They Work On So Many Levels

St. Urbain

Classic turn-of-the-century triplexes on St. Urbain Street

In Montreal, it’s hard to avoid plexes. Found in almost every neighbourhood, they define the landscape and have made this city what it is today, architecturally, culturally and socially. With their distinct form—several superposed flats, each extending from the front of a building to the back—plexes are a popular form of housing, adaptable to many different lifestyles. But what’s their story? How did Montreal come to be a city of walkup apartments, outdoor staircases and balconies?

According to David Hanna, professor of geography at the Université du Québec à Montréal, the origins of the plex can be traced to a nineteenth century “marriage of convenience” between French and Scottish traditions. Historically, some French-Canadian settlers used outdoor staircases to link the first and second floors of their houses; immigrants from Scotland, meanwhile, brought with them the custom of stacking one flat on top of another. “It kept morphing in the nineteenth century until it settled into the form of an outdoor staircase leading to each apartment,” said Hanna.

Architect Susan Bronson, who teaches at the Université de Montréal, notes that turn-of-the-century building codes, designed to improve living conditions, played a big role in reinforcing the dominance of the plex. In Montreal and the suburb of St. Louis (now Mile End), lot sizes were increased from 20 by 60 feet to 25 by 100 feet and laneways were built in between blocks to service new apartments. Setbacks were mandated on newly-built residential streets, indirectly encouraging the use of outdoor staircases as a space-saving measure.

City regulations also dictated a specific amount of fenestration for each apartment, leading to L-shaped buildings that allowed light in every room. They decreed that wood-frame buildings must be clad in masonry or pressed brick. Crucially, they also insisted that each apartment have its own bathroom, a revolutionary gesture in a city racked by disease, where backyard latrines were still the norm in many old neighbourhoods.

In effect, these regulations created an official template for the plex. Contractors were able to quickly and cheaply build high-quality housing. At the same time, the city’s population swelled with new migrants. “There was a really, really urgent demand for housing,” said Bronson. “A typology developed out of what was essentially a building code.”

Plex layouts remained fundamentally similar from one neighbourhood to the next, but there were nonetheless some regional variations. Imposing, ornate plexes were built on prestigious streets such as St. Hubert St. and St. Joseph Blvd. on the Plateau, and along Sir George Étienne Cartier Sq. in St. Henri. Westmount, Outremont and NDG, meanwhile, “had middle-class pretensions,” explained David Hanna. “They did not want working-class architecture,” so they banned outdoor staircases and tried to disguise plexes as single-family homes, the effect of which can be seen in the twee, semi-detached plexes common in NDG.


Late nineteenth-century plexes were built on relatively small lots and often did not have outdoor staircases, which became more common around the turn of the century


Plexes built in Villeray and other north end neighbourhoods had larger lots and deeper setbacks than those in older neighbourhoods such as St. Jean Baptiste on the Plateau


In the 1910s, Outremont building codes mandated indoor staircases and higher-quality building materials than in Montreal


NDG also banned outdoor staircases; it favoured plexes that looked like houses, such as this typical row of semi-detached duplexes built in the 1920s

Whatever their form, one common element among Montreal plexes has always been their unique ownership structure. Often, the owner lives on the premises, renting out the other flats to help pay off the mortgage. In early 20th century Mile End, this gave immigrants a foothold in the neighbourhood. “When the Jews moved in,” said Bronson, “often an entire family would live on one floor, including aunts and uncles, and then in time their kids would grow up and they would live on upper floors. The same was also true for many Portuguese families” in the 1960s and 70s.

Plexes also presented tenants with an opportunity for home ownership. That was the case for Ylan Luong’s parents, originally from Vietnam, when they moved into the ground floor of a Mile End duplex in the late 1970s. When the owner, who lived upstairs, decided to sell it, he approached her father first. “The guy didn’t even put an ad out or anything, he was just like, ‘Oh, I’m selling, I don’t know if you’re interested,’” she said. Her parents bought the building and started renting out the upstairs apartment.

Luong, a 21-year old nursing student, has lived in her family’s seven-room lower duplex since the day she was born. “It’s pretty crowded in my house because I’ve always had my dog and a cat—I had two dogs at one point—so it’s always very busy,” she said. “And before I had to share my room with my sister. But it’s not bad, my parents like having me close to them.”

As a child, Luong used to play in the back alley. Now, as an adult, she appreciates Mile End’s diverse streetlife. In many ways, plexes, with their balconies and multiplicity of entrances, encourage such activity. “What comes out of this dense urban fabric is a very animated streetlife,” remarked Bronson. In the summer months, Montrealers flock to their balconies, staircases and front gardens, creating what the urbanist Jane Jacobs called “eyes on the street,” the feeling of security that comes from such urban bustle.

Neighbourhoods like Mile End were no longer built after the Second World War, although many modern, automobile-friendly plexes—especially popular with Italian families—were built in 1960s suburbs such as St. Leonard and LaSalle. On the whole, though, the plex was largely abandoned in the late 20th century in favour of detached houses and traditional apartment buildings.

But the plex has made a comeback. The “condoplex,” which combines traditional plex layouts with contemporary architecture, has proliferated across Montreal in recent years. Many even have outdoor staircases. Part of the reason for their popularity with developers, explained Hanna and Bronson, is that they conform easily to housing regulations in boroughs like the Plateau Mont-Royal, which favour buildings that blend in with the existing cityscape, while allowing for the contemporary architecture and modern amenities favoured by homebuyers.

“[Condoplexes] are a recognition of a housing type that works in Montreal,” said Bronson—a housing type that, through its effectiveness and versatility, came to dominate the city.


