Area builders and planners say they will watch with interest the success or failure of Montgomery County's Wexford, one of the first subdivisons consisting of all pre-manufactured houses in the Washington area.

Wexford, in Germantown, will have 366 single-family, pre-manufactured homes on 100 acres of land with a trailer park zoning designation, said Al Polocicchio, spokesman for the Wexford Development Corp. Another such development, The Hadley Dairy near Gaithersburg, is also expected to open soon, according to county planning directors.

The two subdivisons are on land zoned RMH, traditionally a zone used for trailer parks, but county planners say the subdivisions are a far cry from traditional rental trailer parks.

"This is a subdivision of single family homes," said Perry Berman, chief planner for Northern Montgomery County.

"The RMH zone allows trailer parks but it allows pre-manufactured homes as well. That doesn't mean the two are the same."

Berman said the county struggled over the zoning designation for Wexford and Hadley Dairy because the type of subdivision is unique to the area.

He said while pre-manufactured homes are allowed in all residential zones, it was decided to zone these two subdivisions as RMH because the houses that will be placed there are technically mobile homes.

A mobile home has a steel undercarriage while a "modular," or pre-manufactured home, has a wooden undercarriage, said Policicchio. He said Wexford is calling its homes "pre-manufactured" because, although they are technically mobile homes with steel undercarriages, they will be double the width of regular mobile homes, put on concrete foundations and landscaped.

The Wexford houses will also have asphalt shingles and will be hooked up to the county water system. The homeowners will also own the quarter-acre lots the houses are situated on.

"They will look just like single family houses with siding," said Berman.

The two- and three-bedroom houses are being sold from $64,490 to $84,500. Hadley Dairy, owned by the Edinburough Corp., still needs a sewer permit before it can open, said Berman.

But he said the houses there will sell at a comparable price to those in Wexford.

Wexford is touting its houses as a moderate-priced alternative to stick- built Montgomery County homes, which average at $125,000.

But some in the county say residents might opt for a comparably priced town house rather than the detached manufactured homes.

"The Wexford houses are not as low as we thought they might be," said John Matthias, Germantown planning coordinator for the county. "These were approved because the county has a commitment to moderate-priced housing. We'll have to see how well they sell."

Berman agreed. "Whether we get more applications for housing developments like Wexford depends on how Wexford does," he said. "We're treading new ground here."

Area builders will be watching Wexford closely, said Susan J. Matlick, director of the Suburban Maryland Homebuilders Association, this week. She said Wexford is the only subdivision of its kind she knows of in this area.

She said most traditional home builders favor modular homes, but she said many are not convinced modular homes are sure-fire sellers.

"But, it's not a case of us against them in the building industry," she said.

"Modular homes are gaining acceptance. They certainly satisfy a need for lower-priced single family homes."

Matlick said subdivisions of pre-manufactured houses are common in the Southwest.

"I was at a complex outside Dallas once and the things were springing up like wildflowers in this desert tract," she said. But she said the Washington area is generally affluent and that most homebuyers will still prefer stick-built or custom-built homes.

"Modular homes are not going to drive the stick builders out of business," she said.

Policicchio said homebuyers can choose from four Wexford model homes. The houses, with heat pumps, carpeting, and fully equipped kitchens, are manufactured by Redman Industries, Marlette Homes and Ritz Craft.

The two halves of each home will be trucked to Wexford, where they will be bolted together, placed on a foundation and landscaped. The whole process will take about 60 days, he said.

"They are sturdy and insulated," he said. "It's a nice home for policemen or newly weds who want their own yard."