The mid-rise horizon

by mdoyle | May 22, 2014 2:10 pm

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By Marco VanderMaas, BES, B.Arch., LEED AP
Within the next two decades, Toronto expects its population to grow by 500,000; the city’s plan is to accommodate half of these new residents in mid-rise developments. In light of the fact mid-rises—defined as between four and 11 storeys—are still often seen as an uneconomical mode of development, the city’s plan may seem overly ambitious.

However, the playing field in favour of mid-rises is being significantly altered by provincial legislation (e.g. the Places to Grow growth plan and the Greenbelt Act), municipal official plan policies related to land use and densities, and, most significantly, building code changes at the provincial and national levels proposing six-storey combustible construction.

In fact, on March 20, 2014, the Ministry of Municipal Affairs and Housing (MMAH) posted proposed amendments to Ontario Regulation 332.12 (Building Code) under the 1992 Building Code Act to the 45-day regulatory review site. The purpose of the proposed amendments would be to permit the construction of up to six-storey wood-frame buildings. (The Ontario Building Code [OBC] currently permits the construction of up to four-storey wood-frame buildings.) This tide of mid-rise development presents those in the design and construction community with a major opportunity.

Developing in the present
This author works at Quadrangle Architects, predominantly involved in design, front-end feasibility, and concept generation. While the firm has a set of design principles that apply to all its work, when engaging in urban-scale design, the aim is to create buildings fitting into the fabric of their contexts—not autonomous structures.

At the same time, this does not mean merely replicating current conditions. The task is often to revitalize a street and, in simplest terms, this means proposing an increase in density. The guiding logic is a neighbourhood, and especially its population, cannot stay the same if the area hopes to gain, or even retain, vitality. Though it may sound paradoxical, a neighbourhood needs to change, even if it only wants to remain the same, and certainly if it wants to move forward.

This way of thinking has an advocate in Toronto’s Chief Planner, Jennifer Keesmaat, who has noted cities with far greater densities, such as Paris and Barcelona, have been able to concentrate their populations while maintaining the integrity of their neighbourhoods and streetscapes. This has been accomplished primarily with mid-rise buildings.

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From the city planner’s point of view, the mid-rise is appealing for numerous reasons. First, mid-rises justify the extension of public transit by providing the necessary increase in riders. Second, they do not tax the water and sewer infrastructure as high-rises and low-rises do. Third, the ground floors of most mid-rises are given over to commercial spaces, which activate the streetscape, creating desirable mixed-use development. Finally, mid-rises do not radically alter the character of the neighbourhood as high-rises can—at their best, they enhance urban assets that already exist.

Still, inserting a mid-rise into a neighbourhood entails a number of complex challenges that are often associated with much larger projects. For example, loading and servicing, such as garbage pickup, demand a significant designated area. The mixed-use component of the building means lobby access, sidewalk use, and landscape maintenance will need to be negotiated between partners. An underground garage, usually a major cost, is a requirement.

Add to this list the complexities involved in construction, material selection, environmental concerns such as light penetration, oversight, and privacy issues, and one has a host of challenges that demand tactful, tailored responses. For all the investment that goes into the design, development, and bureaucratic manoeuvring of the approval process for a mid-rise, logic would seem to dictate building higher to take advantage of the economies of scale or stick with simpler low-rise developments.

In addition to the economic incentive to build higher or increasing low-rise sprawl, developers have frequently cited a further obstacle—a city’s rigid interpretation of mid-rise guidelines may make it more attractive to gain approval for high-rises.¹[3]

Guidelines, not regulations
In 2010, Toronto City Council adopted Avenues and Mid-rise Building Study, an extensive investigation into best practices that included an evaluation of historical, cultural, and built form characteristics of areas that were likely homes for future mid-rises, and established new performance standards for mid-rise buildings. The study was led by Brook McIlroy, and Quadrangle played a significant role in its development.

