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Overview of SLR-DFE Comparison Criteria (All initiatives)
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InitativeAuthor/EntityStarting Elevation MeasurementSLR Scenario and Timeframe

SLR Adjustment
Freeboard
Design Flood ElevationsApplicationRequirement or Recommendation

References
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ASCE Standard 24-14 (National)¹		American Society of Civil Engineers (ASCE)Measured from FEMA BFE.Does not incorporate SLR projections.N/A—freeboard is the primary elevation method used.Class 1 = 0’
Class 2 = 1’ (0.30 m)
Class 3 = 2’ (0.61 m)
Class 4 = 2’ (0.61 m)		• Class 1 = DFE*
• Class 2 = BFE + 1’ (0.30 m) or DFE*, whichever is highest
• Class 3 = BFE + 2’ (0.61 m) or DFE*, whichever is higher
• Class 4 = BFE + 2’ (0.61 m) or DFE*, or 500-year flood elevation, whichever is higher
*For ASCE Standard 24-14, the DFEs are the flood elevations shown on the map adopted by a community (if not using FEMA FIRMS).

For buildings within Coastal High Hazard Areas, Coastal A Zones, and High Risk Flood Hazard Areas: the minimum elevation (listed above) is measured to the bottom of the lowest supporting horizontal structural member of the lowest floor.
For buildings within all other Flood Hazard Zones: the minimum elevation is measured to the top of the lowest floor.		ASCE Standard 24-14 applies to new construction or substantial improvement of buildings and structures in flood hazard areas.Required for all structures subject to building code requirements in flood hazard areas.¹American Society of Civil Engineers (ASCE). 2015. “ASCE 24 Flood Resistant Design and Construction.” ASCE/SEI 24-14. Available online: https://ndl.ethernet.edu.et/bitstream/123456789/58215/1/638.pdf. (accessed February 1, 2025).
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New York City (Municipal)¹NYC Mayor’s Office of Climate and Environmental JusticeMeasured from FEMA BFE.
(BFE Measured from NAVD 88; FEMA 1% Preliminary FIRM (PFIRM) (2015) or FIRM (2007).)
Middle of the 25th–75th percentile range projections from the NPCC. ²Based on end of useful building life (range):
• 2020s (2020–2039): 0’-6” (0.15 m)
• 2050s (2040–2069): 1’-4” (0.41 m)
• 2080s (2070–2099): 2’-4” (0.71 m)
• 2100+: 3’-0” (0.91 m)		24” (0.61 m)SLR-DFE = BFE + SLR adjustment + FreeboardApplies to all city capital projects (new construction and substantial improvements) except coastal flood protection systems.
Applies to city critical and non-critical buildings (defined by NYC) within current or future 1% annual chance flood plain.
Required for NYC capital projects (starting 2026)¹NYC Mayor’s Office of Climate and Environmental Justice 2025. New York City Panel on Climate Change (NPCC). Available online: https://climate.cityofnewyork.us/initiatives/nyc-panel-on-climate-change-npcc/ (accessed May 2025).

²Horton, R., Little, C., Gornitz, V., Bader, D. and Oppenheimer, M. (2015), New York City Panel on Climate Change 2015 Report Chapter 2: Sea Level Rise and Coastal Storms. Ann. N.Y. Acad. Sci., 1336: 36-44. https://doi.org/10.1111/nyas.12593.
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City of Boston (Municipal)¹Boston Planning and Development Agency (BPDA)Measured from FEMA BFE, which uses the Boston City Base (BCB) as their city-wide datum. NAVD88 can be converted to BCB by using a conversion factor of NAVD88 + 6.46 feet (1.97 m). Boston Harbor Flood Risk Model (BH-FRM) is a localized scenario that utilizes data from the U.S National Climate Assessment from (Parris et al. 2012)². The projection is set for the year 2070 for the “High” scenario.40” (1.02 m) SLR adjustment (3.2’ (0.98 m) SLR + 2.5” (0.06 m) land subsidence)1’-0” (0.30 m): all buildings—existing/retrofit
2’-0” (0.61 m): planned/new construction or residential use, or uses, which are conditional within the overlay		SLR-DFE = FEMA BFE + SLR Adjustment + Land Subsidence + FreeboardGuides private development. Applies to all structures within the overlay zone (BH-FRM), which includes areas “anticipated to be flooded with a 1% chance storm event in 2070 with 40-inches (1.02 m) of sea level rise.” (includes 2.5” (0.06 m) of land subsidence)Required within the Coastal Flood Resilience Overlay District (CFROD); Section 25A-6¹Boston Planning & Development Agency (BPDA). 2019. “Coastal Flood Resilience Design Guidelines.” Boston, Massachu-setts: Boston Planning & Development Agency. Available online: https://www.bostonplans.org/getattachment/d1114318-1b95-487c-bc36-682f8594e8b2 (accessed February 2025).;

