Rejecting Superintendent Floretta D. McKenzie's call for no new programs, a key District school board committee yesterday renewed its commitment to smaller classes and better building conditions by approving a $24 million budget increase.

The board's Finance Committee voted unanimously to increase McKenzie's proposed budget to $482 million. The full board is set to vote on the budget next week.

"We felt it was our responsibility to come out with a budget that more closely represented the needs of the schools of the District of Columbia," said committee Chairman Nate Bush (Ward 7).

McKenzie, who plans to leave the District superintendency at the end of January, last month proposed what she called an austere budget designed to recognize the city's tight financial situation and to give the system time to assess the impact of improvements in previous budgets. McKenzie did not attend the committee meeting and could not be reached for comment last night.

Bush said yesterday that "we took a very close look at the superintendent's recommendations and we decided to move forward in reducing the student-teacher ratio from 25-to-1 to 20-to-1 in the third and fourth grades." That would add $3.3 million to McKenzie's plan.

The committee also voted to reduce class size in social studies and science classes in secondary schools, at a cost of $4.1 million.

The panel approved a total of $10.2 million in extra expenses for reduced class size, including money for 393 new teaching positions beyond McKenzie's proposal. Some of that money would go to hire teachers for classes in kindergarten through second grade that have failed to meet the 20-student goal this year.

If the full board approves the new budget, which Bush and other board members said it will, the plan would go to the D.C. Council by Dec. 21.

Council member Hilda H.M. Mason (Statehood-At Large), who heads the council's Education Committee, said the budget additions are "worth our consideration. I've always advocated smaller class size and the adequate repair of buildings and all the things they're talking about."

Bush said parent complaints about sagging roofs, leaks and other physical problems at many city schools made "it very clear that the citizens were very interested in improving buildings." The committee voted an extra $7.5 million for such repairs.

The committee also proposed additional funding for summer school and for athletic programs. While the panel added $150,000 in sports funding yesterday, Bush said the full board expects to increase the athletic budget by up to $2 million.