Raising the roof in New York City does not always mean it is party time.

Five of the 26 items on the calendar for the next meeting of the Landmarks Preservation Commission involve rooftop additions.

Rooftop additions can prove controversial, as was the case when Landmarks recently sent back to the drawing board a proposal for a Sir Norman Foster-designed, 22-story glass tower above 980 Madison Ave. It did the same for a plan to tack on a substantial addition to the two-story building at 746 Madison Ave.

Last week, the New York Historical Society said it abandoned a plan for an 18-story residential condominium tower at 170 Central Park West, a plan that was met with considerable protest from neighborhood groups and some preservationists.

In historic districts, the commission’s general rule of thumb is that rooftop additions should not be visible from the street. Height, massing, and palette are also important considerations, as is the context between the rooftop addition and its “host” building.

On the Upper East Side, Martin Raynes added three floors to two pre-war apartment buildings designed by Schwarz & Gross, at 970 Park Ave. in 1987 and at 525 Park Ave. in 1989. At 970 Park, the developer used red brick to complement the facade of its “host,” but the detailing is noticeably not as fine. At 525 Park, the addition looks somewhat like an Italian villa that might have been designed by Frank Lloyd Wright, and its light palette contrasts significantly with its “host.”

Last year, the Metropolitan Club, at 1 E. 60th St., one of the city’s masterpieces by McKim, Mead & White, opened a split-level, rooftop addition that is barely noticeable from the street. The tasteful construction offers club members a stunning, modern, sky-lit dining room and lounge surrounded by wide terraces overlooking Central Park.

Perhaps the most satisfying rooftop addition can be found at 55 Wall St., which was erected in 1841 as the Merchants Exchange Building and was doubled in height in 1910 by McKim, Mead & White.

Originally built for a bank, it is now the Cipriani Residences. The seamless addition might not have gotten approved nowadays, given the vigorous campaigning of some community and preservationist groups to keep their precincts sacrosanct.

While discrete additions make fewer waves, a little incongruity can make the city a more interesting and surprising place.

In the 1980s, a major rooftop addition transformed the roof of the former Gotham Hotel, now the Peninsula Hotel, on the southwest corner of Fifth Avenue and 55th Street into a large fitness facility and indoor/outdoor bar. While it clashes wildly with the building’s original architecture, it is very popular.

At 2178 Broadway at 77th Street, David Kenneth Specter designed in 1999 an unusually massed, three-story addition for the conversion of a pre-war building into the On The Avenue Hotel. At 936 Broadway at 22nd Street, a rooftop addition looks like a small county cottage atop a rather modern five-story commercial building.

TriBeCa also abounds in substantial, non-contextual rooftop additions, the most visible of which is at 60 Warren St. and 25 Murray St.

Mr. Horsley is the editor of CityRealty.com.