What is a Butterfly Roof?

Jillian Downer

Butterfly roofs are a key design feature of houses and small business in post-war America. Architectural designers sought to bring clean lines and organic elements into urban development and modernize the traditional American home.

What is a Butterfly Roof?

Butterfly roofs were a key characteristic in most urban developments during the Atomic Age and can still be seen in many of the older neighborhoods across the United States. The butterfly roof has several key features important to its organic style, but the designs in this category have unique variables, benefits and a very interesting history.


Architectural style is one of the key elements in dating building structures and one of the many things that made the Atomic Age of mid-century architecture so unique was the modern roof designs in this period. Mid-century roof design was full of forward-thinking elements and modern design principles, including clean lines and bold innovations. Frank Lloyd Wright was one of the leaders of this concept that characterized small business architecture and urban development between 1933 and 1965. The butterfly roof replaced classic English-style housing, like the cozy cottage and medieval Tudor-style homes, with triangle roofs and vertical brick fireplaces. Post-war America and modernism was an influential factor in the progression of the organic style behind mid-century architecture and the butterfly roof. Today, butterfly roofs are one of a few key features from this period that remain as a key element in the recognition of mid-century modernism.


Butterfly roofs were a common feature in home design during the mid-century, so many neighborhoods across the country will have remnants of the butterfly roof. But these roofs are not just an element of our architectural past, and are still very popular in modern home design in places like Hawaii. The valley of a butterfly roof is made to capture rainfall and channel it into a contained space. In the arid climate of Hawaii, this is a helpful element for use during extreme periods of drought. Another reason that the butterfly roof is so popular in Hawaii is because of the organic elements behind the design. Butterfly roofs open the exterior seams of the house, creating high ceilings and allowing for more of the outside to come inside. In places like Hawaii, with mild temperatures year-round, the butterfly roof provides shelter with an open-air feel.


A butterfly roof is formed by two adjacent gables sloping inward toward the middle, so that they dip to create a central valley. The eaves on the exterior of the roof are atypical to most roof designs because they angle upward rather than downward, which is normal in most traditional housing. The design of a butterfly roof is meant to resemble the lines, angles and wingspan of a butterfly when they are flapping in an upward motion. Butterfly roofs can be of varied angle gradations and may not be of identical length or angle on each gable. Some butterfly roofs, in fact, may only have one gable that slopes in either direction.


Butterfly roofs were initially designed for the purpose of capturing rainfall in the central valley of the roof between the inward facing slopes. This allowed the owner to utilize the water for other purposes like watering plants, flushing toilets and even for drinking. Traditional roof designs were made so that rainwater would be immediately expelled from the roof while it rained in order to protect the house from moisture collection, mold and leaks. Butterfly roofs are also very aerodynamic and can be especially useful in climates with severe winds. Besides the ecological benefits, butterfly roofs have aesthetic design benefits as well. They allow for improvements and advancements in exterior design, such as window placement. Because of the height of outer walls, architects have been able to create unique structures by lengthening gallery windows on the seams of the house, allowing nature to become a part of the interior, which is a key element of the organic principles of post-modern design.


There are many unique roof framing options for the butterfly design. The shed roof has one flat or downward-angled gable and one butterfly-angled gable. A saddle roof is similar to the traditional butterfly style, except that the angles are slightly curved so that they follow a concave and convex pattern, resembling the gentle curve of a saddle. The zigzag roof is created by having several butterfly roofs side-by-side so that there are upward-facing points and downward-facing points. In a gable roof, you begin with a traditional triangle-sloped roof, but one gable is slightly longer and melds into an extension of the house with a flat roof. Low-pitch butterfly roofs are characterized by having a slope of less than 30 degrees, and a marina roof has a slightly rounded convex center with two upward-facing eaves.