A butterfly roof house is the image many people have of mid-century modern: two roof planes that tilt down toward a valley in the middle, so the roof looks like a pair of wings. Caltrans' statewide study of postwar tract housing defines the butterfly as a roof "lower in the center and higher at the ends" and lists it among the roof forms of Contemporary style houses, the period's term for houses with a more modern look than the typical tract house.
It is far from the only modern roofline, though, and in the Eichler tracts of Palo Alto and San Jose the records describe flat roofs, shed roofs and low gables instead. Here is how to read each shape, where it came from and what it tells you about the house underneath.
What a butterfly roof is, and where it came from
A butterfly roof turns the usual gable upside down. Instead of rising to a ridge, the two halves rise toward the outside walls, leaving the low point in the center.
A 1945 example on Long Island. Syracuse University's Marcel Breuer digital archive describes Breuer's Geller House I in Lawrence, Long Island, commissioned in November 1944 and dated 1945, as "a binuclear house with a butterfly roof."
The Palm Springs tracts. Caltrans' study says George and Robert Alexander moved their building company to Palm Springs in 1955. Their houses there were designed largely by William Krisel of Palmer and Krisel, with some by Donald Wexler, and many feature butterfly roofs and screen walls of patterned concrete block. The study notes that many were bought as vacation homes, so the builders chose a more exuberant style than in their Los Angeles tracts. The Alexanders built more than 2,000 houses in Palm Springs in the late 1950s and early 1960s.
Elsewhere in California. Fresno's mid-century modernism historic context, prepared for the city, lists "strong roof lines including flat, gabled, shed, or butterfly" among the character-defining features of both its Contemporary and post-and-beam houses.
The Caltrans study is clear about proportions: in Contemporary style houses, the low gable is the common form, and butterfly and single-pitch roofs are seen on some examples.
Flat roofs: the plain default
Flat roofs show up early in Eichler's work. At Green Gables in Palo Alto, built by Eichler in 1950, the National Register nomination says rooflines were flat or gently sloping and that no peaked or gabled roofs were used. Palo Alto's Eichler guidelines list the features of a flat-roof Eichler, including a flat roof with no parapet, overhanging eaves, exposed rafter tails and clerestory windows above the garage.
A flat roof doesn't have to mean one plane. Two of the six Greenmeadow models described in that tract's nomination use an eight-foot "dead-level" roof in front and a ten-foot level roof behind, with clerestory windows in the gap between them to bring diffused light into the house. Palo Alto's guidelines say Eichler roofs are typically covered with visually flat materials such as tar and gravel or rolled roofing.
Shed and flat-with-shed roofs
A shed roof has a single slope, in the guidelines' own glossary. On Eichlers it usually appears in combination:
Flat-with-shed. Palo Alto's guidelines describe a low-pitched shed roof over one bay and a flat roof over the other, with clerestories under the raised portion or over the garage. The guidelines note that these combination roofs give an asymmetrical design.
Greenmeadow's Model Three starts with a shed roof over the garage that runs from eight feet high on one side to ten feet on the other, with the high end pointing toward the center of the house and clerestory windows in the gap between roof pitches.
Greenmeadow's Model Six uses a single shed roof over the garage and center section, again eight feet on one side and ten on the other, with side clerestories facing the bedroom wing, which has a flat roof of its own.
The lesson for a buyer: a change in roof height is often where the clerestory glass lives, so the roofline is a quick guide to where daylight enters the house.
Low gables, center gables and the occasional steep one
Gables are common in Eichler tracts, and they're usually shallow. Palo Alto's guidelines say Eichler roof slopes are typically quite shallow, often 3:12, meaning three inches of rise for every twelve inches of run. San Jose's draft National Register documentation describes flat or 2:12 broad gable roof forms. Typical gable features in Palo Alto include clerestory windows under the gable and exposed beams or braces beneath it.
Greenmeadow's Model Five has a single, low center-pitch roof across the whole front, with trapezoidal clerestory glass filling the triangular gaps up to the roofline.
Greenmeadow's Model Four has a folded-pitch roof, flat on either side with a slight pitch over a wide recessed entry.
