Building Codes for Wind Loads in Texas

Wind power accounts for some 20 percent of the electricity generated in Texas, and it rises almost every year. But while wind is a source of clean energy, it can be catastrophic for poorly constructed buildings—think hurricanes.

It was in response to Hurricane Celia in 1970 that the Texas Windstorm Insurance Association was established within the Texas Department of Insurance (TDI). The agency is responsible for setting building codes, including wind load standards, for areas deemed catastrophe areas, including many coastal counties on the Gulf Coast.

Texas consumes the most energy across all sectors of any state in the nation. But it gives back too, since the industrial sector, including refineries and petrochemical plants, produces over half of what the state uses, plus almost a quarter of the total industrial sector energy use in the nation.

While Texas is known for its oil and gas production—it produces some 43 percent of the nation's crude oil production and 25 percent of its marketed natural gas—it is also a major producer of wind-generated electricity, producing about 26 percent of all wind-powered electricity generated in the U.S. Texas has led the rest of the states for 16 consecutive years in wind power production, surpassing its nuclear and coal-fired generation.

The 2006 International Building Code (IBC) and the 2006 International Residential Code (IRC) contain the requirements adopted to determine a structure’s eligibility for hail and windstorm insurance from the Texas Windstorm Insurance Association. All new construction, additions and repairs since June 1, 2008, should comply with one of these codes.

Hurricane Celia devastated Texas Coast in 1970, and many homeowners were unable to obtain insurance for wind hazards. The Texas Legislature established the Texas Windstorm Insurance Association (TWIA) in 1971 to provide windstorm and hail insurance in the Texas seacoast.

TWIA is governed by Chapter 2210 of the Texas Insurance Code. It is an insurer of last resort, stepping in to offer windstorm and hail insurance only in those portions of the seacoast territory of Texas where windstorm and hail insurance is not reasonably available. These are designated "potential catastrophe areas" by the Texas Insurance Commissioner.

Qualified individuals who live in potential catastrophe areas can file an application for TWIA windstorm and hail insurance through any Texas licensed insurance agent. To be eligible, an applicant must meet certain criteria set out in Texas law:

• Applicant must show they have applied for private insurance coverage with at least one insurer and been denied.
• Property at issue must be located in a designated catastrophe area.
• With limited exceptions, property at issue must be certified as having been built to applicable building codes.
• Proof of flood insurance coverage on the relevant property is required. If the property is located in specified flood zones, called V zones, and was constructed or altered after September 1, 2009, it is eligible for flood insurance through the NFIP.
• Property must be in an insurable condition as specified by the Association in the Plan of Operation

What building standards must be met in Texas for eligibility in the TWIA program? ‌The building codes and inspection requirements are set out in Texas Insurance Code Sections 2210.251 to 2210.252 and 2210.258 to 2210.259.‌

The codes mandate that a property must be certified as meeting windstorm building code requirements for its area in order to be eligible for TWIA insurance coverage. The property owner must supply TWIA with a Windstorm Certificate of Compliance for the property to be eligible.

Without a certificate, the agency does not have evidence that the building conforms to applicable building codes.

Who issues the Certificate of Compliance? TWIA issued Certificates of Compliance for completed construction from January 1, 2017 to May 31, 2020. Since January 1, 2020, the Texas Department of Insurance is the agency that issues certificates of compliance. (WPI-8 and WPI-8-E).

Any property owner whose property has a WPI-8-C from the TWIA does not have to re-certify to remain eligible for TWIA insurance unless they alter or update the premises.

Two types of certificates of compliance are issued:

• WPI-8 for ongoing construction. Inspections can be undertaken by a Texas licensed professional engineer or a TDI windstorm inspector during the work process.
• WPI-8-E for completed construction. Inspections are done by a Texas licensed professional engineer.

Buildings, structures and various components of structures in Texas must be designed to ‌withstand the minimum wind loads‌ as prescribed in the codes. They are not adjusted for potential decreases in wind loads when shielded by other structures.

Wind loads on a structure in Texas are determined either under Chapters 26 to 30 of ASCE 7 or under provisions of the alternate all-heights method in Section 1609.6. Similarly, the type of opening protection required, the ultimate design wind speed, and the exposure category for a site can also be determined under either Section 1609 or ASCE 7.

Whichever wind load standards are selected apply to all exterior openings. These include doors, garage doors, windows and skylights. Specific requirements apply to different areas and the exposure of the opening. For example, structural openings with a seaward exposure in Aransas and Galveston counties must be built to withstand a 3-second wind gust with a wind speed of 130 miles per hour.

However, inland exposures in those counties must be built to withstand only a 3-second wind gust moving at 120 miles per hour. This is also true for all exterior openings in Chambers and Calhoun counties and many other counties in the coastal catastrophe area.

Those parts of the counties that are beyond the coastline are in the Inland II area, where openings must be capable of withstanding 3-second wind gusts of 110 miles per hour.