Mayor Marion Barry yesterday recommended $341 million in capital improvements to schools, public housing, roads, recreation centers and other District facilities in fiscal 1987, a 37 percent increase over the current spending level.

The proposed budget, described as part of a $1.3 billion plan for capital improvements during the next six years, cited repairing and modernizing school buildings as a top priority. Officials said they would "aggressively attack" problems ranging from broken windows to faulty heating and electrical systems.

In recent years, city spending for capital improvements has risen sharply, largely because of the District's entry into the municipal bond market. The city first issued general obligation bonds in December 1984. Previously, the D.C. government relied on loans from the U.S. Treasury for long-term financing.

Capital spending dropped to "a bare minimum" of $88 million in fiscal 1983 as the city prepared to draw down its last available Treasury loans, officials said. The District's capital program then climbed steadily to $249 million this year as a result of "increasing confidence" in the city's financial strength.

Most of the $341 million authorization for fiscal 1987 would be financed by general obligation bonds, officials said. Nevertheless, they warned that some projects are expected to rely, at least partly, on federal outlays -- a prospect viewed as uncertain because of Congress' recent balanced budget legislation.

The Gramm-Rudman-Hollings measure may jeopardize some major District projects, ranging from improvements at St. Elizabeths Hospital to highway repairs, officials said.

St. Elizabeths, which treats mentally ill patients, is scheduled to be transferred from federal to District control, starting next year. The city is seeking $17.5 million in federal aid to renovate the hospital in fiscal 1987.

Under the mayor's plan, about three-fourths of the city's capital spending during the next six years would finance repairs and renovation of existing buildings, equipment and other facilities. Only about one-fourth would be earmarked for new construction projects.

"The size and age of the District's infrastructure requires a steady investment of capital to maintain the streets, bridges and sewers in functional condition," the budget proposal said. "In addition, many government buildings and offices require major renovation to keep them safe and efficient to use."

The mayor proposed $58 million for school improvements in fiscal 1987, more than half the amount slated to be spent on schools during the next six years. "It is crucial that attention be directed toward the long-neglected modernizations, upgradings and repairs to outdated facilities," the budget report said.

The proposed repairs include replacing 34 school roofs, seven boilers, windows at 49 schools and doors at 28 schools, along with overhauling eight schools' electrical systems. The renovation is needed partly because enrollment is expected to remain stable at about 88,000 students, the report said.

The mayor recommended several moves to eliminate hazardous asbestos at schools and other buildings. The plan would provide for $10 million for asbestos removal at schools, $2 million at public housing projects and $5 million at government buildings.

Among construction undertakings proposed by Barry were a new Shepard Park library branch in the 7400 block of Georgia Avenue NW and a fire station at Rhode Island Avenue and Thayer Street NE, designed to be "within three minutes" of the Fort Lincoln housing complex.

Barry also recommended a new center for the elderly on H Street NE, new court chambers for seven appellate judges and a $1.7 million "arts inducement" project aimed at encouraging private developers to provide space for theaters, art galleries and other displays.

Among housing proposals was a $1 million plan to renovate vacant public housing units. The report said the District has more than 700 vacant units that are "not habitable in their present condition." These structures need to be repaired to help offset a shortage of housing for poor residents, it said.