Benefits Of Mass Timber
The use of mass timber will also offer a cost-effective solution for the construction industry. Because mass timber products are custom-made off site and assembled on-site, construction time can be reduced by up to 25%. Using this method of building, constructions sites are also cleaner and safer due to fewer hot tools and machinery.
Tall wood buildings are considered sustainable for multiple reasons.
- Mass timber has a lower carbon footprint than concrete or steel as it is made of a natural resource. Additionally, as it is only one-fifth the weight, mass timber panels have reduced transportation emissions and decreased congestion to and around construction sites.
- Mass timber generates less waste since panels are manufactured custom for each application. Scraps may be re-used by the manufacturer.
- Mass timber is sourced from sustainably managed forests, of which Canada is a leader. One BC company, Structure Craft, is even engineering mass timber products from beetle-kill wood which would otherwise be waste, or worse, kindle for catastrophic wild fires.
The provincial government in Ontario is also in support of mass timber and tall wood structures, having prepared a comprehensive technical resource for engineers, architects, designers, fire service, and building officials. This guide focused on two important topics: architectural design and fire safety.
Building Codes + Safety
- Support from their city council and the planning, building and fire departments;
- Level 3 certified building officials; and
- Land use bylaws for buildings higher than six storeys.
Until now, the biggest hindrance to the use of mass timber in construction was building codes, which deemed tall wooden structures a fire hazard. However, thanks to new mass timber building technologies and techniques, tall wood structures are as safe or safer than traditional steel or concrete structures.
Cross Laminated Timber (CLT), for example, holds a high level of fire resistance thanks to its cross-sectional thickness and air-tight construction, reducing a fire’s ability to spread. If a fire does ignite, the burn is slow and predictable, meeting fire resistance ratings. Fire resistance can and should be enhanced with fire-resistant lining to the flooring or walls.
Cause For Concern
A recent study conducted in the US by Boston College found builder’s risk insurance quotes for concrete buildings to be 22-72% less than quotes for wood frame buildings, and quotes for commercial property coverage was 14-65% less than wooden frame structures. It should be noted that this study was commissioned by the National Ready Mixed Concrete Association (NRMCA) and did not differentiate between dimensioned lumber and engineered lumber which has a higher fire resistance rating.
On the other hand, Vancouver based Globe Advisors conducted a similar study that suggested there were other factors for determining higher insurance costs in wooden structures than fire peril alone. This study indicated that wood buildings are less durable, cost more to maintain, and have shorter life spans, all leading to difficulty in obtaining insurance for wood frame structures.
In addition, wood structures can have major moisture management issues leading to mold. Prevalent in BC and Central Canada, mold not only creates structural issues for the building, but it can also pose significant health risks to occupants, including coughing, nasal congestion, eye, skin, and throat irritation, and can sometimes be fatal.
The study emphasizes the importance of minimizing factors that could lead to mold and water damage in wood structures and claims that much of the annual losses from lumber decay is preventable. There is no one-size-fits-all when it comes to wood structure construction across Canada – what works in Prairie provinces, may not work in the coastal region.
According to the Insurance Bureau in Canada, water damage costs insurers, on average as of 2016, more than $1.7 billion annually. This includes water damage caused by flooding, sewer back ups, and burst pipes which can all lead to expensive repair and clean up bills for insurers. Wood structures are more susceptible to excessive water damage caused by any of these man-made or natural disasters.
Time will tell if insurers will begin to favour the new technologies of mass timber over steel or concrete. Mass timber technologies will need to address all of these additional and important concerns: durability, fire safety, and moisture. For now, BC is committed to growing its mass timber industry and will continue to innovate and find long term, sustainable solutions for the construction industry.
Notable Mass Timber Projects
The experts at Normac keep their finger to the pulse of the construction industry and are familiar with all construction types, materials, and techniques that might impact replacement cost.