From busy rooflines to plastic shutters, mismatched windows to four-car garages, the McMansion has dominated the American suburban residential landscape for almost 40 years without a notable change in aesthetics. Many people know a McMansion when they see one. The typical McMansion follows a formula: It’s large, cheaply constructed, and architecturally sloppy.

Until around 2007, McMansions mostly borrowed the forms of traditional architecture, producing vinyl Georgian estates and foam Mediterranean villas.

But in the last 10 years, this has begun to change: McMansions are now being constructed in architectural styles from the 20th century, specifically modernism. We are witnessing the birth and the proliferation of modernist McMansions: McModerns.

Though McModerns are commonly found in the places where modernism itself thrives—indoor-outdoor climates like the West Coast and the Southwest, and near liberal cities on the East Coast—they are also beginning to pop up in burgeoning tech hotbeds south of the Mason-Dixon, such as central North Carolina and Atlanta, Georgia. McModern houses are following the trail left behind by NPR, Chipotle, and MacBook Pros: They’ve become popular with younger, tech-savvier, and more highly educated individuals.

What makes the McModern a fascinating case study in residential architectural history is its two separate lineages: its foundation as a McMansion, and its origins within the greater historical context of popular modernism—that is, modernism for everyday families.

McMansions have always taken a formal layout and dressed it up in a series of architectural costumes: Mediterranean, Shingle, colonial, Tudor, chateauesque, and now “modern.” All McMansions follow roughly the same structural form.

The McMansion has three contrasting—and disproportionate—parts: a central core with multi-story entryway, a side wing, and a garage wing. There are many variations to this: Sometimes the central wing has its own mass, other times it’s embedded with other masses. The side wing can be distinguished by different cladding or shape, or a focal point, such as a picture, corner, or bay window. Sometimes the side wing is omitted. The garage wing can be perpendicular to the main house as in the example above, or adjacent, with the doors being side-facing or front-facing. None of these forms are proportioned to one another, or scaled to the human form.

In the grand taxonomy of residential architecture, the McModern is a genus within the McMansion family. This is not to say that the “modern” part isn’t as important as the “Mc,” because the McModern as we know it derives from a source not often touched upon: the everyday modern houses not designed by famous architects, but by builders, or from pattern books.

The earliest examples of non-canonical, lowercase-m modern architecture were perhaps the Prairie Style kit houses inspired by Frank Lloyd Wright and designed and built by Sears Roebuck & Co., briefly popular between 1915 and 1920. From 1920 through the 1950s, instances of non-architect-designed modernist houses were few and far between. While a few pattern books offered Art Deco or Streamline Moderne-style house plans in the 1930s and 1940s, these were not as popular as the concurrent minimal traditional style, favored by many for its small size during difficult economic times.

McModern Checklist How to identify a McModern, as per McMansion Hell: Single-family detached home

Constructed from inexpensive materials, such as vinyl, stucco board, and veneers, rather than traditional materials such as stucco or reinforced concrete

Contrasting exterior cladding materials and colors

Attached garage and/or two-story foyer

Sometimes features non-modern details like Tuscan columns or windows with stylized muntins

Massing and rooflines may be over-elaborate, combining several roof forms, e.g. terrace, shed, “butterfly,” or “M-shaped”

May include decorative forms like extruded walls or cantilevers clad in differing materials

Windows are erratically sized and placed in “artistic” configurations without consideration for overall composition

Rarely designed by AIA-licensed architects—more often by building companies or house plan websites

The 1950s saw the dawn of midcentury modernism, popular with the general public for its forward-thinking and whimsical design. The houses built in the early 1950s by West Coast architects, especially those who worked with developer Joseph Eichler, were imitated throughout the 1950s and 1960s as catalog homes, a kit-of-parts situation that soon faded into obscurity, but also in pattern books published by architectural plan companies like the National Plan Service and Garlinghouse, as well as major home economics publications (Better Homes and Gardens, House Beautiful) and building materials companies (e.g. 84 Lumber).

Houses from this period often took the format of either a split-level house, a one-story ranch, or a cottage or vacation home; the most popular version was the A-frame.

The next round of influence on pop modern was the late 1960s work of architect Charles Moore.

Moore’s Sea Ranch condominium transfixed California. Its shack-like forms and materials (it was clad in redwood panels) were radically different from the norms of late modernism, which favored the heavy concrete facades of architects like Paul Rudolph. Moore’s Condominium I pays homage to rural coastal vernacular architecture: sheds, barns, and cabins. To integrate folk forms into a modernist dwelling was anathema at a time when every building was expected to be an individual monolithic architectural statement, but people responded to Moore’s use of wood siding and shed roofs. Charles Jencks said wryly in his book Architecture Today that, in the years that followed its construction, “people started building [little] Sea Ranches all over the country.” He was not wrong.

In the 1970s, the Shed-style house, which featured shed roof forms similar to the Sea Ranch, and the cedar contemporary, which extended the wood-clad, shingled-roof aesthetic to layouts like one-story ranches and houses with non-shed rooflines, replaced the midcentury modernism of the previous decades. (The A-frame would endure, perhaps because of its similar geometric form.) Part of the reason these houses became so successful was that they were easily adapted to the burgeoning environmental movement. The sloping roofs were favorable for attaching solar panels. The flexible interior spaces made for more economic heating and cooling, though several cedar contemporaries feature large floor-to-ceiling picture windows.

The cedar contemporary marked a new turn in the story of the pop modern: stagnation. Modernism as an architectural tradition came to an ideological end with the arrival of postmodernism in the 1970s. Architects as a whole turned away from modernist traditions, and so their influence on modernist residential architecture dwindled.

