Gauge
Commercial hollow metal doors are most commonly 18-gauge or 16-gauge steel. 16-gauge is heavier-duty and standard for high-traffic or higher-security openings; 18-gauge is common for lower-traffic interior doors. The gauge affects both durability and cost, so it’s worth specifying deliberately rather than defaulting.
Fire rating
Many commercial openings require a fire-rated door and frame assembly (20-, 45-, 60-, or 90-minute ratings are common), especially at stairwells, corridors, and rooms housing mechanical or electrical equipment. The rated label has to match the frame, door, and hardware as a tested assembly — mixing an unrated component into a rated opening is a common inspection failure.
Frame types
Welded frames are shop-assembled and arrive as one rigid unit — stronger and cleaner-looking, but they need to be set before the wall goes up. Knock-down (KD) frames ship flat and assemble on site, which makes them easier to get into finished openings or tight schedules, at a small trade-off in rigidity.
Hardware coordination
Hollow metal openings are only as good as the hardware group specified with them — hinges, closers, locksets, exit devices, and increasingly electrified hardware for access control. Getting the hardware set right at takeoff avoids costly field changes later.
Lead times
Hollow metal doors and frames are typically not stock items — expect several weeks of lead time on most commercial orders, longer for fire-rated or electrified assemblies. Building that into the project schedule early avoids delays at close-out.
If you’re putting together a Division 8 takeoff or need help estimating hollow metal doors, frames, and hardware for a commercial project, contact A-1.
