Claudette Reichel, Schultz, Bruce | 5/23/2006 2:28:24 AM
LAFAYETTE, La. – The hurricanes of 2005 demonstrated what works and what doesn’t for the home-building industry, a prominent building expert said recently during a series of seminars across southern Louisiana presented by the LSU AgCenter.
Dr. Joseph Lstiburek, an engineer and internationally recognized building scientist, said the destruction brought by hurricanes Katrina and Rita revealed the strengths and weaknesses of current building practices, and improvements can be made from that.
"All construction is really based on trial and error," he said to the building industry leaders and others at one of the seminars in Lafayette.
The Lafayette session of Best Building Practices for the Gulf Region on May 17 drew more than 100 architects, contractors, home inspectors, interior designers, building material suppliers and manufacturers. Sessions also were held in Lake Charles, Baton Rouge, Houma, Metairie and Mandeville, and a total of almost 700 people attended. The sessions focused on dealing with wind, flooding and rain.
Lstiburek said building codes for plumbing, fire prevention and earthquakes resulted from tragic events.
Hurricane Andrew that hit Florida and Louisiana in 1992 was the turning point for home construction, he said, with Florida adopting an extensive building code overhaul. The positive results were evident in 2004 when the Orlando area got hit by three major hurricanes in 45 days, he said, and no deaths and little structural damage occurred in new homes.
"Build up, or build out of stuff that can get wet, and design it to be cleaned," Lstiburek said. "The whole state of Florida is being built this way."
Lstiburek said it is Louisiana’s turn to change its building practices, because bigger and more frequent hurricanes are likely.
"You saw the hurricane tracking chart," Lstiburek said. "Our luck is running out."
Windows and garage doors are the most vulnerable areas of a house in a hurricane, he said.
If either are blown out, winds can blow a house apart, he stressed, adding, "It’s like turning a cup into the wind."
The expert said one solution is to build garages detached from the house, but he also said garage doors can be reinforced.
Hip roofs with low slopes are less susceptible to wind damage than gabled roofs and steep pitches, he said.
In addition, Lstiburek said ring-shank nails are mandatory for roof decking to endure strong winds – while smooth-shank nails and staples are doomed to failure. He also said plywood and oriented-strand board are equally secure when used with ring-shank nails spaced 6 inches apart.
The expert also explained roof rafter connecters that wrap over the top of each rafter are better than clips that only attach to the side of rafters. With clips, rafters tend to split after wood has been weakened from repeated heat buildup in an attic.
Other recommendations Lstiburek made are:
–Plywood painted on both sides or fiber-cement board are better for soffit materials than vinyl, he said, because the plastic is easily blown away by wind.
–Oriented-strand-board siding or wood siding should not be used in Louisiana’s rainy climate.
–Tile roofing set in mortar doesn’t hold up well to wind.
–Steel-framed homes are a good option if the roof is unvented and insulation is placed between the framing and exterior siding but not in the wall cavities.
–Impact-resistant windows provide good protection without requiring installation of window covers just before a storm and are worth the extra cost.
–Paperless gypsum wallboard is available that doesn’t grow mold and mildew after it gets wet.
–Fibrous insulation acts as a sponge and should be avoided in areas of a home susceptible to flooding. Build the first floor with material that can withstand flooding and be dried without damage. That includes rigid foam insulation, concrete or steel and paperless gypsum wallboard.
–Vinyl wall coverings act as a vapor barrier and create moisture problems.
–All windows and doors should be flashed correctly and installed to allow moisture to drain to the outside.
–All exterior claddings, including brick, will leak, so builders should construct homes with a drainage plane, using a nonperforated housewrap or tar paper with a small drainage space behind the siding.
The Best Building Practices for the Gulf Region curriculum and the seminars were developed through the partnership involving the LSU AgCenter’s LaHouse Resource Center with support from the Building Science Corp., Institute of Business and Home Safety, U.S. Department of Energy’s Building America Program, Georgia-Pacific, Norbord, MARTCO and local Home Builders Association chapters.
For more information about LaHouse and the variety of programs offered by the LSU AgCenter, visit www.lsuagcenter.com.