Due to the firm’s involvement, this author can speak from authority in saying these guidelines were set out as suggestions and not meant to be strict limitations. The goal was to encourage gradual development beginning in the city core and spreading outward. The challenge was to encourage varied and vibrant growth within a consistent, rational framework.

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The building that set precedents for these guidelines was Quadrangle’s design for the Saint James mid-rise, on the corner of Jarvis and King Streets in downtown Toronto. The Saint James was one of the first buildings in the King Parliament by-law that emphasized massing over density and use. The experiment, as it was then regarded, was commissioned by residential/multi-family developer Great Gulf, and signalled an attempt at urban re-invention—a stone and brick-clad, glass, steel, and concrete structure on a street of two- and three-storey, century-old Victorians. Twenty years on, the Saint James mid-rise sits comfortably among its neighbours, while also revitalizing a corner that had previously been at loose ends.

As main streets in the suburban reaches of the city sought to replicate the urban prototype, specifically through the expansion of public transit, Quadrangle continues to use the Saint James as a template. The best example of this replication is in Maple, part of the City of Vaughan, north of Toronto. The lands in Vaughan’s official plan, adjacent to the GO Transit station designated for big box retail, are being re-imagined to make way for a series of mid-rises to meet the desired commercial and residential requirements of the street.

Both the Saint James and the Vaughan examples show a localized insertion of mid-rises can be successful in the core and the suburbs, and on their own they are examples of the incremental spread of the mid-rise throughout the city. Two critical changes seem set to spark a surge in the pattern of mid-rise growth. The first: unit sales in high-rises have slowed, while unit sales in the relatively limited number of mid-rises have increased. The second: the aforementioned proposed OBC change governing the construction materials that can be used in six-storey mid-rises. Combined, these changes will alter the economics of mid-rise construction.

The future comes to the present
The Avenues and Mid-rise Building Study laid out a vision of mid-rises located along the major avenues of the city. The basis for concentrating mid-rises along avenues was simple: the building’s height was related to the avenue’s right-of-way (i.e. the combined width of the sidewalk and street). The typical Toronto avenue right-of-way is 20 m (65.6 ft); 20 m in height accommodates six storeys. In other words, it is the ideal location for the typical mid-rise.

While the plan strongly encourages the proliferation of mid-rises throughout the city, the more consequential change—from the designer’s and developer’s point of view—comes with alterations to building codes with regard to combustible construction: a recommendation that allows for wood construction up to six storeys.²[5]

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In terms of efficiency, ease, and both financial and environmental costs, wood has several advantages. Many of the barriers to mid-rise development appear to be lowered. The introduction of light-frame wood as main structural material into the mid-rise construction equation offers designers and developers an enormous opportunity, but also a new series of challenges.

Great Gulf commissioned Quadrangle to design a prototypical multi-unit residential light-frame wood mid-rise. (Up to that point, the developers had focused on building only low-rises and high-rises.) As part of this project, Great Gulf offered access to its Brockport Homes’ factory, which produces the panelized units for most of its low-rise developments and offers the service to other developers.

In brief, panelization is the prefabrication of wall and floor panels, which can include studs, truss joists, and pre-drilled openings for plumbing and wiring. The panels are built according to the specifications of computer-generated designs, and the controlled manufacturing environment ensures the final product is precise. In terms of performance, the product of a panelization factory is far superior to anything built onsite and the ensuing cost savings are dramatic.

Assuming the advantage of panelization, Moses Structural Engineers was asked to develop a plan of the prototypical four-storey mid-rise (as well as a six-storey one, looking to the future). The result, in broad strokes, is a precisely calibrated light-frame wood structure built on a concrete foundation.

To create an efficient spanning of truss joists, the outside walls and corridor are made load-bearing. Non-structural demising walls are placed inside the building, to make for flexible unit sizes. Additionally, the balconies are designed to be self-supporting, meaning they do not act as thermal bridges and can be replaced, if required, without compromising the structural integrity of the building.

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The result is a kit of parts for what could be called a ‘base case scenario.’ Reproducible and scalable, it can be clad in various kinds of materials and slotted into a number of contexts. Indeed, the proposal was so successful it launched Great Gulf into the construction of its first light-frame wooden mid-rise development, currently underway in Mississauga, Ont.

