The Fenestration and Glazing Industry Alliance (FGIA) updated a mulled assemblies document: AAMA 450-20, Performance Rating Method for Mulled Combination Assemblies, Composite Units, and Other Mulled Fenestration Systems.
The document was last updated in 2010. The performance rating method describes procedures and requirements for determining the air leakage, water resistance, and structural performance of mulled fenestration systems.
The document includes test procedures and calculation procedures for determining the performance of mulled fenestration systems. Mulled fenestration systems may be factory assembled or assembled onsite with parts and instructions supplied by the product manufacturer.
“The North American Fenestration Standard says that ‘mullion ratings shall be determined according to the requirements and procedures of AAMA 450 for both composite units and mulled combination assemblies.’ However, until now, AAMA 450 provided no guidance for composite units,” said Dave Goldsmith (PlyGem), co-chair of the FGIA Requirements for Mulled and Combination Window Assembly Update Task Group. “This document will put powerful new tools into the hands of engineers to assist them in determining how to construct structurally sound and weatherproof fenestration products in the most economical ways, and should also drastically reduce the amount of testing required to validate a large variety of composite unit configurations,” Goldsmith said.