The NAHB has urged its members to oppose a new National Fire Protection Agency model building code, reviving a debate between the two associations over stair tread and riser standards. The NFPA 5000, issued in August 2002, requires a minimum tread depth of 11 inches and a maximum riser height of 7 inches for both residential and commercial buildings.

Ed Sutton, NAHB vice president for construction codes and standards, says those standards either increase new home footprints or require significant redesign. That will hurt low-income and first-time home buyers who often look for smaller homes and townhouses, Sutton says. "When you get into smaller homes, this really becomes a cost adder or it has a significant impact on the layout of the home."

Gary Keith, NFPA's vice president of regional operations, says the new standards are based on those in the NFPA's Life Safety Code. Keith adds that the code has not proved cost-prohibitive where adopted.

Besides, Keith says, safety is at issue, not cost. "Stair tread design is stair tread design, regardless of occupancy," he says.

Four hundred experts on 13 technical committees produced the code. They determined the controversial stair standards "will improve fall statistics," Keith says, noting that the NFPA 5000 is the only building code developed under an American National Standards Institute accredited process.

But, according to Sutton, the NFPA's findings are flawed. He questions the data technical committee members used in writing the code. "The link between stair geometry and accidents on stairs has never been established," Sutton says.

The NAHB backs NFPA rival the International Code Council and has challenged NFPA findings before. For a period in the 1990s, both code councils worked together toward a single uniform code. But the NFPA ended the joint effort in 2000. Sutton says the NFPA 5000 was intended to compete with the ICC's codes and undermines efforts to establish one comprehensive code.

Coordinating with other code councils is not an NFPA priority, Keith says. "We're trying to put forward the best set of codes that we think will improve life safety."