Canadian Architect

Feature

Apostle of Wood

Michael Green’s mass timber innovations prove their mettle in two recently completed projects: the Wood Innovation and Design Centre along with Ronald McDonald House BC & Yukon.

November 1, 2015
by Trevor Boddy

TEXT Trevor Boddy

PHOTOS Ema Peter, unless otherwise noted

Cavities within the CLT floor section accommodate services. Floor chases are covered with an acoustic insulated subfloor with cut-out panels to provide access.

Cavities within the CLT floor of the Wood Innovation Design Centre’s section accommodate services. Floor chases are covered with an acoustic insulated subfloor with cut-out panels to provide access.

It can be a sticky business when prominent architects get overly associated with a single construction material. While he had an early career as a design critic and polemicist, in his later role as building-oriented architect Le Corbusier was a vocal champion of reinforced concrete, notably through his design for the Dom-Ino system for housing construction. But Dom-Ino was never applied in its pure form in his lifetime, and technically, Le Corbusier was not much of an innovator. The look, feel, associations and texture of his beloved béton brut were important to his architecture, especially the late works, but he was not personally disposed to—or skilled in—inventing new modes of construction.

Corbu was a genius not of technique, but rather of aesthetics—architecture students always presume more of his white villas are built of cast concrete than is actually the case. Contrast this with the buildings of his former employer: behind the neo-classical façades of Auguste Perret’s rue Franklin Apartments or the Théâtre des Champs-Elysées, one finds true technical innovation. The same is true of Frank Lloyd Wright, who innovated in concrete because his designs demanded it, from the early Wisconsin warehouses to Fallingwater and the Guggenheim. Here in Canada, the formal repertoires and socially minded ambitions of Bing Thom, FRAIC, and Douglas Cardinal, FRAIC, prompted new building techniques and assemblies in wood, concrete, glass and brick.

It is not untoward to invoke the struggle between Corbu’s polemical writing and his built accomplishments in approaching the work and ideas of Vancouver’s Michael Green, FRAIC. No Canadian architect since Moshe Safdie, FRAIC, has risen into global prominence as blindingly fast. Michael Green has emerged as the apostle of wood, a charismatic Moses bringing forth tablets of CLT, GLT, NLT, MTP, and LSL as the carbon-sequestering solutions to the crisis of climate change. His powerful 2013 TED talk “Why We Should Build Wooden Skyscrapers” has been downloaded an astonishing 1,044,911 times—more video views, without doubt, than those from all other Canadian architects combined. Since his status as an advocate of wood is secure, it is now time to look at some of his firm’s key finished constructions—as this polemicist is also very much a builder. But to better understand both modes, a note first on his biography and early portfolio.

Michael Green was born in 1966 in Baker Lake, Nunavut, where his Scottish-born father worked as an administrator after serving at Hudson’s Bay Company posts. The family relocated to Ottawa when he was a toddler. Green’s American-born mother’s family was Ivy League-linked: grandfather Richard Bennett was the Yale School of Architecture chair who first hired Louis Kahn to teach there. Bennett’s wife
divorced him and re-married a Cornell historian; Green followed family links to begin his architecture studies there in 1984. An indifferent student, his undergraduate passions were mountaineering and ice-climbing; his Cornell design thesis was an indoor climbing centre. Upon graduation in 1989 he followed his girlfriend (and future wife and mother of his two children) to Yale for her doctoral studies.

Green spent eight years working with Cesar Pelli in his then New Haven-based firm, which included design work on the Washington National (now Ronald Reagan) Airport main terminal, Olympia and York’s office towers in London’s docklands, and a college building for Grinnell, Iowa. After his wife received her first academic appointment at Simon Fraser University, Green started work at Vancouver’s Architectura, where he gained more experience with airport design, notably as a key designer for Ottawa International Airport (produced in association with BBB), which required moving back to his old hometown for several years to see the first phase into construction.

Green declined to follow when that firm was sold to Stantec, and used the proceeds of his associate’s shares to found his own practice, joined by Architectura colleagues Steve McFarlane, FRAIC, and Michelle Biggar. During the 10 years of McFarlane Green Biggar (MGB), the firm grew in prominence, notably with a lauded addition to North Vancouver City Hall and a major expansion of the Prince George Airport (itself a set-piece in the innovative use of wood). In 2012, Green split with his partners (who have since re-named themselves office of mcfarlane biggar, or omb) and formed a sole proprietorship as Michael Green Architecture, or MGA.

