A building’s silhouette against the sky tells a great deal about the attention the designer paid to the issue. The roof is frequently neglected on the assumption that “nobody sees it anyhow.” That may be true if we are near a very tall structure, but as we gradually move to a distant view, the roofscape does reveal itself.
One major problem is caused by all the mechanical equipment that must be placed on the roof. An even worse problem is the elevator machinery penthouse necessary in buildings that exceed six floors.
The problem does not exist in lower buildings, because their hydraulic elevators are low-speed (150 feet per minute). The elevator is in fact being pushed up by a hydraulic piston, and the machinery can be housed in a small room near the elevator on the lowest floor.
Structures seven stories and higher need faster elevators (350 or 500 feet per minute), electrically operated by machinery located in a penthouse that rises 17-18 feet above the roof. This tall “bump” is very difficult to disguise.
In addition, somewhere on the roof there must be a large enclosure to accommodate the stairs to the roof, as well as the kitchen and bathroom exhausts, vents, housing for the corridor air supply fans, and chillers and condensing units for air conditioning.
There are buildings where even the boiler is located on the roof. The typical floor of the building determines the most economical location for these mechanical needs: straight up on the roof. Moving them to an aesthetically preferable spot demands expensive horizontal runs that often are not in the budget. This is an
old dilemma for the architect – looks versus cost.
The cheapest solution is to run straight up with ducts or pipes, regardless of the consequences. We have plenty of examples of this in Evanston. Often, I think, it is just carelessness, as at the new Mather building on the northeast corner of Hinman Avenue and Davis Street where, just east of the carefully crafted emblematic cupola, a large metal box is plunked down on the roof.
One elegant remedy is to take the exterior skin of the building and carry it up a floor or more, fencing in the mechanicals and making whatever happens on the roof invisible. This was nicely done on the bank building at the northeast corner of Davis Street and Orrington Avenue.
Another approach to hiding the equipment is at the Church Street Station apartment building at the southwest corner of Church Street and Maple Avenue. The roofscape is simply hidden by making the units on the top floor two stories high.
In Evanston, there are a number of apartment buildings that cleverly camouflage the roof bumps. The two most attractive solutions are on Park Evanston (1630 Chicago Ave.) and on Optima Views (1720 Maple Ave.).
Rarely is the designer so fortunate that the typical floor plan lends itself to revealing the elevator penthouse to make a major feature of it, as was done at Evanston Place, on the west side of Chicago Avenue between Church and Clark streets.
Since most good solutions to the roofscape are expensive, designers tend to soothe their consciences by saying, “Who will see it?”
“God will,” I used to tell my students at the University of Illinois at Chicago School of Architecture.
I only wish the economy would improve, so that I can test the belief system of former students who would build tall buildings in Evanston and would want to make peace if not with me, with God.
…or to quote Longfellow (1849):
In the elder days of art,
Builders wrought with greatest care
Each minute and unseen part;
For the Gods to see everywhere.