Roofing

A roof symbolizes the essence of shelter and protection while embodying the notion of our home as sanctuary. The roof shields us from the elements, keeps us comfortable inside and provides us with the security we need.

A roof reflects the spaces it encloses while shaping the stylistic character of the building it covers. It speaks to the site it inhabits, the climate it tangles with and the neighborhood it adjoins. Since the roof can take on a multitude of forms and shapes it must be carefully considered on a number of levels, from the practical to the abstract, to create a successful architectural composition.

On the most pragmatic level, a roof needs to respond to the climate it occupies. Steeper slopes shed rain and snow better than flatter ones and are generally a good choice in climates that experience large amounts of precipitation. Roofing materials such as metal, asphalt shingles, tile and slate all have different minimum and maximum slope restrictions in their application and require some forethought before being specified. A flat roof would never be clad in cedar shakes just as a steep roof would never be covered with tar and gravel.

Architects generally refer to roof slope as a ratio of vertical rise over a given horizontal run. The convention is to use the number 12 for the horizontal dimension giving us roof pitches described as 2:12, 10:12, etc. — the bigger the first number, the steeper the slope.

You rarely find steep slopes on the traditional bungalow because of the simple overriding factor of cost. Steeper roofs require more framing material to build and more roofing material to cover. This simple reality produces a rather generic roof slope that is steep enough to meet the restrictions of most roofing materials while still being shallow enough to be economical. It sits somewhere around 5:12 and has created a fairly bland housing landscape that could afford a little variation.

Roofs with different slopes call to mind different styles. A steep forested site might suggest one type of roof while a flat, wide open site might suggest another.

The Prairie Style of architecture, best illustrated by the work of Frank Lloyd Wright, was founded in the American Midwest and tried to evoke the flatness of its native landscape through the use of horizontal line. By using flat and shallow sloped hip roofs with large overhangs, Wright and his peers were able to create buildings that were inextricably linked to their “prairie” landscape.

In addition to responding to the site it inhabits, the roof should also reflect the plan it contains. Just as a simple plan warrants a simple roof arrangement, a complex plan, with any number of major and minor elements, requires a more involved roofscape layout.

In these complex situations architects will think of the compositional balance between the larger and smaller roof forms. The building will be anchored in some way by a dominant roof element with smaller more subsidiary roof forms joining to it. The arrangement becomes a sculptural exercise with the overall balance being key to the building’s success.

he largest of the great French chateaux in the Loire Valley is the Chateau de Chambord. At over 400 feet in width this amazing structure houses 440 rooms and is crowned by a forest of turrets, chimneys (365 of them) and dormers stretching across a roof of steep gables and turrets. Although compositionally complex Chateau de Chambord’s roof is in perfect balance and, without question, is one of the most miraculous ever built.

Balancing the very real pragmatic concerns of protection and shelter with the more abstract ones of style and appearance is essential for the design of a successful roof and ultimately a successful building.