The old car barn at 14th and East Capitol streets NE, which once housed Washington's trolley cars and has more recently hosted vandals, pigeons and bill boards, is slated to become a $10 million housing, shopping an office complex.

Robert Hess, a developer active in the Capitol Hill area, said he has signed an option to buy the property from the O. Roy Chalk Company Inc. for a figure "in excess of $2 million."

Robert Stein, a spokesman for Chalk, confirmed the price and that the option agreement, which will expire next April, has been signed.

The car barn, listed on the National Register of Historic Places, will be preserved to form the basis for the complex, which is to be designed by architect Arthur Cotton Moore, according to Hess. The main structure, which fronts on East Capitol Street, is 45-feet deep and covers an entire city block, will be divided into 30 or more units.

Brick walls extend from the front of the building back to 14th and 15th streets and along the back of the property on A Street. Between the walls and the front structure is a courtyard which is covered by a corrugated metal roof jacked up on poles. The metal roof will be removed, according to Hess, and about 70 rowhouses will be built in the court space, using the brick walls as the fronts of the houses.

Preliminary rowhouse plans call for a mixture of three-bed-room single-family and two-family units. The units facing East Capitol Street would be a mixture of apartments and offices, although some may be ear-marked for future use as shops, according to Hess.

"We want to retain some for commercial uses," said Hess, adding that the site, on the fringe of the increasingly affluent Capitol Hill area, isn't ready for a major shopping center.

"It's right in the middle of two classes of people, so you can't develop a theme - which every retail complex needs. If you put in little boutiques to satisfy the upper-income people, you'd create jealousies."

Hess said he wants to retain commercial zoning for the site. It is now zoned CM-1 (commercial/light manufacturing). This zoning must be changed before the site can be used for residential purposes, and Hess said his lawyers will ask the Zoning Commission to change the zoning to C-2-A (medium-density housing and shops).

Hess said he is currently working to secure financing for the project. He said he hopes to start construction by the beginning of 1980 and to finish the project two years later. He would not speculate on the eventual selling price of the units but predicted they would be "in line with housing prices on Capitol Hill."

The massive, red-brick structure, with its square turrets and ironwork balconies, was built in 1896. It was the first Washington building designed by architect Waddy Wood, who later built many of the grand houses in Kalorama, including the Woodrow Wilson house on S Street NW. The car barn, which was the terminus of the line that ran from Mount Pleasant past the Capitol and down East Capitol Street, housed the city's first electrically operated street cars. When the trolley cars disappeared in 1962, the building was used as a storage facility by D.C. Transit.

Community groups several times urged the city buy it and turn it into a recreation center. In 1967, the city included $1 million for such a center in its 1967 budget request, but the item eventually was deleted. When Metro purchased D.C. Transit facilities in 1973, the car barn was not included in the package.