Bosma, Kirk, Ellen Douglas, Paul Kirchen, Katherin McArthur, Steven Miller, and Chris Watson. 2015. “MassDOT-FHWA Pilot Project Report: Climate Change and Extreme Weather Vulnerability Assessments and Adaptation Options for the Central Artery.” Boston, Massachusetts: MassDOT-FHWA. Available online: https://www.cakex.org/sites/default/files/documents/MassDOT_FHWA_Climate_Change_Vulnerability_1.pdf (accessed February 2025).

BPDA. 2023. “Flood Resiliency Building Guidelines & Zoning Overlay District.” Government Planning. Bostonplans.Org. 2023. Available online: https://www.bostonplans.org/planning/planning-initiatives/flood-resiliency-building-guidelines-zoning-over (accessed February 2025).

Boston Planning & Development Agency (BPDA). 2021. “Boston Zoning Code Article 25A Coastal Flood Resilience Review Procedures and Submittal Requirements.” Boston Planning & Development Agency. Available online: https://www.bostonplans.org/getattachment/206a310f-5215-43df-8cef-3dd9a4974215 (accessed February 2025).


²Parris, Adam S. et al. "Global sea level rise scenarios for the United States National Climate Assessment" (2012). Available online: https://repository.library.noaa.gov/view/noaa/11124 accessed April 2025.
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Kauaʻi, Hawaiʻi (County and District)¹County of KauaʻiUses a sea level rise flood elevation (SLRFE) or FEMA FIRM BFE (if higher). Sea level rise flood elevation (SLRFE) is the individual depth above existing grade per grid unit provided by the County of Kauai Sea Level Rise Constraint District Viewer for both the high wave run up hazard and the passive flooding hazard when either of those are associated with 3.2 feet (0.98 m) of SLR occurring within this century.Uses Hawaiʻi’s sea level rise exposure area (SLR-XA), which includes passive flooding, annual high wave flooding, and coastal erosion is based on the high GHG emissions scenario (RCP8.5) used to model exposure to sea level rise 3.2 feet (0.98 m) by 2100.²Flood depth indicated by SLRFE.1’-0” (0.30 m): nonresidential
2’-0” (0.61 m): residential		DFE = SLRFE or BFE + Freeboard (within the ST-CE and S-SLR)Residential and non-residential new construction and major renovation within the S-SLR constraint district.Required in the S-SLR, which is monitored through the use permitting process.¹County of Kauaʻi Planning Department. 2020. A Bill for an Ordinance Amending Chapter 8, Kauaʻi County Code 1987, As Amended, By Establishing A New Special Treatment Coastal Edge (ST-CE) District and Amending Zoning Maps ZM-KL00 (Kekaha), ZM-WL00 (Waimea), ZM-200, and ZM-H200 (Hanapepe). Available online: https://kauai.granicus.com/MetaViewer.php?meta_id=144738 (accessed February 2025).

