Ironworkers erecting a structural steel building frame

Become a Licensed C-51 Structural Steel Contractor

The C-51 Structural Steel classification covers the contractors who fabricate and erect the steel skeletons, columns, beams, and frames, that hold up California's buildings and structures.

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Requirements

Minimum age: 18+ is CSLB's normal applicant path. A minor may qualify only after a court appoints a guardian (BPC §7065.5)
Experience required: 4 full-time-equivalent years of journey-level experience within the past 10 years; CSLB prorates part-time work
Contractor bond: $25,000

About the Exam

Exam format: 2 parts (Law & Business + Trade)
Law & Business exam: 115 questions
School-observed scores: 65% Law / 68% Trade; not published as fixed by CSLB
Application fee: $450

License renews every 2 years. Governing code: CCR §832.51

About this classification

What does a C-51 Structural Steel contractor do?

Under California Code of Regulations (Title 16, §832.51), a C-51 Structural Steel Contractor "fabricates and erects structural steel shapes and plates, of any profile, perimeter or cross-section, that are or may be used as structural members for buildings and structures, including the riveting, welding, rigging and metal roofing systems necessary." This license allows you to build the load-bearing steel frame of a structure.

The C-51 covers the visible steel skeleton, columns, beams, girders, mezzanines, and pre-engineered metal buildings, and the riveting, welding, and rigging needed to erect it. C-51 contractors self-perform the welding required for structural steel connections.

Official source: CSLB C-51 classification · CSLB fee schedule Last reviewed: March 2026

Scope of work

Fabricating structural steel shapes and plates
Erecting columns, beams, and girders
Steel building frames and pre-engineered metal buildings
Steel mezzanines and stairs
Industrial pipe racks and platforms
High-strength bolting and welded connections
Rigging and hoisting of structural members
Metal roofing systems necessary to the structural work

Important notes

The C-51 covers structural steel shapes and plates used as structural members; the rebar and mesh embedded inside concrete is C-50 (Reinforcing Steel) work.
A C-51 contractor self-performs the welding necessary for structural steel, the riveting and welding to erect the frame is part of the C-51 scope and does not require a separate C-60. The standalone C-60 (Welding) classification is for welding performed as its own trade.
The C-51 covers structural members; architectural and decorative metalwork, ornamental railings, bronze doors, decorative iron, is C-23 (Ornamental Metal) work.
On large infrastructure fixed works, structural steel may be erected under an A (General Engineering) prime; the structural-steel trade itself is the C-51.
Projects over $1,000 (labor and materials combined) require a license, and all licensees must carry workers' compensation coverage.

The CSLB exam

What's on the C-51 Structural Steel exam?

California requires you to pass a two-part CSLB exam: the Law & Business exam (the same for every classification) and the C-51 Structural Steel trade exam. CSLS has observed scores of 65% for Law & Business and 68% for the C-51 trade exam. CSLB does not publish fixed passing scores and may vary them by exam version.

Law & Business

Same for all classifications

115 questions, multiple choice, computer-based
3.5 hours allotted
Topics: California contractor law, business management, safety, estimating, project management

C-51 Trade Exam

Structural Steel-specific

about 100 questions, multiple choice, computer-based
3.5 hours allotted
Topics: structural steel fabrication, erection sequencing, welded and bolted connections, rigging and hoisting, steel detailing, blueprint reading, safety

How to Get Your C-51 Structural Steel License

Step 1

Qualify

18+ is CSLB's normal applicant path. A minor may qualify only after a court appoints a guardian (BPC §7065.5). You also need a valid SSN/ITIN and 4 full-time-equivalent years of journey-level structural steel experience within the past 10 years; CSLB prorates part-time work. Up to 3 years may be substituted with approved education or apprenticeship.

Step 2

Apply to CSLB

Submit your application, get fingerprinted, and pay the $450 application fee. Processing times vary; check the CSLB's current processing times.

Step 3

Study & Prepare

Prepare for both exam parts, on your own or with a CSLS exam prep program. 99% of CSLS students pass on their first try, backed by our 100% Money-Back Guarantee.

Compare programs

Step 4

Pass the Exam

Two parts: Law & Business (115q, 3.5 hrs) + C-51 Trade. Multiple choice, computer-based. CSLS has observed scores of 65% Law & Business / 68% C-51 Trade; CSLB does not publish fixed passing scores and may vary them by exam version.

Step 5

Get Licensed

Post your $25,000 contractor bond, pay the $200 license fee, and receive your C-51 license. You're officially in business.

Step 1

Qualify

Step 2

Apply to CSLB

Submit your application, get fingerprinted, and pay the $450 application fee. Processing times vary; check the CSLB's current processing times.

Step 3

Study & Prepare

Prepare for both exam parts, on your own or with a CSLS exam prep program. 99% of CSLS students pass on their first try, backed by our 100% Money-Back Guarantee.

Compare programs

Step 4

Pass the Exam

Step 5

Get Licensed

Post your $25,000 contractor bond, pay the $200 license fee, and receive your C-51 license. You're officially in business.

