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what can you do with a C-4 boiler contractor license in California

What Can You Do With a C-4 License in California?

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What Can You Do With a C4 Contractor’s License?

The C-4 license is a California contractor classification for individuals or companies that specialize in boiler, hot-water heating, and steam fitting services. 

There are a variety of services that can be offered if you have this license, including:

  • Demolishing and Removing existing boilers
  • 24/7 Emergency Service / Monthly Monitoring
  • Hotel Steam Boilers
  • Promoting lighter carbon footprint, maximizing fuel efficiency, lowering operating capital costs, recovering facility resources in production processes
  • Furnishing and Installing Equipment, Selling Equipment, Continued maintenance
  • Certified Welders, Pipe Fitters, Electricians, Electronic Technicians
  • Boiler Troubleshooting
  • AQMD Compliance Testing, Energy Audits, Preventative Maintenance
  • Advanced Mechanical Systems
  • Installation and Engineering
  • Radiant Panel Design & Engineering
  • Boiler Dynamics, Repair, Burners, and Controls
  • Radiant Heat Systems / Heat Services
  • Heat Transfer Solutions
  • Boiler Rentals
  • Energy Services
  • Hydronics/Boiler Works/Hydronic baseboard retrofits
  • Pressure Tests
  • Boiler Services

Boiler Contractors and the CSLB

The C-4 Boiler, Hot-water heating, and steam fitting license is one of 73 contractor licenses available in California. Contractors in the state of California are governed by the CSLB (Contractors State License Board)

There are 4 major classification categories:

Commonly referred to as the “C-4 License”, this classification falls under the C-Specialty category.


Expanding your Boiler Construction and Repair Business in California

Contractors in California can hold multiple licenses. The most common pairings for the C-4 contractor license are typically:


what can you do with a C-4 boiler license in California

CSLB Requirements for C-4 Contractors 

To get a C-4 license you must meet the following basic requirements:

  • 18 Years of Age
  • 4 Years of Journeyman Level Experience
  • Social Security or ITIN #
  • Not Currently on Probation or Parole
  • Signature from a licensed contractor, fellow employee, supervisor, or business associate 


What boiler installation and repair concepts do I need to know for the test?

It is extremely important to understand that the whole point of being a contractor is to protect the consumer public. 

Ultimately the CSLB’s goal is to make sure that you understand how to perform your trade safely and run a profitable business.

Luckily, you can be brought up to speed on these topics, so you can pass with ease.


The examination will be 5 parts.

1. Planning and Estimation (19%)

  • Plan boiler projects
  • Estimate boiler projects

2. Boiler System Removal, Preparation, and Installation (33%)

  • Remove old boiler systems
  • Prepare job site for new boiler systems
  • Install new boiler systems
  • Test and complete boiler systems

3. Specialty Boiler Installation (11%)

  • Commercial boiler systems
  • Industrial boiler systems
  • School and hospital boiler systems
  • Residential hydronic boiler systems

4. Boiler System Maintenance, Repair, and retrofit (15%)

  • Maintain boiler systems
  • Repair boiler systems
  • Retrofit boiler systems

5. Safety (22%)

  • Personnel safety
  • Job site safety
  • Confined space work
  • Dangerous materials

What’s the exam process like?

The exam will be:

  • 115 Questions Law & Business
  • 115 Questions Boiler, Hot-water heating, and Steam fitting
  • Multiple Choice
  • Closed Book
  • 3 Hours to Complete each section
  • Taken via Computer at a CSLB Testing Facility
  • Exam Centers in: Berkeley, Fresno, Norwalk, Oxnard, Sacramento, San Bernardino, San Diego, and San Jose

Math Skills 

There will be math on your CSLB law & business exam.

It is important to remember that questions will be presented to you as if you are a General Building Contractor with multiple projects running simultaneously with several employees.

You can expect math questions related to:

  • Arithmetic
  • Cost Estimation 
  • Calculating Square Footage
  • Units of Measurement
  • Percentages and Decimals

Preparing for Your CSLB law & business exam

Our complete course breaks down all of the essential knowledge you need to be successful on your CSLB law & business examination.

In addition to passing your exam, you will also be equipped with valuable knowledge that will give you a crash course in how to run a contracting business effectively and profitably.

You will learn:

  • Company organization 
  • How to bid effectively
  • Understanding cost control
  • Various contract types
  • Cash management
  • Estimation fundamentals
  • CAL/OSHA
  • Business Structures
  • Worker’s Compensation and Taxes
  • Insurance Types in Construction
  • Labor Laws and Employee Rights
  • Hiring and Firing Practices
  • Contractor Bonds
  • Mechanics Liens
  • State Laws and Statutes
  • Project Management 101
  • Prevailing Wages and Public Works
  • And Much More!