Crawlspace foundations are commonly used to elevate the lowest floors of residential buildings located in Special Flood Hazard Areas (SFHA’s) above the Base Flood Elevation (BFE). This course provides guidance on crawlspace construction and supports a recent policy decision to allow construction of crawlspaces with interior grades up to 2 feet below the lowest adjacent exterior grade (LAG). In many parts of the country, a common practice is to construct crawlspaces with the interior floor 1 or 2 feet below-grade by either (1) backfilling against the exterior of the foundation wall or (2) excavating the crawlspace area to construct footings that result in a below-grade crawlspace floor. Because FEMA wishes to recognize common construction practices that do not increase flood damage.

The construction practices for below-grade crawlspaces were examined to determine whether a crawlspace that was 1 or 2 feet below grade would increase the flood damage potential to the foundation walls. This course introduces the requirements for crawlspace construction for buildings located in special flood hazard areas. Engineers and architects will gain an understanding of the design requirements for crawlspace construction. The content of this course is based on the FEMA publication “Crawlspace Construction for Buildings Located in Special Flood Hazard Areas: National Flood Insurance Program Interim Guidance”.

Topics: Understand common crawlspace construction practices Be familiar with requirements for conventional crawlspace construction Know common requirements for below-grade crawlspace construction Understand general NFIP requirements that apply to all crawlspaces with enclosed areas or floors below the BFE Understand flood forces on buildings Know about flood insurance implications for below-grade crawlspaces Understand best practices for crawlspace foundations in SFHA’s Understand flood-resistant materials Review cases of damage caused by crawlspaces lacking proper drainage systems Understand possible drainage system options Understand utility systems protections Understand requirements for access and ventilation openings.

Intended Audience: This course is intended for Structural, Geotechnical, Civil, Environmental, Water Resources, and other engineers whose job description requires a basic knowledge of crawlspace construction concerns within flood zone regions. 

Publication Source: US FEMA