ALABAMA · JEFFERSON COUNTY

Birmingham Wind Load Requirements

Magic City design wind loads for Jefferson County, Alabama — inland severe-weather and Dixie Alley tornado exposure under ASCE 7-22.

105–115MPH RISK CAT II (3-SEC GUST)
JeffersonCOUNTY · ALABAMA
ASCE 7-22ALABAMA BUILDING CODE (IBC)
Exp BURBAN / SUBURBAN

ASCE 7-22 · WIND & EXPOSURE

Inland speeds, tornado-driven design

Birmingham sits inland in Dixie Alley — moderate basic wind speeds, but a serious severe-weather and violent-tornado record shaped its design environment.

105–115 mph Basic Wind

Risk Category II 3-second-gust range across Jefferson County per ASCE 7-22 maps; higher Risk Categories read a higher-speed map.

3-SEC GUST

Exposure B (Urban)

Most of metro Birmingham is Exposure B from its built-up, tree-covered terrain. Open or hilltop sites may warrant Exposure C — judgment per ASCE 7 §26.7.

SURFACE ROUGHNESS

Ridge-and-Valley Terrain

Red Mountain and Shades Mountain create topographic effects; sites near crests may need Kzt > 1.0 per ASCE 7-22 §26.8.

TOPOGRAPHY

Dixie Alley tornado exposure

Birmingham lies in Dixie Alley, with frequent violent, often long-track tornadoes — most catastrophically the April 27, 2011 Super Outbreak across Jefferson and surrounding counties. ASCE 7-22 Chapter 32 addresses tornado loads qualitatively for applicable Risk Categories; tornado risk informs careful Risk Category and detailing decisions even where basic wind speeds are moderate.

RUN THE NUMBERS

Calculate Birmingham wind loads

Generate ASCE 7-22-compliant pressures for any Jefferson County address — 105–115 mph velocity, Exposure B, Risk Category adjustments, and PE-ready reports.