Hawaiʻi Climate Change Mitigation and Adaptation Commission. 2017. Hawaiʻi Sea Level Rise Vulnerability and Adaptation Report. Prepared by Tetra Tech, Inc. and the State of Hawaiʻi Department of Land and Natural Resources, Office of Con-servation and Coastal Lands, under the State of Hawaiʻi Department of Land and Natural Resources Contract No: 64064.
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Miami Beach, Florida (Municipal)¹City of Miami BeachUses the highest point of adjacent road or above the crown of the nearest street (Flood Zone X) or FEMA BFE (Flood Zone A).“The years 2040 and 2070 were chosen because they represent a near- and long-term planning horizon, respectively. Two of the sea level rise scenarios (NOAA 2017 Intermediate Low and NOAA 2017 Intermediate High) were selected to comply with the Resilient Florida program. The City included a third scenario (NOAA 2017 High), which represents a more rapid rise in future sea level, as a more extreme scenario that can potentially be used for developing adaptation strategies for critical infrastructure (e.g., emergency facilities)”.SLR Adjustment is not required, but the SLR Adaptation Plan² discusses SLR in the FFE.
NOAA 2017¹:
Intermediate-low
• 2040–0.3’ (0.09 m)
• 2070–0.9’ (0.27 m)
Intermediate-high
• 2040–1.0’ (0.30 m)
• 2070–2.9’ (0.88 m)
High (critical)
• 2040–1.3’ (0.40 m)
• 2070–4.1’ (1.25 m)		(City of Miami Beach n.d, §54-35; 54-48; 54-51):
1’ (0.30 m) (min.)–5’ (1.52 m) (max.)
Specifically:
Flood Zone X: 1 foot (0.30 m) (min.) above the highest adjacent grade or above the crown of the nearest street; whichever is higher.
Except seaward of the Coastal Construction Control Line and in Coastal A Zones, All Flood Zone A:
• Non-Residential/Residential: 1 foot (0.30 m) (min.) above the BFE “no lower than 9.0 feet (2.74 m) NGVD (7.44 ft (2.27 m) NAVD), the crown of road or sidewalk plus one foot (0.30 m), or the base flood elevation plus minimum freeboard, whichever is higher.”
• Critical: 2 ft (0.61 m) (min.) above the BFE
Flood Zone V and Coastal A Zone: meets all the above and in addition elevated on pilings or columns plus freeboard “no lower than 8.0 feet (2.44 m) NGVD (6.44 feet (1.96 m) NAVD), the crown of road or sidewalk plus one foot (0.30 m), or the base flood elevation plus minimum freeboard whichever is higher”. 		DFE = BFE or highest adjacent grade or above the crown of the nearest street + (1’ (0.30 m)–5’ (1.52 m)) freeboardFreeboard: all new construction and substantial improvements to existing construction as described in the Flood Zones aboveFreeboard is required as described in the Flood Zones above¹. The SLR Adaptation Plan² discusses SLR in the FFE.¹City of Miami Beach. n.d. Code of Ordinances: Chapter 54 - Floods. Municode Library. Available online: https://library.municode.com/fl/miami_beach/codes/code_of_ordinances?nodeId=SPAGEOR_CH54FL (accessed April 2025).

Sweet, W.V., R.E. Kopp, C.P. Weaver, J. Obeysekera, R.M. Horton, E.R. Thieler, and C. Zervas. 2017. “Global and Regional Sea Level Rise Scenarios for the United States.” NOAA Technical Report NOS CO-OPS 083. NOAA. Available online: https://tidesandcurrents.noaa.gov/publications/techrpt83_Global_and_Regional_SLR_Scenarios_for_the_US_final.pdf (ac-cessed February 2025).