HOT
Located at the corner of a broad right-of-way, the Eglinton Avenue and Winston Churchill Boulevard site of Great Gulf’s ‘Home Ownership Today’ (HOT) mid-rise condominiums is envisioned as a gateway to Mississauga’s Churchill Meadows neighbourhood. Rather than an urban infill project, as mid-rises tend to be, this group of four buildings would be arranged so as to welcome the approaching citizen into a larger community. The plan was to array the mid-rises around a shared courtyard, connect the various spaces with inviting pathways, and have the ground floor doorways face the surrounding sidewalk.

The project is currently under construction. The main lesson thus far has been just how much time is required by designers, contractors, and owners on the front end of a development like HOT. However, these first steps, largely to do with the precise design required to take advantage of the panelization process, are scalable, so this increased effort will be enormously beneficial in the long run. There is every expectation HOT will serve as the base case scenario it was intended to be when the design was originally commissioned.

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The broader context
At present, Toronto’s four-storey timber construction limit is in line with the National Building Code of Canada (NBC). On the country’s West Coast, however, the British Columbia Building Code (BCBC) has allowed builders to begin Canada’s first six-storey timber frame mid-rise. The sense is this change will be adopted nationally. Ontario is currently undertaking a regulatory review of the implications of adopting six-storey combustible construction as well.

In the broader context, though, these are modest steps. With cross-laminated timber (CLT), the potential of timber frame construction can be pushed much further, potentially into what the stratum of what we like to call the intermediate-rise, or ‘i-rise’ (i.e. buildings surpassing the mid-rise definition, but still following the mid-rise guidelines from a performance point of view).

There are international precedents. In London, England, Waugh Thistleton Architects built Murray Grove, a nine-storey, 29-unit residential mid-rise. Melbourne, Australia is home to the 10-storey Forté, currently the world’s tallest timber construction. Back in Vancouver, local architect Michael Green, an advocate for timber construction, has proposed a 30-storey wooden tower.

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This author’s personal approach to design has always been a practical one—focus on primary concerns like performance, comfort, and beauty, rather than any other orthodoxies. In approaching the question of how best to take advantage of the change in building code regulations, the question was considered practically, returning to previous experiences in yacht design and healthy home construction. In that process, the appropriate materials and systems were carefully chosen, and manufacturing and construction of the product meant combining custom design with industrial design.

As the Canadian design/construction community builds urban environments in which our quickly increasing population needs to live, work, and play, the country’s wealth of resources must be embraced, and smart decisions must be made over how to use them in the most valuable way. Our architectural design needs to be inspirational while the materials we use need to provide smart assemblies for living.

Notes
¹ For example, Toronto has been experiencing a building boom in the last decade and planning has been proactive in developing guidelines to help the growth and anticipated continued development. Not all municipalities have the ability to do this, but official plans that have been prepared by all municipalities in the last few years have similar provisions and descriptions to guide development in a similar way. (back to top[10])
² Studies—such as the University of the Fraser Valley (UFV) in British Columbia’s “Fire Outcomes in Residential Fires by General Construction Type”—show regardless of combustible or non-combustible construction, the risk of fire is a reality. Further, advancements in firefighting technologies, such as integrated sprinkler systems, have been successful at reducing the concerns associated with construction material choices. (back to top[11])

[12]Marco VanderMaas, BES, B.Arch., LEED AP, is an associate and design director at Quadrangle Architects. He collaborates with the client and project team throughout a project’s development to encourage consistency and quality. VanderMaas has consulted on the changes to the six-storey mid-rise wood-frame Ontario Building Code (OBC) for Wood WORKS!, a project of the Canadian Wood Council (CWC), and contributed to its “Wood Solutions in Mid-Rise Construction Report.” He can be reached at mvandermaas@quadrangle.ca[13].

Source URL: https://www.constructioncanada.net/the-mid-rise-horizon/

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