Knickelbein Builders
Services
Services estimated based on license classification. Claimed businesses can customize their service list.
About the A — General Engineering License
A General Engineering (Class A) license in California authorizes contractors to perform work requiring specialized engineering knowledge and skill. This includes projects like roads, highways, bridges, dams, pipelines, irrigation systems, and utility infrastructure. General Engineering contractors typically work on large-scale civil projects that shape communities and infrastructure. California requires this license for any project where more than two unrelated building trades are used in a fixed work requiring specialized engineering. When hiring a Class A contractor, consumers should verify they have adequate insurance and bonding for the project scope, as these projects often involve significant investment and safety considerations. The CSLB oversees all Class A licensees to ensure public safety and professional standards.
About the B — General Building License
A General Building (Class B) license is one of the most common contractor licenses in California. It authorizes the holder to construct, alter, or repair buildings and structures. This includes residential homes, commercial buildings, and industrial facilities. A Class B contractor can use two or more unrelated building trades on a single project, making them ideal for comprehensive construction and renovation work. They often serve as the primary contractor who coordinates subcontractors for specialized trades. When hiring a General Building contractor, homeowners should verify the license is active and in CLEAR status, confirm adequate insurance coverage, and always get a detailed written contract before work begins. General Building contractors must maintain a $25,000 contractor bond and carry workers' compensation insurance if they have employees.
About the C-2 — Insulation & Acoustical License
The C-2 Insulation and Acoustical contractor license covers the installation of insulating and acoustical materials for thermal, sound, and fire protection purposes. This includes installing insulation in walls, attics, and crawl spaces, as well as acoustical ceiling tiles and soundproofing systems. With California's strict energy efficiency requirements (Title 24), C-2 contractors play a vital role in helping homes and businesses meet building codes and reduce energy costs. Proper insulation can significantly lower heating and cooling bills while improving indoor comfort. When hiring a C-2 contractor, ask about R-value recommendations for your climate zone, the types of insulation materials they use, and whether they perform energy audits. Quality insulation work is one of the best investments homeowners can make for long-term energy savings.
About the C-6 — Cabinet, Millwork & Finish Carpentry License
The C-6 Cabinet, Millwork and Finish Carpentry license covers the fine woodworking and finishing touches that define a home's character. C-6 contractors build and install custom cabinetry, trim work, crown molding, wainscoting, built-in shelving, and other decorative and functional wood elements. This trade requires precision craftsmanship and an eye for detail, as finish carpentry is highly visible and must meet exacting standards. Whether you're renovating a kitchen with custom cabinets or adding architectural details throughout your home, a skilled C-6 contractor can dramatically improve both the appearance and value of your property. When selecting a C-6 contractor, ask to see examples of their previous work, discuss material options and wood species, and get a clear understanding of timelines since custom work often takes longer than standard installations.
About the C-8 — Concrete License
The C-8 Concrete license authorizes contractors to mix, pour, and finish concrete for a wide range of residential and commercial applications. This includes foundations, driveways, patios, sidewalks, retaining walls, and decorative concrete work like stamping and staining. Concrete is one of the most versatile and durable building materials, and proper installation requires significant skill and experience. Factors like mix design, reinforcement, curing conditions, and finishing techniques all affect the final product's strength and appearance. California's seismic requirements add another layer of complexity, particularly for foundation work. When hiring a C-8 contractor, ask about their experience with your specific project type, the concrete mix they recommend, and how they handle weather-related scheduling challenges.
About the C-9 — Drywall License
The C-9 Drywall license covers the installation, taping, texturing, and finishing of drywall (also known as sheetrock or gypsum board). Drywall is the standard interior wall and ceiling surface in modern construction, and the quality of its installation directly affects the appearance of a finished room. C-9 contractors handle everything from hanging sheets to applying final textures and finishes. Different projects require different finish levels, from basic garage walls (Level 1-2) to smooth, paint-ready surfaces (Level 4-5). Specialty applications include moisture-resistant board for bathrooms, fire-rated assemblies, and soundproof installations. When hiring a C-9 contractor, specify the finish level you expect, discuss texture options, and ask about their process for minimizing dust. Quality drywall work is essential for a professional-looking final result.
