How to read FEMA flood maps when comparing commercial sites

What does a FEMA flood-map screen tell you about a commercial site?

Read FEMA flood maps for a commercial site by matching the building, working yard and every required access route to the effective Flood Insurance Rate Map, Flood Insurance Study and applicable Letters of Map Change. Record the map dates, flood zones, floodway boundaries and elevation datum, then compare the mapped water elevations with surveyed site elevations. Screen access separately: a building outside the mapped floodplain can still depend on a road that crosses it. Use that evidence to retain the site, redesign the layout or reject it against the project’s operating requirements.

Separate mapped exposure, development permission and acceptable operating interruption. Use this within the wider commercial and data-center site-selection screen.

Define the operating footprint before opening the map

Write the required contiguous area, yard function, expansion phase, floor and equipment criteria, delivery and emergency routes, and acceptable interruption into the shortlist brief. Site-selection teams receive commercial-building lists as CSV or Excel within 48 hours through PorchRocket’s Ground Control, keeping the initial shortlist in one format across territories.

Trace each route to the wider network, including its first relevant bridge, culvert or low crossing. Two gates leading to the same low bridge share an exposure.

Which effective FEMA documents should you download?

FEMA’s Map Service Center says the effective FIRM, FIS, National Flood Hazard Layer (NFHL) database and effective Letters of Map Change together establish the official NFIP flood-hazard determination, so a static panel alone is an incomplete screening record. [S01]

Start with MSC Search by Address, verify the physical location, then open Show All Products. Download the complete panel, FIS and map changes with attachments. FEMA’s IS-273 course explains that a static downloaded panel needs a separate changes check; a dynamic FIRMette incorporates revisions already integrated into its source data. [S02]

Read the effective date inside each letter. MSC warns that a letter can appear in Effective Products before its own effective date arrives. Preliminary information is proposed, pending information has a future effective date, and historic products are superseded for NFIP determinations. Overlay newer evidence separately; record local applicability. [S01]

Effective FIRM/FIS/LOMC document register

Keep source edition, observation date and retrieval date separate, following the evidence identities in combining permits, imagery and records.

How often should you refresh the register?

FloodSmart recommends checking flood maps annually. Anvilfield’s transaction workflow also refreshes the register at shortlisting, before the option or acquisition decision, before permit submission, and after a map or layout change. [S22]

What do the flood zones and map symbols mean?

Read the panel legend and exact zone subtype before interpreting the color. SFHA means Special Flood Hazard Area. Keep federal and local regulated boundaries separate. [S01] [S32]

Under 44 CFR §59.1, text dated November 4, 2026, the base flood has a 1% chance of being equaled or exceeded in any year. The Wake FIS legend identifies the separate 0.2% annual-chance hazard, equivalent to 1 in 500 in any year. These probabilities apply each year, including the year after a flood. [S13] [S28]

Anvilfield estimates 26.03% probability of at least one 1% event over 30 independent, stationary years. Subtract the probability of no event from one: 1 − (1 − 0.01)^30. This measures event exceedance, not building loss.

Flood zone versus floodway interpretation

Wake’s effective data include X polygons labeled 1 PCT FUTURE CONDITIONS with SFHA_TF=F. Raleigh UDO §9.3.6.B nevertheless includes those areas in its local SFHA rules. Save subtype and local classification; SFHA_TF alone misses this constraint. [S17] [S32]

How is a regulatory floodway different from the rest of the flood zone?

FEMA defines floodway by its reserved conveyance function; AE alone does not identify its extent. [S26]

Under 44 CFR §60.3(d)(3), current through November 4, 2026, development encroaching on an adopted regulatory floodway needs hydrologic and hydraulic evidence of no increase in base-flood levels within the community unless the separate conditional-revision approval path is satisfied. Section 60.3(d)(4) places that exception through FEMA’s conditional revision process under §65.12. [S03] [S07]

Before a regulatory floodway is designated in mapped AE/A1-A30 areas, §60.3(c)(10) limits the combined rise from proposed, existing and anticipated development to 1 ft anywhere in the community; stricter state or local criteria control under §60.1(d). Section 60.3(c)(13) requires conditional FEMA revision approval before permitting an increase beyond that limit. [S03]

The floodway delineation test and a floodway table’s modeled rise are not unused capacity for a new project. A table showing 0.2 ft of modeled rise does not authorize another 0.8 ft inside an adopted floodway. Screen pad fill, stockpiles, embankments and crossings as encroachments too.

