how to get your C-4 license in California for boilers, hot-water heating, and steam fitting

How To Get Your C-4 License Fast! #1 Online Guide

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What is a C-4 Boiler, Hot-Water Heating, and Steam Fitting Contractor ?

Anyone charging over $500 in California for jobs associated with: 

Boiler, under the sink and or hot water heating, steam/pipe fitting, and solar heating construction, maintenance, or repair projects must have the C-4 License.

The tradesman that get this license may have job titles such as:

  • Pipe fitters 
  • Steamfitters
  • Boiler heater technicians 
  • Heating service specialists 
  • Boiler contractors 

  • Boiler Operator
  • Water Heater Technician
  • Boiler Engineer
  • Steam Boiler Engineers

Typical Duties associated with the C-4 Boiler License

A boiler hot water heating system. Boiler contractors engage in a wide range of activities associated with hot water heating systems

​​​​Contractors specializing in boiler heater and hot water heating systems provide a critical service to homeowners, especially around the winter months.

Boiler Contractors that are professional and licensed can build an incredibly lucrative business in a multi-billion dollar industry. 

Generally, a boiler contractor's job duties can include:

  • Installing and Maintaining Hot Water Heating Systems
  • Repairing and Installing Commercial and Residential Hydraulic Systems
  • Low and High Steam Pressure Boilers
  • Electric Steam Boilers
  • Installing Steam Piping, Pressure Piping and Metal Flues
  • Making Estimating and Cost Calculations
  • Testing and Trouble Shooting Existing Hot Water Heating Systems
  • Working with Fire-tube and steel power boilers, 
  • Valves, gauges, pumps, radiators, convectors, fuel oil tanks, fuel oil lines, chimneys, heat insulation, and solar heating equipment

Get Online Practice Exams and Study Guides

Working as a Subcontractor?

Due to the service-based nature of the Hot-water heating systems industry, most boiler contractors work directly with homeowners or businesses.

However, in some cases, they may function as a subcontractor to a General B or General A as part of a larger construction project. 

A General Contractor would be in charge of finding someone with the C-4 license to execute a portion of the construction process that includes constructing or repairing a hot water heating system. 

C-4 Boiler Contractor License Requirements

To receive an exam date with the CSLB you must meet the following requirements:

  • Be at least 18 Years of Age
  • Valid Driver's License or USA Identification
  • Social Security OR ITIN Number
  • Cannot Currently be on Probation or Parole

You must also have:

  • 4 Years Journeyman Level Experience
  • Signature from a Qualifying Individual
  • Proof of experience if the state requests

Journeyman Level Experience

an industrial boiler system. boiler contractors looking to get the C-4 license must have 4 years journey level experience

Journeyman-level experience means that you have worked unsupervised full time for a boiler company, a contractor with the C-4 License, or a union.

The Contractors State License Board will want to see four full-time years over the last ten years.

The years do not need to be consecutive, but they do need to be four years in total. 

Signature of a Qualifying Individual

A qualifying individual is someone other than yourself who can confirm your experience.

This person can be either a:

  • Licensed General Contractor
  • Licensed Boiler, Hot-Water Heating Systems or Steam Fitting Contractor (C-4 License)
  • Fellow or Former Employee (within the last 10 years)
  • Foreman or Supervisor
  • Business Associate
  • Fellow Journeyman

Whoever you choose to be your qualifying person must include their information and a brief description of your experience.

The main areas of expertise a Boiler Contractor needs to have experience in are:

  • Repairing and Installing Commercial and Residential Boiler and Hot-Water Heating Systems
  • Steam fitting and pipe fitting
  • Retrofitting Boiler Systems
  • Estimating and Planning Boiler Projects
  • Safety

Proving Your Work Experience When Applying for the C-4 License

You must be prepared to submit documentation supporting the experience you claim to have.

The Contractors State License Board gives you many ways to prove your experience including:

  • Tax Returns
  • Check Stubs
  • Contracts
  • Material Order Invoices or Receipts

The CSLB  receives thousands of applications per month so there is a good chance they won’t document your experience but if you are one of the applicants that get reviewed you will need to be ready to submit something. 

The CSLB does not accept pictures of projects.

Blueprint Reading Skills

image features a blueprint with a yellow pencil and ruler laying on top. boiler contractors looking to get the C-4 license should know how to read blueprints

It is essential for boilers, Hot Water Heating, and Steam Fitting contractors to be able to follow specific designs on construction blueprints. 

Read plans and drawings may be required to complete the hot water systems installation process of a construction project. 

Boiler contractors that aspire to hold a General Contractor License in the future will surely want to make sure their blueprint reading skills are up to par.

Check out this Blue Print Reading Course for a basic introduction to the concepts you will want to know about.

EPA Certification for Lead Safety

logo of the united states environmental protection agency

Understanding how to safely contain lead-based paint when altering structures built before 1978 is required by the Environmental Protection Agency.

The most profitable contractors are ones that position themselves as the experts and are the most knowledgeable and helpful to their clients.