Exam Prep Programs

Compare C-51 Structural Steel Exam Prep Programs

Every program prepares you for the required CSLB exam for C-51 Structural Steel. Our 99% first-time pass rate is backed by the 100% Money-Back Guarantee on eligible programs.

Feature-by-feature comparison of all four CSLS exam prep programs
Features	Most Popular All-Inclusive C-51 Structural Steel $1,195.00 Value: $2,500	Live Online C-51 Structural Steel $695.00 Value: $995	Crash Course C-51 Structural Steel $495.00 Value: $695	Home Study C-51 Structural Steel $295.00 Value: $395
Best For	Comprehensive prep with maximum support	Remote learners wanting live instruction	Experienced pros with an exam date soon	Self-directed independent learners
Law & Business Classes	4 Classes + Full-Day Review	4 Live Online + Review	Full-Day Review Only	Not included
Trade Math Training	30-Day Interactive + Review	Online Video Review	14-Day Crash Course	Not included
Test-Taking Skills Seminar	1-Day In-Person	1-Day Online	Not included	Not included
Law & Business Materials	Online; binder add-on available	Online; binder add-on available	Online; binder add-on available	Online; binder add-on available
Trade-Specific Materials	Online; binder add-on available	Online; binder add-on available	Online; binder add-on available	Online; binder add-on available
Study Materials	Full Online Suite	Online Materials + Audio/Video	Online + Audio/Video	Online + Audio
Online Videos	Full Suite: L&B, Trade, H&S, Math	Audio + H&S + Math Videos	Audio + H&S + Math Videos	L&B Audio + H&S Video
Law & Business Practice Exams	6 Months	2 Months	30 Days	30 Days
Trade Practice Exams	6 Months	2 Months	30 Days	30 Days
School Location Access	25+ Locations	25+ Locations	25+ Locations	Self-Study Only
Application Assistance	Preparation & Review	Review Only	Review Only	Not included
Money-Back Guarantee	Included	Included	Included	Not included
Bond Fee Discount	50% off first-year bond, up to $120	Not included	Not included	Not included
Retail Value	$2,500	$995	$695	$395
Choose a program	Get All-Inclusive	Get Live Online	Get Crash Course	Get Home Study

Not sure which fits? Call 800-809-6463. Prices and inclusions are subject to change.

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Common Questions

C-51 Structural Steel license FAQ

The C-51 (Structural Steel) covers fabricating and erecting structural steel shapes and plates, the columns, beams, and frames that act as structural members of a building. The C-50 (Reinforcing Steel) covers the rebar and mesh that reinforce concrete. The visible steel skeleton is C-51; the steel hidden inside a concrete pour is C-50.

No. The C-51 regulation includes the riveting and welding necessary to erect structural steel, so a C-51 contractor self-performs that welding under the C-51. A separate C-60 (Welding) license is for welding offered as a standalone trade, pipeline welds, custom fabrication, or equipment repair done on its own rather than as part of a structural-steel job.

The C-51 (Structural Steel) covers load-bearing structural members, the steel frame that holds up a building. The C-23 (Ornamental Metal) covers architectural and decorative metalwork such as railings, bronze doors, and ornamental iron. The dividing line is structural versus ornamental: if the steel carries load, it's C-51; if it's for appearance, it's C-23.

Plan on about $885 in required costs before exam prep: the $450 application fee (both exams), $200 license issuance, roughly $150 for the first-year premium on your $25,000 bond, and about $85 for fingerprinting. Workers' compensation coverage is also required.

Most applicants reach license-in-hand in 2–4 months, CSLB processing, both exams, and posting the bond. With CSLS exam prep, most students are exam-ready in 4–6 weeks.

The C-51 trade exam is multiple-choice and covers structural steel fabrication, erection sequencing, welded and bolted connections, rigging, and steel detailing. You need the current version-specific CSLB passing score to pass. With CSLS exam prep, 99% of students pass on their first attempt, backed by our 100% Money-Back Guarantee.

4 full-time-equivalent years of journey-level structural steel experience within the past 10 years; CSLB prorates part-time work. Qualifying work may be as a journeyperson, foreperson, supervising employee, contractor, or owner-builder. Up to three years can be met with approved technical training, apprenticeship, or education.

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Become a Licensed C-51 Structural Steel Contractor

What does a C-51 Structural Steel contractor do?

Scope of work

Important notes

What's on the C-51 Structural Steel exam?

Law & Business

C-51 Trade Exam

How to Get Your C-51 Structural Steel License

Qualify

Apply to CSLB

Study & Prepare

Pass the Exam

Get Licensed

Qualify

Apply to CSLB

Study & Prepare

Pass the Exam

Get Licensed

Compare C-51 Structural Steel Exam Prep Programs

Labor Day Promo 2026

What our Structural Steel students say

Try a free C-51 Structural Steel practice exam

C-51 Structural Steel license FAQ

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