A CSLB C-43 Sheet Metal license lets a California contractor select, cut, shape, fabricate, and install sheet metal products — HVAC ductwork, gutters and downspouts, flashings, metal roofing and siding, kitchen exhaust hoods, and patented chimney and flue systems — on any job that exceeds the state’s minor-work threshold. It’s one of more than 40 specialty (“C”) classifications CSLB issues, and it sits at a genuinely confusing three-way border with C-20 (HVAC) and C-39 (Roofing). Most C-43 licensing mistakes come from that overlap, not from the sheet metal work itself.
What the C-43 Classification Actually Covers
CSLB’s official scope of work for C-43, codified in Title 16 of the California Code of Regulations, Division 8, Article 3 (commonly cited as 16 CCR §832.43, under the authority of Business and Professions Code Sections 7008 and 7059), reads:
“A sheet metal contractor selects, cuts, shapes, fabricates and installs sheet metal such as cornices, flashings, gutters, leaders, pans, kitchen equipment, duct work (including insulation), patented chimneys, metal flues, metal roofing systems and any other installations requiring sheet metal.”
That single sentence covers architectural sheet metal (cornices, pans, decorative panels), drainage systems (gutters and downspouts), commercial kitchen ventilation (exhaust hoods and makeup-air ductwork), HVAC ductwork fabrication and insulation, and metal roofing/siding assemblies. A licensed C-43 contractor might spend one week fabricating seamless gutters on a residential re-roof and the next building insulated supply and return ductwork for a commercial rooftop unit.
Where C-43 Ends and C-20 (HVAC) Begins
This is the single most important boundary to understand before you sit for the exam or bid a job. C-20 (Warm-Air Heating, Ventilating and Air-Conditioning) covers the complete, functioning HVAC system: the furnace or air handler, the condensing unit, refrigerant lines, thermostatic and humidity controls, air filters — and yes, the ductwork, registers, and flues that connect to that system. C-20 is a systems license; when a contractor installs a full heating or cooling system, the ducts that are “in connection with” that system fall inside the C-20 scope.
C-43, by contrast, is a materials-and-fabrication license. It authorizes the sheet metal work itself — cutting, shaping, and installing ductwork, plenums, and other sheet metal components — independent of whether that duct run is ever tied to a licensed HVAC contractor’s system. A shop that fabricates and installs commercial kitchen exhaust ductwork, standalone ventilation ducting, or custom architectural ductwork typically operates under C-43. Many commercial mechanical projects use both classifications on the same job: a C-20 contractor handles the equipment and controls, while ductwork fabrication and installation runs under C-43. If you’re unsure which classification your scope requires, CSLB’s classification staff and a licensing attorney are the only reliable sources — don’t guess on a bid.
Where C-43 Overlaps C-39 (Roofing)
The C-43 scope explicitly lists “metal roofing systems,” overlapping with C-39 (Roofing), which covers materials that seal, waterproof, and weatherproof a structure — including metal roofing, flashing, and membrane work. In practice, sheet metal flashing integral to a roofing assembly (valley flashing, step flashing, drip edge on a shingle or tile roof) is routinely performed under C-39 as part of the overall roofing scope. Standalone metal roofing panel systems, architectural standing-seam roofs, and custom-fabricated flashing or sheet metal accessories fall more naturally under C-43. Contractors who do both often hold both classifications, or work as licensed subcontractors to each other, to stay inside their authorized scope.
C-43 Licensing Requirements
C-43 follows CSLB’s standard specialty-contractor path:
- Experience: Four years of journeyman-level (or foreman, supervisor, or contractor-level) experience in sheet metal work within the ten years immediately before you apply. Up to three of those four years can be credited through relevant education, apprenticeship, or technical training, but at least one year must be hands-on trade experience.
- Contractor’s bond: A $25,000 surety bond, required under Business and Professions Code §7071.6. This amount increased from $15,000 as of January 1, 2023 under SB 607.
- Bond of Qualifying Individual (BQI): If your qualifier is not an owner with at least 10% equity, a separate $25,000 BQI bond is also required.
- Live Scan fingerprinting: Required for the applicant and every listed officer, partner, or responsible managing individual.
- Workers’ compensation insurance: Required once you have employees; a certification of exemption is required if you have none.
- Application and license fees: A $450 application fee plus an initial license fee ($200 for a sole owner, $350 for other business types), billed on a two-year cycle along with renewal.
Since January 1, 2025, Assembly Bill 2622 raised California’s “minor work” exemption from $500 to $1,000 — meaning unlicensed sheet metal work is only exempt from licensure if the total job (labor and materials combined) is under $1,000, no permit is required, and no workers are hired for the project. Anything above that, or requiring a permit, needs a licensed C-43 contractor (or an appropriately licensed general contractor).
