofing contractor
• CentiMark Corporation · 4.6★ · Roofing contractor
• Best Contracting Services · 4.7★ · Construction company
• Bigham Taylor Roofing · 3.4★ · Roofing contractor
• Watson Companies Inc · 4.0★ · Roofing contractor
• Summit Roofing Services · 4.7★ · Roofing contractor

If by “best” you mean well-established commercial specialists with strong manufacturer credentials, broad Northern California coverage, and documented commercial experience, I’d put these companies on your bid list. I’m not ranking them, because the right contractor depends heavily on roof type, building size, location, and whether you need repair, restoration, or replacement.

Northern California commercial roofing firms to consider

• Environmental Roofing & Waterproofing, Inc. — Campbell — Strong fit for commercial/industrial roofing and waterproofing in the Bay Area and Sacramento region. Offers TPO/PVC, fluid-applied systems, coatings and metal-roof work.
• California Roofing Company. . — San Jose — Long-established commercial and industrial roofer serving the Bay Area and Northern California. GAF lists it as a GoldElite Commercial Contractor.
• Peterson Roofing Co, Inc — Modesto — Particularly relevant for Central Valley commercial/industrial properties, with TPO, PVC, EPDM, modified bitumen and metal systems.
• CentiMark Corporation — Livermore — A large commercial roofing specialist suitable for larger re-roofing, maintenance and industrial projects.
• Best Contracting Services — Union City — More of a building-envelope specialist, covering commercial/industrial roofing, waterproofing, sheet metal and related envelope work.
• Bigham Taylor Roofing — Hayward — Established commercial/industrial contractor serving Northern California, with low-slope, steep-slope, coatings, waterproofing and tenant-improvement capabilities.
• Watson Companies Inc — Sacramento — Commercial/industrial specialist offering new roofs, re-roofing, leak service, maintenance, TPO, built-up roofing, modified bitumen, coatings and sheet metal.
• Summit Roofing Services — Manteca — Commercial/industrial contractor serving Northern and Central California, particularly worth considering for warehouse, industrial and multi-unit properties.
• Northern California Roofing Co. — Vacaville — GAF identifies it as a GAF Certified Commercial Contractor and CoatingsPro contractor; the company reports Master Commercial certification since 2008 and Duro-Last Elite credentials.
• Roofmax / Yorkshire Roofing of Northern California — East Bay — Diamond Certified reports 21 consecutive years of its highest-quality/helpful-expertise designation, with commercial service in Alameda and Contra Costa counties and GAF Master Elite credentials.

A few things I'd use to narrow the field

For a commercial roof, I wouldn't select solely from Google ratings. I'd ask each bidder for:

1. Three comparable commercial projects completed in the last 2–3 years.
2. Their manufacturer certifications for the exact system they're proposing (GAF, Carlisle, Johns Manville, Sika, Firestone/BMI, Duro-Last, etc.).
3. Warranty terms — especially whether it's a manufacturer NDL warranty and what workmanship coverage remains.
4. A written roof assessment, including moisture survey/core samples where appropriate.
5. The proposed membrane/system, insulation R-value, attachment method and drainage plan.
6. Proof of current California contractor licensing, liability insurance and workers' comp.
7. A maintenance program and annual inspection price after installation.

Manufacturer certification is particularly useful because programs such as GAF's commercial certification have specific insurance/licensing and training requirements, although certification itself isn't a guarantee of project quality.

If you tell me the city, approximate roof square footage, building type (warehouse/office/retail/etc.), and whether you're looking for repair, restoration or full replacement, I can narrow this to 5 contractors that are specifically appropriate for your project and compare their commercial credentials, service area, certifications, reviews, and contact information.

Places ChatGPT showed

• Watson Companies Inc · 4.0★ · Roofing contractor

If by “best warranties” you mean the strongest combination of long duration, workmanship coverage, manufacturer backing, and no-dollar-limit protection, there are several California contractors worth putting on your bid list.

Contractors I’d investigate first

The GAF certification level is particularly important. GAF says its PlatinumElite commercial contractors can offer the Diamond Pledge NDL guarantee for up to 35 years on qualifying systems. The guarantee covers both material and workmanship, includes labor for covered repairs, and provides unlimited-dollar coverage on qualifying Diamond Pledge systems.

Watson Companies is particularly interesting because its own site documents decades of commercial work and GAF/Firestone elite credentials.

For comparison, California Roofing Company in San Jose is currently listed by GAF as GoldElite, which permits a Diamond Pledge NDL guarantee of up to 25 years on qualifying systems.

One important distinction

Don't compare warranties solely by the headline number.

