February 1 2019
Building for the Future: Modern Timber Construction
Innovations in timber products and technologies have made it an increasingly viable choice in building design and construction, as it offers many advantages when compared with traditional building materials, such as steel and concrete. Advanced building materials, such as cross-laminated timber (CLT) and glued-laminated timber (glulam), offer impressive structural and sustainability properties.
With such important qualities, mass timber is a meaningful option when it comes to construction materials. And like all building materials, there are significant considerations to keep in mind when opting to build with timber.
Below, we look at the top advantages and challenges of building with mass timber.
Why Build With Mass Timber?
Mass timber products offer advantages in sustainability, architectural expression, and construction.
Timber-based structures have a lower carbon footprint compared to traditional building materials. Trees sequester carbon dioxide from the atmosphere as they grow, which remains stored in the wood when trees are harvested, meaning timber begins its construction life as a carbon-negative material.
In addition, manufacturing wood products requires significantly less energy than producing other building materials. Recycled steel and concrete emit up to seven times more carbon than the production of engineered wood products.
In order to maintain the sustainable benefits of building with wood, it is important to develop an end-of-life strategy for structural timber.
“Without an end-of-life strategy, some of the benefits of building with timber will be undone when the wood itself breaks down,” says Eric Gordon, principal at Entuitive. “A properly sustainable build will have a plan in place so that we delay the release of carbon as long as possible.”
Finally, the same parcel of land can be reused to plant new trees in place of cut ones, continuing the area’s ability to sequester carbon as well as maintaining its health and biodiversity. A study has estimated that approximately 25% to 30% of Europe’s forests would be required to house the entire population of Europe indefinitely.
Building with visually exposed timber allows for the creation of beautiful, unique interior and exterior designs that truly make a statement. Timber offers a built-in richness and elegance that can elevate any building project, creating a pleasing and attractive environment for occupants.
Further, a building with visually exposed timber can alleviate some of the potential pressure of living in a so-called urban concrete jungle. Natural settings have been shown to improve mental health and wellness.
Wood offers the advantage of speed when it comes to building construction. Panelized and modular timber elements are manufactured off-site and erected faster, lowering site time and on-site labour costs. A mass timber building can be constructed up to 20% to 30% faster than a steel building.
Additionally, mass timber products are manufactured under controlled conditions, meaning each piece achieves the highest quality in building performance.
What Are the Challenges of Mass Timber Construction?
The benefits of mass timber buildings are numerous, and just like with traditional options, timber comes with its own set of considerations.
“As building in wood becomes more popular it is important to deal with the material’s challenges,” says Gordon. “At Entuitive, we ensure each project makes use of the right materials and products. That means understanding the advantages and challenges of each building option, including wood.”
Cost of Construction
Project costs depend on specific project requirements. For any given project it is recommended that cost comparisons be carried out by an experienced cost consultant who is familiar with mass timber construction.
Mass timber buildings are often cost-competitive when all factors, including construction time, are considered.
Supply Chain & Competitive Pricing
Products are not yet standardized in the mass timber industry. Because of the specific products and capabilities of each timber supplier, early engagement of the timber trade in the design process is preferred. As such, alternative methods of procurement to the traditional lump sum bid become attractive.
Mass timber elements can be encapsulated in drywall or a similar material to achieve the required fire resistance rating. If left exposed to view, mass timber elements can in some cases be engineered to achieve the required fire resistance by using the initial charred layers to provide insulation to the timber beneath. The post-fire rehabilitation or residual value of the building also requires consideration.
“The biggest misconception about timber buildings is that they do not perform well in fire, but this is because most people associate timber buildings with stick-built residential construction rather than the large, engineered mass timber systems used in contemporary buildings,” says Matt Smith, fire and structural engineer at Entuitive. “The second biggest misconception is that fire safety is only achieved by covering all timber with drywall. However, with performance-based fire engineering we can quantify performance, optimize encapsulation, and meet or exceed all safety requirements in a mass timber building.”
Most timber used in construction is susceptible to decay if the moisture content exceeds 20% for extended periods. The source of moisture could be from leaks in the building envelope or internal services, or from wetting during construction if the site was not properly protected. Either way, leaks must be identified and repaired quickly.
While construction site time is reduced when building with mass timber, this is only realized/replaced to some degree by fabrication time in the manufacturing facility.
Accordingly, locations and sizes of openings for mechanical and electrical services should be fully detailed in advance to leverage the precision of CNC machining and to avoid delays on site. This detailed coordination during the design stage can be facilitated by the preparation of BIM models by all disciplines involved.
Why Choose Timber?
Timber can be an excellent choice for both new builds and renovation projects. It’s a sustainable material that offers faster construction time and a more natural setting for occupants to spend time in. While the challenges of working with timber must be taken into consideration, they certainly aren’t insurmountable, and in many cases, timber is the best option for a project.