FPIS ci has a long history of successful applications on building foundations. Foundation insulation requirements can be found in IECC Section C402.1.3 and IECC Section R402.1.3. For any foundation construction, be sure to also comply with code-required termite protections (see Helpful Resources).
Common foundation applications of FPIS ci include:
Below Grade Walls (Basements & Crawlspaces)
FPIS ci improves energy and moisture management for conditioned basements (see Figure 1) and crawlspaces when placed on the interior or exterior side of the foundation walls. For unvented/conditioned crawlspaces, insulating the crawlspace walls – not the floor above – provides optimal energy efficiency, moisture control, comfort, and cost savings (see Figure 2).
See IRC Section R408.3 for guidance on properly constructing an unvented/conditioned crawlspace. For basement slab floors and crawlspaces a ground vapor barrier is always required.
Slab on grade
FPIS ci is especially suited to slab on grade construction by providing slab edge insulation or a fully insulated slab for better performance with less insulation thickness. A well-insulated slab with FPIS ci provides energy savings and comfort while also helping to prevent condensation on slab surfaces. FPIS ci also provides compressive strength capable of supporting slabs and even foundation loads with appropriate specification.
Frost Protected Shallow Foundations (FPSF)
FPIS enables code recognized shallow foundation options in cold climates to reduce foundation cost, save energy, and prevent frost heave in places with deep seasonal frost depths. Find code-compliant construction and design requirements in IRC R403.3 | IBC 1809.5 | ASCE 32.
Helpful Resources
- Foundation Insulation & Frost Protection
- ci for Residential Foundations
- ci for Commercial Foundations
- Termite Protection