TENNESSEE · SHELBY COUNTY
Memphis wind loads, from the Mississippi bluffs to Dixie Alley
Where southwest Tennessee meets the river: Shelby County design demands 105–115 mph velocities, split Exposure B/C terrain, and severe-storm detailing under ASCE 7-22.
WHY 105–115 MPH
What sets the Bluff City design speed
An inland river city in Dixie Alley: no hurricane wall, but a relentless severe-storm season and an open Mississippi fetch.
Dixie Alley supercells
Spring storm season drives the velocity floor across Shelby County.
SEVERE STORMTornado track exposure
Documented EF3–EF4 events demand robust anchorage and load paths.
TORNADICOpen river fetch
The Mississippi and its floodplain strip away upwind roughness.
EXPOSURE CNew Madrid overlay
Seismic detailing rides alongside wind, often shaping the lateral system.
MULTI-HAZARDVELOCITY PRESSURE · ASCE 7-22
Two Memphis sites, two exposure outcomes
Downtown and Beale Street read as sheltered Exposure B; the riverfront, Mud Island and Tom Lee Park read open Exposure C — a real jump in pressure at the same height.
| Parameter (30 ft, Risk II) | Downtown / Beale (Exp B) | Riverfront / Floodplain (Exp C) |
|---|---|---|
| Kz at 30 ft | 0.70 | 0.98 |
| Kzt (flat floodplain) | 1.0 | 1.0 |
| Kd (buildings) | 0.85 | 0.85 |
| Relative Kz shift | baseline | +40% vs Exposure B |
Velocity pressure follows qz = 0.00256 Kz Kzt Kd Ke V². Holding V and height fixed, moving from urban Exposure B to open river Exposure C raises Kz from 0.70 to 0.98 at 30 ft — a 40% pressure increase. The B-to-C transition near the bluffs is engineering judgment, driven by upwind fetch across the river and Arkansas floodplain.
SHELBY COUNTY COMPLIANCE
Getting a Memphis permit through plan review
Tennessee adopts the IBC referencing ASCE 7-22; city and county each run their own inspection desks.
Code basis
Tennessee IBC with state amendments, ASCE 7-22 referenced for wind.
TN IBCCity permits
Memphis Construction Code Enforcement handles work inside city limits.
MEMPHIS.GOVCounty permits
Unincorporated Shelby County permits run through county Building & Permits.
SHELBY COPE sealing
Commercial and complex projects need a TN-licensed Professional Engineer.
TN PE BOARDState oversight
TN Dept. of Commerce & Insurance administers the state code program.
TN.GOVMulti-hazard check
New Madrid seismic and wind detailing are reconciled in one lateral system.
WIND + SEISMICRisk category sets the map, not a multiplier. Higher categories pull V from a longer return-period map — Risk II ~700-yr (105–115 mph), III ~1,700-yr, IV ~3,000-yr — so schools, hospitals and shelters design to higher Memphis speeds. There is no fixed Risk factor under ASCE 7-22.
ACROSS TENNESSEE
Compare Memphis with the wider map
Same baseline speeds statewide, different controlling hazards by region.
RUN THE NUMBERS
Calculate Memphis wind loads site by site
Enter a Shelby County address and get the right velocity, B-or-C exposure call, and PE-ready MWFRS and C&C pressures for permit submission.