About the C10 — C10 License
A C10 (C10) licensed contractor in California is authorized to perform specialized work in their trade area. California's Contractors State License Board (CSLB) requires contractors in this classification to meet education, experience, and examination requirements before receiving their license. When hiring a C10 contractor, always verify their license is active and in CLEAR status, confirm they carry adequate insurance, and get a detailed written contract before work begins. Licensed contractors must maintain a $25,000 contractor bond and comply with all applicable building codes and regulations.
About the C20 — C20 License
A C20 (C20) licensed contractor in California is authorized to perform specialized work in their trade area. California's Contractors State License Board (CSLB) requires contractors in this classification to meet education, experience, and examination requirements before receiving their license. When hiring a C20 contractor, always verify their license is active and in CLEAR status, confirm they carry adequate insurance, and get a detailed written contract before work begins. Licensed contractors must maintain a $25,000 contractor bond and comply with all applicable building codes and regulations.
About the C23 — C23 License
A C23 (C23) licensed contractor in California is authorized to perform specialized work in their trade area. California's Contractors State License Board (CSLB) requires contractors in this classification to meet education, experience, and examination requirements before receiving their license. When hiring a C23 contractor, always verify their license is active and in CLEAR status, confirm they carry adequate insurance, and get a detailed written contract before work begins. Licensed contractors must maintain a $25,000 contractor bond and comply with all applicable building codes and regulations.
About the C29 — C29 License
A C29 (C29) licensed contractor in California is authorized to perform specialized work in their trade area. California's Contractors State License Board (CSLB) requires contractors in this classification to meet education, experience, and examination requirements before receiving their license. When hiring a C29 contractor, always verify their license is active and in CLEAR status, confirm they carry adequate insurance, and get a detailed written contract before work begins. Licensed contractors must maintain a $25,000 contractor bond and comply with all applicable building codes and regulations.
About the C33 — C33 License
A C33 (C33) licensed contractor in California is authorized to perform specialized work in their trade area. California's Contractors State License Board (CSLB) requires contractors in this classification to meet education, experience, and examination requirements before receiving their license. When hiring a C33 contractor, always verify their license is active and in CLEAR status, confirm they carry adequate insurance, and get a detailed written contract before work begins. Licensed contractors must maintain a $25,000 contractor bond and comply with all applicable building codes and regulations.
About the C35 — C35 License
A C35 (C35) licensed contractor in California is authorized to perform specialized work in their trade area. California's Contractors State License Board (CSLB) requires contractors in this classification to meet education, experience, and examination requirements before receiving their license. When hiring a C35 contractor, always verify their license is active and in CLEAR status, confirm they carry adequate insurance, and get a detailed written contract before work begins. Licensed contractors must maintain a $25,000 contractor bond and comply with all applicable building codes and regulations.
About the C36 — C36 License
A C36 (C36) licensed contractor in California is authorized to perform specialized work in their trade area. California's Contractors State License Board (CSLB) requires contractors in this classification to meet education, experience, and examination requirements before receiving their license. When hiring a C36 contractor, always verify their license is active and in CLEAR status, confirm they carry adequate insurance, and get a detailed written contract before work begins. Licensed contractors must maintain a $25,000 contractor bond and comply with all applicable building codes and regulations.
About the C51 — C51 License
A C51 (C51) licensed contractor in California is authorized to perform specialized work in their trade area. California's Contractors State License Board (CSLB) requires contractors in this classification to meet education, experience, and examination requirements before receiving their license. When hiring a C51 contractor, always verify their license is active and in CLEAR status, confirm they carry adequate insurance, and get a detailed written contract before work begins. Licensed contractors must maintain a $25,000 contractor bond and comply with all applicable building codes and regulations.
About the C54 — C54 License
A C54 (C54) licensed contractor in California is authorized to perform specialized work in their trade area. California's Contractors State License Board (CSLB) requires contractors in this classification to meet education, experience, and examination requirements before receiving their license. When hiring a C54 contractor, always verify their license is active and in CLEAR status, confirm they carry adequate insurance, and get a detailed written contract before work begins. Licensed contractors must maintain a $25,000 contractor bond and comply with all applicable building codes and regulations.