With hip Gastown studios and a staff of 24, the MGA office reminds me of Bjarke Ingels Group’s West Chelsea Manhattan studios—where everyone is clever, good-looking and young. Frankly, both firms could use a few crusty old captains of construction to take pressure off their rock-star principals, who are currently obliged to be at the centre of everything designed, detailed, managed, written, promoted or spoken from their respective offices.

Michael Green’s wood construction skills began with summers on Vermont house-building sites, then deepened with the restoration of his own 1855 Greek Revival house in New Haven. He says, “there was virtually no wood used in Pelli’s designs” while he worked there. While the first phase of the Ottawa airport under Architectura had quite limited use of wood, he convinced clients that the second phase (produced under the direction of his own firm, in association with J.L. Richards Architects) should include glulam structure in the main departure hall. He also pushed for wood to surround the departure gates for arctic destinations—a gesture to his treeless birthplace. It was not easy, according to Green. “We couldn’t find a mill who would take on re-planing the BC fir from an old hangar on site,” he recalls.

When Green arrived in Vancouver in 1997, there was already an advanced wood design scene emerging around architects Bing Thom FRAIC, Peter Busby FRAIC, Florian Maurer MRAIC, Larry McFarland FRAIC, John and Patricia Patkau FRAIC, engineers Paul Fast, Gerry Epp, Robert Malczyk, Eric Karsh and manufacturers StructureCraft of Delta and Structurlam of Penticton. While still at MGB, Green got intrigued with the possibilities of mass timber high-rise construction—buildings of 20 storeys and more—and formed a friendship with trail-blazing British timber architect Andrew Waugh. MGB and consultants lined up essential research and publication support funding from some of Canada’s wood industry organizations, and in 2012 co-authored the publication “The Case for Tall Wood Buildings” with engineer of choice and frequent collaborator Eric Karsh of Equilibrium Consulting. With this, the lecture invitations poured in and his career took off.

Located in Prince George, BC, the Wood Innovation and Design Centre showcases innovative techniques for building with mass timber.

Located in Prince George, BC, the Wood Innovation and Design Centre showcases innovative techniques for building with mass timber.

Wood Innovation Design Centre, Prince George

In 2013, the British Columbia government announced a competition for a design-build project demonstrating high-rise wood construction in downtown Prince George. MGA, Equilibrium as engineers and PCL Construction as builders won the $25.1 million PPP contract. However, the commission came with onerous conditions: rigorous testing and documentation requirements for its emerging building technologies, and a timeframe of only 15 months for design and construction, with significant penalties for delays. (An incoming class for the University of Northern British Columbia’s wood engineering program needed the space.)

If there is another Canadian building so technically innovative, so powerful in its built arguments to the rest of our industry, achieved with such architectural finesse, and completed in a shorter time than the Wood Innovation and Design Centre (WIDC), I do not know it. Upon topping out a year ago at 30 metres (measured from concrete foundation to roof), WIDC was the tallest mass timber tower in the world. WIDC’s architects and engineers designed components for functionality in a tower at least twice that tall; the height limit was set by funding availability and program space needs, not structural capabilities.

Connections between columns, beams, floors and ceilings and carefully detailed to create a wood-on-wood aesthetic.

Connections between columns, beams, floors and ceilings and carefully detailed to create a wood-on-wood aesthetic.

Taller all-wood towers are soon to be completed, but this remains one of the most handsome office buildings Western Canada has seen in years. WIDC’s eight storeys (officially six, plus a mezzanine and a penthouse) required a site-specific revision of the BC Building Code for non-residential construction. The building’s program was an improvised and evolving one, mainly devoted to a new University of Northern British Columbia wood engineering program, wood-oriented design programs for Emily Carr University of Art and Design, and offices related to the provincial forestry industry. By virtue of both its program and construction, the Wood Innovation and Design Centre is very much a demonstration project.

Being a demonstration project means that many design details exist to show possibilities—there is a strong rhetorical dimension to this tower. For example, Green decided against the skiff of concrete that is typical for the upper floors of mass timber buildings “for purity and buildability reasons—mainly to avoid a ‘wet trade.’” By limiting concrete forming trades to the foundation, the design would demonstrate the rapidity of erecting mass timber structures using drop-in dry elements, many of them milled off-site. As well, a concrete floor was not needed for structural reasons, and the flexibility of CLT floor plates of varying thicknesses made for easy in-floor provision of sprinkler, electrical and network connections. Duct space was minimized through the use of perimeter heating and management of air movement via Jaga units with micro-fins.

