A Guide to California Contractor CSLB License Classifications

TLDR: The Contractors State License Board (CSLB) in California regulates the construction industry and issues licenses to contractors in various classifications. These classifications cover a wide range of specialties and trades, including general engineering, general building, and specialty contracting. Contractors performing work exceeding $500 in labor and materials are generally required to have a CSLB license. At first, the types of licenses might be overwhelming, however, we have broken down all the different categories below and what tasks they generally do below!


The Contractors State License Board exists to protect those who hire contractors in California. It does so by by regulating the construction industry through ensuring that contractors are licensed and qualified. 

The primary functions of the CSLB include:

  • Licensing: The CSLB issues licenses to contractors in different classifications, such as general contractors, electricians, plumbers, landscapers, etc. These licenses ensure that contractors meet certain standards and qualifications in their respective fields.
  • License Enforcement: The CSLB investigates complaints and takes appropriate action against contractors who violate the law or fail to meet their contractual obligations. This includes pursuing disciplinary actions, such as license suspension or revocation, against those found guilty of misconduct.
  • Bond Enforcement: They ensure that California contractors are equipped with a $25,000 California contractor license bond. This bond exists to compensate customers in case there is financial harm caused by irresponsible contracting work.
  • Consumer Protection: The CSLB educates consumers about their rights and offers resources to help them make informed decisions when hiring contractors. They provide information on how to check a contractor's license status, verify insurance coverage, and understand contract terms.
  • Contractor Regulation: The CSLB sets and enforces regulations, such as the California Contractors License Law, to ensure that contractors operate ethically and professionally. They establish standards for contractor bonding, insurance, advertising, contracts, and other industry practices.
  • Industry Assistance: The CSLB offers support to licensed contractors by providing resources, training programs, and workshops to help them stay updated on industry standards, regulations, and best practices.

To carry out its responsibilities, the CSLB employs investigators, administrative staff, and legal professionals who work together to enforce licensing laws, investigate complaints, and ensure compliance with industry regulations. They collaborate with other governmental agencies, law enforcement, and consumer advocacy organizations to protect the public from unscrupulous or incompetent contractors.

Who needs a license from the CSLB

In California, contractors performing work that exceeds $500 in labor and materials are typically required to have a license from the CSLB. This requirement applies to both general contractors and subcontractors in various construction trades, including but not limited to:

  • General Engineering Contractors: Those who are involved in projects such as roads, highways, bridges, tunnels, and dams.
  • General Building Contractors: Individuals or businesses involved in constructing or remodeling residential and commercial structures.
  • Specialty Contractors: This category covers specialized trades such as electrical, plumbing, HVAC (heating, ventilation, and air conditioning), roofing, landscaping, flooring, painting, and more.

CSLB Licensing Classifications

The CSLB has different classifications that depend on the nature of the work the contractors do and their areas of expertise. Below is a guide to the different licesing classifications.

(A) General Engineering Contractor

A general engineering contractor is a professional or business entity that specializes in performing construction work related to engineering projects. There are 5475 licensed general engineering contractors in California which makes up 2% of the contractors. They are typically involved in the construction, alteration, and repair of infrastructure projects. This includes roads, highways, bridges, tunnels, dams, and similar structures. General engineering contractors are equipped with the knowledge and expertise to manage and oversee large-scale projects that involve significant engineering aspects and divisions like the following:

  • Irrigation
  • Drainage
  • Water power
  • Water supply
  • Flood control
  • Inland waterways
  • Harbors
  • Docks and wharves
  • Shipyards and ports
  • Dams and hydroelectric projects
  • Levees
  • River control and reclamation works
  • Railroads
  • Highways
  • Streets and roads
  • Tunnels
  • Airports and airways
  • Sewers and sewage disposal plants and systems
  • Waste reduction plants
  • Bridges
  • Overpasses 
  • Underpasses
  • Pipelines
  • Parks 
  • Refineries
  • Chemical plants
  • Power plants 
  • Mines and metallurgical plants
  • Land leveling and earthmoving projects 

The general engineering contractor license covers a number of professions and it is important to get an understanding of whether the nature of your work falls within this category. If you are looking to become a contractor and are unsure whether or not you will fall under the class A license, you should contact the CSLB for further guidance. 