What document settles the encroachment decision?

Retain the effective hydraulic model identity, existing and proposed geometry, signed analysis and local determination. A CLOMR records FEMA’s conditional response to proposed changes; it neither changes the effective map nor issues a construction permit. Retain local authorization and the applicable final revision. [S07]

Where do you find the BFE, depth and vertical datum?

Obtain BFE, the base flood elevation, at the asset’s hydraulic location. Read profiles, cross-section/floodway and stillwater tables, and study methods. The July 19, 2022 Wake FIS treats its digital hazard database, water-surface elevation rasters, FIRM and report as a combined study product. [S13]

Match the river reach, section station and hydraulic position before selecting a water elevation. Crossings and backwater require the applicable profile, raster or model interpretation.

Read the named elevation column, not the nearest number

Wake FIS 37183CV000E, Table 22, printed page 123, supplies these Crabtree Creek values in feet NAVD 88. Its regulatory elevations are corroborated by NFHL layer 14. Apply each value at its cross-section. [S13] [S18]

Compare water and site elevations in the same datum and units. NOAA distinguishes orthometric elevations from ellipsoidal GPS heights, and FEMA’s 2022 Elevation Certificate instructions require building and BFE datum compatibility with documented conversion. Use a location-specific accepted NGVD 29-to-NAVD 88 conversion. [S08] [S09]

Keep BFE, local regulatory/design elevation, highest and lowest adjacent grade, lowest floor, and equipment elevations in separate fields. AO’s printed depth is measured relative to ground rather than a vertical datum; apply the specified nonresidential depth criterion to highest adjacent grade. In the worked NFHL extracts, STATIC_BFE=-9999 marks unavailable data and must never enter elevation arithmetic. [S03] [S17]

For coastal AE sites, also read the Limit of Moderate Wave Action (LiMWA) and Coastal A Zone treatment. FEMA Technical Bulletin 3, January 2021, explains that ASCE 24-14 excludes dry floodproofing in mapped Coastal A Zones as well as Zone V; the adopted edition controls the project. [S21]

What if Zone A has no BFE or the building sits on the line?

Under 44 CFR §60.3(b)(3)-(4), communities must use available federal, state or other BFE/floodway data, and covered subdivision and other development proposals exceeding 50 lots or 5 acres, whichever threshold is reached first, must include BFE data. Smaller proposals still need the community’s accepted elevation basis. [S03]

Raleigh UDO §9.3.4 assigns boundary interpretation to the designated local official and records the result on a map or plat. Resolve uncertain lines with mapping, survey and local interpretation. [S33]

FEMA’s October 2023 EC FAQ says a complete, correct existing certificate does not expire with the form’s printed expiration date; physical changes that invalidate its information require an update. For a new certificate, confirm the accepting authority’s current form requirements and start with FEMA’s underwriting library: the reviewed download is FF-206-FY-22-152, 2022 edition, marked 10/22, with printed expiration June 30, 2026. [S09] [S10] [S23]

What do LOMA, LOMR-F, LOMR and CLOMR change?

Read the determination, legal description, attachments and outcome. Record case, panel, effective date, removal object and later revalidation/supersession; a nearby case point is a document lead.

Map-change evidence and scope

Choose the document by its scope under FEMA guidance. [S01] [S05] [S07]

For commercial LOMA/LOMR-F submissions, use the MT-1 package or Online LOMC route; FEMA identifies MT-EZ as the form for a single residential lot or structure. FEMA’s process page requires a structure LOMA’s lowest adjacent grade to be at or above BFE, while whole-lot removal requires the lot’s lowest point to meet BFE. For whole-lot LOMR-F removal, FEMA’s process page requires both the lot’s lowest point and the structure’s lowest floor at or above the base-flood elevation. A high floor alone does not establish the ground finding. [S05]

Read a real structure-only letter

FEMA’s March 1, 2021 LOMA 21-04-1555A determined removal for the named structure at 2401 Atlantic Avenue against the then-effective 2006 panel, while its attachment retained possible SFHA exposure elsewhere on the property; application after the 2022 panel requires a revalidation/status check. [S19] [S20]

The letter lists shaded X and lowest adjacent grade of 210.8 ft NAVD 88, with a blank BFE cell. It addresses panel 3720171500J, effective May 2, 2006, and supersedes a February 22, 2010 determination. Keep its blank BFE and structure-only scope. [S19]

The NFHL vicinity attributes mark this case “Not incorporated,” describing its integration into the map layer rather than establishing whether the letter remains effective. Match each vicinity letter to the subject property and verify its effective status. [S20]

How do you overlay the building, yard, utilities and expansion area?