Throughout the facility, thickened columns and beams allow for a degree of inherent fire resistance, because large timber elements char at a slow and predictable rate. The charred layer serves to insulate the relatively cool core, allowing each member to continue carrying the required structural load to achieve a one-hour fire resistance rating.

Throughout the facility, thickened columns and beams allow for a degree of inherent fire resistance, because large timber
elements char at a slow and predictable rate. The charred layer serves to insulate the relatively cool core, allowing each member to continue carrying the required structural load to achieve a one-hour fire resistance rating.

MGA’s all-wood construction created significant challenges for acoustics, especially since many of the spaces were classrooms requiring UNBC’s high sound isolation standards—to boot, there is a noisy wood shop off the main lobby. MGA had to work closely with engineers and builders, developing new details and establishing their worth in testing.

WIDC’s primary structure is an innovative combination of post and beam construction with built-up cross-laminated timber (CLT) floor panels. Glulam beams frame into glulam columns using proprietary aluminium dovetail Pitzl connectors. This allows columns to run continuously from the foundation to the roof, eliminating all cross-grain bearing and shrinkage. Steel connectors are embedded and concealed within the timber elements, which provide the required fire resistance rating. The entire building core, including elevator shaft and exit stairs, is constructed of CLT. The floor assembly is a staggered panel system consisting of overlapping 3-ply upper CLT panels on 5-ply or 7-ply lower CLT panels, joined with HSK epoxy and metal mesh connectors to form a fully composite corrugated structural section. Spanning six metres between the post and beam frames, this wood-only floor system was selected to minimize the use of concrete (and thus weight). The corrugated CLT floor system provides significant acoustic separation while allowing services to be run in the alternating floor and ceiling chases, while the beauty of the wood structure remains exposed.

WIDC’s primary structure is an innovative combination of post and beam construction with built-up cross-laminated timber (CLT) floor panels. Glulam beams frame into glulam columns using proprietary aluminium dovetail Pitzl connectors. This allows columns to run continuously from the foundation to the roof, eliminating all cross-grain bearing and shrinkage. Steel connectors are embedded and concealed within the timber elements, which provide the required fire resistance rating. The entire building core, including elevator shaft and exit stairs, is constructed of CLT. The floor assembly is a staggered panel system consisting of overlapping 3-ply upper CLT panels on 5-ply or 7-ply lower CLT panels, joined with HSK epoxy and metal mesh connectors to form a fully composite corrugated structural section. Spanning six metres between the post and beam frames, this wood-only floor system was selected to minimize the use of concrete (and thus weight). The corrugated CLT floor system provides significant acoustic separation while allowing services to be run in the alternating floor and ceiling chases, while the beauty of the wood structure remains exposed.

A similar set of issues informed the structural connections between columns, beams and CLT floor plates. While some high-rise wood towers use standard platform framing, MGA elected for wood-on-wood connections, capitalizing on wood’s vertical dimensional stability. (Horizontally, trees and columns shrink back to their cores with extended drying—cross-laminated composites such as CLT balance wood’s strengths and weaknesses.)

Engineer Eric Karsh dubs the metal connectors, seats and braces often used in North American mass timber construction “pots and pans connections.” Codes require that metal wood-to-wood connectors be fire-separated, meaning that many of these visually interesting building elements have to be bulked up and hidden within enclosures.

WIDC’s approach to connections takes advantage of a key virtue of mass timber construction—the time-tested principle of “charring” as a code-acceptable equivalent to ensure structural integrity during fires. (The outside layer of wood burns away, but there is enough residual structural strength in the remainder to ensure stability.) The WIDC metal connections—blades, seats, braces—are thus set within the columns and beams, which remain proudly exposed.

The stair core walls are built from CLT panels, contributing to the lateral load resistance of the structure.

The stair core walls are built from CLT panels, contributing to the lateral load resistance of the structure.

This means a clean wood-on-wood aesthetic, with most of the structural connections hidden out of sight. The glowing all-wood clarity of the column and beam connections is one of WIDC’s finest interior features. “Our design solutions are driven by technical reasons, but we are also interested in the aesthetic, the beauty that emerges out of that kind of thinking,” says Green. Similarly, the sets of exit scissor stairs made of exposed CLT are an unexpected delight. Here’s hoping that smart manufacturers soon follow Green’s lead to mass produce all-wood versions of banal necessities such as exit stairs, rendering the architectural surroundings more sensuous for those healthy extra flights.