Thousands of plexes were built in the 1950s and 60s in burgeoning suburbs such as LaSalle, St. Leonard and Chomedey. These detached fourplexes in Lasalle, with their deep setbacks and below-grade garages, are typical


Condoplexes, such as this one on the Plateau built in 2005, feature front-to-back flats and outdoor staircases just like older plexes, but their units are individually owned

This article originally appeared in the Montreal Gazette.

This entry was written by Christopher DeWolf , posted on Thursday May 03 2007at 02:05 pm , filed under Architecture, Canada, Heritage and Preservation, Society and Culture and tagged , , , , . Bookmark the permalink . Post a comment below or leave a trackback: Trackback URL.

6 Responses to “They Work On So Many Levels”

  • Evan Druce says:

    Montreal’s plex vernacular is remarkably similar to Chicago’s, especially in places like Outremont and NDG. It’s bizarre how two cities with such different histories and topographies end up developing such similar residential architectural styles.

    Chicago, at least the innermost two-thirds of it, is a city of plexes. We call them “x-flats,” where “x” is the number of units in the building. The most common types are the two-flat, the three-flat, the four-flat, and the six-flat. Two-flats and three-flats look like single-family homes, with the apartment entrances (one up, one down, and possibly one in the basement) inside a front door, although their prairie detailing means we get flat roofs rather than pitched ones. Four-flats and six-flats are larger and have a single indoor staircase leading to the apartments, two on each level. A variation of this type of building slices it down the middle to make a two-flat or three-flat.

    We don’t have separate entrances, outdoor staircases, or front balconies in Chicago. Instead, we have substantial back porches and front stoops. This makes for interesting differences in the summer street life of the two cities; Chicagoans have back-porch parties instead of hanging out on the balcony. In many neighborhoods, it is not uncommon to see entire families congregating on the front stoops around sunset (the setting sun hitting a row of brick two-flats is one of the most beautiful images I’ve ever seen), drinking beer and watching the children play.

    Even some of our more recent constructions resemble those found in Montreal. We have a type of building called a “four-and-one” that appeared around the 1960s, especially near the lake. It’s not a plex (rather, it’s a large, 24-unit building with four floors of apartments and an elevator), but it shares some of the design characteristics of the examples you posted from LaSalle/Saint-Leonard/Chomedey. Namely, four-and-ones share the underground garages, light-colored brick, and California-style architectural details of Montreal postwar plexes. Even more recently, the condos that are going up in most Chicago neighborhoods are drawing on the form of the plex. You can see both three-flat and six-flat styles that resemble their vintage neighbors in most inner Chicago neighborhoods.

    In both Montreal and Chicago, the plex is the perfect scale and design for urban life. The balconies and outdoor staircases (or front stoops) create public space, and the scale is dense enough to be lively without being overwhelming (like the grim six-story walk-ups that populate many New York City neighborhoods, or the ten-story faux-Parisian apartment buildings of Buenos Aires).

    The plex still appears to be a much more resilient form in Montreal than in any of the American cities where it once proliferated. Chicago’s plex neighborhoods give way to two single-family (but high-density) “bungalow belts” (1920s and 1960s-vintage) and then the low-density forms of the suburbs. But what strikes me about Montreal is the persistence of the plex even in the suburbs. The newer plex forms (condoplexes, mostly) are still being built off the highway in places like Longueuil, Mirabel, and Fabreville.

  • Thanks for the information, Evan. One of the interesting things David Hanna mentioned was that, as far as he can tell, Montreal’s plexes developed independently from those in the United States. He said there were three general development patterns:

    Scotland > Montreal

    Scotland > Boston > Chicago

    Scotland > Richmond, VA > St. Louis

  • Evan Druce says:

    So where do we put the San Francisco plexes in that typology? I’m inclined to classify them as twee relatives of the Boston-Chicago family. And I can see Hanna’s comment about Montreal plexes developing independently from their American cousins, but is the Toronto plex a descendant of the late-19th-century Montreal plex, or a brother of the St. Louis plex? Complicating factor: the bungalows of Scarborough resemble those of Chicago rather than those of St. Louis.

    Vancouver seems to have developed its own style of plex, which cannot easily trace its roots back to one of the original Scottish families. The “Vancouver special,” as it is called, is a two-apartment plex with a large setback and a garage or carport on the bottom level. It appears to be formed from the unholy marriage of the San Francisco single-family terrace and the 1950s-1960s Saint-Leonard/LaSalle plex.

    I also don’t think Scotland > Boston > Chicago tells the whole story. It accounts well for the “prairie Victorian” style of two-flat or three-flat in Chicago, but many plexes of that size in Chicago–especially in areas contemporary to the “bungalow belts”–have a prairie style that doesn’t resemble anything in Boston. They are flat-roofed with no front stoop (or a small front stoop) and feature large bay or box windows in the front. Once again, porches are in the back. Unlike many Chicago styles, which reproduced themselves over much of the Midwest (Minneapolis, St. Louis, Cleveland, and Milwaukee all have six-flats that look like Chicago’s) this form appears to be unique to Chicago. It is also the only form of Chicago plex found in large numbers in inner Chicago suburbs such as Rosemont, Niles, Summit, and Skokie.

  • I’m a Montreal’s tour guide and pretty much in each city tour I need to explain our city’s vernacular residential model. Your article summuns it up quite clearly. I was aware of most of what you wrote but the scottish influence came to a surprise to me.
    Since english is my second language, I could not explains it as clearly as you : I might find in your article the inspiration to make my presentation more understandable to my clientele.

  • […] in large part to planning ordinances of the time, Montreal developed a style of housing in triplexes with exterior staircases.  Today this type of […]