A 30-year material warranty isn't necessarily better protection than a 20-year NDL system guarantee. I'd want your proposal to specify:

• Workmanship duration — preferably 10+ years for a major commercial reroof.
• Manufacturer/system warranty — not merely a membrane material warranty.
• NDL (No Dollar Limit) — particularly valuable for commercial properties.
• Whether labor is included when a covered leak occurs.
• Whether consequential damage is covered or excluded.
• Whether the warranty is transferable if you sell the building.
• Required inspections/maintenance and how failure to perform them affects coverage.
• Whether ponding water, wind, punctures and rooftop equipment work are excluded.
• Exactly which roofing components are covered: membrane, insulation, flashings, edge metal, drains, etc.

For example, GAF's published comparison shows that its Diamond Pledge NDL guarantee can cover the entire GAF system, workmanship, labor, 100% replacement material, and be transferable—but the maximum term depends on the contractor certification and system.

If you tell me the California city/area, building type, approximate square footage, and whether it's TPO, PVC, EPDM, modified bitumen, metal, or a coating/restoration project, I can narrow this to 5–10 contractors and compare their actual warranty terms side-by-side.

Places ChatGPT showed

• Central Roofing · 4.3★ · Roofing contractor

If by “trust” you mean companies with a meaningful track record serving property managers, building owners, and facilities teams—not just residential roofers with good reviews, I’d put these California firms on a due-diligence shortlist.

I’m treating “trusted” descriptively here: evidence of repeat commercial/property-management work, longevity, responsiveness, and relevant customer testimonials—not as an overall ranking.

Southern California

• Central Roofing — Gardena / Los Angeles–Orange County. Family-owned since 1992, with 30+ years in commercial roofing. Their published testimonials specifically include property-management firms and commercial building owners, including repeat work and warranty experience. They handle repairs, restoration, replacement and preventative maintenance.
• Sadler Roofing Inc. — Orange County / Southern California. Family-owned since 1963 and focused heavily on commercial work. Their testimonials include work for apartments managed by Sterling Property Management and describe repeat commercial use.
• West Coast Roofing Co — Los Angeles / Southern California. A multigenerational, family-owned commercial/industrial roofer operating since 1969, with a focus on flat and low-slope commercial roofs and service to property managers and building owners.
• Commercial & Industrial Roofing Co Inc — San Diego County. Family-owned, locally based in Spring Valley, with a commercial/industrial focus and experience with systems such as TPO and EPDM.
• Reata Roofing Services — Duarte / greater Southern California. Owner-led commercial roofing operation that specifically targets property owners, property managers, HOAs and general contractors, with preventative maintenance, leak response and larger replacement projects.
• Syntech Roofing & Waterproofing — a family-owned Southern California building-envelope contractor serving commercial properties. Its work extends beyond roofing into waterproofing, sealants and concrete restoration, which can be useful for property managers dealing with recurring building-envelope leaks.

Bay Area / Northern California

• Andy's Roofing Company, Inc. — San Leandro / Bay Area. Family-owned and operated since 1957, with a substantial commercial, institutional and public-works orientation. They provide commercial inspections, maintenance, repairs and reroofing.
• California Roofing Company. . — San Jose / Bay Area. Long-established family-owned/operated contractor with commercial and industrial experience. Their credentials include a California C-39 license and GAF GoldElite Commercial Contractor status.
• Enterprise Roofing Service, Inc. — Concord / East Bay. Commercial/industrial roofing and waterproofing contractor with industry affiliations including NRCA, WSRCA and RCACal.

Central Valley

• Peterson Roofing Co, Inc — Modesto / Central & Northern California. Family-run, C-39 licensed contractor with a strong commercial/industrial emphasis. Its stated customer profile includes commercial property owners, facility managers and property-management teams.
• Specialty Roofing of CA - Modesto Commercial Roofing — Modesto / San Joaquin Valley. Commercial-focused local contractor offering installation, repairs, inspections and maintenance across common low-slope systems.

One caveat on “property managers trust”

I would not rely solely on a contractor's own website saying “property managers trust us.” The stronger signals are:

• documented repeat work for named property-management organizations;
• commercial rather than predominantly residential experience;
• preventative-maintenance programs;
• 24/7/emergency response capability;
• ability to provide COIs, W-9s, licenses and safety documentation;
• manufacturer-backed warranties;
• references from current commercial property managers, rather than homeowners;
• evidence that they actually coordinate around tenants and occupied buildings.

For example, Central Roofing has a particularly relevant combination of family ownership + 30+ years + commercial specialization + property-management testimonials, while Sadler has documented repeat work for managed apartment properties.

If you're a property manager looking to build a California vendor list, I can also narrow this to 10–15 genuinely local/family-owned commercial roofers by region (LA/OC, Inland Empire, San Diego, Bay Area, Sacramento, Central Valley) and check their CSLB status, years in business, commercial specialties, manufacturer certifications, reviews, and evidence of property-management clients.