AAMA Updates Rating Document for Mulled Fenestration Assemblies

The Voluntary Performance Rating Method for Mulled Fenestration Assemblies has been updated and published as AAMA 450-06 by the American Architectural Manufacturers Association (AAMA). First developed in 2000, the standard details a voluntary testing and rating method to determine air infiltration, water penetration resistance, and structural performance of factory-built or knocked-down field mulled fenestration assemblies, according to Larry Livermore, AAMA Technical Standards Manager.

A mulled fenestration assembly is defined by AAMA as an assembly of two or more individual products installed in a single rough opening. This is also known as a mulled combination assembly. The assembly is not defined as a curtain wall, and 450-06 is not intended for curtain wall performance testing, Livermore noted.

Prior to establishing AAMA 450, there was no defined procedure for determining the performance level of field mulled fenestration assemblies. Products tested to AAMA/WDMA/CSA 101/I.S. 2/A440-05 (and its predecessors) are certified as single units only. This updated standard, which covers the placement of multiple units into a single opening, provides a procedure for evaluating and testing the mulled assembly. Also included in AAMA 450 is a set of Grouping Rules and Engineering Design Rules, offering structural engineers a uniform methodology to use when performing analysis.

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