The Montgomery County Council unanimously approved a requirement yesterday that builders provide a two-year warranty on any new house in the county. The County Department of Consumer Affairs will oversee the program.

Department spokeswoman Barbara Gregg said that under the new ordinance, house builders must belong either to a private warranty plan, approved by the county, which would operate much like an insurance fund, or to a county-administered program. The county program, she said, would require builders to pay a percentage of the selling price of each house into a fund to be used to pay claims.

A similar program, Gregg said, is being used on the state level in New Jersey.

"It's a good step for us to take. There have been so many complaints from consumers about this type of thing . . . defects. This is a good law."

The program was proposed in June by County Executive Charles W. Gilchrist, who estimated that 1 in 10 houses built in the county had problems such as faulty plumbing or roofing. The county received 276 complaints last year from homeowners who were not satisfied with their new houses, according to officials.

The warranty will cover the cost of repairs required because of defects in materials or workmanship.

Gregg said builders who fail to perform the warranty work would risk revocation of their builders' licenses. The consumer affairs office and an independent panel consisting of citizens and people from the construction industry will mediate disputes.