Here's an example to illustrate the role of a general engineering contractor:

Example: ABC Construction Company is a general engineering contractor based in California. They have extensive experience in managing and executing infrastructure projects. Recently, they were awarded a contract to construct a new bridge over a major river. As a general engineering contractor, ABC Construction Company is responsible for overseeing the entire project, including planning, designing, obtaining permits, managing subcontractors, ensuring compliance with safety regulations, and completing the construction of the bridge within the specified timeline and budget.

(B) General Building Contractor

A general building contractor, also known as a general contractor or builder, is a professional who oversees and manages construction projects. This is the second biggest category of contractors in California, with 76,056 licensed contractors. This makes up 32% of all licensed contractors in the state. In California, a general building contractor is licensed and qualified to handle various types of construction work, including residential, commercial, and industrial projects.

Here are some key responsibilities and tasks performed by a general building contractor in California:

  • Project Management: General building contractors are responsible for the overall management of a construction project. This including planning, scheduling, and coordination.
  • Estimating and Bidding: Contractors analyze project requirements, create cost estimates, and submit bids to clients or project owners.
  • Hiring and Supervising Subcontractors: General contractors often hire and manage subcontractors such as electricians, plumbers, carpenters, and other specialized tradespeople.
  • Material Procurement: They are responsible for procuring and managing the necessary construction materials, ensuring they meet project specifications and quality standards.
  • Obtaining Permits: Contractors navigate the complex process of obtaining building permits and complying with local building codes and regulations.
  • Construction and Execution: General contractors oversee the actual construction process, ensuring work progresses smoothly, coordinating activities, and resolving any issues that arise.
  • Quality Control and Inspections: They perform regular inspections to ensure that the work is being carried out according to plans and specifications, and that quality standards are met.
  • Budget and Cost Control: General contractors manage project budgets, track expenses, and make adjustments to control costs and maintain profitability.
  • Communication and Client Relations: They serve as the primary point of contact for clients, keeping them informed about project progress, addressing concerns, and
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(C) Specialty Contractors

In California, a specialty contractor is a professional who specializes in a specific trade or aspect of construction. This is the biggest class of contractors in California making up 52% of all the contractors. Unlike a general contractor who manages the overall construction project, a specialty contractor focuses on a particular area of expertise. They typically work under a general contractor or directly with clients, depending on the scope and nature of the project.

We will cover the major specializations below. The below list are the most common specialty contractor licenses by license count.

C-10 - Electrical Contractor

The C-10 Electrical Contractor license is the largest specialization in the specialty contractor category. They make up 7% of all contractors in California and have 17,666 contractors in total. It is a big class with a lot of potential. An electrical contractor places, installs, erects or connects items that generate, transform or utilize electrical energy like the following:

  • Electrical wires
  • Fixtures
  • Appliances
  • Apparatus
  • Raceways
  • Conduits
  • Solar photovoltaic cells

Here's an overview of what an electrical contractor typically does with a C-10 license:

  • Electrical Installations: C-10 contractors are responsible for installing electrical systems in various construction contexts. This includes wiring, switches, outlets, circuit breakers, lighting fixtures, and other electrical components.
  • Electrical Repairs: They diagnose and repair electrical problems in existing electrical systems. This can involve troubleshooting issues such as power outages, faulty wiring, circuit overloads, or malfunctioning electrical equipment.
  • Electrical Upgrades: C-10 contractors handle electrical upgrades and improvements to meet safety standards, code compliance, or specific client requirements. This may involve upgrading electrical panels, replacing outdated wiring, installing energy-efficient lighting, or adding additional electrical circuits.
  • Electrical Maintenance: They perform routine maintenance tasks on electrical systems to ensure their proper functioning and longevity. This can include inspecting electrical components, testing electrical equipment, cleaning electrical connections, and identifying potential hazards or issues.
  • Electrical Design and Planning: C-10 contractors may assist in the design and planning phase of electrical systems for construction projects. They work with architects, engineers, and other professionals to ensure that electrical systems are designed efficiently, safely, and in compliance with building codes.
  • Safety and Compliance: Electrical contractors prioritize safety and ensure compliance with electrical codes and regulations. They must follow industry standards and best practices to ensure that electrical installations and repairs meet relevant safety requirements.

