What’s the one thing that all roofs have in common? Regardless of shape or size, all roofs—even the ones that look flat—need to be sloped to some extent to provide for rain and melted snow runoff. This requirement means that designers, builders, and architects over centuries have developed many different roof shapes tailored to local climate and spatial needs—from subtle and simple to dramatic and complex—but all having that one characteristic in common. Let’s take a look at some of the most common traditional and modern roof shapes.
If you think of the quintessential "house," you're most likely imagining a gabled roof, which is probably the most typical roof shape employed in residential architecture in cold, temperate, or rainy climates. Gabled roofs are ubiquitous in parts of the world that experience snow or rain, since the pitch of the roof (which can vary depending on region and snowfall) ensures that the roof sheds water easily, preventing leaks and damage from puddling.
Shaped like an upside-down "V," gable roofs are usually constructed using simple timber framing members: roof rafters that are placed at an angle along the ridge beam, the large central beam that supports the other roof members. While gable roofs excel at shedding water and snow, their sloped shape means that they create areas with low head-heights, often making spaces like attics non-occupiable.
A gambrel roof seeks to resolve some of the headroom issues that result from a simple gabled roof shape by breaking the pitch of a gabled roof into two separate angles. This creates a shallower angle near the ridge beam and a steeper angle that allows for more usable floor space as the roof nears the building’s exterior walls.
While gambrel roofs do allow for more usable space, they're often more complex to construct because of the specific angle where the roof rafters meet. Up until the 19th century, they were usually referred to in England and North America as "Dutch roofs," and to this day still evoke a Dutch colonial or barn connotation.
Another common roof type is a mansard roof, which is similar to a gambrel roof, except that the double-angled roof continues all the way around the building without a front or end gable. Like gambrel roofs, mansard roofs can provide more headroom with a lower roof than a gabled roof can, and because it's continuous around a building, there's no default front or rear facade.
Mansard roofs were so capable of maximizing attic space, that they were frequently employed in cities like Paris where local building laws restricted building heights up to its cornice, but not the tallest occupiable floor. In fact, the word"mansard" in French is derived from the 17th-century French architect François Mansart, who popularized the roof design. With an occupiable attic level, builders were able to get an extra floor out of a building of the same height as its neighbor with a gabled roof.
Hip (or Hipped) Roof
This treatment is a mix between the classic gabled roof and the four-sided mansard roof, in which all sides of a roof slope down to exterior walls at a consistent angle (with no breaks or changes in angle). The result is a pyramid-shaped roof whose slope is often shallow to create more headroom, or steep to create a dramatic presence.
One of the major drawbacks of a hip roof is further reduced head space because of the sloping rafters. Furthermore, they're even more complex than a gambrel roof to construct because of their more intricate framing system. At the same time, hip roofs are better suited for hurricane-prone areas. They lack the large, flat ends of gabled roofs that catch strong uplifting winds in a hurricane, and they’re also more structurally stable because they’re braced more symmetrically. While they have their disadvantages, hip roofs certainly have environmental benefits and aesthetic qualities that outweigh the negative.
This treatment is perhaps the simplest, most versatile roof shape that can be constructed. Its name derives from its frequent use for more utilitarian structures or add-ons to existing buildings, where the high point of the roof is leaned on an existing wall or roof member and then sloped downward in a single plane, as if it were one half of a gabled roof.
Because of its single-sided slope, however, shed roofs might run into drainage problems where they meet an existing building (if it’s an addition), and its simple form means that it's not appropriate for all building types. At the same time, it's often the humble shape of a shed roof that attracts designers, and it can work well in minimalist designs or when used in multiples.
Unlike a common shed roof, a butterfly roof is a more unique shape, but is one that has risen in popularity since the 1950s and was a defining characteristic of many midcentury-modern homes. It's characterized by its inverted gable shape, resembling a wide "V," and can often be formed with wings of different lengths.
Butterfly roofs are aesthetically arresting because of their non-traditional shape and the the fact that they allow you to install very large windows. However, this also presents waterproofing challenges. Instead of having water and melted snow drip off the roof edges as it would in a gabled roof, water instead must be drained to the center of the roof where the two wings meet. If this area of the roof is not properly installed, it will only be a short period of time before water infiltrates inside.
Finally, flat roofs are another common roof shape that has became de rigueur in contemporary architecture. Calling a roof "flat," however, is a bit of a misnomer. Even flat roofs have a pitch of at least two percent so that they can shed water, but this slope might not be evident unless you’re at roof level. Even then, a roof might be covered with raised walkways or rooftop pavers that help even out the top surface of a roof but allow for water to drain underneath.
Of course, a flat roof is not ideal for all places or buildings, particularly in areas that receive significant amounts of rain or snow (snow in particular can be an issue because of its weight on a roof). However, a flat roof is ideal for warmer, dryer areas or in situations where an occupiable roof is desired.
Throughout history, the shapes of roofs have been explored, combined, refined, and assigned to various architectural styles. While we’ve covered many of the basic roof shapes here, there are countless others that designers continue to experiment with, along with the accompanying structural framing, waterproofing, and abstract shapes. Have a favorite? Please share in the comments!