Flat-with-gable. Palo Alto's guidelines describe a flat roof with a steeply pitched gable over the entry, and list an entry atrium among its features. Caltrans credits A. Quincy Jones with adding a central carport topped by a high-pitched gable to the atrium plan, introduced in Eichler's Lucas Valley tract in Marin County, begun in 1963.
See our Jones & Emmons page for more on the firm behind the Greenmeadow models.
Claude Oakland's later roofs and the hipped exception
Palo Alto's guidelines say Claude Oakland expanded Eichler's roof vocabulary beyond the relatively simple forms of the 1950s, introducing hipped roofs, gabled roofs with flat peaks and gables set parallel to the street. In the early 1970s he developed center gables, turned gables, flat-topped center gables and hipped roofs in Palo Alto's Los Arboles Addition and Community Center tracts. Shingled roofs, uncommon on Eichlers, appear in the Community Center tract. In San Jose, his SJ-4 "D" model for the Fairglen Additions set an A-frame roof with clerestory windows over a central atrium. See our Claude Oakland page.
Hipped roofs are still the exception. The guidelines note that they were used in later neighborhoods such as Community Center but are not typical of Eichlers. On a tract ranch house, by contrast, Caltrans describes hipped or gabled roofs with a relatively low pitch and broad overhangs, usually clad in asphalt shingles. For more on the two types, see the difference between an Eichler and mid-century modern.
Palo Alto's guidelines don't list the butterfly among the city's Eichler roof forms. Their list includes gables, flat roofs, flat-and-shed combinations, a chevron roof found in Greenmeadow and Oakland's later forms.
What the roofline means when you own one
Historic surveys pay close attention to roof shape. The Greenmeadow nomination counted noticeable changes of pitch to the original roofline against a house's historic rating, and Palo Alto's guidelines make several related points:
Raising a roof above its original height is not preferred, nor is adding a roof form that substantially changes the look of the house.
Keep the narrow profile of the roof edges, the overhanging eaves, the exposed beam ends and the fascia boards. Avoid boxing in beam ends or covering wood fascia with aluminum or vinyl.
When re-roofing, use plain materials such as tar and gravel, single-ply, foam or composite shingles. Standing-seam metal is not encouraged, and where shingles were original, as in the Community Center tract, re-roof with shingles.
For additions, try to make the new roof continuous with the original. Arched roof forms are not considered appropriate in Eichler neighborhoods.
Any roof with a low point in the middle, a butterfly or an inward-sloping shed, deserves a question on the tour: where does the water go? Our materials and construction page and mid-century modern design guidelines cover related topics. Palo Alto's guidelines are voluntary, and rules differ by city, so check with your planning and building departments and a licensed roofer before changing a roof.
Frequently asked questions
What is a butterfly roof?
It is a roof with two planes that slope down toward the middle, so it is lower in the center and higher at the ends. Caltrans' tract housing study lists it among the roof forms seen on some Contemporary style houses.
Do Eichlers have butterfly roofs?
The Palo Alto guidelines and the National Register documents we read for Palo Alto and San Jose Eichler tracts describe flat, shed and low gable roofs, not butterflies. That doesn't rule out a butterfly somewhere in Eichler's work, so check the original plans for any specific house.
What roof pitch do Eichlers have?
Shallow. Palo Alto's guidelines say slopes are often 3:12, and San Jose's draft National Register documentation describes flat or 2:12 broad gables. Steeper gables do appear over some entries and carports.
Where were butterfly roof tracts built?
Caltrans' study points to Palm Springs, where many of the houses the Alexanders built from 1955 on feature butterfly roofs. Fresno's mid-century context also lists the butterfly among its local modern roof lines.
Related reading
Mid-Century Modern Design Principles: Overhangs, Orientation and Glass
Mid-Century Clerestory Windows and Window Walls: How They Work
Curious what a roofline says about a house you're considering? Call or text the Boyenga Team at Compass at (408) 373-1660 or (650) 383-8606, or contact the Boyenga Team and we'll help you read it before you tour.
