Climate shift may change building codes

Wind, rain and snow just weather. But when it comes in amounts unprecedented, recent disasters prove that structures can't always withstand the onslaught.

Scientists blame global warming for an increase in weather extremes and that brings calls for boosted structural strength and even faster rates of depreciation to allow for earlier replacement.

There's little question weather worldwide is getting more extreme.

A 2004 analysis by the National Climatic Data Center, for instance, found a 14 percent increase in "heavy rain events" of greater than 2 inches in one day, and a 20 percent by past realities, not future possibilities.

For example, terrorist activity changed building design to withstand bigger blasts, says Gary Norris, professor of civil and environmental engineering in the College of Engineering at University of Nevada, Reno.

"It takes catastrophes to spur the public to demand action of politicians," Norris says.

And the International Building Code is driven by what is found through the results of dramatic weather, says Scott Garrison at Miles Construction.

"You don't design a building for worst case scenario because you can't sell a client on that building," Garrison says.

He points to 50-year-old buildings that are still around. "They've had no problems in 50- and 100-year storms. And in comparison, he adds, "The new buildings are tanks; they're absolutely bulletproof."

But before they happen, high-intensity weather events can't be predicted.

"Should we be building for them in future? The answer is probably yes," says Peter Blakely, president of BJG | Architecture +Engineering in Reno. "But the code process looks to the highest past. It's reactive as opposed to proactive."

Building codes, updated every three years and then tweaked to suit by local jurisdictions, set the bar for snow load and for wind load, including pocket wind effects caused by the mountains.

The local tweaking is important because the High Sierra is a wind machine.

"Nowhere do you get more severe weather than on the north shore of Lake Tahoe," says Larry Ezgar, general superintendent at Q&D Construction. High winds can intensify effects of heavy rain and snow.

"Everything we build at the lake must withstand some of the most severe weather in the world," Ezgar says.

And with rain and snow come floods.

In flood zones, bridges are most at risk, says Blakely. Bridge footings are designed to withstand water scour and in colder climates, ice forces.

But if buildings are developed in a flood zone, designers typically attempt to raise rather than fortify. However, it's possible to install watertight flood control doors.

Looking to the future, Reno City Council is taking steps to mitigate possible future floods. Past law required people to build out of the 100-year flood zone, says Councilman Dave Aiazzi. Now the city is talking of requirements to build out of the 125-year flood zone.

And the city is discussing rules that would require developers to pay more attention to on-site control of rainwater that otherwise might add to flooding streams.

"You'll see depressions with grass in some developments, designed to hold rain water," Aiazzi says. But not everyone supports the better-safe-than-sorry philosophy.

"When you make a law requiring people to do more, people call that a taking," the city councilman says.

And tightened standards trans