Opponents of proposals to curb Montgomery County's housing boom gained key support from county planners yesterday as the County Council began debate on a controversial measure to cap residential and commercial development for three years.

County Planning Board Chairman Norman Christeller told the council during a legislative work session that the proposed cap would "severely distort" the cost of housing and could spark a shortage of low- and moderately-priced houses in the county.

"We recognize there is a problem with traffic congestion over the next six years, but we're not at all convinced the cap isn't worse than the problem it's supposed to solve," he said.

The five-member County Planning Board voted unanimously this week to oppose both the cap and a proposal that would require that necessary county and state roads be under contract before a subdivision served by them could be approved.

The measures, proposed by council members David L. Scull and Neal Potter, are designed to curb the record pace of residential and commercial development until new roads can be built to ease widespread traffic congestion.

The board joins a list of opponents that includes most county builders, businessmen and zoning lawyers, and County Executive Charles W. Gilchrist.

"Any way you review this thing, it comes out the same way. . . . It's not a workable approach," Gilchrist said yesterday in a telephone interview.

The county executive said amending the measure would not change his mind about it, but stopped short of saying he would veto a building cap. "Threats of veto don't help, but we've made it very clear we don't like any part of this situation."

It takes four votes on the seven-member council to pass most bills, but five votes would be needed to override a veto.

Scull said the planning board offered "nothing new" in its assessment of the legislation. "It's the same as the executive and the business community. They think we should tough it out and hope the roads get built," he said.

The council debate coincided with the released of data by the planning board yesterday showing Montgomery County leading in residential and commercial development over other jurisdictions in Maryland.

During the last five years, almost half of the state's 102,498 new jobs and a third of the 106,668 dwelling units built in Maryland were located in Montgomery County, according to the figures.

The county's assessable tax base grew by $632 million during the same time, accounting for nearly a third of the $2 billion growth in the state's tax base, the figures show.

"Even if we cut back to 60 percent of the current level of growth we'd still be No. 1 in the state," Scull said.

Scull and council member Esther Gelman introduced amendments to the proposed building cap. The changes are designed to ease the impact of a curb on developers and "minimize uncertainty" in the housing market, they said.

The council session ended without action and on an acrimonious note, however, after council member William E. Hanna refused to debate the amendments.

Scull charged afterward that Hanna was attempting to filibuster the bill.

The council has set aside next Tuesday morning and all day Wednesday to continue the debate.