Tag: CLT

Black Spruce- The Unlikely Hero of Mass Timber

Posted on by Gary Snider

This feisty little tree grows throughout the northern regions of Canada. It survives harsh conditions, long, cold winters, and short 60-day growing seasons. 

Black spruce thrives in low, boggy landscapes. It reaches maturity at around 80 years and can live up to 120. Under ideal conditions, it can reach 30 metres into the sky and grow up to 36 centimetres across. But this is rare.  Most black spruce will top out at 20 metres (65 ft) and have trunks only 11-15 cm (4-6 inches) in diameter.

Black spruce is well adapted to wildfires and is one of the first trees to return after a fire. Rather than dropping cones, it holds them in its uppermost branches where they can remain unopened for years. The cones are tough, resisting weather, squirrels and insects, opening only slowly over time, or quickly when heat from fire softens the cone scales to release the winged seeds. 

Left: Wearing a winter cloak of snow, black spruce branches stay flexible.
Right: These cones, held for years, await a fiery dispersal and the start of a new forest

So far, none of this seems very heroic. In fact, it’s almost surprising that the black spruce is even considered for construction. But here come’s a plot twist where small is beautiful, slow is strong, and even early mortality can lead to a new life that can save the day.

Black spruce is the hero. Its list of hardships is now a checklist of preferred traits for sustainable mass timber construction:

  1. The short growing season faced by black spruce produces tight growth rings, which is ideal for creating high-strength wood fibre. 
  2. The tree has small downward-sloping branches, designed to survive heavy snow loads. Small branches leave only small knots in the milled lumber, which allows it to retain superior strength characteristics. 
  3. It often grows in dense stands and is exceptionally straight. As a result, black spruce boards have straight, uniform grain, giving them exceptional stiffness and stability.
  4. Black spruce is a short-lived tree which begins to decline in health around age 80. They also stop taking up CO2 and start to release it as they age further. Not surprisingly, this coincides closely with the historic frequency of natural wildfires. Harvesting black spruce before they decline helps to reduce CO2 emissions.

In contrast, large western conifer species like Douglas Fir continue to absorb CO2 throughout their lives and can act as growing carbon sinks for 300 years or more. As a climate-change mitigation strategy, the science makes a compelling case for protecting long-living trees, allowing them to remain in forests to take up and store carbon. At the same time, using black spruce for mass timber is environmentally responsible, as it locks the carbon of end-of-life trees into durable products and reduces the occurrence and intensity of wildfires.

To make mass timber, black spruce requires a passionate and innovative ally. That ally is Nordic’s parent company, Chantiers Chibougamau, who has worked in Quebec’s northern forests since 1961, turning black spruce into lumber and I-joists. In 2000, after years of development and testing, the company introduced the Enviro-Lam process, a method for making large-section glulams out of small-diameter logs. It was a breakthrough that allowed previously unutilized wood fibre to find a high-value use. In 2010, Nordic Structures built North America’s first Cross Laminated Timber (CLT) line and kick-started the continent’s mass timber movement, with black spruce as its undisputed champion.

Understanding and working with nature provides the best innovations and outcomes. When we adapt our approach to fit the resource, both nature and people can thrive.

 

Glulam & CLT- What’s the Difference?

Posted on by Gary Snider

The Building Blocks of Mass Timber

The spheres of architecture and construction are abuzz with the new ways that timber can be used in larger and higher buildings. “Mass Timber” provides faster builds, lighter foundations, more appealing spaces, and higher lease rates. It’s bringing heavy timber back to the forefront of modern design thanks to simple innovations in wood.

Let’s take a quick look at the two main ingredients in mass timber: glue-laminated timber (GLT or glulam), and cross-laminated timber (CLT).

Glulams have been around for over 100 years and grew rapidly in popularity and use in North America following WWII. Their first “golden age” occurred in the 1960’s when they were specified by architects in many civic, institutional and church projects.  Today, a second golden age is arriving for glulam, thanks to a new companion product: cross-laminated timber panels.

CLT’s were first used in construction in Europe in the 1990’s. They became available in North America in 2010 when Nordic Structures built its first CLT plant at Chibougamau, Quebec.

A Cornerstone installer guides a CLT to its final location atop Perimeter Aviation’s new Terminal Expansion.

Glulams and CLTs have several things in common. Both utilize small section lumber (lamella, lamstock), dried to 12% or less.  Both then use a combination of glue, heat, and pressure to bond the lamella together to create very large and long timber components.  The finished products have well-defined strength characteristics allowing them to span farther and carry loads greater than natural timbers.

The long lengths of both products rely on a process called “finger jointing” that takes short lamella pieces, cuts sharp zig-zags on their ends, applies glue and presses them together in a high-speed jointing line. The resulting joint is stronger than unjointed wood, increases the stability of the lamella and allows for lengths of 60’ and more.

Glulams orient their lamella in one direction, creating a big beam or column out of what essentially looks like a bundle of sticks or a stack of lumber.
A set of Nordic glulam beams and arches are prepared at the Cornerstone finishing shop.

The CLT’s innovation seems so simple: orienting lamella layers crossways to each other. But that’s genius, taking an existing technique and using it to make something no one has yet imagined.

CLT lamellae are arranged with each layer running perpendicular to its neighbours to create bending strength in two directions.
In many mass timber structures, glulams are used as columns and beams to support CLT floor and roof panels.

Bergen Gardens is a 6 storey, 149-unit, seniors’ apartment in Winnipeg, Manitoba, completed in 2023 with timber fabrication and install support provided by Cornerstone Timberframes.

Quebec City: Origin is a 12-storey mass timber eco-apartment completed in 2017

For certain applications, CLTs can also be used on their own, with the CLTs acting as beams, columns and shear-resistant diaphragms.

Mass timber will continue to become more competitive with concrete, steel and “stick framing”.  In many markets, it’s already become the obvious choice, realizing higher lease rates and faster market uptake.

 Article in BISNOW, a leading webzine for the commercial real estate industry.

Are you an architect, developer or builder with a potential mass timber project?  Contact Cornerstone Timberframes today and let’s talk about how we can help you achieve big impacts with timber!