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.