code update

Building Better, Safer
2004 and 2005 seasons show need for reevaluation.

LOUISIANA BUILDING CODES
Following the devastation of Hurricane Katrina on New Orleans, the Louisiana House Commerce Committee in November began considering a bill to implement a uniform statewide building code.
Institute for Business & Home Safety (IBHS) building code manager Jeff Burton testified before the committee November 8. His presentation included recent IBHS study findings as well as previous reports based on implementation of the International Residential Code (IRC) in other states.

A study of Charlotte County, FL, permits for garage door replacements and shingles following Hurricane Charley showed a significant decrease in damage and need for replacement in homes built after 1994. Stricter wind standards were implemented in the wake of Hurricane Andrew, which struck south Florida in 1992. Homes built under the new Florida Building Code, implemented in 2001, fared best.

Burton cited a 1997 report from the National Association of Home Builders (NAHB) that said the cost of improving wind resistant construction methods from the 1997 Standard Building Code to the 2003 IRC code was approximately 1.8 percent to 4.5 percent per home or $29.97 per month (based on a $100,000 home mortgage at seven percent interest over 30 years).

Burton showed a map of Louisiana applying the ASCE 7-98 wind contours and explained the highest wind standards of 110 mph or greater, where homes would require window and door protection, affect only the lower fourth of the state. He noted that the IRC includes choices in window and door protection with a range of affordability.

HIGH-RISES GLASS FAILS IN SOUTH FLORIDA
Hundreds of windows were reported blown out in dozens of high-rises in Miami and Fort Lauderdale, FL, during Hurricane Wilma in 2005 causing extensive damage—which even included the Broward County Courthouse, according to a published report in the Miami Herald.

The damage puzzled building experts because many of the buildings were built under what’s considered the nation’s strictest building and wind codes. Wilma, also, was not a major hurricane. The highest reported wind gusts were 100 mph in For Lauderdale.

One obvious suspect was wind-blown debris, such as gravel from the roofs of surrounding high-rise structures. In older buildings, it likely was a case of the glass never being designed to withstand hurricane winds. In newer buildings, however, possible causes ranged from poor construction techniques to faulty materials to specific designs of some buildings and to the wind tunneling effect as wind blew around and among buildings possibly increasing its force.

Before Hurricane Andrew a building’s outer cladding fell into a poorly regulated gray area. When Miami-Dade and Broward counties adopted a tougher building code that was later adopted statewide for coastal areas in 2001 high-rise windows were supposed to withstand not only the higher pressure of more powerful upper-level winds but some debris as well. Like windows in homes, they are supposed to withstand impact tests, including the two-by-four fired from a cannon. But windows above 60 feet are supposed to be designed to withstand small debris flying at Category 3 levels, or around 120 mph.

The Institute for Business & Home Safety, Tampa, FL, has stated that it is important to determine what failed and why because of the coastal high-rise building boom in hurricane zones. Also, building designs and building codes need to be evaluated.

NEW TILE ROOF INSTALLATION GUIDELINES RECOMMENDED IN FLORIDA
After Florida’s relentless 2004 hurricane season, the tile roofing industry surveyed the damage to tile roofs and found one prevalent failing: “hip and ridge” tiles, those tiles that trim the edges of the roof, were likely to be missing or damaged, even on homes built to current code standards and on homes that were located farther inland where wind speeds were considerably less (see HP, Summer 2005, page 6).

Improper installation was primarily to blame. In response, the Tile Roofing Institute (TRI), Chicago, IL, and the Florida Roofing, Sheet Metal and Air Conditioning Contractors Association (FRSA) worked together to create an extensive set of guidelines for hip and ridge tile attachment. The new instructions, intended to strengthen and clarify current installation procedures, will be incorporated into the latest Installation Manual for Florida in mid-October and officially adopted into the Florida Building Code November 1.

In surveys of 2004 hurricane damage, TRI and FRSA compared tile roofs installed before and after Florida’s 1997 building code revisions (following Hurricane Andrew). As expected, tile roofs installed after 1997 weathered the storms much better—with this one exception. “We realized more had to be done to address hip and ridge tile attachments,” explains Rick Olson, technical director for TRI. “In the past, trim tiles have been treated as decorative accessories. As a result, they were not adequately addressed and were susceptible to uplift forces from high winds.”

Instructions for attaching hip and ridge tiles have always been a part of the industry’s installation manual, but not to the degree of these latest guidelines. “Most of the procedures we are recommending are not new, they have just now been put into a tremendously detailed document,” says Steve Munnell, executive director for FRSA. “It gives contractors step-by-step instructions and diagrams for doing proper hip and ridge tile installation.”

The new guidelines break out hip and ridge attachment instructions for each method of roof tile application—mechanically fastened, adhesive-set and mortar-set systems. One of the primary guidelines for mechanically and adhesive-set systems is the requirement that contractors securely fasten hip and ridge tiles to a metal or wood nailer board.