Basements and Crawlspaces: What s the Difference, and Who Cares?

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1 Basements and Crawlspaces: What s the Difference, and Who Cares? Cadastral Consulting, LLC The difference between a basement and a crawlspace seems clear by common perception of what each one is. But when it comes to floodplain management, the distinction, while very specific, may not be as easy for some to discern. Whether designing a structure to be constructed in a 1% chance floodplain, completing an Elevation Certificate for insurance or LOMC purposes, or completing paperwork for processing a buyout, the differentiation is critical for achieving the basic objectives of the National Flood Insurance Program. This session is designed to clarify the distinction and underscore its significance. NFIP Purpose 42 USCS Congressional findings and declaration of purpose (e) Land use adjustments by State and local governments; development of proposed future construction [Minimize damages from flooding by constricting development of land exposed to flooding and guiding proposed future development away from such areas] NFIP Basic Objectives Reduce the exposure to flood damages through the use of minimum standards for the placement and design of structures located in flood hazard areas. Lowest Floor (44 CFR 59.1)... the lowest floor of the lowest enclosed area, including basement. An unfinished or flood resistant enclosure, usable solely for parking of vehicles, building access or storage in an area other than a basement area is not considered a building s lowest floor; provided that such enclosure is not built so as to render the structure in violation of the applicable non-elevation design requirements of Sec Regulation NFIP minimum standards in 44 CFR 60.3 regarding floodplain management and land use in flood prone areas establish relationship of lowest floor to Base Flood Elevation Regulations: 44 CFR 60.3 (c) 2, 3 SFHA w/ BFE identified (Zones A1-30, AE and AH), but no floodway, or coastal hazards; some SFHA w/o BFE (2) Residential: elevate lowest floor (including basement) to or above the base flood level (3) Non-residential: elevate lowest floor (including basement) to or above the base flood level [or design for water tightness]

2 Regulations: 44 CFR 60.3 (c) 7, 8 SFHA identified, but no BFE, floodway, or coastal hazards (Zone AO) (7) Residential: elevate lowest floor (including basement) above HAG at least as high as depth number (2 if not specified) (8) Non-residential: elevate lowest floor (including basement) above HAG at least as high as depth number (2 if not specified) Community compliance: 44 CFR 60.3 Minimum standards for communities participating in the NFIP Require and review permit applications to determine if reasonably safe from flooding 44 CFR Local flood mitigation plans; risk assessment, emergency preparedness, disaster response where will it flood first? 44 CFR Variances and exceptions Insurance premiums not affected; variance from floodplain management regulations Variances for historic structures and for structures functionally dependent upon water No rise in BFE if in floodway Floodproofing, flood warning When is flood insurance required? 42 USC 4012a. Flood insurance purchase and compliance requirements and escrow accounts (When an institution makes, increases, extends or renews a loan, and all three factors are present:) 1. The loan is secured by improved real estate or a mobile home affixed to a permanent foundation 2. The property is located or will be located in an SFHA as identified by FEMA; and 3. 3.The community participates in the NFIP. Insurance Agent s Manual, Lowest Floor Guide Rating Non-Elevated Buildings in A-type Zones Rate at lowest floor, including basement, if any For attached garage with machinery/equipment on floor: rate at floor unless properly vented Rating Elevated Buildings in A-type Zones Rate at lowest elevated floor, unless lower floor size, use, improper flood openings disqualify Why Lowest Floor Elevation Matters

3 Appraisals What is the risk to the structure? Marketability and insurability questions Buyouts What was the pre-disaster appraised value of the structure? Disaster assistance Was structure properly insured? Definition of Basement Basement means any area of the building having its floor subgrade (below ground level) on all sides. (44 CFR 59.1) Any area of the building, including any sunken room or sunken portion of a room, having its floor below ground level (subgrade) on all sides. (NFIP Insurance Agent s Manual, DEFINITIONS 1) Special Certifications What s a crawlspace? Not specifically defined by federal NFIP statute or regulation Who cares? NFIP rules and regulations specify that a crawlspace with its interior floor below grade on all sides is considered a basement. (NFIP Insurance Agent s Manual, RATE 25) Crawlspace (TB-11) Relation of crawlspace to LAG and BFE affects insurance and structural integrity For a crawlspace not to be considered a basement, drainage and velocity also must be considered.

4 Caution (From Technical Bulletin 11) Buildings that have below-grade crawlspaces will have higher flood insurance premiums than buildings that have the preferred crawlspace construction, with the interior elevations at or above the lowest adjacent grade (LAG). Floodplain Management Bulletin: Elevation Certificate (FEMA 467-1, May 2004) 5) Why is it necessary to obtain the elevation of a crawlspace floor? 6) How can the elevation of a crawlspace floor be measured when the area is inaccessible? Building Diagrams 2A and 2B Use only for basements Use Diagram 9 for subgrade crawlspace Diagram 9 Crawlspace at or below grade on all sides Beware criteria for basement vs. crawlspace Design and engineering in the 1% annual chance floodplain Technical compliance does not equate to exemption from mandatory insurance requirements 44 CFR 65.2(c) Reasonably safe from flooding means base flood waters will not inundate the land or damage structures to be removed from the SFHA and that any subsurface waters related to the base flood will not damage existing or proposed buildings.

5 From Technical Bulletin 10 Cross-Sectional View of a LOMR-F Request The complications of LOMR-Fs Why the application now differs from LOMA: o Woodhill Corporation v. FEMA (IL, 168 F3d 1025, 1999) o Orchard Hill Construction, LLC v. FEMA (IL, 2001 US Dist. LEXIS 2041) Effect on later site development Design and engineering in the 1% annual chance floodplain Mechanical and electrical equipment: location and Floodproofing requirements Location reported on Line C2(e) of Elevation Certificate Mechanical and Electrical Equipment

6 Elevators (TB ) Mechanical & electrical equipment Machine room location Float switch system Water-resistant components Report location and elevation on Line C2e of Elevation Certificate Reducing Flood Effects in Critical Facilities Maintaining functionality Protecting components of essential systems and equipment Code requirements, FEMA recommendations Mitigation measures for utilities, equipment Design considerations for essential systems and equipment Vulnerability assessments Designing for Flood Levels Above the BFE After Hurricane Sandy Elevating to BFE isn t enough. FIRM accuracy depends upon data and analyses used to create them. FIRMs do age. Flooding levels above LFE increase damages dramatically, particularly in coastal areas. BMPs can lessen damages. How high to elevate above BFE? Required Design Considerations Building codes and floodplain management regulations Building height restrictions Importance of the building to the community Grant requirements How high to elevate above BFE? Recommended Design Considerations Building owner tolerance for damage Age of the Effective Flood Analysis. Availability of Preliminary FIRMs Availability of ABFEs Future conditions Wet Floodproofing (TB-7) Required in residential structures Optional in non-residential buildings Planning and design considerations Approaches to Floodproofing TB -3: Non-Residential Floodproofing Requirements and Certifications for Buildings located in Special Flood Hazard Areas TB-6: Below-Grade Parking Requirements for Buildings Located in Special Flood Hazard Areas