Overlay parcels, buildings, grading, yards and routes in one documented horizontal reference; retain separate hazard layers. Parcel data pitfalls explains why a parcel record alone misses the physical operating asset.

Give each building, dock, electrical room, generator, fuel store, service entry and pad an ID. Intersect the entire grading footprint, staging and phase-two corridors.

Building, yard and access overlay record

Tie yard lows, dock approaches and outlets to the survey scope in industrial yard paving and drainage.

Save north, scale, source dates, object IDs, hazard layers and intersected geometry. Request missing building/grading drawings before assigning their findings.

How do you screen a sole access road, bridge or culvert?

Trace the route beyond flood exposure, including off-parcel sections. Identify employee, emergency, fuel and heavy-equipment paths with their operating criteria.

A road-centerline intersection identifies mapped exposure; overtopping depth, velocity, timing, duration and passability require crossing elevations and hydraulic evidence. Keep road-owner closure history and bridge/culvert records beside the map finding.

Raleigh UDO §9.3.9 requires streets in SFHAs to provide 2 ft of freeboard from the predicted 10-year peak to the low point of the curb top or, for streets without curbs, pavement edge, and specifies protection against overtopping in the 50-year storm for thoroughfares and 25-year storm for other streets, subject to its stated exceptions. Record the design event and any approved exception. [S11] [S30]

Outside National Inventory of Dams inundation areas, §9.3.9 also prohibits public-street overtopping in the predicted 100-year flood and limits private-street overtopping to 1 ft. The same section requires public streets inside designated dam-inundation areas to sit at or above the 100-year flood elevation and requires downstream roadway slopes to resist overtopping erosion. Record road ownership and dam-inundation status, apply the watercourse-crossing provisions of §9.3.8, and retain the sealed design statement identifying applicable provisions and exceptions. [S29] [S30]

The National Weather Service directs drivers to avoid flooded roads and never bypass flood barriers. A design allowance for overtopping supplies no permission to drive through floodwater. [S34]

What proves an alternative route is independent?

Verify the alternative’s legal availability, controls, dimensions, loads and flood crossings beyond any shared exposure.

Redesign or reject if the only confirmed route fails continuity. When the actual route remains unconfirmed, hold for route verification. The worked example’s nearby named-road windows are an initial screen with this full-route determination still open.

What survey and drainage evidence still matters in Zone X?

Zone X still needs a drainage-path investigation. Separate river or coastal overflow from local runoff, groundwater, blocked inlets, outlet tailwater and storm-sewer surcharge. Subsurface drainage: French drains and catch basins follows the source and collection problem; a collection drain does not change a river’s mapped water surface.

Survey the assets and drainage points listed below. Record benchmark, horizontal reference, vertical datum, units, date and whether elevations describe design, construction or finished conditions. Site grading and earthwork carries the resulting grades into the work scope.

A detention basin adds storage and an outlet whose condition needs its own record. Read drawings, maintenance history and receiving-water conditions through stormwater detention pond management. Retain bioretention and infiltration evidence for drainage design.

Elevation and local-drainage evidence checklist

• Identity and datum: match parcel/building IDs; record CRS, datum, benchmark, units and survey stage; name any conversion method and location. Hold elevation comparisons with a datum mismatch.
• Exposed assets: obtain floor/basement, door, dock, equipment and utility elevations; yard lows and stockpile limits; full grading and expansion boundaries. Assign every missing measurement to a survey task.
• Drainage path: record inlet rims, pipe sizes, accessible inverts, authorized outlet, tailwater, overland exceedance path, basin drawings and maintenance state. An unverified outlet remains an open constraint.
• Wet-weather evidence: retain dated locations, rainfall context, ponding edges and high-water marks, noting which are surveyed; record inlet blockage, backflow and operator/road-owner event logs.
• Access and closeout: confirm legal routes, crossing/road-low elevations, ownership, dam-inundation status, local design event and interruption limit; assign the closing document, responsible party and decision date.

