Air doesn't move where you want it unless someone builds the path, and the path —\nthe ductwork — has to be the right size, sealed, and supported, or the building\ncan't breathe, heat, or cool. A sheet metal worker exists to turn flat coil and\nsheet into the ducts, fittings, plenums, flashings, and architectural metal that\nmove air and shed water through a building, and to make those parts fit a space\nthat was never quite drawn the way it got built. The craft is layout, fabrication,\nand installation in one: it lives on the geometry of unrolling a three-dimensional\nshape onto flat metal, and on the physics of moving air through it without\nwasting the fan or whistling the occupants out of the room.
\n","wordCount":125},{"heading":"Core Mission","id":"core-mission","markdown":"Fabricate and install duct and metalwork that delivers the design airflow to\nevery space at the intended static pressure, sealed to the required leakage\nclass, supported and balanced — so the system moves the air it was engineered to\nmove, quietly and without leaking conditioned air into the ceiling.","html":"Fabricate and install duct and metalwork that delivers the design airflow to\nevery space at the intended static pressure, sealed to the required leakage\nclass, supported and balanced — so the system moves the air it was engineered to\nmove, quietly and without leaking conditioned air into the ceiling.
\n","wordCount":48},{"heading":"Primary Responsibilities","id":"primary-responsibilities","markdown":"Reading mechanical drawings and developing flat patterns for fittings; cutting,\nforming, and seaming duct on the brake, roll, and seamer; fabricating elbows,\ntransitions, takeoffs, and offsets; hanging and sealing duct to the leakage class;\ninstalling diffusers, grilles, dampers, and VAV boxes; making architectural metal\n— flashings, copings, gutters, kitchen hoods, and panels; and balancing the\nfabrication shop's standards against the field's reality. Beneath the visible\nmetal is constant geometry (triangulation and parallel-line development to unfold\na shape) and constant airflow arithmetic (static pressure, velocity, and the\nfriction the duct adds), because a duct that fits perfectly but chokes the airflow\nis a failed duct.","html":"Reading mechanical drawings and developing flat patterns for fittings; cutting,\nforming, and seaming duct on the brake, roll, and seamer; fabricating elbows,\ntransitions, takeoffs, and offsets; hanging and sealing duct to the leakage class;\ninstalling diffusers, grilles, dampers, and VAV boxes; making architectural metal\n— flashings, copings, gutters, kitchen hoods, and panels; and balancing the\nfabrication shop's standards against the field's reality. Beneath the visible\nmetal is constant geometry (triangulation and parallel-line development to unfold\na shape) and constant airflow arithmetic (static pressure, velocity, and the\nfriction the duct adds), because a duct that fits perfectly but chokes the airflow\nis a failed duct.
\n","wordCount":104},{"heading":"Guiding Principles","id":"guiding-principles","markdown":"- **Air follows the path of least resistance, and every fitting adds\n resistance.** A sharp elbow, a sudden transition, a crushed flex — each robs\n static pressure the fan has to make up. Sweep the turns and ease the\n transitions or pay for it in noise and energy forever.\n- **Seal to the leakage class, not to \"good enough.\"** Unsealed duct leaks 10–30%\n of the air into the plenum, and that's conditioned air you paid to move.\n Mastic, gasket, and the right SMACNA seal class are part of the install, not\n optional finish.\n- **Layout is the job; the metal just does what the layout says.** A fitting is\n right or wrong before you cut it. Develop the pattern, check it, then cut —\n metal cut to a bad layout is scrap.\n- **Size for velocity and pressure, not just to fit the chase.** Squeezing a duct\n to clear a beam raises velocity, pressure drop, and noise. The space and the\n airflow both have to win.\n- **Support it before you trust it.** Duct sags, joints open, and seals fail when\n hangers are too far apart or undersized. Support spacing is engineered, not\n eyeballed.\n- **Sharp metal cuts; handle and edge it like it bites.** Every cut edge is a\n blade until it's hemmed or gloved past.","html":"The shop's shear, brake (box-and-pan and press), slip roll, and seamers; hand\ntools — hand seamers, snips (straight, left, right), notchers, hammers and\nmallets, rivet guns; the Pittsburgh lock machine and cleat formers; layout tools\n— scribes, dividers, squares, and protractors for pattern development; in the\nfield, the screw gun, mastic and brushes, drill, and the manometer and balometer\nto read static pressure and airflow; coil lines and plasma/laser cutters in modern\nshops. Cut-resistant gloves and edge awareness, because every sheet is a blade.
\n","wordCount":86},{"heading":"Collaboration","id":"collaboration","markdown":"Sheet metal workers run inside the mechanical sequence with the pipefitters and\nHVAC techs, fighting plumbing, electrical, and fire protection for the same\nceiling space — which is why big jobs coordinate the trades in a shared 3-D model\nto settle the clashes before anyone fabricates. They take the design from the\nmechanical engineer's drawings and hand the finished system to the test-and-\nbalance technician, whose airflow readings judge whether the duct does what it was\nsized to do. The friction lives in the ceiling plenum congestion and at the\ndiffuser, where what the architect wants to see meets where the duct can actually\ngo.","html":"Sheet metal workers run inside the mechanical sequence with the pipefitters and\nHVAC techs, fighting plumbing, electrical, and fire protection for the same\nceiling space — which is why big jobs coordinate the trades in a shared 3-D model\nto settle the clashes before anyone fabricates. They take the design from the\nmechanical engineer's drawings and hand the finished system to the test-and-\nbalance technician, whose airflow readings judge whether the duct does what it was\nsized to do. The friction lives in the ceiling plenum congestion and at the\ndiffuser, where what the architect wants to see meets where the duct can actually\ngo.
