Amid the chaos and heartbreak in New Orleans and other Gulf Coast areas ravaged by Hurricane Katrina, the National Association of Home Builders says the disaster is expected to have far reaching implications for those involved in home construction. A preliminary report issued by NAHB says "the number of homes destroyed by this catastrophe is almost certain to dwarf the losses from any previous U.S. natural disaster." While the trade group is anticipating heavy demand for services offered by its members, it cautions that a ripple effect will be seen in the supply and cost of building materials including concrete and wood.

"Of necessity, rebuilding will have to wait," says the initial assessment from NAHB. "The immediate need will be to clean up and repair damage to structures that are still viable. The repair process will absorb much of the construction labor near the affected area and several key materials that would otherwise have been used to build new homes. The materials that will be most affected include roofing and wood panels (plywood and OSB). Demand for other materials, such as concrete, is likely to decline initially, as planned projects are cancelled or delayed during the initial recovery period.

"The storm will have impacts on the supply of materials as well as demand," continues the NAHB report. "The areas affected by the storm have a significant number of wood product facilities that may have been damaged or destroyed. On the other hand, trees that have been blown down will need to be harvested on an accelerated basis, perhaps helping to lower wood product prices in the medium term."

NAHB notes that while the damage in Mississippi, and Alabama and parts of Louisiana beyond New Orleans is extensive, the flooding in New Orleans, Mobile, and elsewhere is likely to translate into much larger numbers of homes destroyed.

From the NAHB report:

"Although the floods generally did not tear off roofs or walls or cause structures to collapse, many homes will be permanently uninhabitable. The flood waters carried contaminants that cannot easily be removed, and even if the water were clean, prolonged submersion would cause structures to be damaged beyond repair. This is likely to be the fate of a large share of the more than 200,000 homes in the city of New Orleans. Additionally, imports of building materials will be disrupted by the damage to port facilities. New Orleans was the top destination for imports of cement and a number of other building materials into the U.S. in 2004. Cement imports, in particular, involve the use of specialized terminal facilities. The New Orleans and Mobile customs districts reported about 12 percent of national cement imports in 2004.

"Congestion caused by diversion of shipping to other ports will also probably disrupt some supplies of materials, as will land transportation problems caused by damage to roads, rail, and reload centers.

"The number of housing units destroyed (made uninhabitable and beyond economically-justified repair) by Hurricane Andrew in 1992 was estimated at over 28,000. The combined effect of Hurricanes Jeanne, Ivan, Frances, and Charley in 2004 was almost as large, with nearly 27,500 housing units destroyed, according to estimates compiled by the American Red Cross. In those cases, most of the destruction was caused by winds or the immediate force of the storm surge. The number of homes with major but reparable damage was more than twice the number destroyed. The 1906 San Francisco earthquake/fire reportedly destroyed 28,000 buildings.

"From July 1992 to September 1992, largely as a consequence of Hurricane Andrew, the average price for plywood increased from about $222 per 1,000 square feet to $321, and the price of Southern pine framing lumber rose from $264 per 1,000 board feet to $308. The hurricanes in 2004 did not trigger a similar increase, and prices actually fell during the relevant period, after soaring during the preceding year. The combination of greater (partly speculative) demand and disrupted supply produced a spike in lumber and panel prices in the final days of August 2005. With production already running at full capacity for wood panels, further increases for those products, as well as for roofing, are likely.

"Although the loss of tens of thousands of homes implies increased demand for, and construction of, new homes, past experiences have shown that there is no massive surge in home building in affected areas. Replacing units destroyed by the storm will not begin for many months and will take place slowly, over a number of years.

"In Dade County (now called Miami-Dade), the number of residential permits was 9,026 or 7.8 percent of the state total in 1993, the year following Hurricane Andrew. That share of the state was slightly lower than the county's 7.9 percent share in 1991. By 1995, there was an increase to 14,718 or 12.0 percent of the state, but that number still wasn't much greater than what might have been expected if there hadn't been a hurricane. The experience in other areas, such as Alameda County, Calif., following the 1991 fires and Charleston, S.C., after Hurricane Hugo in 1989, was similar. Homes were rebuilt or replaced very slowly."