Life Safety

Lessons Learned from Hurricane Harvey – Coastal Bend

While the most pop­u­lat­ed city of the Coastal Bend area of Texas, Cor­pus Christi, was spared the brunt of Hur­ri­cane Har­vey, the coastal towns of Port Aransas and Rock­port saw the force of the high winds and storm surge that came with the Cat­e­go­ry 4 hur­ri­cane. Bau­tex had the oppor­tu­ni­ty to vis­it the Coastal Bend of Texas ten days after the area was hit so hard by Har­vey. While clean up and repair were well under­way, util­i­ties were only par­tial­ly restored. The destruc­tion from Port Aransas to north of Rock­port was immense and gave us insight to the pow­er of hur­ri­canes and what that means for build­ings in hur­ri­cane zones. Our obser­va­tions, con­ver­sa­tions, and tours of pre­vi­ous­ly con­struct­ed projects locat­ed in the area led to the fol­low­ing lessons learned.

Wind and Water Damage

Every build­ing we passed suf­fered dam­age from wind, water, or both. The wind loads in Rock­port were over 130 mph, slight­ly exceed­ing the design code of 120 mph for Inland I cat­e­go­ry. This result­ed in most roofs suf­fer­ing some amount of dam­age, many roof fail­ures and a con­sid­er­able amount of com­plete struc­ture fail­ures. The age of the build­ing, prox­im­i­ty to open water or fields, and loca­tion to oth­er struc­tures and trees were the major fac­tors in how the high winds affect­ed the struc­ture. Old­er build­ings with no wind pro­tec­tion fared the worst.

Wind debris caused dam­age where struc­tures failed or tree limbs were torn off. In both cas­es the debris became mis­siles. These impacts were clear­ly shown through 2×4 sized holes in walls of build­ings, win­dows and doors bro­ken from fly­ing debris, and build­ing mate­ri­als and limbs still pro­trud­ing from struc­tures. The dan­ger from this fly­ing debris can­not be under­stat­ed and makes FEMA 320361 and ICC 500 mis­sile debris impact test­ing crit­i­cal for build­ing mate­ri­als along the coast.

Water dam­age was ram­pant wher­ev­er we trav­elled as evi­denced by the moun­tains of insu­la­tion, dry­wall, and fur­nish­ing being removed from every build­ing. Some of this dam­age came from storm surge, espe­cial­ly in Port Aransas, but much of the water dam­age came from roof and win­dow fail­ures.

What Types of Structures Failed and Why

Town after town the total struc­tur­al fail­ures we saw indi­cat­ed that build­ing types with the high­est num­ber of com­plete loss build­ings were wood framed or pre-engi­neered met­al build­ings. Both types of struc­tures are sus­cep­ti­ble to rot/​rust from cycli­cal wet and dry cycles as well as salt air con­di­tions. Both of these types of sys­tems are light­weight assem­blies and depend on the sheath­ing, whether wood or met­al for shear resis­tance. Once their roofs were com­pro­mised, the wind pres­sures forced fail­ures of the sheath­ing, which con­tributed to par­tial and total col­laps­es. The rot and rust of con­nec­tions clear­ly added to the struc­tur­al fail­ure.

Recommendations for Rebuilding

Clear­ly, Hur­ri­cane Harvey’s destruc­tion was dis­as­trous for the Coastal Bend of Texas, but the loss­es can be used as a learn­ing expe­ri­ence for the con­struc­tion indus­try to build bet­ter. There is not a sin­gle answer to rebuild­ing or redesign­ing struc­tures along the coast. The design has to be looked at holis­ti­cal­ly and not as indi­vid­ual design aspects or mate­ri­als. The roof mat­ters, the walls mat­ter, the win­dows mat­ter, the fin­ished floor ele­va­tion mat­ters but when designed togeth­er and con­struct­ed as an assem­bly they can cre­ate a hur­ri­cane resis­tant struc­ture that will stand up to fierce storms like Har­vey.

Build­ing at fin­ished floor ele­va­tion well above the storm surge mod­el can pro­tect a build­ing from the onslaught of rush­ing sea­wa­ter into the struc­ture. This can be done by build­ing on pil­ings and in some cas­es by bring­ing the build­ing pad up a few feet with fill mate­r­i­al.

Using resilient wall sys­tems to build in hur­ri­cane areas can pro­tect both the struc­tur­al integri­ty of the build­ing but also elim­i­nate the chance for fly­ing debris to pen­e­trate the walls. Con­crete wall assem­blies like Bau­tex should be con­sid­ered for the inher­ent strength against high winds but also for the lab test­ed resis­tance to wind-borne mis­sile debris. These types of walls do not reply upon sheath­ing for shear strength and are far less like­ly to suf­fer cat­a­stroph­ic fail­ure.

Roofs have to be designed with low pitch­es to min­i­mize the amount of wind pres­sure on the struc­ture. Con­nec­tions to the wall assem­bly should be designed to be robust and if pos­si­ble to exceed the pre­scribed code. Hav­ing an adhered weath­er bar­ri­er on the roof sheath­ing will add pro­tec­tion against water pen­e­tra­tion should the roof­ing mate­r­i­al become com­pro­mised dur­ing the storm.

There are oth­er design details that should be con­sid­ered includ­ing win­dow and door pro­tec­tion, exte­ri­or fin­ish­es that don’t have an air gap to allow high winds to pull them off the wall, and air and mois­ture bar­ri­er sys­tems that are ful­ly adhered should all be con­sid­ered in look­ing at rebuild­ing or new con­struc­tion along the coast.

As a Texas-based com­pa­ny, Bau­tex is com­mit­ted to solu­tion-based wall designs that help along the Texas coast. To read a more detailed analy­sis of lessons learned from Hur­ri­cane Har­vey, the full arti­cle can be found here. To find out more about Bau­tex and how The Bau­tex Wall Sys­tem can be used as part of a robust wind­storm design go to bau​texsys​tems​.com.