On the exterior of the tower, MGA alternated panels of naturally aging cedar with charred surfaces of the same. The latter employs the traditional Japanese technique of shou sugi ban, which in theory creates a low-maintenance surface with some flame resistance. A common-sense strategy regarding the placement of fenestration sets the highest ratio of glazing on the south and east elevations (for light and early-day heat), the least on the north (to reduce radiant heat loss) and west (where late-day heat gain is an issue). The variability of the curtain wall glass and alternation of charred with natural wood create a crisply
dynamic presence in downtown Prince George.

WIDC should become a pilgrimage point for every Canadian architect interested in the new possibilities of wood. When it comes to a true appreciation of the substance of architecture, one site visit is worth 1,044,911 page views. However, a bit like the most brilliant but least known of Le Corbusier’s villas—the Maison Curutchet in La Plata, Argentina—WIDC’s geographic isolation may keep many away.

Vancouver’s Ronald McDonald House is built using tilt-up CLT wood panels. The exterior is clad with grey iron-spot brick, complementing the residential forms and materials of the surrounding neighbourhood. (Photo: Ed White)

Vancouver’s Ronald McDonald House is built using tilt-up CLT wood panels. The exterior is clad with grey iron-spot brick, complementing the residential forms and materials of the surrounding neighbourhood. (Photo: Ed White)

Ronald McDonald House, Vancouver

If by the nature of its commissioning WIDC is polemical—a series of arguments and explorations in favour of mass timber construction—the 73 apartments of the Ronald McDonald House near Vancouver’s Children’s and Women’s Hospital complex is equally inventive, but understated. Here wood is a means, not an end.

Run as non-profit facilities independent of the fast food purveyor, Ronald McDonald Houses provide lodging for the families of young patients for periods ranging from a few days to a year and longer. Most of the families who stay here hail from the Canadian North and B.C. Interior, and kitchens and laundry facilities are provided so a semblance of family life can continue while ailing children receive treatment nearby.

Each grouping of aggregated apartments includes its own kitchen and dining area; play features such as miniature wooden houses and a tube slide that can be used in lieu of the staircase are integrated in the design.

Each grouping of aggregated apartments includes its own kitchen and dining area; play features such as miniature wooden houses and a tube slide that can be used in lieu of the staircase are integrated in the design.

There are Ronald McDonald Houses all over the continent, and many opt for a shiny happy look that does little to reduce the stress of resident parents and siblings—more likely increasing it by forcing them to live in comic book-coloured rooms. I have been a long-time skeptic of the happiness industry—those books and corporate stratagems intended to render us pleasant and positive. Nothing makes this architecture critic happier than innovative architecture of substance that serves its clients and communities. Vancouver’s Ronald McDonald House makes me happy.

With its Nordic-seeming grey iron-spot brick catching light in all conditions, its boxed dormers nodding to French residential vernacular, and its tightly honed layouts in plan and section, the first quality that comes to mind about the MGA design is not forced happiness but “dignity.” To appreciate the design accomplishment here, one must push past the Ronald McDonald rubric. This is serious architecture for a serious purpose: enriching and making more peaceful the lives of families so they can support their sick children.

The design includes generous outdoor and indoor common areas, composed in a mature contemporary aesthetic. Dormer assemblies for the apartments were pre-fabricated off-site and dropped in by crane. (Photo: Ed White)

The design includes generous outdoor and indoor common areas, composed in a mature contemporary aesthetic. Dormer assemblies for the apartments were pre-fabricated off-site and dropped in by crane. (Photo: Ed White)

One of the cleverest aspects of the design is how it balances the iconography of the wooden house as a place of refuge with the task of forging a sense of community for over 200 ever-changing residents. A key means to this balance is found in Ronald McDonald House’s section, with shared amenities and gardens on the ground floor, topped by four brick-clad “houses” of aggregated apartments for families. Each of the “houses” has a communal kitchen and dining room on the first floor; a complete ring of corridors linking them encourages intermingling. This allows for efficiencies of operation, although it has the side effect of creating long, unfortunately hospital corridor–­like vistas. Crucial to the social and visual success of this public floor are the lush plantings, water elements, amphitheatre and play structures of the landscape design, with general garden layouts by MGA and detailed landscape design by Vancouver’s PWL Partnership.

