Sheet metal worker screening questions: layout, duct fabrication, installation, state licenses and apprenticeship
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Sheet metal worker screening questions should establish where the candidate works (shop, field or both), what they fabricate and install, and whether they can lay out a fitting from a drawing without someone else doing the math. The trade covers HVAC ductwork, architectural sheet metal, kitchen hoods and industrial work, and candidates often know one corner well. A strong screen finds which corner, then tests it with specifics: layout methods, seams and connections, hangers and supports, and how they read drawings.
This page covers sheet metal workers at mechanical contractors, fabrication shops and architectural sheet metal firms. For the equipment side of HVAC, use HVAC technician screening questions; for metal roofing, roofer screening questions.
Which sheet metal worker
| Setting | Typical work | Ask the candidate |
|---|---|---|
| Fabrication shop | Layout, cutting, forming and assembling duct and fittings; CNC plasma or coil lines; brakes, shears, rollers | "Which machines have you run, and what did you make most?" |
| Field installer, commercial HVAC | Hanging duct, connecting fittings, dampers, sealing, coordinating with other trades | "What was the largest duct system you installed, and in what kind of building?" |
| Residential HVAC | Flex and rigid duct, plenums, change-outs, attics and crawlspaces | "How do you size and connect a supply run in an attic?" |
| Architectural sheet metal | Copings, flashings, gutters, wall panels, standing seam | "Which systems and metals have you worked with?" |
| Testing, adjusting and balancing | Airflow readings, adjusting dampers, reports | "Which instruments do you use, and who certified you?" |
Licenses and apprenticeship
As of October 2026, not legal advice. Licensing of the trade varies by state and city. We checked the two examples below against the statutes. Confirm requirements for the job's location.
- Massachusetts: no person may work as a master, journeyperson or apprentice sheet metal worker without a license from the board (M.G.L. c. 112, § 238). The statute defines sheet metal work to include fabricating, installing and repairing commercial duct and air exhaust systems, commercial kitchen hoods, related dampers and grilles, and the testing, adjusting and balancing of air-handling equipment and ductwork in new or remodeling construction, with exceptions (§ 237). Apprentices must be at least 16 and work under a master or journeyperson.
- Connecticut: sheet metal work is one of the occupations under the state's occupational licensing chapter, and no one may perform the work of a licensed occupation without a license or a registration card from the Labor Department or the board (Conn. Gen. Stat. §§ 20-330 and 20-334). A license applicant must be at least 18.
Many states do not license sheet metal workers, though cities may, and some jobs are covered under a mechanical or HVAC license held by the contractor. Ask the client what the job requires.
Many sheet metal workers train through a registered apprenticeship, which the Department of Labor describes as paid work with structured on-the-job learning, a mentor and related instruction, approved by the Department of Labor or a State Apprenticeship Agency (Apprenticeship.gov). The Verify My Apprenticeship tool lets an employer verify a completion record with the person's apprentice number and date of birth.
Knockout questions
| Question | What a strong answer sounds like | Red flags |
|---|---|---|
| Are you a journeyworker or apprentice, and through which program? | Names the program, local or sponsor, year or completion date. | Vague about any formal training while claiming journey-level pay. |
| Do you hold the license this job requires [state, level]? | Yes, with number and expiry. | "I can work under someone else's" in a state that licenses apprentices too. |
| Shop, field or both, and which do you prefer? | Clear and matches the order. | Field-only candidate for a layout-heavy shop role. |
| Do you have your own hand tools? | Snips, hand seamers, Pittsburgh hammer, drivers, levels, layout tools. | No tools for a role that expects them. |
Layout and fabrication questions
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"Talk me through laying out a transition or offset from a shop drawing."
- Strong answer: reads the dimensions and connections, picks the layout method (parallel line, radial line or triangulation) or programs it on the CNC software, adds allowances for seams and connectors, checks the pattern before cutting.
- Red flags: only cuts patterns someone else laid out, for a layout role.
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"Which seams and connections do you use, and when?"
- Strong answer: Pittsburgh lock and snap lock longitudinal seams, S and drive slips or flanged connections for transverse joints, and knows the job specification and the industry construction standard decide what is allowed for the duct pressure class.
- Red flags: "Whatever's quickest."
-
"How do you choose the gauge?"
- Strong answer: from the drawings and specification, based on duct size and pressure class, and asks when the drawing is silent.
- Red flags: uses whatever is on the rack.
