Roofs need a sloped shape to direct rainwater and melting snow away from your home’s structure, even when they appear flat. Architects and builders can explore a wide range of roof designs that shape both function and style. From gable to mansard roofs, this guide introduces the most common roof shapes, provides expert tips from This Old House’s Tom Silva, and shows how each option adds character and visual appeal to a home.
Gable Roof Shapes
Gabled roofs are the kind young children typically draw. They have two sloping sides that come together at a ridge, creating end walls with a triangular extension, called a gable, at the top.
Gable Roof
The house shown here has two gable roofs and two dormers, each with gable roofs of their own. The slant, or pitch, of the gables varies, an inconsistency that many builders try to avoid.
When building a gable roof, Silva recommends using two pieces of lumber for the ridge beam to reduce the physical strain of carrying two large pieces of lumber.
False-Front Gable
This house appears to have two gable roofs, but only if you drive by quickly. The real roof has a very low pitch. The gables are false fronts, similar to the showy facades often found on small commercial buildings. Their only purpose is to change the look of the house.
L-Shaped Gable
Gabled roofs take many forms, including this L shape. When the floor plan calls for a T-shaped house, the roof is called “cross-gabled.” If one of the sloping sides ends in a wall that’s shorter than the wall on the other side, it’s a “saltbox.”
There are also terms to distinguish gabled roofs that show their slanting side on the front (“side-gabled”) from those where the pointed wall is prominent (“front-gabled”).
Gambrel
Gambrel roofs are a type of gabled roof. Commonly associated with Dutch building traditions and barns, they break each sloping roof section into two parts—one close to the ridge that is relatively flat and one closer to the eaves that drops down steeply. This design makes maximum use of space under the roof.
Shed
Shed roofs, shown on the three dormers of this house, slant in only one direction. They fall within the basic category of gabled roofs, provided you think of them as half-gables. Shed roofs are easy to build because all rafters are identical.
Gabled but Curved
Because most gabled roofs consist of flat sections, you can cover them with virtually any roofing material. Gabled roofs with eyebrow dormers, shown here, or other curved details are the exception. Shingles made of wood, stone, tile or metal work fine. But metal roofing that comes in panels isn’t suitable.
Curved
Curved roofs usually require a lot of skill and time to create today, but when builders had only primitive tools and natural building materials, it was often easier to bend branches into curved shapes than to force them into straight lines.
Perhaps that’s why curved roofs, even this slate-covered example, often take on a look that resembles thatch.
Octagon
Octagon roofs have eight sides, as the term implies. Builders often choose this shape when they need to roof a building that’s round or nearly round.
Instead of dealing with the awkward fractions that another shape might require, they simply divide 360 degrees into half, then half again, then half a final time, winding up with the 22 1/2-degree angle that’s needed to build an eight-sided roof.
Hip
Hip roofs slope back from all four sides. If that’s all there is to the roof, the roof winds up looking interesting and yet it is still free of complications, such as valleys where leaves collect.
Hip roofs can also be linked up to fit L-shaped buildings or combined with gabled roofs, such as on this house.
Hip roofs use special rafters called jack rafters, which need to get cut at a 45-degree angle to properly fit against the hip roof’s beam, according to Silva.
Mansard
Mansard roofs are a type of hip roof where each sloping section is divided in two. To create maximum space under the roof, the section near the walls rises steeply. Then the roof continues at a milder pitch toward the center.
Standing on the ground, you see only the steep section and may think that the house is flat on top. Mansard roofs are common on buildings with styles borrowed from France.