About the C60 — C60 License
A C60 (C60) licensed contractor in California is authorized to perform specialized work in their trade area. California's Contractors State License Board (CSLB) requires contractors in this classification to meet education, experience, and examination requirements before receiving their license. When hiring a C60 contractor, always verify their license is active and in CLEAR status, confirm they carry adequate insurance, and get a detailed written contract before work begins. Licensed contractors must maintain a $25,000 contractor bond and comply with all applicable building codes and regulations.
About the D06 — D06 License
A D06 (D06) licensed contractor in California is authorized to perform specialized work in their trade area. California's Contractors State License Board (CSLB) requires contractors in this classification to meet education, experience, and examination requirements before receiving their license. When hiring a D06 contractor, always verify their license is active and in CLEAR status, confirm they carry adequate insurance, and get a detailed written contract before work begins. Licensed contractors must maintain a $25,000 contractor bond and comply with all applicable building codes and regulations.
About the D16 — D16 License
A D16 (D16) licensed contractor in California is authorized to perform specialized work in their trade area. California's Contractors State License Board (CSLB) requires contractors in this classification to meet education, experience, and examination requirements before receiving their license. When hiring a D16 contractor, always verify their license is active and in CLEAR status, confirm they carry adequate insurance, and get a detailed written contract before work begins. Licensed contractors must maintain a $25,000 contractor bond and comply with all applicable building codes and regulations.
About the D28 — D28 License
A D28 (D28) licensed contractor in California is authorized to perform specialized work in their trade area. California's Contractors State License Board (CSLB) requires contractors in this classification to meet education, experience, and examination requirements before receiving their license. When hiring a D28 contractor, always verify their license is active and in CLEAR status, confirm they carry adequate insurance, and get a detailed written contract before work begins. Licensed contractors must maintain a $25,000 contractor bond and comply with all applicable building codes and regulations.
About the D62 — D62 License
A D62 (D62) licensed contractor in California is authorized to perform specialized work in their trade area. California's Contractors State License Board (CSLB) requires contractors in this classification to meet education, experience, and examination requirements before receiving their license. When hiring a D62 contractor, always verify their license is active and in CLEAR status, confirm they carry adequate insurance, and get a detailed written contract before work begins. Licensed contractors must maintain a $25,000 contractor bond and comply with all applicable building codes and regulations.
About the D65 — D65 License
A D65 (D65) licensed contractor in California is authorized to perform specialized work in their trade area. California's Contractors State License Board (CSLB) requires contractors in this classification to meet education, experience, and examination requirements before receiving their license. When hiring a D65 contractor, always verify their license is active and in CLEAR status, confirm they carry adequate insurance, and get a detailed written contract before work begins. Licensed contractors must maintain a $25,000 contractor bond and comply with all applicable building codes and regulations.
💡 Tips for Hiring a General Engineering Contractor
- Get multiple bids for large engineering projects
- Verify the contractor carries adequate liability insurance for the project scope
- Ask for references from similar completed projects
- Ensure all necessary permits are pulled before work begins
- Get a detailed written contract with project milestones and payment schedule
✅ Verify This License
Always verify contractor licensing directly with the Contractors State License Board (CSLB) before hiring. You can look up license #375620 to confirm it is active and check for any complaints or disciplinary actions.
Check on CSLB.ca.gov →🏢 Are you Knickelbein Builders?
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Claim This Page →Frequently Asked Questions
What does a Class A General Engineering license cover in California?
A Class A license covers projects requiring specialized engineering knowledge including roads, bridges, dams, pipelines, utilities, and other infrastructure work. It does not cover general building construction, which requires a Class B license.
Do I need a licensed General Engineering contractor?
Yes. California law requires any contractor performing engineering work valued at $500 or more to hold a valid CSLB license. Hiring an unlicensed contractor puts you at risk and may void your ability to file complaints with the CSLB.
What is the difference between a Class A and Class B contractor license?
A Class A (General Engineering) license covers infrastructure projects like roads, bridges, and utilities. A Class B (General Building) license covers building construction, remodeling, and structural work on homes and commercial properties.
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