Foam plastic insulating sheathing is a very effective means of insulating the interior or exterior of foundation walls, preventing heat loss and lowering the risk of condensation issues. Use of foam sheathing on foundations for frost protection can save thousands of dollars in construction cost and energy bills.

See Thermal Insulation for additional resources.
Tools & Education

This Educational Program, originally presented by Jay H. Crandell, P.E., gives an in-depth background and guidance on the use of Frost Protected Shallow Foundation (FPSF) technology and foam plastic insulating sheathing for reduced construction cost and energy savings.


This standard is a code referenced guide for designing and constructing cost-effective and energy-efficient foundations using foam plastic sheathing.


To assist U.S. home builders, remodelers and trade contractors in the design, construction, and code approval of frost protected shallow foundations.


This guide produced for the U.S. Dept. of Housing and Urban Development initiated modern recognition of frost-protected shallow foundations in the U.S. – ultimately resulting in building code acceptance and development of the ASCE 32 standard.


This tool from the Cold Climate Housing Research Center (CCHRC) calculates the minimum recommended insulation R-value and width for a frost protected shallow foundation per the references listed. Note that this tool is limited to slab-on-grade construction for heated buildings in Alaska.

Best Practices

This guide introduces some best practices for insulating foundations with FPIS properly installed as continuous insulation (ci). It provides details for basement walls, conditioned crawl space walls, slab-on-grade, and frost-protected shallow foundations.


This Quick Guide outlines steps for properly insulating and finishing a basement wall with FPIS ci to improve property value, comfort, and the usable square footage of any building with below-ground space.

Provides information and construction details concerning thermal protection, subdrainage, waterproofing, vapor controls, structural requirements, radon control, and termite damage prevention when constructing or renovating residential or small commercial projects.

Frost-Protected Shallow Foundation (FPSF) technology has become a widely accepted practice for protection of foundations against frost heave in the United States. The approach uses strategic placement and sizing of polystyrene insulation to protect a foundation and underlying soils against freezing temperatures and frost heave. This article gives an overview of FPSF and its many benefits.

In this article, Joseph Lstiburek examines what works and what doesn't work for insulating concrete slab-on-grade foundations.

Additional Information

Building America Solution Center guide to construct an unvented basement or crawlspace or air seal an existing vented crawlspace and insulate the interior walls with rigid foam insulation.

Building America Solution Center guide to install slab edge insulation when constructing slab-on-grade foundations in cold climates,

Building America Solution Center guide to using foam as a vapor barrier as part of a capillary break beneath slab foundations (for example, a slab-on-grade or basement slab foundation)

Building America Solution Center guide to damp-proof the exterior surface of the below-grade walls of basements and unvented crawlspaces.