With upper-middle-class houses across the street, Green’s residential iconography is displaced through its rare-in-Vancouver use of brick (minimal maintenance was paramount) and a strange-making use
of rare grey brick. These choices combine for a masterstroke of neighbourhood accommodation without imitation. Patterned brickwork appears on some walls;
MGA is evidently as interested in experimenting with masonry as it is with wood. Green and team have designed variety into the residential units, and there are television lounges, games rooms and more intimate outside decks to complete the rich range of social spaces in the building.

MGA_RMH_In14_emapeterOther than the ceiling of the large, living room-like entrance hall and a bridge at one end, the CLT construction is not visible. This strategic decision was facilitated by Eric Karsh of Equilibrium Consulting (engineers for both MGA projects reviewed here, as well as for Perkins+Will’s UBC Earth Sciences complex and other large CLT constructions in Vancouver). Current codes and operational needs conspire against seeing wooden walls and floors, explaining Green’s need at WIDC to show how it might be done. For example, interior wallboard could have been eliminated at Ronald McDonald House by adding two layers of wood to the CLT wall panels (for dimensional stability, CLT panels always need to be an odd number of layers) on the principle of char-equivalency, but there would have been a prohibitive cost in both materials and in a sacrifice of floor area.

Ronald McDonald House — construction process diagram

Ronald McDonald House — construction process diagram

Ronald McDonald House uses tilt-up assembly for its CLT walls; each panel is assembled horizontally then levered up into place, exactly like tilt-up concrete. Nonetheless, the trades bidding for the contract had to be actively educated in how simple this unusual procedure for wood construction could be. The boxed dormers were pre-fabricated off-site, and then dropped into position by crane.

The primary building structural system for Vancouver’s Ronald McDonald House is a tilt-up cross-laminated timber (CLT) wall panel system with infill wood I-joists supporting plywood decking. Laminated strand lumber (LSL) floor ledgers support the joists, decking and a two-inch concrete topping (which accommodates radiant heating). The structural system employs CLT wall panels in a balloon frame application, an innovation over more typical platform construction. Used as wall elements, CLT panels provide both vertical and lateral stability in one detail. CLT panels and connections were pre-fabricated off-site and assembled quickly by crane, reducing construction time compared with other methods. The dimensional stability of the CLT panels provides a solid stable backup for the brick façade, minimizing differential movement between the façade and building structure.

The primary building structural system for Vancouver’s Ronald McDonald House is a tilt-up cross-laminated timber (CLT) wall panel system with infill wood I-joists supporting plywood decking. Laminated strand lumber (LSL) floor ledgers support the joists, decking and a two-inch concrete topping (which accommodates radiant heating). The structural system employs CLT wall panels in a balloon frame application, an innovation over more typical platform construction. Used as wall elements, CLT panels provide both vertical and lateral stability in one detail. CLT panels and connections were pre-fabricated off-site and assembled quickly by crane, reducing construction time compared with other methods. The dimensional stability of the CLT panels provides a solid stable backup for the brick façade, minimizing differential movement between the façade and building structure.

WIDC and Ronald McDonald House represent the leading edge of West Coast architecture. They are much more the true inheritors of the values of the Case Study Houses, Ron Thom, and Fred Hollingsworth than is Canada’s cubic fungus of Neo-Modern villas growing to fill our every wooded glen. There is something inevitable about Vancouver being the point of confluence for fusing the multi-unit housing and offices of a sustainable city with the most carbon-friendly construction system imaginable: wood.

As this article goes to press, the piled wooden boxes of the Herzog and de Meuron proposal for the Vancouver Art Gallery has just been announced. In an interview on CBC radio, Green congratulated the high-profile choice of wood, but questioned the specific design choices. The proposed design uses wood as a veneer on a concrete tower—a veneer that may well need to be preserved under glass. It’s a far cry from MGA’s integral use of the material.

By virtue of having already designed a city hall, airport terminal and office building before turning 50, Michael Green is uniquely positioned to get around Canada’s ultra-conservative commissioning practices (you have to have already designed a building type to get to design one; architectural styles are not to be invented but meekly imitated or imported) that hamper the careers of some of our key emerging designers, and blocks a needed generational renewal.

Those seemingly all-concrete Corbusian villas were no less enthralling to my students after they came to understand their construction is actually hybrid. Similarly, the differing approaches to mass timber construction in WIDC and Ronald McDonald House are proof that Michael Green is more than a polemicist with a popular TED talk, but a widely talented architect working his way up the rock walls
of a major career.

Trevor Boddy’s exhibition Rethink: Behind San Diego’s Skyline runs all fall, and his text for City-Builder: The Architecture of James K. M. Cheng will be published in early 2016.