ASCE 7-22 · CHAPTER 32 · TORNADO LOADS
Tornado Alley wind loads & tornado-load safety
ASCE 7-22 codified tornado loads for the first time. Across the central and eastern U.S. tornado-prone region, essential and high-occupancy buildings now face a dedicated, separate design check.
THE HAZARD
A tornado bearing down on the central U.S. corridor
The tornado-prone region is a broad band of the central and eastern United States — not a single state — where Chapter 32 tornado loads must be evaluated for the buildings in scope.
WHAT CHANGED
What ASCE 7-22 Chapter 32 introduced
For the first time, tornado loads sit inside the standard — evaluated on their own terms and weighed against ordinary wind.
First tornado provisions
The first dedicated tornado-load chapter in ASCE 7 history.
NEW IN 7-22Applies to RC III & IV
Scoped to Risk Category III and IV buildings in the tornado-prone region.
RC III / IVA separate check
Tornado loads are evaluated separately from the regular ASCE 7 wind-load analysis.
PARALLEL PATHGoverning case controls
You compare tornado vs. standard wind — the larger demand governs the design.
WORST CASE WINSINTENSITY
The Enhanced Fujita (EF) scale
Tornado intensity is rated EF0 through EF5 from observed damage. Higher EF ratings mean progressively more destructive winds — described qualitatively, not as a design wind speed.
EF0
Minor damage. Lightest end of the scale.
WEAKEF1
Moderate damage to roofs and exteriors.
WEAKEF2
Considerable damage; major roof loss.
STRONGEF3
Severe damage to well-built structures.
STRONGEF4
Devastating; well-built homes leveled.
VIOLENTEF5
Incredible damage at the top of the scale.
VIOLENTThe EF scale rates what a tornado did, after the fact. ASCE 7-22 Chapter 32 instead defines the tornado design loads a building must resist — a distinct, code-based framework rather than a post-event rating.
DESIGN & SAFETY STRATEGIES
Building to survive the tornado-prone region
Beyond running the Chapter 32 check, resilient detailing protects occupants and property when the worst case arrives.
Safe rooms & shelters
Hardened spaces give occupants a survivable refuge during a strike.
LIFE SAFETYContinuous load path
Tie roof to walls to foundation so uplift transfers fully to the ground.
ROOF-TO-FOUNDATIONRobust connections
Hurricane ties, anchors and fasteners hold the envelope together under load.
ANCHORAGEUse the latest ASCE 7
Design to ASCE 7-22 so the Chapter 32 tornado provisions are in play.
ASCE 7-22Check both governing cases
Evaluate tornado and standard wind, then design for whichever governs.
WORST CASEProtect the envelope
Impact-resistant glazing and rated openings limit pressurization and debris entry.
OPENINGSGO DEEPER
Run the numbers for tornado-prone projects
Professional ASCE 7-22 wind load calculator software built for high-risk regions — from our sister site, WindLoadCalc.com.