Use field photo documentation to tie observations to locations and dates. Ponding beside an obstructed inlet points first to collection failure. Water backing through several clear inlets while the receiving channel is high points toward outlet tailwater or surcharge. Compare event timing, water levels and pipe/outlet elevations before enlarging the collection system.

Which requirements can be stricter than the FEMA map minimum?

Under 44 CFR §60.3(c)(3)-(4), current through November 4, 2026, new and substantially improved nonresidential buildings in AE/A1-A30/AH must place the lowest floor, including basement, at or above BFE or satisfy the certified watertight floodproofing alternative with attendant utility and sanitary facilities; §60.1(d) preserves stricter state and local rules. [S03]

Raleigh UDO §9.3.6.B applies stronger floodway-style standards to new development applications received after July 19, 2022 in FEMA floodway-fringe and future-conditions areas. Those standards restrict structures and foundations as well as requiring no-rise evidence or the approved revision path. Its exemptions include lots no larger than 0.5 acre recorded before that date and lots with existing development not subdivided or created by subdivision after that date; qualifying lots can be recombined. Exempt status removes that extension of floodway restrictions; §9.3.6.B.3 still sets a 50% coverage limit on the affected fringe/future-conditions portion of covered lots, subject to its separate exceptions and variance process. [S32]

Retain recording and subdivision history, proposed-work classification and the local applicability finding under §§9.3.2, 9.3.6 and 11.4.6. [S12] [S31] [S32]

ASCE’s public introduction to ASCE/SEI 24-24 expands the flood-hazard area to the 500-year floodplain and describes design flood elevation as the greater of the community elevation or the Flood Design Class event elevation plus sea-level rise. Apply the adopted building code and referenced ASCE edition; publication of the 2024 standard does not establish local adoption. [S06]

FEMA Technical Bulletin 3, January 2021, compares NFIP criteria with the 2018 IBC and ASCE 24-14. Its dry-floodproofing discussion identifies water depth, velocity, waves, seepage, deployment warning and maintenance as design considerations. For an active system, obtain the deployment and maintenance plan and verify that staff can close the barriers before the route becomes impassable. Keep building protection and access continuity as separate findings. [S21]

Does an existing commercial building avoid current requirements?

Under 44 CFR §59.1, text dated November 4, 2026, substantial improvement reaches the federal threshold when improvement cost equals or exceeds 50% of the structure’s market value before construction starts; substantial damage uses the same threshold for restoration cost against pre-damage structure value. Land value is excluded from that denominator. Retain the valuation basis, permit/damage history, work scope, limited code-correction or historic-structure exclusions, and local determination, including any stricter cumulative rule. [S28]

Does the land’s flood zone decide the insurance requirement?

The federal banking agencies’ May 2022 Interagency Flood Insurance Q&As distinguish a collateral building partly in an SFHA in a participating community from overlap limited to surrounding land: the former triggers mandatory purchase for a covered loan, while land-only overlap does not trigger it for that building. Check every collateral building and retain the lender’s Standard Flood Hazard Determination Form. [S27]

A lender can require coverage outside the SFHA, including after map removal. Retain financing determinations separately; obtain actual coverage terms from the insurer. [S05] [S27]

How long do FEMA map changes take, and what starts the review clock?

FEMA’s LOMA/LOMR-F process page says it normally issues a determination within 60 days after receiving a complete package. Under 44 CFR §65.9, current through November 4, 2026, FEMA responds to a complete revision request within 90 days; that response can request additional information or another 90 days rather than grant final approval. [S05] [S07]

Start the transaction schedule with survey availability, the required hydraulic work and community sign-off. Then add FEMA review and the effective date stated in the resulting document. An application receipt, conditional response and effective removal are different milestones.

Order professional work against the unresolved decision: title/access confirmation, survey, hydraulic modeling, drainage design or permit support. Give bidders identical geometry, datum, source edition and work limits. Assign an owner and due date to each missing item so an incomplete submission does not consume the acquisition window.

Worked example: which of three Raleigh sites has usable area and access exposure?

Anvilfield estimates the following area and road intersections from Wake County parcel and street geometry and effective FEMA polygons retrieved November 5, 2026. The screening brief requires 2.00 contiguous acres outside mapped SFHA for the combined operating footprint and a documented access determination. This acreage is the project input, not a FEMA threshold. [S17] [S24] [S25]

Measure each parcel, subtract unioned SFHA, and find the largest connected remainder. Repeat with SFHA and future-conditions X combined because Raleigh regulates both. Determine usable area by also excluding the union of easements, setbacks, wetlands, drainage facilities and retained uses, then checking footprint width and layout fit.

