By Brent Bellamy, Creative Director and Architect
An artist's conception of the 62M condo project, a hybrid wood/concrete-frame building near the Disreali Bridge. Designers are expanding the possibility of wood-frame construction thanks to new technologies. (RENDERING BY 5468796 ARCHITECTURE)
Prosperous residents make prosperous cities. With housing costs typically constituting the largest portion of personal expenditures, housing affordability has become a principal determinant of the standard of living in urban areas. Access to adequate housing plays an important role in building strong communities and is a vital social indicator of health, equality and inclusion.
Consistently rising real estate values during the last decade have made access to affordable housing a difficult challenge for cities across Canada. In Winnipeg, since 2005 the average cost of a home has increased by 100 per cent and rental rates have grown by 70 per cent, while the average annual income has increased by only 34 per cent.
One strategy provincial governments are looking at to help bridge this financial gap is reducing construction costs for multi-family housing by revising provincial building codes to allow an expanded use of less expensive wood-frame construction. Currently in Manitoba, buildings made of wood are restricted to a height of four storeys. In 2009, a strong lumber industry pushed the British Columbia government to increase the allowable limit to six storeys, resulting in more than 250 of these structures now being built or nearing completion. Since that time, Ontario and Quebec have followed suit, and last week, the Alberta legislature passed a private member's bill to do the same.
Cities in these provinces see this move as an opportunity to improve access to quality housing options for citizens while at the same time increasing neighbourhood densities to create a more sustainable overall urban form.
In British Columbia, the cost of mid-rise wood construction has been found to be up to 20 per cent lower than steel or concrete framing, and has the added benefits of easier winter fabrication, faster construction periods and more flexible on-site modification.
The environmental benefit of wood-frame buildings is also an important advantage in cities looking to reduce their carbon footprint. Wood is a natural, renewable resource that is far less energy-intensive in its extraction and processing than alternative materials. Trees sequester carbon dioxide that remains stored in the lumber, lowering the overall carbon footprint for the building by up to 75 per cent. The USDA believes that because of this, a single five-storey, wood-frame building would cut emissions by levels equivalent to removing as many as 600 cars from the road for a year.
Designers are using new technologies to expand the potential of wood construction by overcoming structural limitations as well as the shrinkage, movement and sound-transmission issues often found with typical 2x6 residential construction methods. Engineered wood products that laminate different types of wood strands, veneers or dimensional lumber together are used to create high-strength structural columns and beams.
A new product called cross-laminated timber is a solid panel similar to a giant piece of plywood that is up to a half-metre thick, three metres wide and 20 metres long. These panels are used to create walls, floors and roofs and can arrive on site with door and window openings precut in the factory, increasing the speed and ease of construction.
Fire safety is often cited as a barrier to constructing larger wood-frame buildings, but research indicates these engineered wood products perform very well in a fire. Like a log in a fireplace, thick wood is very difficult to ignite and when it does, it burns slowly and predictably. A layer of char forms on the surface of burning wood, which insulates the interior from heat penetration, allowing it to maintain much of its structural strength as it burns. In contrast, a steel column very quickly loses its strength when high temperatures are reached, which can lead to sudden failure.
As wood buildings grow taller, the need for greater precision and improved construction quality has meant prefabrication of building components is becoming a popular construction technique in provinces that allow the increased height. Shop fabrication in a controlled environment can speed the process by reducing weather delays and allowing typically sequential elements such as floors and walls to be built simultaneously and taken to site when required.
The versatility of wood construction coupled with the accuracy and speed of the prefabrication process can produce architecture that is both innovative and affordable.
An example of this is a hybrid wood/concrete-frame building currently rising at the foot of the Disraeli Bridge that will uniquely alter Winnipeg's skyline. Designed by 5468796 Architecture, the 62M Condominium will resemble a two-storey wood-frame flying saucer hovering 10 metres in the air on 20 concrete stilts. Components that include 40 pie-shaped residential units are being assembled off-site by Holz Custom Prefab, who have become pioneers in the local wood-frame prefabrication market, constructing many of the most innovative multi-family residential buildings in Winnipeg.
Designers in other countries are going even further by using engineered wood structural systems to push the boundaries of mid-rise wood construction beyond even the six-storey limit. The world's tallest timber frame building is a 14-storey condominium under construction in Bergen, Norway, surpassing a 10 storey apartment built in Melbourne in 2013.
Large-scale wood-frame buildings are not a new idea in Winnipeg. They have long defined the city's architectural character and heritage. The Exchange District is filled with examples of century-old heavy-timber structures that rise as high as eight storeys. These buildings demonstrate wood construction shouldn't necessarily be considered a less permanent solution to other materials. Their transformation from warehouses and factories to modern office or residential developments illustrates the long-term versatility, durability and attractive natural esthetic that can be achieved through wood construction.
The preconceptions of wood as a building material is changing across Canada. The opportunity exists in Manitoba to follow the lead of other provinces and return to our historic construction roots. Revising the provincial building code to allow wood-frame construction for buildings up to six storeys tall and possibly beyond might be an important strategy to improve access to affordable housing while at the same time increasing residential density in our neighbourhoods, resulting in a more sustainable, equitable and prosperous city.
Brent Bellamy is senior design architect for Number Ten Architectural Group.
bbellamy@numberten.com
Republished from the Winnipeg Free Press print edition March 23, 2015 B5