-
"Which shop machines have you run, and how do you stay safe on them?"
- Strong answer: names brakes, shears, roll formers, plasma tables; guards in place, hands clear of the shear, lockout before clearing jams or changing tooling.
- Red flags: describes reaching into a running machine.
Installation questions
| Question | What a strong answer sounds like | Red flags |
|---|---|---|
| How do you hang a long run of rectangular duct? | Hanger type and spacing from the specification, anchors suited to the structure, level and aligned, coordination with other trades for space. | Hangs it from pipe or conduit. |
| How do you seal duct, and how is it tested? | Sealant class from the specification, sealing seams and joints, pressure or leakage testing when required. | "Tape everything." |
| Where do fire dampers go, and what do you check? | At rated wall or floor penetrations shown on drawings, installed to the manufacturer's listing, access to reset. | Has never installed one but claims commercial experience. |
| The duct does not fit because a pipe is in the way. What do you do? | Checks drawings, coordinates with the foreman and the other trade, makes or orders an offset per approval. | Cuts into the duct to get around it. |
Drawings and coordination
- "How do you read a duct shop drawing or coordination model?" Strong: elevations, bottom-of-duct heights, fitting tags, hanger locations, and checks clashes with pipe, conduit and structure before installing.
- "How do you take field measurements for a fitting?" Strong: measures from fixed references, notes the connection type at each end, sketches clearly for the shop.
- Architectural roles: "How do you lay out and install a coping or counterflashing?" Strong: material and thickness from the specification, cleats and fasteners, expansion joints, laps that shed water, and no contact between incompatible metals.
Safety at height and on site
Field sheet metal work means ladders, lifts and scaffolds. Under OSHA's construction fall protection standard, employees on walking or working surfaces with an unprotected side or edge 6 feet or more above a lower level must generally be protected by guardrails, safety nets or personal fall arrest systems (29 CFR 1926.501). Ask: "What fall protection did you use on your last job, and how did you inspect your harness and lanyard?" and "Which aerial lifts are you trained on, and by whom?" Strong candidates also talk about cut protection, sharp edges and handling long sections in wind.
How sheet metal experience gets overstated
- Installer-only experience presented as layout. Ask them to describe a fitting they laid out by hand.
- Residential flex duct presented as commercial. Ask about duct pressure classes and fire dampers.
- CNC operator without understanding the patterns. Ask what they do when a nested part comes out wrong.
- Welding listed without process or qualification. See welder screening questions for depth.
Scoring
Pass or fail
- Level, apprenticeship and any required license match the order.
- Shop or field setting matches.
- Tools, travel and schedule accepted.
- Describes fall protection and machine safety correctly.
Scored 0 to 2 each (10 possible)
- Layout methods and drawing reading.
- Seams, connections and gauges.
- Installation, hangers and sealing.
- Coordination and problem-solving on site.
- Specialty (architectural, kitchen hoods, balancing, welding).
In the submittal, list license and number, apprenticeship and completion date, shop machines and software used, types of buildings and systems, and the candidate's description of a fitting layout in their own words. For a broader trades screening process, read the interview guide for skilled trades. Ask whether the candidate can meet the job's physical demands, with or without accommodation, not about past injuries.
Questions people ask
Do sheet metal workers need a license?
In some states. As of October 2026, Massachusetts requires masters, journeypersons and apprentices doing sheet metal work, as its statute defines it, to hold a license from its Board of Examiners of Sheet Metal Workers, and Connecticut lists sheet metal work among the occupations that require a state license or an apprentice registration. Many other states do not license the trade, though cities may. Check the job's state and city; this is not legal advice.
How do I verify a sheet metal apprenticeship?
For programs registered with the U.S. Department of Labor or a State Apprenticeship Agency, an employer can verify a completion record through Apprenticeship.gov's Verify My Apprenticeship tool with the person's apprentice number and date of birth, gathered only at the verification step with the candidate's agreement. Union training centers can also confirm status.
What is the difference between a sheet metal worker and an HVAC technician?
Sheet metal workers fabricate and install ductwork and other sheet metal systems, and some balance air systems, while HVAC technicians install, service and repair the heating and cooling equipment itself, including refrigerant work. On many jobs they work side by side.
What is the best single question for a sheet metal screen?
Ask them to talk you through laying out and making a transition or offset fitting from a shop drawing: the layout method, allowances for seams and connections, which seam and connector they would use for the duct class, and how they check it fits before it leaves the shop.