Coastal Houston-metro basic wind speed — 150 mph V_ult for Galveston Island and seaward Designated Catastrophe Area

Per ASCE 7-22 Figure 1609.3(1) (the basic wind speed map for Risk Category II buildings), Galveston Island, the seaward edges of Brazoria and Chambers Counties, and the coastal sliver of Harris County (east of State Highway 146, including the city limits of Seabrook, La Porte, Shoreacres, Pasadena, and Morgan's Point) sit in the 150 mph V_ult contour — the highest design wind speed band in the Houston metropolitan region. ASCE 7-22 increased basic wind speeds along the south Texas coast by approximately 10 mph relative to the prior ASCE 7-16 map. V_ult is the ultimate design wind speed (3-second gust at 33 feet, Exposure C) that drives strength-design wind pressure calculations and roof-system install requirements. The TDI windstorm program covers this corridor through its Designated Catastrophe Area. TDI no longer uses the older "Seaward" windstorm zone classification — that coastal zone was tied to the 2006 I-Codes (under which the Seaward zone carried a 130 mph 3-second-gust nominal design wind speed) and was retired when TDI adopted the 2018 I-Codes; TDI now determines the windstorm design wind speed by ASCE 7 risk category, consistent with the 150 mph V_ult above. Practically, this means: 6-nail high-wind shingle install patterns apply, starter-course adhesive bands and ridge-cap securement specs are stricter, and the WPI-8 windstorm certificate of compliance (KB-D5-001) is required for new and re-roofed residences in the TDI Designated Catastrophe Area (KB-D5-002) to maintain TWIA windstorm insurance eligibility. Class 4 impact-rated shingles (KB-D5-005) are independently relevant in this corridor due to hail exposure. The wind speed is a building-code requirement; deductible structures, premium implications, or claim/coverage questions belong with the homeowner's insurance agent or the Texas Department of Insurance (tdi.texas.gov) — V Advisor educates on the code, not on insurance decisions. [Source: ASCE 7-22 Figure 1609.3(1); Texas Department of Insurance Adopted Codes; Texas Department of Insurance Galveston County designated catastrophe area map]