What "Gauge" Actually Means
In the hollow metal industry, gauge refers to the thickness of the steel sheet used to fabricate a door or frame. The gauge numbering system runs counter-intuitively: a lower gauge number means thicker steel. So 14 gauge steel is thicker and heavier than 16 gauge steel. Both are commonly used in commercial hollow metal door manufacturing, but they are not interchangeable — each has defined applications where it performs best.
Gauge is specified as part of the door's base construction, determined at the time of manufacture. You cannot upgrade a door's gauge after it has shipped. Getting this specification right before you place your order is essential.
16 Gauge: The Standard Commercial Choice
16 gauge steel (nominal 0.053", minimum 0.042") is the workhorse of commercial hollow metal construction. It is the default specification for a wide range of commercial, institutional, and light-industrial openings. If the architectural drawings or door schedule do not specify gauge, 16 gauge is typically implied for standard interior and exterior commercial applications.
Appropriate applications for 16 gauge doors include:
- Standard interior corridor openings in office buildings, schools, and healthcare facilities
- Stairwell and exit doors in low-to-moderate traffic areas
- Utility and mechanical room doors
- Interior fire doors in standard assemblies
- Exterior doors in light commercial applications where abuse resistance is not a primary concern
16 gauge doors are lighter and lower in material cost than 14 gauge, making them the economical standard choice when structural demands are moderate.
14 Gauge: Heavy-Duty Applications
14 gauge steel (nominal 0.067", minimum 0.053") is specified where doors will be subjected to heavy use, physical abuse, or where enhanced security or structural performance is required. The thicker steel provides significantly greater dent resistance and rigidity.
Common applications for 14 gauge doors include:
- High-traffic openings in schools, hospitals, and detention facilities
- Exterior doors in high-abuse environments (loading docks, warehouses, correctional facilities)
- Doors subject to cart or equipment impact
- Security applications where forced-entry resistance is a design consideration
- Any opening where the architect or spec explicitly calls out 14 gauge
14 gauge doors add weight and cost, so specifying them beyond their appropriate use cases is unnecessary. However, under-specifying gauge for a demanding application leads to premature denting, door sagging, and accelerated hardware wear.
Fire Rating and Gauge Requirements
Fire-rated hollow metal doors must meet the requirements of NFPA 80 and carry a listing from a recognized testing laboratory (typically UL or Intertek). Gauge requirements for fire doors depend on the door construction method and the required fire rating period:
- 20-minute and 45-minute fire doors are commonly available in 16 gauge in flush construction.
- 60-minute and 90-minute fire doors typically require 16 gauge minimum, though some configurations require 14 gauge facesheets or reinforced construction depending on door size and construction type.
- 3-hour (180-minute) fire doors require heavier construction and are typically 14 gauge minimum.
Always verify gauge requirements against the specific fire rating listed on the door schedule and the assembly's required rating. If you are specifying a fire door for a rated wall assembly, confirm that the door's construction and gauge are appropriate for the required listing.
Gauge Specifications at a Glance
| Gauge | Nominal Thickness | Minimum Thickness | Typical Use |
|---|---|---|---|
| 16 GA | 0.053" | 0.042" | Standard commercial interior and exterior |
| 14 GA | 0.067" | 0.053" | Heavy-duty, high-traffic, security, and abuse-resistant |
Important: Ordering the wrong gauge is costly to fix after delivery. Unlike a field modification to hardware or a minor dimensional adjustment, changing gauge requires manufacturing a new door. Always confirm the gauge on your order against the door schedule before you submit — especially when taking over a project mid-stream or converting a competitor quote.
A Note on Frame Gauge
Frame gauge follows the same numbering convention and is often specified independently from door gauge. A standard commercial welded frame may be 16 gauge while the door it receives is 14 gauge — or both may be 14 gauge in a heavy-duty application. Frames have their own ANSI/SDI standards governing minimum gauge by application, and masonry or high-security applications may call for 14 gauge or heavier frames. Review both the door and frame gauge columns on the door schedule before ordering.