Designs for wind loads have been in building codes for a long time. Prior to the creation of the International Building Code, the three primary legacy codes had wind load provisions but they mostly dealt with wind loads on the building frame and had little load information about the building components or the exterior cladding.

Since Hurricane Andrew in 1992, building codes include more wind design information that comes from disaster investigations and wind engineering research conducted primarily at the university level. In 2000, the legacy building codes were replaced with the International Building Code (IBC). Residential buildings must comply with the International Residential Code (IRC). Both of these building code documents reference the engineering load standard, ASCE 7 Minimum Design Loads and Other Criteria for Buildings and Other Structures. This load standard has also been in existence for a long time; it now is revised every six years and the building codes revised every three years (IBC and IRC) reference ASCE 7 so the provisions in ASCE 7 become part of the building code requirements.

Since 2000, the IBC and IRC have been including more wind design provisions based on past experience and research. The Florida Building Code (FBC) has also been referencing ASCE 7 for a number of years. It takes a long time to have enough buildings constructed to newer building codes, given the normal turnover of building stock, to begin to see a difference in building performance after a hurricane.

The first major hurricane during which a noticeable building performance difference was recognized was Hurricane Charley, which hit on the west coast of Florida in 2004. To determine how the building code requirements are working, wind speeds typically need to be near the design wind speed in the code; there have been very few of those new-design wind speed events in the last 20 years or so. Hurricane Charley was one such near-building code level wind speed event.

After every landfalling hurricane, damage investigators are looking at how buildings performed compared to how they should have performed based on the year built and the building code that was in place at the time of construction. These investigations were conducted after Hurricane Irma that hit the U.S. Virgin Islands (USVI) and Florida in 2017. Wind speeds in the USVI, especially St. Thomas, were near design-level wind speeds. The wind speed in south Florida was estimated to be 120 mph, which is significantly lower than the 180 mph design wind speed. There was wind damage in both locations from Irma, but it was obvious that the buildings built to current codes performed much better than the older building stock that had not been remodeled or rebuilt to the current code.

Since 2000, the codes have adopted provisions that address problems observed in construction after a high wind event. The issues today are primarily related to the building envelope coming apart in places and allowing wind driven rain into the building. The most failures during recent hurricanes have been residential soffits being either pulled from the overhang or blown up into the roof/attic space.

Depending on the age of the roof cover, there are still losses to asphalt roof shingles, tile roofs and, occasionally, standing seam metal roofs. The FBC is requiring secondary roof membranes, which add a layer of water protection under the shingles, tile or metal to help prevent water entry through the roof. Water infiltration through glazing systems is now being recognized as a serious problem as well, particularly for glazing panels that must move such as windows and doors that open. High winds will fail the weakest parts of the building; now that the structural frame, roof coverings, roof and wall sheathing systems have been improved, the high winds and associated moisture is finding other, smaller cracks and crevices to enter. In very high winds associated with heavy rain, the quantity of water that enters some of the buildings can cause serious damage to the interior of the building.

After Irma, the investigating organizations and researchers will consider if there are any new code provisions that should be introduced to deal with failures that have been observed either during Irma or from prior storms and will continue to work to strengthen the code and improve the ability of buildings to resist the high winds and become more resilient.