R609.8.3

Section 609.8.3 is titled 'Structural safety factor' and covers requirements for exterior windows and doors. The requirement for mullions to be able to withstand a load 1.5x the design pressure loads applied by window and door assemblies, and where the mullion is tested, for the test load to be applied for a minimum amount of time, and a maximum allowed permanent deformation is established. The purpose of this section is to prevent detachment of window and door assemblies from the building.

The model shows a wall section with a window assembly including a highlighted mullion and an arrow representing a 1.5x design load.