Builders and contractors were all too happy to fill the gap, and thus, the McMansion was born.

Even in McModern-heavy states like Washington and Texas, homes built in 2004 and 2005 weren’t McMansions in the middle of some sort of Darwinian evolution into McModerns. They were simply McMansions. Rarely, however, does a style evolve without some transitionary period.

Starting around 2007, as the housing market began to shrink, the Craftsman style from the early 20th century became popular again for newly constructed homes. In the immediate wake of the recession, as people become less interested in building bloated houses, the average new home size decreased for the first time since 1980. The sunken market furthered the spread of small Craftsman homes because the style was old enough to become new and exciting again and the aesthetic was well-suited to smaller home sizes; it was also facilitated by new exterior materials such as fiber cement board or shingles, which had a wood-like appearance that fit the Craftsman style better than their predecessor, vinyl siding.

McMansions easily adopted motifs from the Craftsman style, such as the tapered piers and Prairie-inspired window muntins. It then proceeded to mash these elements with elements from the earlier Shingle and Stick styles in a West Coast, premodern soup. Like an insidious, fast-forwarded rehash of the early 20th century, the McCraftsman evolved into the McPrairie, which evolved into the McModern.

Like modern art, many seem to think they can design a “modern” house—it’s just a box made up of smaller box-like shapes, right? To look at the simplicity of Philip Johnson’s Glass House and say, “I could design that” is—though flawed—relatively understandable: To the casual observer, it is a box made of windows sandwiched between a roof and a floor. Just as Jackson Pollock’s paintings are merely “paint splatters,” modern houses are merely “boxes.”

But a prospective house should be backed by some knowledge of its aesthetic language.

The McModern’s boxy forms and smooth visuals have their roots in the European International Style, which was disseminated throughout America by Walter Gropius and Ludwig Mies Van der Rohe and their students. Modernism informed the design of Fallingwater, Frank Lloyd Wright’s most famous work, and was transmitted to the West Coast by Wright, Richard Neutra, Ray and Charles Eames, and Rudolph Schindler. It became the language of corporate America at the hands of Eero Saarinen and Philip Johnson, evolved into dramatic monumentality through the works of Louis Kahn and Paul Rudolph, and was finally reinterpreted within a historical framework by Charles Moore and Robert Venturi, who paved the way for postmodernism and its subsequent movements.

Above all, modern houses have almost entirely been designed, associated with, or manipulated in some fashion by architects.

Proactive developers working in the postwar automobile suburbs, like Joseph Eichler, who collaborated with firms including Jones & Emmons and Anshen & Allen, continued the idea that a fine modernist house required some sort of involvement with an architect. This idea eroded partially in the 1970s, after the Shed and cedar contemporary styles became established, as younger architects shifted toward postmodernism.

The socioeconomic and technological development of the 21st-century McModern is strongly tied to the relentless pursuit of minimalism, beginning with industrial design: At the turn of the millennium, we entered the iPod age. Even more importantly, we fully embraced the internet age, and then subsequently the mobile age. These shifts triggered the beginning of the McModern.

Other cultural changes helped pave the way: A new generation rediscovered midcentury modernism with the debut of Mad Men in 2007, which quickly became a cult sensation with the largest house-building demographic: white middle-class people. Architecture, too, reset its clock, pursuing extreme minimalism in the residential realm, and glass box elaborations in the corporate. Ikea, around since the 1990s, became a household name. Luxury modernist houses like those by Robert Young graced the television screens of millions via their stardom in luxury car commercials, such as this Lexus ad from 2010.

It’s not just the stylistic effacement of modernism that makes the McModern particularly thorny, it’s the politics of them. In cities, McModerns are frequently constructed in rapidly gentrifying areas, such as the Greenway/Upper Kirby neighborhood in Houston, where $1 million, five-to-10-bedroom, builder-designed McModerns have been increasingly sprinkled among houses selling for $200,000 to $700,000: an earmark of speculation based on the increasing land values brought by rabid development.

There’s also the question of old modernist houses, and what will happen to them as the demand for McModerns grows. Regional organizations from around the country have developed ways of cataloging threatened historic modern houses in areas of dense speculation and redevelopment, and fight alongside the National Trust for Historic Preservation and its cousin Docomomo to save them from ever-increasing demolitions. In California, it’s not unheard of to tear down midcentury modern homes to build McModerns. The land has been deemed more valuable than the architecture, even in the case of the home of Nobel Prize-winning novelist Thomas Mann. (A common tactic of California Realtors hoping to win big on land speculation is to show no photographs of an existing property at all, but rather a glossy rendering of a sleek new McModern home.)

Are old modernist houses definitively better than McModerns? Perhaps not—all styles have their duds, after all. However, it is the indulgent, inefficient, and architecturally botched nature of the McMansion that lies beneath the sleek surface of the McModern. In the eyes of McMansion builders, modern architecture is perceived by potential buyers as the culturally significant, high-brow form of architecture, revered by the educated and glossy magazines. To see something only for its superficial attributes or financial potential and execute it carelessly is perhaps the most “Mc” thing anyone can do.

Kate Wagner is the creator of the viral blog McMansion Hell, which roasts the world’s ugliest houses. Outside of McMansion Hell, Kate is a guest contributor for Curbed, 99 Percent Invisible, and Atlas Obscura. In addition to writing about architecture, Kate has worked extensively as a sound engineer and is currently a graduate student in Acoustics as part of a joint program between Johns Hopkins University and Peabody Conservatory, where her focus is in architectural acoustics.