Three-site usable-area constraints and approach-road comparison

Calculation and reproducibility note

Subtract the unioned hazard polygons from the parcel, measure the remainder and largest connected component, then intersect the named road with the same hazard inside the parcel’s outward buffer. Divide square feet by 43,560 for acres. In symbols: outside area = area(parcel \ union(SFHA)); road exposure = length(union(road paths) ∩ buffer(parcel, 1,000 ft) ∩ union(SFHA)).

The calculation uses NAD83 / North Carolina (ftUS), EPSG:2264, with Shapely 2.2.0 and pyproj 3.8.0. Wake geometry was requested in that CRS; FEMA WGS 84 coordinates were transformed. Ring nesting, invalid-ring repair, unioned same-class polygons and dissolved road duplicates preceded measurement.

At Hodges, 22.70 minus 21.82 leaves 0.88 acre outside SFHA, with the smaller connected remainder shown above. The 12.97 floodway acres are already inside SFHA; subtracting them again double-counts the constraint. Excluding future-conditions X as well leaves 0.09 acre total and a largest component of 0.08 acre, calculated before rounding.

Extend the survey from the confirmed gate to the wider network, including any crossing beyond this window.

Retain raw ArcGIS responses, query extent, CRS and source dates; distinguish missing coverage from a calculated zero. Check error objects and transfer-limit flags on repeat requests, paging where necessary and covering the full route. Hodges’ 22.70 GIS acres versus its 21.34 deed-acre attribute requires survey/title reconciliation; the spatial calculation consistently uses the GIS polygon.

Reading the result before ordering more work

Retain Atlantic Avenue first for survey, drainage, local and full-route review. Hold Industrial Drive for approach-road investigation. Reject Hodges Street for this outside-SFHA acreage brief; a changed program allowing floodplain development creates a different local and hydraulic review. Test the actual operating footprint and minimum working width in every retained remainder, because connected acreage alone does not prove layout fit.

Repeat queries: FEMA site A, FEMA site B, FEMA site C, Wake road extract, Wake three-PIN extract.

What evidence releases a site, requires redesign or rejects the brief?

Release a site only to a named next stage supported by the record. A map-screen release moves it into further diligence; development or operating release requires the applicable approvals, accepted design and resolved operating criteria. Use hold for missing evidence and reject for a demonstrated failure of the brief.

Release, redesign or reject decision record

Save rejected layouts and failed criteria for future revisions. When redesign proceeds to land disturbance, hand its work limits into the separate erosion-control and SWPPP scope.

Handoff and update checklist

• Save the document register, dated map/geometry view, building and phase IDs, applicable study elevation, survey and exact LOMC scope/status.
• Close full-route and alternative-route findings, drainage/outlet questions, local future-conditions treatment, code edition, lot history and redevelopment classification; retain the lender determination separately.
• Sign the release, hold, redesign or reject record with its criterion, decision owner, next document and due date.
• Reopen after new maps/letters, altered grading, a changed footprint, route restrictions or an amended operating brief; preserve the earlier finding and reason for revision.

Sources, method and how to cite this page

Sources checked and reviewed November 5, 2026. Federal text is dated November 4, 2026. Raleigh rules apply within their stated jurisdiction; the adopted code determines which ASCE edition governs.

Use the stable evidence records for the effective documents, asset overlay, zone/floodway interpretation, survey/drainage checklist, three-site comparison and decision record.

Update log: 2026-11-05: Source and calculation recheck; expanded road, coastal-zone and local coverage guidance; corrected rendered links; replaced fees with review timing.

How to cite this page: Anvilfield, How to read FEMA flood maps when comparing commercial sites, 2026, https://anvilfield.com/field-guides/datacenter/fema-commercial-site-flood-screening/.

