Door structural performance speaks to door structural specifications and door structure regulations.
It is considerations of the designer’s task in selecting doors, windows and skylights using testing programs that allow objective comparisons of the structural, thermals and other requirements of products of different types and from different manufacturers.
The first of these standards is the Standard/Specification for Windows, Doors and Unit Skylights, jointly published by the American Architectural Association (AAMA), the Window and Door Manufacturers Association (WDMA) and the Canadian Standards Association (CSA) officially designated as AAMA/WDMA/CSA 101/I.S.2/A440.
This specification establishes minimum requirements for air leakage, water penetration, structural strength, operating force and forced entry resistance of aluminum, plastic and wood framed windows, doors and unit skylights.
The AAMA/WDMA/CSA Standard/Specification uses a letter designation called Performance Class and a numeric designation called Performance Grade to indicate the minimum capabilities of fenestration products.
Performance Classes, on order of increasing capability are, R, LC, HC and HW. These letter designations were associated with the terms Residential, Light Commercial, Commercial, Heavy commercial and Architectural respectively. Although these plain word descriptions have been removed from the newest editions standard knowledge of them is still helpful in recalling the intended ranking of the letter designations.
Each Performance Class sets criteria for resistance to wind loads, resistance to water penetration and maximum air leakage.
Numeric Performance Grades correspond to maximum design wind pressures. For example, Grade 30 indicates a unit suitable for design wind pressures up to 30 pounds per square foot (psf) (1440 Pa). Grades are specified starting at 15 psf (720 Pa) and increasing in increments of 5 psf (240 Pa). Each Class letter designation has a minimum acceptable Grade or design wind pressure and higher than minimum Grades can be specified where resistance to higher wind forces is required.
An example of a manufacturer’s complete tested product designation is C-R30 760 X 1520 (30 X 60 inches) where C stands for casement window, R is the Performance Class and the final pairs of numbers indicate the maximum size of the tested unit that meets these criteria, as expressed as width by height, first in millimeters and then in parenthesis in inches.
In practice, the designer may choose a Performance Class based on the building type and general expectations for durability of the system. For example, a Class LC window may be specified for lowrise multifamily building, a class HC window for a hospital or a school, or a Class AW window for a large institutional or high rise building.
The required Performance Grade should be based on the design wind pressures acting on the building, information that is usually provided by the structural engineer.