LOUISIANA · ORLEANS PARISH
A City Below Sea Level Engineered for the Gulf's Worst Hurricanes
Pinned between the Mississippi River and Lake Pontchartrain, New Orleans designs to 150-160 mph under the post-Katrina Louisiana code and ASCE 7-22.
THE CRESCENT CITY · GEOGRAPHY OF RISK
Caught Between the River, the Lake & the Gulf
A bowl of low ground ringed by water — the exact terrain that drives an open, coastal Exposure C and elevated design speeds.
KATRINA LEGACY · COASTAL WIND
Why the Bayou City Designs So High & So Hard
Flat, open, water-fringed terrain plus a direct Gulf fetch puts most Orleans Parish sites at Exposure C and 150-160 mph for ordinary buildings.
150-160 mph Basis
3-second-gust design speed for Risk Category II across Orleans Parish, per ASCE 7-22 maps.
RISK CAT IIExposure C Coastal
Open terrain near the lakefront, river and Gulf drives Exposure C for most sites; dense inland blocks may qualify for B.
EXPOSURE CIda Validated It
Hurricane Ida's 2021 landfall winds proved the post-Katrina code: newer structures far outperformed older stock.
2021 LANDFALLDebris Region
Coastal Orleans Parish falls in the wind-borne debris region — glazing protection or impact-rated openings required.
GLAZINGTWO STORMS, SIXTEEN YEARS APART
The Storms That Rewrote New Orleans Code
Both made landfall on August 29 — Katrina exposed the flaws, Ida confirmed the fixes.
Hurricane Katrina · 2005
Category 3 winds at landfall, but levee failures flooded most of the city and drove sweeping rebuilds of Louisiana's building and flood codes.
CODE TURNING POINTHurricane Ida · 2021
A Category 4 strike with 150 mph winds that matched the design basis head-on; modern, code-compliant buildings held up markedly better.
DESIGN-SPEED PROOFASCE 7-22 · RISK CATEGORIES
How Occupancy Shifts the Orleans Parish Map
Higher risk categories read a longer-return-period map — so design speeds climb above the 150-160 mph standard baseline.
| Risk Category | New Orleans Design Wind Speed | Typical Buildings |
|---|---|---|
| I · 300-yr map | ~140-145 mph | Minor ag, storage, low-hazard structures |
| II · 700-yr map | 150-160 mph | Homes, retail, offices, most occupancies |
| III · 1,700-yr map | ~165-175 mph | Schools, large assembly, hazardous materials |
| IV · 3,000-yr map | ~175-185 mph | Hospitals, fire stations, EOCs, shelters |
Risk category does not apply a fixed multiplier — there is no wind importance factor in ASCE 7-22. Each category simply points you at a different basic-wind-speed map with a longer mean recurrence interval.
PERMIT-READY · ORLEANS PARISH
What a New Orleans Submittal Has to Show
The Louisiana State Uniform Construction Code adopts the IBC and ASCE 7-22; sealed Louisiana PE calcs carry every line below.
LSUCC Code Basis
Louisiana State Uniform Construction Code, adopting the IBC with ASCE 7-22 wind provisions.
ASCE 7-22Design Wind Speed
150-160 mph for Risk Category II, located by address against ASCE 7-22 maps.
150-160 MPHExposure Category
Documented Exposure C for coastal and waterfront sites; B only where dense terrain supports it.
EXP C / BRisk Category
Classification per ASCE 7-22 Table 1.5-1, selecting the correct speed map for the occupancy.
TABLE 1.5-1MWFRS & C&C
Main wind-force pressures plus component and cladding values for walls, roofs and openings.
PRESSURESLouisiana PE Seal
Calculations sealed by a Louisiana-licensed Professional Engineer for permit approval.
PE SEALEDOPENINGS · COMMON ERRORS
Where New Orleans Projects Trip Up
Debris protection and parish-correct details separate an approved set from a kickback.
Glazing Protection
Coastal debris-region openings need impact-rated glazing or shutters tested to ASTM E1996 / E1886.
ASTM E1996/E1886Parish, Not County
Louisiana uses parishes — it is Orleans Parish, never "Orleans County," on every submittal.
ORLEANS PARISHNot HVHZ
New Orleans is not in Florida's HVHZ and does not require Miami-Dade NOA product approvals.
NO NOAOFFICIAL SOURCES
New Orleans & Louisiana Code Authorities
Verify permitting, codes and licensure straight from the agencies of record.
EXPLORE MORE
Beyond Orleans Parish: Statewide & Coastal Context
Compare New Orleans against Louisiana's wider wind picture and the national maps.
RUN THE NUMBERS
Get New Orleans-Compliant Wind Load Calcs
Enter an Orleans Parish address and pull the 150-160 mph basis, Exposure C, risk-category speeds and PE-ready ASCE 7-22 reports.