Hardward and lumber store executive John W. Hechinger offered yesterday to build a privately financed convention center for the District of Columbia on the site of what is now his firm's lumber yard and warehouse at the end of the depressed H Street corridor in Northeast Washington.

Hechinger's proposal comes at a time when the city's hopes for building a publicly financed $110-million convention center near Mount Vernon Square NW have encountered stiff, possibly fatal opposition in Congress.

City officials and members of the Metropolitan Washington Board of Trade have urged approval of both the convention center project and the Mount Vernon Square location as a way to attract increased convention business to the city and at the same time spur redevelopment of Washington's old downtown core east of 15th Street NW.

Hechinger said yesterday his proposed privately financed facility - to be located on an 8.5-acre triangular lot formed by the intersection of Benning Road, Maryland Avenue and 17th Street NE - could be built cheaper and faster than the Mount Vernon Square project because the Hechinger properly is already under single ownership and would be donated free of charge to the city.

"Hechinger (Properties Company) will build the convention center and ease it to the city on a long-term basis . . . who no rental charge for the land," said Hechinger, a former D.C. City Council chairman and currently D.C. Democratic National Committeeman.

He described his proposed convention center site as being located at the confluence of seven major streets and avenues, eight blocks from Metro, serviced by more buses than any other city or suburban location and as being about equidistant from Union Station and a high-speed link to the Beltway via U.S. 295.

Development of this particular section of the city, Hechinger said, "will stimulate the rebirth of the blighted II Street commercial corridor" and provide low-cost land for hotel and retail development that will bring in more tax gains to the city than the downtown center location.

Hechinger announced his convention offer to the city at a news conference held at his firm's Northeast corporate headquarters, which are adjacent to the proposed site.

At one point he pulled back the curtains of his office windows to show off the views of the Capitol. Washington Monument, Robers F. Kennedy Stadium and D.C. Armory as seen to the west and south of the Hechinger property.

He said the proposed site is zoned for high-density commercial development and will support a structure of more than 1 million square feet. The shapre of the lot will affect the design of the facility but the floor size of the building would be expected to be as large as that proposed for the Mount Vernon Square property.

Hechinger said he had "kept quiet" while city officials and downtown business interests lobbied for the Mount Vernon Square location. Now, however, he said the apparent convention center committee on D.C. appropriations has convinced him "That the time for injecting a new solution is here."

Hechinger said he had only recently discussed his convention center proposal with city officials and had not yet been able to talk to congressional leaders about the project.

Ben Gilbert, director of the city's Municipal Planning Office, yesterday called Hechinger's offer "an interesting proposal and one we will certainly look at."

Privately, however, members of Mayor Walter E. Washington's staff expressed concern for what one planner called "the 11th-hour nature" of the proposal. And city officials yesterday were still optimistically voicing hopes that Congress will ultimately approve the convention center project at the Mount Vernon Square location recommended by the city.

Foster Shannon, president of the Board of Trade, was less guarded in his appraisal of the Hechinger offer.

"It's absolutely the wrong location, 15 blocks from the Capitol and most of the city attractions people come to see," he complained. "It's just not a logical place for development to occur."

Shannon said consideration of the Hechinger site would bring to 14 the number of locations the city has already spent $1.5 million studying in preparation for construction of a convention center.

He said he doubted there was any way to build a privately funded convention center in a suitable location.

"You can't rent the civic center for enough to justify the expenditure," Shannon said. "The city wants to have it because of other pluses, like jobs and development and taxes and other revenue."

The Hechinger proposal would mean the city would be giving ownership and control of its convention center to a private developer "and that completely defeats the whole purpose of such a major project," Shannon said.

Hechinger's proposal is similar to that made in Prince George's County last spring when a private developer offered to help finance and develop a convention center near the county's Capital Centre arena. The Maryland General Assembly, however, refused to approve the necessary bond issue to complete financing of the project.

The Hechinger Co. plans to move its lumber yard to Ardwick in Prince George's County and the firm had discussed plans to utilize the site as a trade center similar to Chicago's McCormick Place.

But Hechinger said yesterday he has been assured by New York City financiers - whom he declined to identify - that he can get financing for the convention center "if a lease from the city is forthcoming.

Under the proposal he unveiled yesterday, Hechinger would construct and retain ownership of the convention center building and the property on which he proposes to build it.

However, Hechinger said the yearly rent paid by the city would reflect only the cost of constructing and financing the center but not the value of Hechinger's property - which he said he would, in effect, donate to the project.

Donating the land in this way would be a definite "tax break," Hechinger said. He added that he could also use the depreciation of the center building itself "to shelter the income that comes from the project."

Hechinger said he could not estimate the overall cost of the project and therefore could not estimate what he might charge the city to rent the facility. But he said the free use of his land would save the city from $22 million to $30 million - the amount the city would need to acquire its proposed site near Mt. Vernon Square.

In addition, he said, the city would not have to pay to relocate residents or businesses and would be getting a convention center that is adjacent to unlimited land "for spin-off development."

The Hechinger firm owns about another four acres of adjacent property, but Hechinger said the majority of land ownership in the area is divided into small parcels among individual owners.

This, he said, is in district contrast with the situation at the Mount Vernon Square site, where property owners such as Woodward & Lothrop, Chesapeake and Potomac Telephone Co., and parking executives Leonard B. Doggett and Dominic F. Antonelli Jr. own large chunks of property.

"A lot of development is already going on downtown right now or is planned," said Hechinger. "The Hechinger offer will get this part of our city - the near Northeast - moving . . . We're not out in the boondocks, you know." He said other cities have built centers away from the downtown area and use shuttle services from the hotels.