The D.C. Joint Committee on Landmarks opened hearings into an application by Don't Tear It Down, a citizen preservationist group, to declare all of five blocks and parts of four other blocks in the city's Chinatown area as the Downtown Residential Historic District.

A companion request was filed, seeking to establish the lower Seventh Street and downtown F Street commercial strips--virtually all of Washington's "old" downtown--as the Downtown Commercial Historic District. Hearings on that proposal will begin next Tuesday.

Business interests are opposing the applications because they view them as a roadblock to redevelopment, including the assemblage of small lots into sites for large new office and retail buildings. Putting the area into historic districts gives the landmarks commission control over demolitions and the design of remodelings.

Yesterday's hearing dealt with an area centering on Seventh and I streets NW that, according to Kim Hoagland, architectural historian for Don't Tear It Down, contains the only remaining concentration of residences from Washington's early years that exists between the Capitol and the White House. As a mirror of early ethnic Washington and other factors, she said, it deserves to be protected.

The petition was opposed by W.P. Dinsmoor White, an Annapolis consultant in historic preservation retained by property owners.

White called the petition "an ill-founded effort merely to preserve old buildings that are not worthy," and said that any pretense of the area being residential should be ruled out by demolitions, remodelings and the conversion of the area largely to commercial use.

White said there are better examples of early residential architecture in the existing Capitol Hill and Georgetown historic districts.

A second Chinatown hearing will be scheduled for a later date.