All Doors Are Not Created Equal

Authored by Chris Resig, AIA, LEED AP, DHT, CFDAI, SCUP

At first pass, the casual observer might think that a door is a door is a door. Everybody can plainly see all metal doors are the same, and all wood doors are the same. Not so. There are many factors that come into play in defining what doors would be appropriate for specific applications or end uses. The primary factors that establish the characteristics of a door include its material, series, type, and grade.

• Door Material defines what material the door is made of.

• Door Series defines the specific construction requirements for the door.

• Door Type defines the specific geometry of the door leaf, such as a flush, half glass, full glass, narrow vision glass, etc.

• Door Grade defines the grade or “duty” of the door, establishing the durability and some aesthetics of the door, which drive the durability of the door for specific applications and frequency of use.

This blog explores the grade of doors and how the grade impacts the appropriateness of using certain doors in specific applications. Regardless of the door material/construction (i.e., hollow metal, wood, aluminum, or other types), the grades of doors are established utilizing specific industry standards to determine the grade of the door. The industry standards for the primary door materials are:

• Hollow Metal: SDI (Steel Door Institute) 108-18 “Recommended Selection and Usage Guide for Standard Steel Doors” is to be used for hollow metal doors.

• Wood: WDMA (Wood Door Manufacturer Association) IS 1A-13 “Industry Standards for Interior Architectural Wood Flush Doors” and IS 6A-13 “Industry Standard for Interior Architectural Wood Stile and Rail Doors” grading standards are to be used for both flush and rail & stile wood doors respectively.

• Aluminum: FGIA (Fenestration & Glazing Industry Alliance) “North American Fenestration Standard” (NAFS) (AAMA/WDMA/CSA101/A440) is to be used for aluminum doors.

Hollow Metal: The SDI steel door (hollow metal) considers a variety of things when grading a door, with the primary characteristics being the frequency of use, level of possible abuse, and metal thickness (gauge). As the door’s duty increases, the capacity of each of these characteristics increases. The various hollow metal door duties include:

• Standard Duty Doors (Level 1) are typically provided in situations with the lightest frequency of use and least level of abuse. Standard Duty doors have a 20-gauge steel skin and can be provided in either 1 3/8” or 1 ¾” thick doors. Examples of standard-duty doors would be a bedroom, private bathroom, closet, or office.

• Heavy Duty Doors (Level 2) are typically provided in situations with a moderate frequency of use and a moderate level of abuse. Heavy-duty doors have an 18-gauge steel skin and can be provided in 1 ¾” thick doors. Examples of heavy-duty doors would be a main entrance, stairwell, mechanical/electrical, bedroom, bathroom, storage, closet, or office.

• Extra Heavy Duty Doors (Level 3) are typically provided in situations with a heavy frequency of use and a heavy level of abuse. Heavy-duty doors have a 16-gauge steel skin and can be provided in 1 ¾” thick doors. Examples of heavy-duty doors would be main entrances/exits, stairwells, mechanical/electrical, storage, utility, kitchen, production, loading docks, equipment rooms, boiler rooms, gymnasiums, or cafeterias.

• Maximum Duty Doors (Level 4) are typically provided in situations with the heaviest frequency of use and most extreme level of abuse. Maximum Duty doors have a 14-gauge steel skin and can be provided in 1 ¾” thick doors. Examples of heavy-duty doors would be main entrances/exits, stairwells, tools, trucking, loading docks, industrial, detention, or gymnasiums.

Wood: The WDMA wood door standards for both flush wood doors and rail & stile doors deal with similar performance characteristics when grading the door; such as the number of anticipated cycles of the door opening, hinge-loading capacity, and screw holding capacity. As the door’s duty increases, the capacity of each of these characteristics increases. The various wood door duties include:

• Standard Duty typically involves door openings that have a low frequency of use, requiring the lowest level of performance standard. Examples of standard-duty doors would be a closet, wardrobe, or private bathroom.

• Heavy Duty typically involves door openings that have a moderate frequency of use, requiring an intermediate level of performance standard. Examples of heavy-duty doors would be offices, stairwells, storage, mechanical/electrical rooms, hallways, or apartment entry.

• Extra Heavy Duty typically involves door openings that have a heavy or high frequency of use, requiring the highest level of performance standard. Examples of extra heavy-duty doors would be classrooms, patient rooms, public restrooms, dorm rooms, assembly areas, and gymnasiums.

Aluminum: Because most aluminum doors are found on the exterior or vestibules of buildings, the NAFS standard looks primarily at the performance characteristics of the door or other fenestration (windows), including design pressure, and water resistance test pressure. The various grades of aluminum doors per the NAFS can be summarized as follows:

• Class R (Light Duty) is intended primarily for one or two-family dwellings, with an application that is more residential in nature.

• Class LC (Moderate Duty) is intended for low to mid-rise structures where larger sizes and higher loading requirements are anticipated, with an application that is more light commercial in nature.

• Class CW (Heavy Duty) is intended for low to mid-rise structures where larger sizes and higher loading requirements are anticipated, including limitations on deflection and heavy use are anticipated, with an application that is more commercial in nature.

• Class AW (Severe Duty) is intended for mid to high-rise structures where increased loading requirements and limitations on deflection, and extreme use could come into play, with an application that is more architectural in nature.

While there is considerable detail that goes into how doors should be graded for their specific application, having a general understanding of the grading of hollow metal, wood and aluminum door openings goes a long way in making sure the right doors are being used in the right locations.