WDMA Recommends Revisions to AAMA 450 Standard

The Window & Door Manufacturers Association (WDMA) is working with the American Architectural Manufacturers Association (AAMA) on revisions to AAMA 450, Voluntary Performance Rating Method for Mulled Fenestration Assemblies. The purpose of AAMA 450 is to establish a level of uniformity in procedures used for determining the structural performance of mulled fenestration assemblies. It excludes bay/bow windows and other three-dimensional products and curtainwalls.

One of WDMA's recommendations is to separate engineering design from the guidelines for comparative and rational analysis which are combined with certification requirements, to make it possible to better standardize calculation package formats. The association has also proposed revisions in mullion anchoring. The question raised relates to the extent that test results or design parameter values can be integrated into anchoring schedules.

"The intent of these changes is to clearly distinguish the rules for testing the mullion element from the rules for testing a total assembly. The change would allow air and water tests of a mullion element to be valid for assemblies incorporating adjacent units wider than those tested," said Rick Perry, director of industry standards for WDMA.

The revised document should be completed during the first half of 2005, according to AAMA.


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