One state, two wind worlds. The Gulf coast runs up to 150 mph. El Paso sits near 90 mph. Enter a Texas ZIP to pull the right ASCE 7-22 number — with a TWIA flag where it counts.
Roughly 800 miles wide, the design wind speed nearly doubles from the Gulf to El Paso. Picking one number for "Texas" is how submittals come back rejected.
The TWIA 14-county strip carries the hurricane contour. Coastal exposure, wind-borne debris rules, and WPI-8 inspection all stack on top of the speed.
No TWIA layer, no coastal exposure D, no debris region. Still real loads — and Risk Category III or IV steps the inland number up fast.
Representative ASCE 7-22 Risk Category II speeds for the Texas metros that show up most on permits. Baseline values — the calculator returns the exact figure for any ZIP.
| Location / County | Sample ZIP | Risk Cat II speed | Notes |
|---|---|---|---|
| Galveston (Galveston Co.) TWIA | 77550 | ~145–150 mph | Inner coastal zone; debris region |
| Galveston west end (Galveston Co.) TWIA | 77554 | ~145–150 mph | Same coastal regime as 77550 |
| Corpus Christi (Nueces Co.) TWIA | 78401 | ~140–145 mph | Coastal; SH-358 corridor |
| Corpus Christi south (Nueces Co.) TWIA | 78411 | ~140–145 mph | Coastal |
| La Porte / Seabrook (Harris Co.) partial | 77571 | ~135–140 mph | Seaward of SH-146 — inside TWIA |
| Houston downtown (Harris Co.) | 77002 | ~130 mph | Inland of TWIA boundary |
| Houston / Memorial (Harris Co.) | 77024 | ~130 mph | Inland; standard ASCE 7-22 |
| San Antonio (Bexar Co.) | 78201 | ~105–110 mph | Inland; outside TWIA |
| Austin (Travis Co.) | 78701 | ~105–110 mph | Hill Country edge |
| Dallas (Dallas Co.) | 75201 | ~105 mph | North Texas inland |
| Fort Worth (Tarrant Co.) | 76101 | ~105 mph | North Texas inland |
| El Paso (El Paso Co.) | 79901 | ~90 mph | Lowest in the state |
The coastal transition is sharp, the TWIA line cuts through Harris County along SH-146, and Risk Category III or IV bumps every figure. Run your exact address before sizing the lateral system or quoting glazing.
The Texas Windstorm Insurance Association is the windstorm insurer of last resort on the coast — chartered by the Legislature in 1971.
A state residual-market insurer for the Gulf counties, created in 1971 after carriers kept fleeing the coast post-hurricane. TWIA coverage requires a WPI-8 windstorm certification.
The Texas Department of Insurance administers the WPI-8 inspection program. A structure must be built and certified to TWIA windstorm standards to qualify for coverage.
Most of Houston is outside TWIA. But the eastern slice seaward of State Highway 146 — La Porte, Seabrook, Shoreacres — sits inside it and triggers the full coastal package.
WindLoadCalc flags TWIA ZIPs on page one of every report. We supply the wind analysis; the WPI-8 itself is signed by your Texas PE or Qualified Inspector.
Texas enforces no single statewide commercial code — adoption is municipal, and the TDI/TWIA windstorm program governs the coast. WindLoadCalc applies the latest ASCE 7-22 across the whole state.
Houston, San Antonio, Austin, Dallas, and Fort Worth each adopt and amend the building code locally. Our wind analysis applies ASCE 7-22 — the current standard — to every Texas project.
The TDI/TWIA windstorm program covers the 14 first-tier counties plus the SH-146 slice of Harris County. We supply the ASCE 7-22 wind analysis that a Texas PE rolls into the WPI-8 deliverable.
ASCE 7-22 is the most current edition of the standard. Its lookups, coefficients, and exposure logic carry the newest hazard data, giving you the most up-to-date basis available.
Texas building departments commonly reference an earlier ASCE 7 edition; WindLoadCalc applies the latest ASCE 7-22 — the most current, conservative standard. If your jurisdiction requires a specific edition on the submittal, contact us before you run the project.
The coastal framework is forensic, not theoretical. Three landfalls each left a mark on how Texas designs.