\n","wordCount":106},{"heading":"Ethics","id":"ethics","markdown":"Most duct disappears above a hard ceiling the day it's installed, and a leaky,\nunder-sealed, choked system looks finished while it quietly wastes energy and\nunderserves the rooms for the life of the building. The duties: seal the joints no\none will ever reach again; build the fittings to flow the air the design called\nfor rather than the easy square turn; insulate where condensation would otherwise\nrot the ceiling; and tell the engineer when the space genuinely can't hold the\nduct the airflow needs, instead of crushing it to fit and blaming the fan. The\noccupants breathe and pay to condition air through work they'll never see.","html":"Most duct disappears above a hard ceiling the day it's installed, and a leaky,\nunder-sealed, choked system looks finished while it quietly wastes energy and\nunderserves the rooms for the life of the building. The duties: seal the joints no\none will ever reach again; build the fittings to flow the air the design called\nfor rather than the easy square turn; insulate where condensation would otherwise\nrot the ceiling; and tell the engineer when the space genuinely can't hold the\nduct the airflow needs, instead of crushing it to fit and blaming the fan. The\noccupants breathe and pay to condition air through work they'll never see.
\n","wordCount":109},{"heading":"Scenarios","id":"scenarios","markdown":"**A new office wing where the back rooms never get cool.** The balancer can't get\ndesign airflow to the far diffusers. The expert sheet metal worker traces the run\nand finds two square miter elbows with no turning vanes and a long-radius reducer\ncrushed flat to clear a sprinkler main — together eating most of the available\nstatic pressure. The fix isn't a bigger fan; it's rebuilding the two elbows with\nturning vanes and rerouting the reducer with a gradual transition above the main.\nRecovering the lost static pressure delivers the airflow the design always\nintended.\n\n**Cold supply duct sweating onto a finished ceiling.** A tenant reports brown\nstains spreading on a new drop ceiling. The duct above carries 55°F supply air\nthrough a humid return plenum, uninsulated, and it's condensing like a cold glass\nin summer. The worker insulates the duct with a sealed vapor barrier so the metal\nsurface stays above the dew point. Replacing the ceiling tiles without insulating\nthe duct would just stain the next set; the cause is condensation, and the cure is\nkeeping the cold metal from meeting moist air.\n\n**A duct route that doesn't fit the as-built beam.** The model shows the main duct\nclearing a structural beam by two inches; in the field the beam is lower than\ndrawn and the duct won't fit. A rushed crew might flatten the duct to squeeze\nunder. The expert checks the velocity and pressure that flattening would create,\nfinds it pushes the run into noise and excess pressure drop, and instead transitions\nthe rectangular main to round (which clears in less height) through gradual\nfittings, keeping the area and the airflow. He coordinates the change with the\nengineer rather than silently choking the system to make it fit.","html":"A new office wing where the back rooms never get cool. The balancer can't get\ndesign airflow to the far diffusers. The expert sheet metal worker traces the run\nand finds two square miter elbows with no turning vanes and a long-radius reducer\ncrushed flat to clear a sprinkler main — together eating most of the available\nstatic pressure. The fix isn't a bigger fan; it's rebuilding the two elbows with\nturning vanes and rerouting the reducer with a gradual transition above the main.\nRecovering the lost static pressure delivers the airflow the design always\nintended.
\nCold supply duct sweating onto a finished ceiling. A tenant reports brown\nstains spreading on a new drop ceiling. The duct above carries 55°F supply air\nthrough a humid return plenum, uninsulated, and it's condensing like a cold glass\nin summer. The worker insulates the duct with a sealed vapor barrier so the metal\nsurface stays above the dew point. Replacing the ceiling tiles without insulating\nthe duct would just stain the next set; the cause is condensation, and the cure is\nkeeping the cold metal from meeting moist air.
\nA duct route that doesn't fit the as-built beam. The model shows the main duct\nclearing a structural beam by two inches; in the field the beam is lower than\ndrawn and the duct won't fit. A rushed crew might flatten the duct to squeeze\nunder. The expert checks the velocity and pressure that flattening would create,\nfinds it pushes the run into noise and excess pressure drop, and instead transitions\nthe rectangular main to round (which clears in less height) through gradual\nfittings, keeping the area and the airflow. He coordinates the change with the\nengineer rather than silently choking the system to make it fit.
\n","wordCount":295},{"heading":"Related Occupations","id":"related-occupations","markdown":"The HVAC technician installs the equipment the ductwork connects to and lives in\nthe same mechanical room. The roofer and the sheet metal worker overlap on\narchitectural metal — flashings, gutters, copings, and standing-seam panels. The\nwelder joins heavy plate and stainless for hoods and industrial work. The\nmechanical engineer sizes the system the sheet metal worker fabricates and\ninstalls.","html":"The HVAC technician installs the equipment the ductwork connects to and lives in\nthe same mechanical room. The roofer and the sheet metal worker overlap on\narchitectural metal — flashings, gutters, copings, and standing-seam panels. The\nwelder joins heavy plate and stainless for hoods and industrial work. The\nmechanical engineer sizes the system the sheet metal worker fabricates and\ninstalls.
\n","wordCount":60},{"heading":"References","id":"references","markdown":"- *SMACNA HVAC Duct Construction Standards — Metal and Flexible*\n- *ASHRAE Handbook — Fundamentals* (duct design, pressure loss)\n- *SMACNA Architectural Sheet Metal Manual*\n- Pattern development texts on parallel-line, radial-line, and triangulation layout","html":"