Volume 8, Issue 10 - November 2007

WDMA Opens Up

New Edition 
Standard/Specification for Windows, 
Doors and Unit Skylights is Updated

by Patty Elliott

The second edition of AAMA/ WDMA/CSA 101/I.S.2/A440-08 Standard/Specification for Windows, Doors and Unit Skylights has been completed with an anticipated publication date of early 2008. This consensus-based publication is jointly developed by the Window and Door Manufacturers Association (WDMA), the American Architectural Manufacturers Association (AAMA) and the Canadian Standards Association (CSA). 

This voluntary standard/specification is material neutral and establishes the levels of performance for exterior doors, windows and unit skylights. The two fundamental applications are product performance comparison and code compliance. Fenestration categories include single and dual windows, single and dual side-hinged door systems, sliding doors, unit skylights and tubular daylighting devices (TDDs) for new construction and replacement applications. The document is an updated version of previous standards referenced in the building codes and remains a principal document for the third-party Hallmark Certification Program used by manufacturers, architects, builders, engineers, code officials and government agencies. 

This edition contains the following significant changes and has been structured to promote clarity and ease of use for testing and rating designations. 

Reduction of the number of window and door Performance Classes from five to four by elimination of Class C. The reduction of the number of Performance Classes from five to four was accomplished by the elimination of Performance Class HC. Along with that change, Performance Class C has been renamed Performance Class CW. The major difference is that Performance Class CW now has an L/175 deflection limitation requirement. To meet the requirements of the new standard, products that were tested previously to the Performance Class HC will qualify automatically for the new Performance Class CW. Products that were tested previously to Performance Class C will also qualify for the new Performance Class LC requirements. 

To qualify a Performance Class LC to Performance Class CW, products must now be tested for the L/175 deflection limit requirements.

What the Designations Mean

  • Design Pressure (DP) applies only to the wind load pressures a product is rated to withstand. 
  • Performance Grade (PG) is a numeric designator that defines the performance of a product in accordance with 101/I.S.2/A440-08 Standard/Specification. This is only achieved when the product meets all of the performance requirements that are inclusive of structural loading, resistance to water penetration, resistance to air leakage, operating force and forced-entry resistance. For example, an R-class window designated R-PG15 (R-PG720 metric) establishes a DP of 720 Pa or approximately 15 psf (for SI metric units the DP is expressed in Pascals followed by the word metric.) To qualify for a given PG, a representative specimen or specimens of the product need to pass all required performance tests and all required auxiliary (performance and durability) tests for the applicable product type and desired performance class. These performance tests include: operating force (if applicable); air leakage resistance, water penetration resistance, uniform load deflection test, uniform load structural test and forced-entry resistance (if applicable).
  • Structural Test Pressure (STP) is the pressure differential applied to a door, window, unit skylight or TDD. In this Standard/ Specification, the STP is 150 percent of DP for doors and windows, and 200 percent of DP for unit skylights, roof windows and TDDs.

Other noteworthy changes include: 

  • The addition of a new product category for tubular daylighting devices (TDD);
  • The clarification of the primary designator for Design Pressure (DP);
  • The definition of Performance Grade (PG);
  • Revised pressure caps for the R and LC classes; and
  • Introduction of an option permitting a product to enter Performance Class R by testing an alternative minimum test size smaller than the gateway test size, provided the minimum PG is increased correspondingly. 

This voluntary Standard represents the continuing development of an internationally accepted performance Standard/Specification for inclusion in the U.S. International Building Codes and in the National Building Code of Canada. 

AAMA/WDMA/SA 101/1.S.2/A440-08 Standard/Specification Requirements 
The AAMA/WDMA/CSA 101/I.S.2/A440-08 Standard/Specification defines requirements and levels of performance for four performance classes now designated R, LC, CW, and AW. 

It is important to note that product selection is always based on performance requirements of the particular project and not solely these suggestions specified in Items (a) to (d). The performance class ratings should be regarded as an indication of the level of performance, with the least stringent requirements established for the R performance class, and the most stringent for the AW performance class. 

The following descriptions can be used as a general guide in helping to determine which class is suited for a particular application:
(a) R: Used commonly in one- and two-family dwellings.
(b) LC: Used commonly in low-rise and mid-rise multi-family dwellings and other buildings where larger sizes and higher loading requirements are expected.
(c) CW: Used commonly in low-rise and mid-rise buildings where larger sizes, higher loading requirements, limits on deflection and heavy use are expected.
(d) AW: Used commonly in high-rise and mid-rise buildings to meet increased loading requirements, limits on deflection, and buildings where frequent and extreme use of the products are expected.

Patty Elliott serves as manager, communications and public relations, for the WDMA. Ms. Elliott’s opinions are solely her own and do not necessarily reflect those of this magazine.


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