Montreal

An exception in North America, Montreal offers an alternative history of medium-density housing encouraged by the city’s distinct regulations allowing curved and spiral stairs to serve as exits.

Along with Saint John, Winnipeg, Vancouver, and Lloydminster, Montreal is one of the few chartered cities in Canada with the power to draft municipal bylaws that contravene provincial and federal regulations. The “Montreal triplex” is a form of missing-middle housing made possible by these powers: it consists of three or more stacked dwelling units that share a curved exterior staircase on the front and a spiral stair at the rear of the building. The National Building Code requires any curved or spiral stair that serves more than one dwelling unit to have “an inside radius that is not less than twice the stair width,” which translates to such stairs being so inefficient as a measure of floor area that they are only used for monumental and processional spaces like a theatre or grand entrance. However, Article 29 of Montreal bylaw 11-018 includes an exception to the National Building Code to allow for tight-radius spiral stairs as a shared means of egress for two dwelling units per storey in buildings of up to three storeys.

The economy of scale that results from this exception to the building code is one of the reasons why Montreal’s density and mix of housing options is so distinct within Canada. Modern infill projects, like ‘Les Quatres Arbres’ at 4878 Avenue Henri-Julien in the Plateau neighbourhood, are feasible precisely because of this particular code exception. Anywhere else in Canada - including in Laval and Brossard (directly adjacent to Montreal) - such designs are not permitted and municipalities do not have the legal authority to create an exemption from the provincial building codes that prohibit them. 

Alarie, Marie-Hélène. (2013).
“Architecture - Et l’escalier extérieur s’imposa au pays du triplex.” Le Devoir.

Les Quatre Arbres

Atelier Raouf Boutros Architect (2009)
4878 Rue Henri-Julien, Montreal, QC

Height: 3 storeys
Use: 20 dwelling units
Floor Area: 1100m²
Construction: Protected Wood Frame
Stair: Exterior Spiral Stair (Steel Frame with Wood Guard)
Sprinklered: No

The exemption conditions of the Montreal By-law allow for these exterior spiral stairs to serve as an exit. This project was designed with a spiral stair at the front and back of each unit, serving the maximum of two dwelling units per storey, such that a total of four units are served by each of the spiral stairs.

            

Le Jardinier

Adhoc Architectes (2018)
3160 Rue de Rouville, Montreal, QC

Height: 3 storeys (plus mezzanine and half-sunken basement)
Use: 16 dwelling units
Floor Area: 749m²
Construction: Wood Frame
Stair: Wood Frame (interior), Galvanized Steel (exterior stair)
Sprinklered: No

“The Gardener” is a modern version of the traditional Montreal triplex.  This building internalizes the main access stair, reducing the setback from the front property line that would otherwise be necessary for an exterior stair. The second means of egress is provided as a NBC code-compliant exterior metal stair accessed from the shared balconies facing the rear yard.

NMBHD

Jean-Verville architecte (2020)
Private address - Rosemont, Montreal, QC

Height: 3 storeys
Use: 3 dwelling units
Floor Area: ?? m²
Construction: Wood Frame
Stair: internalized within each dwelling unit
Sprinklered: No

This building wraps and stacks three dwelling units around each other. Each unit is independently accessed directly from grade with circulation internalized within each unit. The project is within Part 9 of the building code such that code provision 9.9.9.1.(2) allows for single exit construction at three storeys in height, so long as balconies or operable windows with a sill height no more than 7m above adjacent ground level function as alternative rescue access (implying evacuation by fire department ladder).

Habitations Saint-Michel Nord

Saia Barbarese Toupouzanov Architectes (2020)
8550 Allée Léo-Bricault, Montreal, QC

Height:
Use:
Floor Area:
Construction:
Stair:
Sprinklered:

Hanna, David B., and Dufaux, Francois. (2002). “Montreal: A Rich Tradition in Medium Density Housing.” CMHC Research Report (External Research Program).

“In the urban arena, rarely have architectural historians dared tread very far into the reaches of the urban vernacular, such that noteworthy works by Eric Arthur on Toronto or Jean-Claude Marsan on Montreal, while granting some recognition to the existence of an urban vernacular tradition, have done so only fleetingly. Other architectural historians who have attempted to focus exclusively on the subject of the urban vernacular, such as Stefan Muthesius and the English terraced house or Lucie K. Morisset, on Arvida, are of a fairly new breed and stand out as unusual. More typical are works like Norbert Schoenauer who, in a massive life-consuming investigation of urban housing, seems to have missed entirely the existence of rich traditions of superposed flats in Scotland, France, Italy and the United States, to name but a few countries. Having spent the better part of his career in Montreal, he felt the need to at least acknowledge their existence, devoting one page to the genre out of an opus of 500, and dismissing it as a mere regional peculiarity. Apparently, one is left to conclude that urban housing historically is made up of single-family housing and apartment buildings!

The same blind spot towards superposed flats crops up in virtually all the architectural guides to individual cities in North America. The American Institute of Architects' Guide to Chicago is symptomatic of the tendency. Despite having North America's largest volume of two-flat and three-flat housing both historically and today, the architectural historians selected only eleven such sites out of a total of 1527 sites covered in the guide, excluding the central business district. Of course the guide is full of single-family houses, even very modest ones, and none of the eleven superposed flats are discussed in any depth, almost as though they were of little meaning. Other cities where superposed flats are common (e.g. Boston, Richmond, St. Louis to name but a few) have not even been that lucky in their architectural guidebooks.

How does such a systematic blind spot arise? Perhaps the obsession with single-family housing in twentieth-century North America has conditioned researchers to ignore other forms of housing, excepting, of course, apartment buildings because of their sheer bulk and the fact that they tend to be architect designed. Perhaps also superposed flats are seen superficially as merely single-family type houses which have been divided into two or three flats, ignoring the fact that they are a house type of their own. Clearly what has been missed are the deep cultural and historical roots of such housing and their powerful significance in terms of generating eminently habitable low-cost housing in dense yet human-scaled neighbourhoods.”

“By the turn of the century, Montreal’s working-class neighbourhoods had developed a distinctive housing form known as the ‘superposed’ flat. These were two or more commonly, three-storey structures, with an apartment on each floor, exterior staircases, and balconies both at the front and the back. In areas like the Plateau, the superposed flats not only created an unusually dense urban form but provided owners with an opportunity to live on one floor and generate welcome additional income by renting out the others. ‘In the nineteenth century’, according to a CMHC study on Montreal’s housing, ‘the appeal of real estate ownership resided in the potential rental income, rather than the propriety of one household to own its own dwelling.’ This model, which acknowledges the high carrying costs of urban houses, was also common in cities like Philadelphia and Glasgow, and continues to find currency in the guise of basement apartments and secondary suites.”

- John Lorinc, excerpt from “Housed Divided:
How the Missing Middle can Solve Toronto’s Affordability Crisis”