Vented Crawlspaces, Elevated Coastal Foundations and Overhangs

As with applications on roofs and walls, FPIS ci can provide multiple functions for the floor assembly, including improved comfort of the floor surface by helping to minimize thermal bridging through floor framing. Floor band/rim joists must be air-sealed as required by code and, ideally, this could be done with use of FPIS ci on above-grade walls installed continuous across the exterior side of the floor band/rim joists. 

FPIS ci can be applied to the underside of floor overhangs such as the recessed entry porch ceiling shown in Figure 1 below. The floor/ceiling above a garage constitutes a similar application. Some specific applications of FPIS ci on the underside (exterior side) of floors for energy code compliance can be found in IECC Section R402.1.3. As with exterior walls (see Figure 2), the appropriate amount of FPIS ci on the exterior side is important for control of water vapor in the colder climates. 
 

Floor overhang with FPIS ci above a recessed entry porch
Figure 1. Floor overhang with FPIS ci above a recessed entry porch (prior to installation of the porch soffit/ceiling finish).
[Source: Shaunna Mozingo]
Floor overhang with FPIS ci above a recessed entry porch
Figure 2.  Floor/ceiling over unconditioned garage, vented crawlspace, or similar unconditioned interior space. (Note: The gypsum board shown may not be required for a fire thermal barrier depending on the qualification of the FPIS product for interior exposure – refer to the FPIS product manufacturer for appropriate code-compliance data. For many exterior applications covered by cladding, the gypsum also is not needed as shown in Figure 2.)

Helpful Resources

Back to Multifunctional Applications   

See Also: Roofs • Walls • Windows • Foundations