Along the Gulf shores of the Texas Coastal Bend, Harvey’s fierce Category 4 winds delivered a massive blow to an area that is still recovering one year later.
When Hurricane Harvey made landfall near Rockport, Texas, on August 26, 2017, with maximum sustained winds of 130 mph, it was the first major (Category 3 or higher) hurricane to make landfall in the United States since Hurricane Wilma in 2005. Harvey was also the second most costly hurricane in U.S. history after Hurricane Katrina, causing an estimated $125 billion in damage.
The team consisted of four IBHS engineers, two staff from Swiss Re and two staff from State Farm’s Technology Research and Innovation Lab. The team performed wind damage assessments on 213 structures spanning five wind speed zones, collecting quantitative data using IBHS’ custom damage assessment software.
Help guide insurers
What did they discover? Key findings in this report can help guide insurers and catastrophe modelers, as well as home repair, roofing and construction considerations for years to come in wind-prone and wind damaged communities.
The highest wind speeds did not always correlate with the highest damage frequencies. The influence of building age and the residential building code in effect at the time of construction, construction type, and exposure also contributed to damage frequencies and sometimes outweighed the wind speed effects.
Nearly a quarter of the attached structures surveyed — such as porches, sunrooms and pool cages — were damaged by the storm, often becoming the culprit in further damage to the main house structure.
Unprotected doors were damaged up to six times more frequently than protected doors. Of all the doors assessed, sliding glass doors fared the worst, with up to 60% damaged regardless of protection.
Covering doors and windows with shutters or even plywood helps reduce wind damage and water intrusion, but works best if ALL doors and windows are protected, not just the side facing the water.
Hip roofs, which are more aerodynamic than gable end roofs, were damaged less frequently.
Single garage doors failed more often than double garage doors.
Although asphalt shingles are the most popular form of roof cover — used on 85% of the 213 houses studied — more than half the homes assessed had lost shingles, and many of those suffered further underlayment or structural damage.
3-tab shingle roofs had higher damage frequencies than architectural shingle roofs. This could be due to the age of the buildings, as architectural asphalt shingles have become more popular in recent years. However, 3-tab shingles have also been found to have higher damage rates compared to architectural shingles of the same age.
The majority of visible damage was associated with damage to the roof covering in the field, eave or rake edge.
Total roof collapse occurred for less than 10% of the buildings surveyed.
Damage rates for roof accessories such as vents and skylights were low.
Building terrain exposure played a large role in the amount of damage that occurred. Elevations surrounded by relatively open exposures (open water, open land) had high damage frequencies.
Jayleen R. Heft
Jayleen Heft is the digital content editor for PropertyCasualty360.com. Contact her at [email protected]