The National Capital Planning Commission, spurning advice from its own staff director, voted yesterday to endorse the D.C. government's proposal to create a special 88-acre zone on the northern rim of downtown Washington in which the construction of new hotels and apartments would be encouraged.

Creation of the zone along a mile-long section of Massachusetts Avenue from Union Station Plaza almost to 14th Street NW was proposed by the D.C. planning office with support from the hotel industry and other business groups and opposition from many residents who want the area zoned exclusively for housing.

The D.C. Zoning Commission agreed in a preliminary vote last month to create the zone, which would permit taller and larger buildings than are otherwise allowed if they contain housing or hotel units. Under the city's Home Rule Charter, NCPC -- a federal agency charged with monitoring the U.S. government's interests in the city -- must review and advise on such proposals before the Zoning Commission takes its final action, now scheduled for next Thursday.

Among other recommendations, NCPC executive director Reginald W. Griffith urged that building heights in the zone be limited to 90 feet instead of the Maximum 130 feet, or 13 stories, voted by the Zoning Commission. NCPC members, agreeing with D.C. planning chief James O. Gibson that such a vote would intrude upon the city government's powers, rejected the broad curtailment. Of the 11 NCPC members who voted, only Ann Loikow, a nominee of Mayor Marion Barry, was opposed.

The NCPC members agreed, however, to limit to 90 feet the heights of building fronts bordering Mount Vernon Square, the old D.C. public library site at Seventh Street and Massachusetts Avenue NW, which was a major element of the city's original 1791 L'Enfant plan. The rear portions of the buildings could rise higher.