WHAT THE EXPERTS SAY

Benefits of Wood Construction

Wood offers a renewable, low carbon, highly durable, and naturally beautiful building material that has fewer environmental consequences of any other material – and also has the ability to sequester and store carbon.

Structural materials can account for up to half the materials in a building and offer the single largest opportunity to reduce embodied environmental impacts.

The Carbon Advantage

A Mass Timber solution will sequester thousands of tonnes of carbon dioxide in the structure, while avoiding the release of further carbon dioxide into the atmosphere. A single building can be the carbon equivalent of taking a thousand cars of the road.¹

Mass timber offers a low carbon, renewable building material solution with the following benefits:

Wood material is composed of 50% carbon by dry weight. Trees absorb carbon from the atmosphere in their early growth cycle₂.
Every cubic metre of wood stores approximately 0.9 tons of CO2₃.
Buildings constructed with wood will sequester the carbon for the entire life of the building and longer if the wood is recovered and reused or repurposed₄.
Wood requires less energy for the raw material acquisition, processing, transportation and manufacture than other materials₅.
Wood supports a high performing envelope and has four times the thermal resistance of steel or masonry₆.
As a poor conductor of heat and natural insulator, wood minimizes thermal bridging, improving the effectiveness of timber-based envelope assemblies compared to conventional assemblies₇.
Off-site prefabrication of mass timber products have resulted in 4% cost savings and 20% construction schedule savings for documented projects₈.

Structurally Sound

In recent years, wood products have evolved to exhibit structural qualities similar to other traditional construction materials. The term Mass Timber can refer to a category of wood products, or a form of construction, which uses large engineered wood members to form the structure for buildings or infrastructure.

Common mass timber products can be fabricated as panels or columns and beams and there are many examples of low-, mid-, and high-rise buildings around the world demonstrating the important advantages of mass timber.

Fire Resistant

Mass timber structures are required to meet the same fire resistance rating as steel and concrete structures set by the building code. Wood is a combustible material and the conditions that it burns under are well understood. Significantly, the size and arrangement of mass timber elements are key in creating conditions that are not conducive to quickly promoting the growth of fire. Mass timber burns at a predictable rate, and has lower flame spread characteristics compared to typical wood or other combustible interior finishes, so it will contribute less than during the growth stages of a fire compared to typical wood or other combustible interior finishes.

Mass timber structures meet the required fire resistance rating required by code in two key ways: encapsulation and char method.

Encapsulation is a fundamental approach to all structural systems. Mass timber structural elements are protected with layer(s) of drywall (that do not have structural capacity) that act as a non-combustible insulator, protecting the wood from flame and heat. Similarly, steel structures are protected by in the same way, or through fibrous or cementitious materials. Reinforced concrete uses a non-load-bearing layer of concrete ‘cover’ to protect the essential steel reinforcing that is placed inside the concrete.
The char method is unique to mass timber. In the event of a fire, an outer ‘sacrificial’ layer of wood (that is not relied upon for structural capacity) that is exposed to fire risk is permitted to char, creating an insulating later of burnt wood that protects the inner structural wood from exposure and degradation.

Both methods are reliable, tested, and proven in mass timber buildings, and using either does not imply additional risk compared to other structural systems. All high-rise buildings in Vancouver are regulated to be protected by sprinklers, adding a reliable layer of safety to the building.

Stable Moisture Content

Mass timber (i.e., engineered wood products specifically) typically has a lower and more stable MC (moisture content) level than light wood frame elements. Glulam and CLT have lower water absorption and penetration than composite products such as LVL, LSL, and PSL. The key to preventing water-related damage is monitoring, which is a best practice regardless of type of structure selected. This can be achieved through a number of simple design strategies including ongoing moisture monitoring, locating highly visible shut-off panels in case of pipe breakage etc. In the unlikely event of a burst pipe or sprinkler turning on, the mass timber panels can be ventilated to dry.

Reinforced by Steel and Concrete

A mass timber building is not 100% wood. They use other materials such as steel and concrete selectively and strategically so that all materials are used to their best capacities. For example:

Steel is typically used for connections—timber to timber, and timber to concrete.
Concrete is typically used as a floor topping—which when coupled with a timber subfloor it provides a finished (or easily finishable) floor surface and improves acoustic separation between floors.

SOURCES

Mass Timber

Mass timber is the solution for healthy, environmentally responsible, ethical, and structurally resilient buildings of the future. That we can build today.