The Structure of a Butterfly Roof

Basic Structure

• A butterfly roof consists of two roofs joined at their low points to form a valley, which sometimes serves as a reservoir. The angle of the two roofs is determined by the architect or designer, but it typically creates slight but visually discernible slopes that give the building a more modern and less angular appearance than that of a traditional roof.

Advantages

• In areas that regularly experience drought, the central areas of butterfly roofs are used to catch rainwater, which is then directed into containers for crop irrigation or other jobs that require water that doesn’t have to be purified. Butterfly roofs create taller-than-average walls on two sides of the buildings they cover, so large, tall windows and glass doors let in more sunlight than do conventional structures with pitched roofs. They may also give rooms an open, airy ambiance.

Disadvantages

• The main drawback of a butterfly roof is drainage, which makes the design impractical in regions with heavy rainfall. When the water accumulates in the center of the roof and is not regularly routed into a container, the weight of the water either blocks the drainage system or overburdens the supporting beams and causes leakage. Although butterfly roofs provide tall walls on two sides of buildings, the center of the structure has low ceilings with upward slopes on either side, which create challenges in lighting and decor.

Butterfly Roof Versions

• Several unique styles of roofs have emerged based on the atypical pitches of butterfly roofs. A shed roof has a single slope and typically includes the slope at different levels on top of the building. A saddle roof is shaped like a Western style saddle used to ride a horse, with a convex curve on one side of the axis and a concave curve on the other. Gabled butterfly roofs generally have a triangular sloping roof attached to a flat roof with windows placed near the top of the walls beneath it. Zigzag roofs look like the edge of a saw blade, with many acutely angled peaks in a row. Architects sometimes mix and match roofs of different pitches on a single structure.