Ongoing research and testing at the IBHS Research Center proves that stronger, more durable homes can be achieved through objective engineering solutions. As part of our commitment to real-world impact, IBHS launched its FORTIFIED Home™–High Wind program in 2017 at the National Tornado Summit. This program will help homeowners located in inland areas build safer, stronger new homes, and retrofit or repair existing homes to make them more resistant to high winds.
The highest designation IBHS offers, FORTIFIED Home–High Wind Gold, requires (among other things) a sealed roof deck, reinforced porches, carports and garage doors, and a strong continuous load path that ties a home together from the roof to the foundation, so it can withstand the stress of high winds.
In 2017, IBHS conducted a series of groundbreaking tests on a full-scale home with a two-car garage. The home was typical of those in the middle of the country, with one critical difference—it was built with a strong continuous load path that meets FORTIFIED Home–High Wind Gold. It was called the science house because it was fully instrumented with sensors to monitor wind pressure and loads being carried through critical elements and connections, and to measure the stresses and any deformation of the building as it experienced those forces.
The house was subjected to wind tests from different directions; at different wind speeds; at different stages of construction; with different levels of wall anchorage; and with various exterior wall openings (as if individual windows and doors were damaged or breached).
This extensive testing revealed some new precautions that improved resistance to high winds, including closing interior doors to compartmentalize a home into smaller areas and reduce the overall force on the roof structure, giving the roof a better chance of staying intact.
High winds place homes under intense pressure; wind entering a home through an open or broken window, for example, can create strong upward pressure on the roof. Pressure in a home can build like air in a balloon, eventually causing the roof to fail and blow apart.
The Science House tests:
- Validated the benefits of a strong continuous load path.
- Determined the least amount of structural reinforcements needed to affordably and reasonably achieve significantly greater durability.
- Examined how a continuous load path safely transfers the forces that wind inflicts on a home and disperses those forces through the strongest parts of the home safely into the ground.
- Generated a new, much-needed benchmark data set for home designers and builders (previously, architects and engineers had to make estimates based on much less precise data).
This new data will provide important scientific guidance for all stakeholders in the building and construction industry, including informing technical standards and building codes, and also provides further proof of the value of FORTIFIED construction standards and the critical importance of IBHS’s continuous load path recommendations.
The new data set includes wind speeds and wind gusts over time, along with measurements of the wind pressure being exerted throughout the test house, and the complete wind loads placed on the house, all the way from the roof to individual trusses and walls, down to foundation anchor bolts.
Once testing on the Science House was completed, the FORTIFIED components related to the continuous load path were removed, including straps that tie together the roof, walls and floors, along with the anchor bolts that tie the house to the foundation. IBHS scientists then subjected the house to the kind of high winds typical of severe thunderstorms in the middle of the country—and, as expected, the house came apart once wind speeds reached 100+ mph.
This demonstrates what, sadly, too often happens to homes in the middle of the country when severe thunderstorms occur, or when they are on the peripheral edges of tornadoes (EF-0 to EF-1). These relatively common events cause billions of dollars in insured property damage each year, which can be greatly reduced using stronger construction methods.
- A second identical house, known as the demonstration house, was constructed to demonstrate existing homes’ vulnerability to wind damage.
- There are three primary differences between the two test houses:
- Unlike the science house, the demonstration house did not have a FORTIFIED Home–High Wind Gold strong continuous load path.
- Unlike the science house, the demonstration house was not instrumented for gathering precise scientific data.
- The demonstration house was fully furnished like a typical family home.
- The demonstration house was subjected to the same high winds placed on the science house.
- IBHS engineers expected the demonstration house to fail, demonstrating what—sadly—too often happens to homes in the middle of country when thunderstorms occur, or when they are on the peripheral edges of tornadoes (EF-0 to EF-1). These relatively common events, including straight-line windstorms, cause billions of dollars in insured property damage each year. That damage and associated costs to homeowners and communities can be greatly reduced.
Shut the Doors on Wind
This study supports recommendations in the IBHS FORTIFIED Standards.