Faced with the deterioration of the Law School's 84-year old central library, law professors yesterday approved initial plans for the school's most ambitious renovations in at least 19 years.

At a three-hour meeting, law professors voted 33 to 7 in favor of undertaking multimillion dollar renovations on Langdell Hall, the school's main library. In addition, the faculty agreed to erect a new building in the northern part of Holmes Field--the school's main quadrangle--to house about 20 faculty offices that will be preempted by the Langdell renovations.

Although the plans need finetuning and await approval from the Corporation, one faculty member who has played a key role in devising it said that yesterday's vote represented an auspicious move for the fate of the renovations.

"This is a big step along the way," said Fairchild Professor of Law Andrew L. Kaufman '51, chair of the school's student-faculty space committee, which first recommended the proposal last month after a one-and-a-half-year study.

Details of the plan the faculty approved yesterday include:

.Constructing a building in the northern part of Holmes Field. The space committee recommended erecting a four-story, 23,000 square-foot building on a 10,000 square-foot part of the quad, although the faculty yesterday did not make any conclusive decisions about the building's dimensions.

Such a new building would represent the first large-scale construction at the Law School since Pound and Griswold Halls entered its landscape in the early 1970s.

.Restoring and improving Langdell's major mechanical and electrical systems, as well as installing airconditioning systems throughout the library.

.Adding reading rooms throughout the stacks for increased student access. Currently the library has only one main reading room, located outside the stacks, and only faculty members have reading facilities in the shelving area.

Although Kaufman said that precise costs cannot be determined until architects design more detailed blueprints, he estimated that the new building will cost about $8 to $10 million. He added that the total cost of all the library renovations will considerably exceed that figure.

The school's faculty agreed in principle last year to allot about $35 million of a planned $150 million fund drive for improvements to the library's infrastructure.

Kaufman said the main reservation faculty members expressed during yesterday's meeting concerned exactly how much space in the new building should be allotted for faculty offices.

"The faculty's going to have to do more work on that," Kaufman said. "Given the reservations that were raised and the questions that were asked, that's a fair resolution."

Kaufman said he expects that it will take a substantial amount of time to make the plans more precise and have them approved by the Corporation, but added that he was not concerned with such a prospect.

"We want to do it right. It should be," Kaufman said. "This committee's going tobe in business for a long time."

Professor of Law Frank I. Michelman, who votedagainst the proposal, said he would have preferrednot to construct a new building at the expense ofso much prime green space in Holmes Field. But headded that his choice was "very close" and that henow views the issue as closed.

"I thought the vote that prevailed was a veryreasonable vote," Michelman said