²City of Miami Beach, AECOM. 2025. Sea Level Rise Adaptation Plan (draft). Available Online: https://www.mbrisingabove.com/wp-content/uploads/CMB_SLR_Adaptation_03032025.pdf (accessed July 2025).
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Satellite Beach, Florida (Municipal)¹City of Satellite BeachFEMA BFE or highest point of abutting street In their 2019 Sea-Level Rise Technical Planning Assessment (Evan et al.), the city acknowledges data from the U.S. Army Corps of Engineers (USACE 2013) “High” Scenario, which was derived from the U.S. Army Corps of Engineers Sea-Level Change Calculator (accessed July 6, 2018;). Projection through the year 2070.SLR Adjustment is not required, but the Sustainability Action Plan V2² discusses SLR incorporated into future DFEs.
USACE “High” Scenario (2070): 2.85 feet (0.87 m) above 1992 mean sea level (MSL).
- Commercial, Institutional and Industrial: minimum 18 inches (0.46 m) (current requirement)/30 inches (0.76 m) (recommended code modification) above the highest point of any abutting street.
- Residential: “above the dune vegetation on stilts/pilings to a minimum of three feet (0.91 m) above the BFE” if located east of Highway A1A. An owner may elevate the structure more than three feet (0.91 m) above the BFE as desired and if approved by the building official and in accordance with FEMA and NFIP standards.
- Variance: Property less than 15 feet (4.57 m) landward of the construction control line (CCL): 10 feet (3.05 m) above the BFE.		DFE = Street + 18–30”(0.46–0.76 m)
DFE = BFE + 3’ (0.91 m)
DFE = BFE + 10’ (3.05 m)		“…construction, reconstruction, modification, repair or replacement of principal or accessory structures or portions thereof for all properties located east of Highway A1A.”Freeboard: required. Note recommended code modification (above). ¹Satellite Beach. n.d.(a) Code of Ordinances. § 30-738. Design Standards. Municode Library. Available online: https://library.municode.com/fl/satellite_beach/codes/code_of_ordinances?nodeId=PTIICICO_CH30LADERE_ARTVIIREPR_DIV4COCOCOLICCSTCR_S30-738DEST (accessed 18 March 2025).

Satellite Beach. n.d.(b) Code of Ordinances. § 30-739. Variances and action by the board of adjustment. Municode Library. Available online: https://library.municode.com/fl/satellite_beach/codes/code_of_ordinances?nodeId=PTIICICO_CH30LADERE_ARTVIIREPR_DIV4COCOCOLICCSTCR_S30-739VAACBOAD (accessed April 2025).

Satellite Beach. n.d.(c) Code of Ordinances. § 30-555. Floor level. Municode Library. Available online: https://library.municode.com/fl/satellite_beach/codes/code_of_ordinances?nodeId=PTIICICO_CH30LADERE_ARTVBURE_DIV8OTPR_S30-555FLLE (accessed April 2025).

Evans, J.M., E. Mitchell, A. Carr, C. Goodison, P. Zwick, and T. McCue. 2019. Sea-Level Rise Technical Planning Assessment for the City of Satellite Beach. Gainesville: Florida Sea Grant. Available online: https://www.stetson.edu/other/iwer/media/Sea-Level%20Rise%20Technical%20Planning%20Assessment.pdf (accessed April 2025).

USACE 2013. ER 1100-2-8162 Incorporating Sea Level Change in Civil Works Programs. Washington, DC. Available Online: https://www.publications.usace.army.mil/Portals/76/Users/182/86/2486/ER_1100-2-8162.pdf accessed (April 2025).

²City of Satellite Beach. January 18, 2023. 2022 Sustainability Action Plan. Available online: https://satellitebeach.gov/residents/sustainable_satellite/sustainability_action_plan/sustainability_action_plan.php (accessed April 2025).
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Rhode Island (State)¹RI CRMC, Shoreline Change Special Area Management Plan, and STORMTOOLS.Once in 100-year (1% chance) return period storm scenario referenced to NAVD 88.Choose an appropriate design life and identify the associated projected sea level. The Coastal Hazard Application recommends a minimum 30 year “design life” be considered.

