![]() Note that crawlspaces are not considered occupiable or habitable space, whether vented and unconditioned or non-vented and conditioned. Non-vented crawlspaces are conditioned and are inside the thermal envelope (i.e., the walls of the crawlspace are insulated). Vented crawlspaces are not conditioned and are outside the thermal envelope (i.e., the floor above the crawlspace is insulated the walls of the crawlspace are not insulated). There are two common crawlspace foundation approaches - the crawlspace is either vented and unconditioned or non-vented and conditioned. See the Ensuring Success tab and the Climate tab in this guide for more information on risk assessment and flood mapping. This broad wall area also causes more disruption of floodwaters, resulting in local scouring which can undermine footings (FEMA P-55 Volume II 2011).Ī flood hazard risk assessment should be done prior to design and construction. Due to the broad wall area that crawlspace foundations expose to moving floodwaters, they can experience greater lateral forces than pile or column foundations. Per IRC 2021 Section 322, basements, slab-on-grade foundations, crawlspaces, and any other foundation types other than pilings or columns are not allowed in new construction in these areas. Despite their ubiquitous use, they are not recommended in flood-prone areas, particularly in coastal high-hazard areas including SFHA Coastal Zone A or Zone V. This guide also references topics covered in the flood Design Guide including wet floodproofing, dry floodproofing, and scouring.Ĭrawlspaces are a common foundation approach in many regions that can experience flood events. See the flood Overview Guide for background information on types of floods, flood mapping, the National Flood Insurance Program (NFIP), and terms used throughout this guide such as Special Flood Hazard Area (SFHA), Zones V, A, and Coastal A, the Flood Insurance Rate Map (FIRM), Base Flood Elevation (BFE), and Design Flood Elevation (DFE). This guide provides information on how to design or retrofit a crawlspace to reduce the risk of damage during a flood event. ![]()
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