The C-43 Exam: What to Expect
Like every CSLB classification, becoming licensed in C-43 requires passing two separate closed-book exams: the trade-specific C-43 exam and the Law and Business exam (shared across all classifications). CSLB’s own C-43 study guide organizes the trade exam around four broad content areas: planning and estimating, fabrication (layout, pattern-making, and sheet metal processing including welding and soldering), installation (gutters and drainage, flashings, hoods and exhaust, metal roofing and siding), and safety (personal, shop, and job-site safety, plus hoisting and rigging). We’re not going to publish specific percentage weightings here — different secondary sources online quote different breakdowns for the same exam, which tells you they’re guesses, not verified CSLB figures. Treat any site that states an exact percentage breakdown for C-43 with skepticism unless it links directly to CSLB’s own materials.
Real Sheet Metal Work in California
C-43 contractors work across a wide range of project types: fabricating and hanging seamless rain gutters and downspouts on residential re-roofs; building insulated supply/return ductwork for tenant-improvement HVAC systems; fabricating commercial kitchen exhaust hoods and grease ductwork for restaurants; installing standing-seam metal roofing and custom flashing; and producing architectural sheet metal (copings, reglets, custom trim) for building envelopes. Ductwork fabricated and installed in California is also subject to the California Mechanical Code (Sections 601–605) and the ANSI/SMACNA-006 HVAC Duct Construction Standard, and new duct systems fall under California’s Title 24 Energy Code sealing and insulation requirements — ducts generally must be sealed to a maximum leakage rate and insulated (commonly R-6 or R-8 depending on climate zone), often verified through HERS field testing. These aren’t abstract rules: they show up in the C-43 exam’s installation and fabrication content, and they’re enforced by local building inspectors on nearly every ducted job in the state.
Who Needs a C-43 License?
HVAC contractors and mechanical subcontractors needing ductwork fabricated and installed on commercial and residential systems; restaurant owners and commercial kitchen designers needing custom exhaust hoods; and metal-roofing installers and gutter companies needing sheet-metal fabrication for drainage and roofing systems.
C-43 FAQ
Is C-43 the same as an HVAC license?
No. C-43 is a sheet metal fabrication and installation license; C-20 is the HVAC systems license, covering the furnace, air handler, condensing unit, and controls that make up a complete heating/cooling/ventilating system. Many mechanical contractors hold both, but they’re separate classifications with separate exams.
Does C-43 cover gutters and downspouts?
Yes. Gutters, leaders (downspouts), and related drainage sheet metal are explicitly listed in CSLB’s official C-43 scope of work, and gutter/downspout/drainage installation is a dedicated content area on the C-43 trade exam.
Can a C-43 contractor install a full HVAC system?
Not on their own. C-43 authorizes the ductwork and sheet metal portions of a job. Installing the furnace, condenser, or a complete warm-air heating/air-conditioning system requires a C-20 license.
Does C-43 cover metal roofing and flashing?
Yes, “metal roofing systems” are explicitly named in the C-43 scope, and flashing work integral to a metal roof assembly is common C-43 work. Where flashing is part of a broader shingle, tile, or membrane roofing job, that work is more often performed under a C-39 Roofing license. If your business does both, confirm your specific scope with CSLB before bidding mixed-material roofing jobs.
Do I need a C-43 license for a small sheet metal job?
Only if the job qualifies for California’s minor-work exemption: under $1,000 total (labor and materials), no permit required, and no hired workers, per Assembly Bill 2622 (effective January 1, 2025). Any job above that threshold, or requiring a permit, needs a licensed C-43 contractor.
Do C-43 contractors need a separate license to fabricate ductwork in a shop versus installing it on site?
No — the classification covers both fabrication and installation as a single scope (“selects, cuts, shapes, fabricates and installs”), so a C-43 licensee can run a fabrication shop, install on jobsites, or both under the same license.
Get Licensed With Confidence
The C-43 trade exam and the Law and Business exam are both pass/fail, closed-book tests — and CSLB doesn’t publish past questions. If you’re preparing to sit for either exam, Contractor Pathway’s C-43 exam prep course was built specifically around CSLB’s published classification scope and study guide content, as part of one of the most competitive contractor exam-prep programs available for California licensing candidates. Not sure C-43 is the right classification for your scope of work? Use our classification finder to compare C-43 against C-20, C-39, and every other CSLB specialty class before you apply. You can also see how our study guides and practice exams work, review current course pricing, or contact us with questions about your specific licensing path.