It's important to note that electrical contractors must have a deep understanding of electrical theory, wiring methods, electrical codes, and safety practices. They are responsible for ensuring that electrical systems are installed, repaired, and maintained correctly to provide reliable and safe electrical power to buildings and structures.

C-33 - Painting and Decorating Contractor

C-33 Painting and decorating contractors are the second largest specialization in the specialty contractor class. They make up 5% of all lisenced contractors on California and consist of 12,450 contractor in total. A C-33 contractor specializes in providing painting and decorating services for residential, commercial, and industrial properties. They are skilled in surface preparation, paint application, and finishing techniques. Here is an overview of what they do.

Here's an overview of what a C-33 contractor typically does:

  • Surface Preparation: C-33 contractors prepare surfaces for painting and decorating. This includes tasks such as sanding, scraping, filling cracks or holes, and applying primers to ensure a smooth and even surface for paint application.
  • Paint Application: They are skilled in applying various types of paints. This includes interior and exterior paints, enamel, latex, oil-based paints, and specialty coatings. C-33 contractors use brushes, rollers, sprayers, or other application methods to achieve the desired finish and coverage.
  • Decorative Finishes: C-33 contractors may also specialize in decorative finishes such as faux painting, texture coating, wallpaper installation, or specialty wall coverings. They have expertise in techniques such as glazing, ragging, sponging, stenciling, or mural painting to create unique decorative effects.
  • Color Consultation: C-33 contractors may provide color consultation services to clients, assisting them in selecting appropriate paint colors, finishes, and coordinating color schemes to achieve the desired aesthetic and ambiance.
  • Surface Repair: They perform minor surface repairs, such as patching damaged drywall, repairing wood surfaces, or addressing other surface imperfections before painting.
  • Protective Coatings: C-33 contractors apply protective coatings, such as sealants or weatherproofing coatings, to protect surfaces from moisture, UV damage, or other environmental factors.

C-36 - Plumbing Contractor

A C-36 plumbing contractor specializes in the installation, repair, and maintenance of plumbing systems. Plumbing systems include water supply, drainage, and gas systems in residential, commercial, and industrial buildings. There are currently 10,503 licensed plumbing contractors in California making it one of the biggest license categories in the state. Here's an overview of what a C-36 contractor typically does:

  • Plumbing Installations: C-36 plumbing contractors install plumbing systems in new construction or renovation projects. This includes installing pipes, fixtures, valves, and fittings for water supply lines, drainage systems, and gas lines.
  • Fixture Installation: They install various plumbing fixtures, such as sinks, toilets, showers, bathtubs, faucets, and water heaters. C-36 plumbing contractors ensure proper connections, sealing, and functionality of these fixtures.
  • Piping Systems: They work with different types of piping materials, including copper, PVC, PEX, and galvanized steel. C-36 plumbing contractors install and connect pipes for water supply, drainage, and gas systems, ensuring proper sizing, slope, and alignment.
  • Drainage Systems: C-36 plumbing contractors design and install drainage systems to ensure the efficient removal of wastewater and prevent plumbing issues. This includes installing drainage pipes, traps, vents, and sewer lines.
  • Water Supply Systems: They install water supply lines, including pipes, valves, and fixtures, to provide clean and potable water to various parts of a building. C-36 plumbing contractors ensure proper water pressure, flow, and distribution.
  • Plumbing Repairs: C-36 plumbing contractors diagnose and repair plumbing issues, such as leaks, clogs, or damaged pipes. They use appropriate tools and techniques to address the problem and restore proper plumbing function.
  • Plumbing Maintenance: They perform routine maintenance tasks on plumbing systems, such as inspecting pipes, checking for leaks, and maintaining water heaters. C-36 plumbing contractors ensure the ongoing functionality and efficiency of plumbing systems.

