Air/water/structural performance 

Proven by rigorous testing and field experience, windows can be installed over up to 1½" FPIS ci with integral flanges using window manufacturer specified shim/fastener schedules (with only the flange fastener length adjusted to accommodate the FPIS thickness). For >1½" FPIS, use of bucks or window support brackets is recommended. Integrate flashing to either the WRB face (using a qualified FPIS WRB system as shown in Figure 1) or a separate WRB material layer per 2024 IBC/IRC (see Figure 2). 
 

Window flashed to the surface of an FPIS ci WRB installation
Figure 1. Window flashed to the surface of an FPIS ci WRB installation. Alternatively, an “inny” (recessed) window install also may be used  with a separate WRB provided behind the FPIS and appropriate flashing and trim details to accommodate the recessed windows install (Figure 2). 
Window flashed to a separate WRB material
Figure 2. Window flashed to a separate WRB material located behind an FPIS ci installation (FPIS ci is not also used as the WRB in this case).

 

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See Also: Roofs • Walls • Floors • Foundations