Sheet Metal & Duct Fabrication
SMACNA-standard duct, plenums, hoods and welded lab exhaust — fabricated to the job and installed by our own crews.
Duct is not a commodity when the system has to hold pressure, resist corrosive lab exhaust, or fit through a hospital corridor that is still in use. CMI fabricates ductwork and sheet metal to SMACNA standards in galvanized steel, stainless steel and aluminum, sized and detailed for the actual project rather than pulled off a shelf.
We build rectangular and round duct, spiral and oval, transitions and fittings, plenums and casings, air handler and fan housings, mixing boxes, sound attenuators, kitchen grease hoods, welded lab and fume exhaust duct, dryer and dust collection duct, roof curbs, dunnage, equipment supports and custom sheet metal. Coordination drawings and spool-level detailing come before anything is cut.
Field installation is by our own crews, so fabrication tolerances and installation reality stay connected. Systems are sealed and leakage tested to the specified pressure class, seismically braced per code, insulated, and balanced by our TAB group — one contractor accountable from the shop floor to the balance report.
Scope & capabilities
- Rectangular, round, spiral and flat-oval duct in galvanized, stainless and aluminum
- Plenums, casings, mixing boxes, transitions and custom fittings
- Roof curbs, curb adapters, dunnage and equipment supports
- Duct liner, external insulation and acoustic treatment
- Duct leakage testing to SMACNA pressure classes
- Welded stainless and coated duct for laboratory, fume and corrosive exhaust
- Kitchen grease hoods, make-up air and Type I/II hood systems
- Coordination drawings, BIM/shop detailing and spool-level fabrication
- Seismic bracing and hanger systems to California code
The technical envelope
- Standards
- SMACNA HVAC Duct Construction Standards, pressure classes to 10" wg
- Materials
- Galvanized, 304/316 stainless, aluminum, coated steel
- Detailing
- Coordination drawings and shop tickets before fabrication
- Testing
- Duct leakage testing with documented results
- Install
- CMI field crews — no sheet metal subcontractor gap
Facility types
Sheet Metal & Duct Fabrication — straight answers
- Do you fabricate in house or buy duct?
- We fabricate, which is why we can hold a schedule when a field condition changes. Shop capacity also means custom plenums, welded exhaust and odd transitions are routine rather than a change order with a six-week lead time.
- Can you build welded stainless exhaust for laboratory fume systems?
- Yes — welded 304/316 stainless and coated duct for perchloric, acid and solvent exhaust, with the fittings, drains and washdown provisions those systems require.
- Do you provide coordination and shop drawings?
- Standard on every project of consequence. Coordination drawings against structure, plumbing, electrical and fire protection are how we avoid discovering a conflict above a finished ceiling.
Get a number you can budget against
We walk the plant before we price it. You get equipment condition, options, phasing and a schedule — not a guess with a contingency wrapped around it.