C-27 - Landscaping Contractor

A C-27 landscaping contractor specializes in the planning, installation, and maintenance of landscaping and related outdoor features. They work on both residential and commercial projects, creating attractive and functional outdoor spaces. There are 8569 landscape contractors in California. A lanscape contractor does the following.

  • Landscape Design: C-27 landscaping contractors may offer landscape design services, working with clients to create a plan that incorporates their preferences, site conditions, and budget. They consider elements such as plant selection, hardscape features, irrigation systems, and outdoor lighting.
  • Planting and Turf Installation: They install plants, trees, shrubs, flowers, and lawns to create visually appealing landscapes. This involves preparing the soil, selecting appropriate plant species, and ensuring proper planting techniques for healthy growth.
  • Irrigation Systems: C-27 landscaping contractors design and install irrigation systems to provide water to plants efficiently and effectively. This includes selecting and installing sprinklers, drip irrigation systems, controllers, and ensuring proper water distribution and drainage.
  • Hardscape Construction: They construct hardscape features such as pathways, patios, decks, retaining walls, fences, pergolas, and outdoor structures. C-27 landscaping contractors work with various materials, such as stone, concrete, wood, or composite materials, to create functional and aesthetically pleasing outdoor spaces.
  • Grading and Drainage: C-27 landscaping contractors address grading and drainage issues to ensure proper water flow and prevent erosion or water damage. They may regrade the landscape, install drainage systems, or create swales and berms to manage water runoff.
  • Outdoor Lighting: They install outdoor lighting systems to enhance the aesthetics, safety, and functionality of outdoor spaces. This can include pathway lighting, accent lighting, security lighting, or decorative lighting features.
  • Landscape Maintenance: C-27 landscaping contractors may provide ongoing landscape maintenance services, including lawn mowing, trimming, pruning, fertilizing, weed control, and seasonal clean-up. They help to keep the landscape healthy, attractive, and well-maintained.
  • Water Features: They may design and install water features such as ponds, fountains, or waterfalls to add beauty and tranquility to outdoor environments.
  • Sustainable Landscaping: C-27 landscaping contractors may promote sustainable landscaping practices, such as water-efficient irrigation systems, drought-tolerant plant selections, native plantings, and eco-friendly landscaping materials.

C-2 - Insulation and Acoustical Contractor

In California, a C-2 classification is a contractor's license designation specifically for Insulation and Acoustical contractors. A C-2 contractor specializes in insulation and acoustical work for both residential and commercial buildings. They are responsible for installing insulation materials and implementing soundproofing measures to enhance thermal efficiency and control noise within a structure. Here's an overview of what a C-2 contractor typically does:

  • Insulation Installation: C-2 contractors install various types of insulation materials to improve energy efficiency and regulate temperature within buildings. This includes installing insulation in walls, ceilings, attics, floors, and other areas where heat transfer occurs.
  • Insulation Material Selection: They assess the building's needs and recommend appropriate insulation materials such as fiberglass, cellulose, foam, or reflective insulation. The selection depends on factors like the building's construction, climate, and desired insulation properties.
  • Vapor Barrier Installation: C-2 contractors install vapor barriers, which are protective layers that prevent moisture intrusion into the building envelope. Vapor barriers help control condensation and moisture-related issues.
  • Soundproofing: Acoustical work is another aspect of a C-2 contractor's specialization. They implement measures to reduce noise transmission between rooms or from external sources. This may involve installing soundproofing materials, such as acoustic panels, insulation, resilient channels, or sound-dampening systems.
  • Fireproofing: In some cases, C-2 contractors may also handle fireproofing installations. They apply fire-resistant materials or coatings to structural elements to enhance fire safety and compliance with building codes.
  • Energy Efficiency Consulting: C-2 contractors may provide advice on improving energy efficiency within a building. They can suggest insulation upgrades, air sealing measures, and other strategies to reduce energy consumption and lower utility costs.

It's important to note that while a C-2 contractor specializes in insulation and acoustical work, they may subcontract other trades for related tasks such as electrical work, carpentry, or drywall installation, depending on the specific project requirements.

