B — General Building

What a CSLB Class B License Lets You Do

A Class B (General Building Contractor) license is the credential you need to take a prime contract on almost any building project in California, as long as the job requires at least two unrelated building trades or crafts to complete — for example, framing plus electrical, or concrete plus plumbing (Business & Professions Code §7057). It’s the classification most ground-up builders and full-scope remodelers carry, since it lets one license holder bid, contract, and supervise a job from foundation to finish instead of being boxed into a single trade.

What a B license does not do is turn you into a specialty contractor. If a project needs only one trade — say, only roofing or only painting — CSLB requires the specific C classification for that trade (or a subcontractor who holds it), with framing and rough carpentry carved out as the one specific exception a B contractor may always contract for on its own.

Scope of Work: What a B Contractor Actually Builds

CSLB’s official classification description defines B as covering “any structure built, being built, or to be built, for the support, shelter, and enclosure of persons, animals, chattels, or movable property,” where the work pulls in two or more unrelated trades. On real job sites, that plays out as:

• Ground-up single-family and multi-family construction — foundation, framing, roofing, electrical, plumbing, and finish trades all under one contract.
• Whole-house and whole-building remodels that touch structural framing along with at least one other trade, such as a kitchen gut-remodel that moves walls and reroutes plumbing/electrical.
• ADU (accessory dwelling unit) construction, new or conversion, which almost always combines framing, electrical, plumbing, and finish work.
• Room additions and second-story additions requiring new framing tied into structural, electrical, and HVAC work.
• Commercial tenant improvements — build-outs of retail, office, or restaurant shell space into finished, code-compliant tenant space.
• Prime or subcontracted framing/carpentry-only work, the one project type a B contractor may take on alone without a second trade, per CSLB’s classification rules.

A B contractor self-performs any trade it’s also licensed for and must subcontract the rest to properly licensed specialty (C) contractors — CSLB singles out C-16 Fire Protection and C-57 Well Drilling by name as never covered by a bare B license.

The B Trade Exam: What’s Covered, and What CSLB Doesn’t Publish

Every B applicant sits for two separate PSI-administered exams: the Law & Business exam (shared across all classifications) and the B trade exam covered on this page. Both are closed-book, computer-based, multiple-choice exams given at PSI test centers, and CSLB allows 3.5 hours per exam (CSLB Examination FAQ). A basic calculator is provided on-screen for the math questions, and there’s no penalty for guessing.

CSLB’s official General Building (B) Examination Study Guide (current for exams scheduled on or after January 1, 2025) breaks the trade exam into five weighted content areas:

• Planning and Estimating — 15% (scope of work, code compliance, plan/spec reading, field inspection, cost estimating)
• Framing and Structural Components — 20% (subfloor/wall framing, roof framing, seismic hardware, siding/stucco, decks and stairs)
• Core Trades — 30% (plumbing, electrical, HVAC, concrete, earthwork/surveying, insulation/weatherproofing, roofing)
• Finish Trades — 20% (painting/coatings, tile and stone, floor covering, cabinetry/millwork, drywall/plaster, windows and doors, landscaping)
• Safety — 15% (personnel safety, traffic control, environmental safety)

What CSLB does not publish: the board doesn’t release an exact scored-question count or a numeric passing percentage for the B exam. It uses a criteria-referenced (Angoff) standard set independently per exam form, and your results show pass/fail only — a failing report gives a section-by-section breakdown, but a passing report shows no overall score (CSLB Examination FAQ). Treat any specific question-count or “you need X%” figure you see on other sites as a third-party estimate, not a CSLB-confirmed number.

