Issues of sustainability and the environment can be complicated. They usually involve a number of interrelated factors, which can make it hard to determine causes and effects. Whether or not global climate changes have led to more violent weather patterns, though, it’s clear that the cost of natural disasters has increased substantially in recent decades. Hurricanes, tornadoes, and floods now cause more widespread and lasting damage than they used to, at least partly because too many buildings have not been designed to withstand their effects.
A forum on that subject, and how concrete systems can help solve these problems, was held at World of Concrete in January. Speakers addressed the ways that changes to building codes and development patterns have contributed to higher damage costs, and proposed further changes that could help reduce them in the future. Encouraging greater use of concrete to produce more resilient residential structures would be a major step in the right direction.
What has changed?
It isn’t the frequency of severe storms, according to one of the forum participants, Donn Thompson, director, market development, for the Portland Cement Association (PCA), who cited National Weather Service data showing that the number of strong tornadoes has declined since the 1970s, while the cost of damage from tornadoes, hail storms, and thunderstorms has increased by 1700% over the same period. Part of the increase surely can be explained by residential and commercial development of formerly rural areas in storm-prone regions. Thompson, however, believes that building code changes have contributed more to the problem.
“In the 1950s, the federal government created minimum property standards that dictated how residential projects backed by government loans would be built. These requirements sought to ensure that the buildings were well-constructed, and would provide effective fire resistance not only to provide for the safety of residents, but also to allow the structure itself to survive.
“The development of consensus-based model building codes has gradually changed the objective of codes. The priority now is to reduce loss of life, which of course is important, but it shouldn’t be the whole story. These newer codes permit cheaper and less robust construction systems, which often results in excessive structural damage and losses in a natural disaster or fire,” Thompson says. “In fact, one study for the National Trust for Historic Preservation estimates that a third of all buildings in existence in 2008 will be demolished by 2030, just because they weren’t designed to last any longer. And most of them were built to code during the last several decades.”
Consolidating the model codes into the International Building Code (IBC) beginning in 1997 resulted in the adoption of the least common denominator for passive fire protection and acceptance of the most aggressive trade-offs for sprinkler systems. By focusing on life safety rather than property protection in the event of fire, codes have served to reduce the resilience of buildings subjected to natural forces as well.