China's demand for cement comes up often in discussions with home builders about rising materials costs.

With the world's fourth-largest economy in the midst of an unprecedented expansion, there's not much left over for others, say the analysts.

China is taking about 40 percent of the world's cement production and about a third of its steel, according to the National Association of Home Builders. And, perhaps more important, its demand for cement and other products is affecting the shipping fleet that used to carry materials here.

"The ships that were being used to transport cement here are being diverted to the Orient, to China," NAHB chief executive Jerry Howard said. "It's more attractive financially for them to make a run from Southeast Asia . . . and from Greece [two big cement-exporting nations] to China than to ship to the United States."

America imports about 20 percent of the cement used here, but Florida, the hottest building market in the nation, imports about 40 percent of its supplies. Florida's demand for cement is high because building codes require concrete framing materials to protect against hurricane damage.

Before this year's hurricanes, the NAHB said its survey of builders showed 41 percent of respondents citing cement shortages, a huge jump from May, when 11 percent of those polled reported problems, and from March, when only 3 percent of builders noted difficulties.

The Portland Cement Association, a trade group representing U.S. and Canadian companies, last month said that 29 states were experiencing shortages.

Cement industry experts say the recent hurricanes could ease the cement problem temporarily because Florida builders can't work, at least for a little while. But they anticipate that reconstruction and the resumption of new building will quickly push demand back up.

"Locally, we will probably feel the impact of the hurricanes when the Florida reconstruction process gets into full swing. . . . There will be significantly more demand [for cement] then," Howard said.

"It's the worst time for it to happen because every region and every market sector is in the height of their building cycle," he said.

Cement manufacturers say the mild winter this year exacerbated their problems. Because builders kept building in the winter, cement plants didn't have time to build inventories as they usually do.

"It's almost impossible to get concrete," Potomac builder and remodeler John L. duFief said. "Where it used to take two days or a day to get an order in, it takes five days."

Because of the backlog for orders and problems getting cement shipments across country by rail, building contractors say they're stretching their projected construction schedules.

Cement producers don't see much hope for prices to drop or supplies to grow soon.

Dennis Skidmore, senior vice president of the St. Lawrence Cement Group, which has a large facility in Hagerstown, predicts the shortage will "worsen significantly this month and next because it's the peak construction season, but all of us have zero inventory."

Skidmore added that he anticipates similar conditions in the marketplace in 2005.