Landfall on Galveston Island as a Category 2 on Sep 13, 2008. Wood-frame roof failures from weak roof-to-wall connections drove tighter WPI-8 fastener scrutiny.
A rainfall catastrophe for Houston in Aug 2017, not a wind one. Its lesson was Exposure Category honesty — many 2000s "Exposure B" sites were really Exposure C.
Landfall near Matagorda as a Category 1 on Jul 8, 2024. It renewed the conversation on WPI-8 inspector shortages and TWIA solvency under repeat losses.
Coastal Exposure Category matters as much as the speed. A 145 mph site in Exposure D carries meaningfully higher C&C pressures than the same speed in Exposure C. On the Texas coast, claiming Exposure B has aged badly.
From ZIP to permit-ready report — coastal flags preset where they apply.
We pull the ASCE 7-22 speed, name the county, and flag TWIA coastal or seaward-Harris automatically.
Cat II covers most buildings. Cat III for schools and assembly; Cat IV for hospitals and EOCs — each steps the speed up.
Exposure C is the Texas default; D for open coastal water within a mile. Add footprint, roof height, pitch, and roof type.
Zone-by-zone C&C and MWFRS pressures with debris-region flags. Export a permit-ready Engineering Report.
No paid testimonials — a verifiable track record and explicit scope.
Galveston Island sits in the TWIA inner coastal zone at an ASCE 7-22 Risk Category II speed around 145–150 mph. Most of Harris County inland of SH-146 sits near 130 mph.
The two cities are roughly 50 miles apart, yet that 15–20 mph gap reshapes every C&C pressure. Never read a wind speed off a city name — run the exact ZIP.
South to north along the Gulf: Cameron, Willacy, Kenedy, Kleberg, Nueces, San Patricio, Aransas, Refugio, Calhoun, Matagorda, Brazoria, Galveston, Chambers, Jefferson, and Orange.
TWIA also covers eastern Harris County seaward of State Highway 146 — La Porte, Seabrook, and Shoreacres are inside, most of Houston is not.
No. WindLoadCalc generates the ASCE 7-22 wind load analysis. The WPI-8 windstorm certification that qualifies a structure for TWIA coverage must be signed by a Texas-licensed PE or a TDI-appointed Qualified Inspector.
Our report is the analytical input they roll into the WPI-8 deliverable.
WindLoadCalc applies ASCE 7-22, the most current ASCE 7 edition. Texas building departments commonly reference an earlier ASCE 7 edition, but ASCE 7-22 is the latest and most conservative standard — and the lookups, coefficients, and exposure logic are version-aware.
If your jurisdiction requires a specific edition, contact us.
Under ASCE 7-22, two triggers apply. A coastal Texas site is in the wind-borne debris region when the design speed exceeds 140 mph.
It also qualifies when the building is within one mile of the coastal mean high water line at 130 mph or higher.
Inside that region, impact-rated glazing or approved shutters become the practical baseline, and the calculator flags it on page one.
Our in-house PE sign-and-seal is Florida-only, up to three stories. A sealed Texas wind load report must come from a PE licensed by the Texas Board of Professional Engineers and Land Surveyors.
PE sign-and-seal is available in all 50 states through the firm's PE network. Run the numbers here, then route the report to a Texas-licensed PE for review and seal.
Relatively. San Antonio and Austin sit near 105–110 mph, Dallas and Fort Worth near 105 mph, and El Paso near 90 mph — the lowest in the state.
Those are real loads, but a different design world from the 145–150 mph Gulf coast. Risk Category III or IV still steps the inland numbers up.
Yes. The C&C and MWFRS reports follow ASCE 7-22 in the format Houston, San Antonio, Austin, Dallas, Fort Worth, Corpus Christi, and coastal jurisdictions accept.
For TWIA-region work the report becomes the wind analysis underpinning a WPI-8 certification a Texas PE or Qualified Inspector signs.
Drop in a Texas ZIP and get permit-ready ASCE 7-22 pressures with TWIA and debris-region flags preset where they apply. Or try the free wind speed lookup first.
Reviewed by WindLoadCalc's in-house Florida-licensed P.E.