Cutting before approval
Why it happens: the piece almost fits.
Check instead: Check latest print, system, access, rating, nearby utilities, and who approved the change.
Do not: Do not cut just to make it fit.
Common mistakes
First-year mistakes that create rework.
Each mistake gives the reason it happens, what to check instead, and what not to do.
Burying damper access
Why it happens: ceiling/insulation comes fast.
Check instead: Check label, actuator, access side, sleeve, and future service path.
Do not: Do not cover dampers, labels, actuators, or access doors.
Using flex as a reroute
Why it happens: flex seems easy.
Check instead: Check route length, sag, kinks, collar connection, and airflow impact.
Do not: Do not use flex to hide a coordination problem.
Mastic over a bad joint
Why it happens: the crew is trying to pass test fast.
Check instead: Fix mechanical fit-up, gasket, corners, cleats, screws, and surface prep first.
Do not: Do not use sealant as a substitute for missing parts.
Moving supports casually
Why it happens: hanger is in the way.
Check instead: Check load path, anchor type, support spacing, seismic/brace notes, and duct weight.
Do not: Do not delete/move supports without direction.
Installing from old print
Why it happens: someone handed you a sheet.
Check instead: Check revision, date, clouds, shop drawings, and field condition.
Do not: Do not install from unverified drawings.
Wrong equipment clearance
Why it happens: duct route looks open.
Check instead: Check panels, filters, coils, belts, drains, controls, and service doors.
Do not: Do not block service access to make duct fit.
Treating grease duct like normal duct
Why it happens: it looks like exhaust.
Check instead: Check material, weld/wrap, slope, cleanouts, access, and AHJ/code details.
Do not: Do not cut/weld/wrap/seal without direction.
Not taking useful photos
Why it happens: panic mode.
Check instead: Take wide photo, close photo, measurement photo, and drawing/detail photo.
Do not: Do not send a mystery zoomed-in photo with no location.