CRMC policy, RICRMP Section 145, relies on the “high” sea level change curve (RI CRMC 2018) included in the most recent NOAA sea level rise data (NOAA 2022).
• 2030–1.67’ (0.51 m)
• 2050–3.25’ (0.99 m)
• 2080–6.69’ (2.04 m)
• 2100–9.6’ (2.93 m)		Maps illustrating SLR depths of 2’ (0.61 m), 3’ (0.91 m), 5’ (1.52 m), 7’ (2.13 m), 10’ (3.05 m) are available in STORMTOOLS.²
Maps illustrating a 100-year return period (1% annual chance) COASTAL STORM with or without 2 feet (0.61 m) of SLR are available in STORMTOOLS.
SLR scenarios are relative to 2010 and suggested design elevations are referenced to NAVD 88.		Recommended: 1 foot of freeboard (elevation) above BFE is required but up to 5 feet of additional freeboard may be provided voluntarily. It is unclear if freeboard should be added to the SDE (described below).
Standards for Shallow Flooding Zones (A-Zones) in SFHZs:
• Residential: 3’-0” (0.91 m)
• Non-residential: 3’-0” (0.91 m)
Critical facilities: 2’-0” (0.61 m) (minimum) lowest floor either elevated or dry floodproofed to or above the 500-year flood plus 2 feet (0.61 m) of freeboard		SLR-DFE = 100-year return period storm scenario + SLR based on design life + Freeboard

STORMTOOLS uses the term STORMTOOLS Design Elevation (SDE) to represent the “once in hundred year flooding and associated wave environment”, and SLR of varying depths (and does not mention freeboard).
All projects (new or expanding residential, commercial, industrial) within the CRMC jurisdiction require a CRMC permit.Freeboard for substantial improvements for critical facilities is required.

Permit is required by the Coastal Resources Management Council (CRMC)’s jurisdiction (extending from the territorial sea limit to two hundred feet (60.96 m) inland from any coastal feature). Permit requires completion of Coastal Hazard Application Worksheet and Viewer and design evaluation.

SAMP includes additional adaptation recommendations from FM Global, an insurance company.
¹RI CRMC. 2018. “Shoreline Change SAMP Volume 1.” http://www.crmc.ri.gov/samp_beach/SAMP_Beach.pdf.

Spaulding, Malcolm L., Annette Grilli, Chris Damon, Reza Hashemi, Soroush Kouhi, and Grover Fugate. 2020. “Stormtools Design Elevation (SDE) Maps: Including Impact of Sea Level Rise.” Journal of Marine Science and Engineering 8 (4): 292. https://doi.org/10.3390/jmse8040292.

RI CRMC. 2023. “RI CRMC FAQs.” http://www.crmc.ri.gov/faqs.html.http://www.crmc.ri.gov/faqs.html.

²RI CRMC. 2019. (2) Updated 28 March 2022. “RI CRMC Coastal Hazard Application.” https://ri-crmc-coastal-hazard-map-tool-crc-uri.hub.arcgis.com/ and “Main Page.” https://stormtools-mainpage-crc-uri.hub.arcgis.com/
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Federal Flood Risk Management Standard (National)¹FFRMS Science Subgroup of the Flood Resilience Interagency Working Group of the National Climate Task Force.FEMA BFE is used for the Freeboard Value Approach (FVA) and 0.2-Percent Annual Chance Flood Approach.Uses best-available science when using the Climate Informed Science Approach (CISA) (if climate science data is available).Determined by climate science data (if CISA available).For FVA (only):
• Non-Critical action: 2’-0” (0.61 m)
• Critical actions: 3’-0” (0.91 m)		If CISA is not available; the FVA is as follows:
• Non-Critical action: DFE= BFE + 2 ft (0.61 m)
• Critical actions: DFE= BFE + 3 ft (0.91 m) or 2% annual chance flood (whichever is higher)		FEMA-funded projects involving new construction, substantial improvement, or repairs to address substantial damage. Required for FEMA-funded projects.¹National Climate Task Force. 2023. “Federal Flood Risk Management Standard Climate-Informed Science Approach (CISA) State of the Science Report.” National Climate Task Force. Available online: https://www.epa.gov/system/files/documents/2024-08/ffrms-climate-informed-science-approach-state-of-the-science-report.pdf (accessed February 2025).

Berginnis, Chad. 2023. “FEMA’s Proposed Rule on FFRMS: What Floodplain Managers Need to Know.” October 16, 2023. https://www.floods.org/news-views/from-the-directors-desk/femas-proposed-rule-on-ffrms/.
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