The Montgomery County Planning Board has approved a 75-house subdivision near Burtonsville, despite objections by the county school system that new students will overcrowd nearby schools.

For the past four months, the planning board has been struggling with a request from the county council to deny new residential subdivisions if surrounding schools are filled to capacity, planners say.

Board members have said repeatedly that they are hesitant to deny new subdivisions solely on the grounds that the county does not have adequate school space because they fear such arguments will not hold up in court should a developer decide to sue.

Until the county can come up with a policy decision on the issue -- expected this summer -- the planning board has been delaying approval of some residential developments and approving others.

"The board felt that, with portable classrooms, the school system could handle the extra children in this case," Charles Loehr of the county's development and review office said.

The subdivision is planned for the 16-acre Conway tract east of Route 29 near Burtonsville.

School officials say it will overcrowd Burtonsville Elementary School and Banneker Junior High School and push Paint Branch Senior High School to near capacity.

Council and school board members contend that the Adequate Public Facilities Ordinance allows the county to deny or delay development if there are not enough public facilities -- such as roads, sewers or schools -- to accommodate new residents.

Questions arising from the ordinance have generated a spirited debate over the past few months, with developers starting to complain that the county is using the controversial law to shirk its responsibility to new residents.

The county has used the public facilities ordinance for years to deny development in areas where roads are congested, planners say.

But only recently has the county also begun to consider overcrowded schools as a reason to deny development.

That's because the county is dealt a double blow: increased student enrollments and decreased state aid for school construction, said Bruce Crispell, a demographic planner for the schools.

"We've only just started advising the planning board on whether to approve or deny new developments," he said.

"Sometimes they've sided with us, but if it's a close call, they go with the developer."

By all accounts, the Conway tract is a close call, according to Crispell.

Montgomery County attempts to keep its schools at 90 percent capacity, and the three schools surrounding the undeveloped tract are already near or at 100 percent capacity, Crispell said.

These conditions are expected to be alleviated by 1988 by new schools and additions that have been approved but not yet funded, he said.

The newly approved 75 single-family and town houses are expected to bring 61 new school children into the area by 1987, according to a report released by the school system.

"As a matter of principle, we felt that exceeding 90 percent utilization of a school is not attuned to our goals, so we recommended denial of this subdivision at this time," Crispell said.

"But we did say we could put a few more portables classrooms into Banneker Junior High School, and the planning board felt that was good enough for them."

Banneker, originally built for 890 students, has six portable classrooms and a current enrollment of 1,011.

Crispell said the junior high school will have 10 portable classrooms by 1987 and a projected enrollment of 1,098, including new students from the Conway tract.

And Burtonsville Elementary, with a capacity of 610 students, will have 679 students by 1987, Crispell projects.

"That's really pushing it, when you consider that [Banneker's] library, gym, cafeteria . . . were built to accommodate 890 at most and about 800 students ideally and will be used by 400 more than that," he said.