Requirements to Qualify for the B License

1. Experience: four full years of journey-level, foreman, supervisor, or contractor experience in general building work within the ten years before you apply. Up to three of those four years can be substituted with directly related education or apprenticeship training, but CSLB still requires a minimum of one year of hands-on practical experience regardless of education.
2. Age, identity, and application: at least 18, with a verifiable Social Security number or ITIN. File the Application for Original Contractor License with CSLB along with an experience certification (signed by someone who can verify your work history) and fingerprinting/Live Scan for a background check.
3. Fees (current CSLB fee schedule): $450 original application fee (exam or waiver, one classification), plus a $200 initial license fee for a sole owner ($350 for a partnership/corporation/LLC) once you pass. Fingerprinting adds roughly $32 (DOJ) + $17 (FBI).
4. Contractor’s bond: $25,000 surety bond (or cash deposit/equivalent) on file before licensure, per Business & Professions Code §7071.6 as amended by SB 607 (effective January 1, 2023, up from $15,000).
5. Workers’ compensation: required once you have employees; sole owners/qualifying partners/officers with no employees may file a signed exemption instead. SB 1455 delayed a broader mandate — WC coverage for nearly all active licensees regardless of employee count — from January 1, 2026 to January 1, 2028, so confirm your status with CSLB as that date nears.

B vs. the Classifications People Confuse It With

B vs. A (General Engineering Contractor): A is for fixed works requiring specialized engineering — roads, bridges, dams, pipelines, sewage systems, and similar civil infrastructure (Business & Professions Code §7056). B is for structures — buildings people occupy or use for shelter/storage. If your work is a building, you want B; if it’s infrastructure, you want A.

B vs. C-5 (Framing and Rough Carpentry): C-5 covers framing, sheathing, subflooring, roof decking, and related rough-carpentry work as a standalone specialty. If framing/carpentry is genuinely the only trade on the job, C-5 alone is sufficient and cheaper to qualify for. B is the better fit once a second unrelated trade enters the picture — and B already covers framing/carpentry-only jobs on its own, no C-5 needed.

B vs. a single-trade C classification (e.g., C-33 Painting, C-36 Plumbing): if a client’s entire project is one specialty — repaint a building, replace a plumbing system — CSLB requires that specific C license (or a subcontractor holding it), not a bare B. Many general contractors hold a B plus the relevant C classification(s), letting them legally take single-trade prime contracts as well as multi-trade ones.

Who Actually Needs This License

Custom home builders, remodeling companies whose projects cross structural/electrical/plumbing work, ADU builders, developer/investors self-managing flips or new builds, and commercial tenant-improvement contractors typically need a B license to legally hold the prime contract. Homeowners, property managers, and real estate agents sit on the other side of that contract — they’re the ones who should confirm whoever they hire actually holds an active B (or correct C) license before signing anything.

B License FAQ

Do I need a B license to build an ADU in California?

In almost every case, yes — ADU construction combines framing with at least one other trade (electrical, plumbing, or both), which is exactly the two-unrelated-trades test CSLB uses to define the B classification (Business & Professions Code §7057).

Can a B contractor do electrical or roofing work without a specialty license?

Only as part of a multi-trade project, and only for trades the contractor is actually licensed to self-perform. A bare B license doesn’t authorize a single-trade prime contract in a specialty like electrical or roofing — that still needs the matching C license or a licensed subcontractor.

What’s the difference between the B trade exam and the Law & Business exam?

Every applicant for every classification takes the Law & Business exam — it covers licensing law, contracts, business finance, labor law, and risk management, not construction technique. The B trade exam (covered on this page) tests hands-on building knowledge across the five content areas above. Both are 3.5-hour PSI exams and both must be passed to get the license.

Does a B license cover commercial and public-works projects, or just residential?

B covers both — the classification is defined by the type of work (a structure needing two-plus trades), not by whether the owner is a homeowner, a business, or a public agency. Public works add separate bidding, prevailing-wage, and registration requirements, but they don’t require a different CSLB classification.

Can I hold a B license along with C classifications?

Yes, and many general contractors do. Adding one or more C classifications to an existing B license lets you legally take single-specialty prime contracts (e.g., an all-plumbing remodel) in addition to your multi-trade B work — each additional classification generally requires passing that trade’s own exam or qualifying for a waiver.

Is framing-only work covered by a B license, or do I need C-5?

Framing/carpentry is the one specialty CSLB carves out as an explicit exception — a B contractor may take that work alone without a second trade. If framing is genuinely all you ever do, qualifying for C-5 directly is usually the more efficient path.

What code books should I actually study for the B exam?

CSLB’s official B study guide points candidates to the current California Building Code (Title 24) and related California code books, available for reference through the Department of General Services (dgs.ca.gov/bsc) and the International Code Council. Since the exam is closed-book, the goal is studying from current code rather than bringing references to the test.