Becoming EPA Certified is important for boiler contractors and can be completed in a one-day, 8-hour course.

Staying EPA compliant is not only important to the survival of your business but also the safety of your customers.  

For a complete guide on how to get the EPA Certification, check out this article.

Application Processing, Fees, and Criminal History

The time it takes to get your application processed and assigned a test date fluctuates throughout the year.

Typically you can expect:

  • 6-8 Week Application Processing Time
  • 3-4 Week wait for an Exam date

I have seen some situations where applicants got their test date sooner and somewhere they got their test date much later.

The most common reasons your application would get held up are:

  1. Time of year (processing time slows down during the holidays) 
  2. Criminal History 
  3. Proving Experience
  4. Mistakes on your application 

CSLB License Fees
  • State Application Fee – $330 

Can you get a Contractors License with a Felony in California?
a picture of a wooden gavel. when applying for the scaffold contractor license, you should be 100% honest about your criminal history because you will be required to do a background check

Having a criminal record in no way stops you from getting a C-4 License. I have personally helped guys with all types of criminal records obtain multiple licenses.

The key is, to be honest on the application, even if the felony or misdemeanor happened years ago and even if it was expunged.

BE 100% HONEST ON THE APPLICATION, because they will see everything anyway when you do fingerprinting.

The CSLB handles criminal records on a case-by-case basis. Remember, their responsibility is to protect the public. In my experience, they are primarily concerned with criminal charges associated with:

  • Fraud
  • Embezzlement 
  • Forgery 

In the state of California, you are required to divulge any criminal charges when applying for any state license even if they have been expunged.

You will need to be prepared to submit anything they ask for regarding your criminal history. 

Contractor License Exam: C-4 Boiler License

Contractor licenses are broken down into four categories:

1) A-General Engineering                            (LAW + TRADE )

2) B-General Building                                     (LAW + TRADE)

3) C-Specialty Classes                                    (LAW + TRADE)

4) C-61/D- Limited Specialty                     (LAW TEST ONLY)

The C-4 License Exam consists of two parts:

  • 115 Questions on Contractor LAW 
  • 115 Questions on Boiler, Hot-water heating, and steam fitting
  • 3 Hours To Complete Each Portion
  • Closed Book Exam

Recommended Courses

The Boiler, Hot Water Heating, and Steam Fitting (C-4) Examination is divided into four major sections:

Planning and Estimation (19%)

  • Plan boiler projects
  • Estimate boiler projects

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

Specialty Boiler Installation (11%)

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

Boiler Systems Maintenance, Repair, and Retrofit (15%) 

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

Safety (22%)

CSLB Test Locations

logo of the CSLB, which is the governing agency for contractors in the state of california. Contractor license law is essentially set by the CSLB

  • Berkeley
  • Fresno
  • Norwalk
  • San Jose

  • Oxnard
  • Sacramento
  • San Bernardino
  • San Diego

  • You have 18 months after your application is accepted to pass both examinations
  • You must wait 3 weeks to re-take the exam. $60 Per Re-take
  • You must score 70% or more

What is on the Law & Business portion of the Boiler, Hot-water heating and steam fitting Contractor License exam?

California Contractors License Exam Prep

A pressure clock commonly used by boiler contractors

  • The questions you will see on the exam may use outdated terms

  • Processes may be completely different from how things are done on the job site

  • You will see questions about things you may have never done before

  • Questions will be presented to you as if you are running a large scale construction business with several
  • employees and jobs happening all at once. 

Thousands of construction professionals from various backgrounds, trades and experience levels get licensed in California each year.

The truth is that most are startled by how different the subject matter on the state exam is from their years of first-hand experience. 

Be as prepared as you possibly can.

Studying just 15 minutes a day consistently can dramatically increase your chances of passing the test on your first try.

Focus on and study ONLY the information that you need to pass the C-4 License exam.

Construction Apprenticeships

Construction apprenticeships are an excellent way to get into the industry

If you don’t have the four years required journeyman level experience to obtain a Boiler Contractor License, not to worry.

Your journey begins here.

Construction is a trillion-dollar industry and highly skilled tradesmen are always in demand.

Whether you are completely new or have some experience already, there are resources available to you

Generally, someone looking to become a boiler contractor would want to look into a boilermaker apprenticeship program.

For a detailed explanation of this process, check out my article: Apprentice vs Journeyman!

OSHA Certification

Statistically, 21% of all work-related fatalities are in construction.

That equals about 1 and 5 worker deaths on average. In the construction industry, the leading cause of worker deaths is reported as:

  • Falls
  • Struck by an object
  • Electrocution
  • Caught-in/Between

Getting OSHA certified can help you greatly in getting the boiler license, learn more about getting an OSHA Safety Certification 


Getting the C-4 License can be a huge step up in your career if you are looking to start your own boiler heater company or become an RMO

The key is to take action and follow these steps from beginning to end. 

If you have found this article helpful feel free to drop a comment below and be sure to check back for updates!