C-4 - Boiler, Hot Water Heating and Steam Fitting Contractor

A C-4 contractor specializes in the installation, repair, and maintenance of boilers, hot water heating systems, and steam-related equipment. Here's an overview of what a C-4 contractor typically does:

  • Boiler Installation and Repair: C-4 contractors are responsible for installing and repairing boilers in various types of buildings, including residential, commercial, and industrial. They ensure proper sizing, placement, and connection of boilers to meet heating requirements.
  • Hot Water Heating Systems: C-4 contractors work with hot water heating systems, including hydronic heating systems. They install and repair components such as boilers, piping, radiators, baseboard heaters, and other equipment involved in hot water circulation for heating purposes.
  • Steam Fitting: C-4 contractors specialize in steam fitting, which involves working with steam-based systems. They install, repair, and maintain steam boilers, pipes, valves, steam traps, and other steam distribution components. This can include steam heating systems or industrial applications that utilize steam for various processes.
  • System Inspection and Testing: C-4 contractors conduct inspections and tests on boilers, hot water heating systems, and steam-related equipment to ensure they are functioning safely and efficiently. This includes checking for leaks, pressure testing, combustion analysis, and verifying proper operation of safety controls.
  • Maintenance and Servicing: C-4 contractors perform routine maintenance and servicing of boilers, hot water heating systems, and steam equipment. They clean components, check for corrosion or wear, replace faulty parts, and perform necessary adjustments to ensure optimal performance and prevent breakdowns.

C-5 - Framing and Rough Carpentry Contractor

A C-5 contractor specializes in structural framing and rough carpentry work during the construction of buildings. They are responsible for the initial stages of construction, which involve creating the framework and structural components of a structure. Here's an overview of what a C-5 contractor typically does:

  • Structural Framing: C-5 contractors are skilled in framing buildings, which involves constructing the skeletal structure or framework. This includes setting up the primary structural components such as walls, floors, roofs, and partitions using wood, steel, or other framing materials.
  • Rough Carpentry: C-5 contractors perform rough carpentry work, which involves the installation of structural elements and components. They work on tasks such as erecting wall and roof framing, installing beams, columns, trusses, and joists, and creating structural supports and bracing.
  • Blueprint Interpretation: C-5 contractors are proficient in reading and interpreting construction blueprints and specifications. They understand the architectural and engineering plans to ensure accurate framing and compliance with design requirements.
  • Material Selection: C-5 contractors choose appropriate framing materials based on project specifications and local building codes. This includes selecting and procuring lumber, engineered wood products, metal framing components, or other materials required for framing and rough carpentry work.
  • Layout and Measurement: C-5 contractors accurately measure and lay out the framework according to construction plans. This involves marking positions for walls, openings, stairs, and other structural elements, ensuring precise alignment and proper spacing.

C-20 - Warm-Air Heating, Ventilating and Air-Conditioning Contractor

A C-20 HVAC/AC contractor specializes in the installation, repair, and maintenance of HVAC systems. Here's an overview of what a C-20 HVAC/AC contractor typically does:

  • Heating Systems: C-20 HVAC/AC contractors install, repair, and maintain heating systems, including furnaces, boilers, heat pumps, and other heating equipment. They ensure proper sizing, ductwork, and ventilation to provide efficient and comfortable heating.
  • Air Conditioning Systems: They handle the installation, repair, and maintenance of air conditioning systems, including central air conditioning units, ductless mini-split systems, rooftop units, and other cooling equipment.
  • Ventilation Systems: C-20 HVAC/AC contractors work with ventilation systems, which involve the circulation and exchange of air within a building. They install and maintain ventilation equipment such as fans, ductwork, and air filters to ensure proper indoor air quality and fresh air exchange.


The CSLB in California regulates the construction industry and issues licenses to contractors in various classifications. These classifications cover a wide range of specialties and trades, including general engineering, general building, specialty contracting, and more. Each classification represents a specific area of expertise and defines the scope of work a contractor is qualified to perform. This article provides an overview of the different CSLB licensing classifications, including examples such as insulation and acoustical contractor (C-2), roofing contractor (C-39), and ceramic and mosaic tile contractor (C-54), among many others. While the list may seem extensive, we hope this information has helped shed light on the topic, allowing you to make an informed decision if you're considering a career as a contractor in California.