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Sources checked

• S01: FEMA MSC, live Products and Tools Effective products, map status and revalidation. Checked November 5, 2026.
• S02: FEMA IS-273, undated course unit MSC retrieval and static/dynamic map changes. Checked November 5, 2026.
• S03: eCFR, title 44 part 60, current through 2026-11-04 Federal minimum development, floodway and elevation criteria. Checked November 5, 2026.
• S05: FEMA LOMA/LOMR-F process, live Removal criteria, forms and complete-package response. Checked November 5, 2026.
• S06: ASCE/SEI 24-24, publisher’s public introduction Public explanation of 2024 changes; adoption governs application. Checked November 5, 2026.
• S07: eCFR title 44 part 65, current through 2026-11-04 Revision procedures and response periods. Checked November 5, 2026.
• S08: NOAA/NOS VDatum, live datum tutorial Vertical reference systems and conversions. Checked November 5, 2026.
• S09: FEMA FF-206-FY-22-152, 2022 edition, form marked 10/22 Elevation Certificate fields, datum and certification instructions. Checked November 5, 2026.
• S10: FEMA Floodplain Management Division, Elevation Certificate FAQ, October 2023 Completed-certificate validity and physical-change triggers. Checked November 5, 2026.
• S11: City of Raleigh, Current Floodplain Development Regulations, updated 2026-07-01 Local policy summary; ordinance supplies exact design criteria. Checked November 5, 2026.
• S12: Raleigh UDO §11.4.6, live ordinance Local permit/certification requirements. Checked November 5, 2026.
• S13: FEMA/NC, Wake County FIS 37183CV000E, effective 2022-07-19, full document Complete 2022 FIS; Table 22, printed page 123. Checked November 5, 2026.
• S14: FEMA MSC effective panel 3720171500K full download Complete effective panel package, 1:6,000. Checked November 5, 2026.
• S15: FEMA MSC effective panel 3720171400K full download Complete effective panel package, 1:6,000. Checked November 5, 2026.
• S16: FEMA NFHL layer 3, effective-data query Panel dates, scale and version attributes. Checked November 5, 2026.
• S17: FEMA NFHL flood polygons, layer 28 Zone/subtype/SFHA schema; exact geometry requests linked in the worked method. Checked November 5, 2026.
• S18: FEMA NFHL cross-sections, exact query Cross-section identity, station and regulatory elevation. Checked November 5, 2026.
• S19: FEMA LOMA 21-04-1555A, 2021-03-01, complete two-page determination Complete two-page letter; structure-only scope and remaining-property attachment. Checked November 5, 2026.
• S20: FEMA NFHL LOMR and LOMA layers, effective-data query Vicinity map-change records; applicability requires identity and status checks. Checked November 5, 2026.
• S21: FEMA NFIP Technical Bulletin 3, January 2021, full document Dry-floodproofing explanation, with 2018 IBC/ASCE 24-14 comparison. Checked November 5, 2026.
• S22: FEMA/NFIP FloodSmart, live zone explanation Zone definitions and annual map-check recommendation. Checked November 5, 2026.
• S23: FEMA underwriting form library, live Linked Elevation Certificate form. Checked November 5, 2026.
• S24: Wake County official Parcels service, schema Parcel identifiers and geometry; exact three-PIN request linked in the worked method. Checked November 5, 2026.
• S25: Wake County official Streets layer, schema Street centerline paths; exact request linked in the worked method. Checked November 5, 2026.
• S26: FEMA floodway help, undated live Floodway conveyance and local review. Checked November 5, 2026.
• S27: Federal banking agencies, Interagency Questions and Answers Regarding Flood Insurance, issued 2022-05-11, live Federal Reserve text Applicability Q3-Q4: building/land distinction and lender discretion. Checked November 5, 2026.
• S28: eCFR title 44 part 59, text dated 2026-11-04 Base flood and substantial improvement/damage definitions. Checked November 5, 2026.
• S29: Raleigh UDO §9.3.8, live Crossing-specific requirements. Checked November 5, 2026.
• S30: Raleigh UDO §9.3.9, live Street event/freeboard criteria and public/private distinctions. Checked November 5, 2026.
• S31: Raleigh UDO §9.3.2, live Development and alteration applicability. Checked November 5, 2026.
• S32: Raleigh UDO §9.3.6, live Future-conditions treatment and exemption conditions. Checked November 5, 2026.
• S33: Raleigh UDO §9.3.4, live Boundary interpretation and retained evidence. Checked November 5, 2026.
• S34: NOAA/National Weather Service, Turn Around Don’t Drown, live safety guidance Flooded-road safety, separate from allowable design overtopping. Checked November 5, 2026.