The low carbon movement has seized the building design industry, where—according to a 2019 World Green Building Council paper–building activities are responsible for 39 percent of worldwide carbon emissions.
Luckily, timber is a building supply of choice for multi-storey buildings. In Toronto, Google supported Sidewalk Labs in proposing a $US1.3 billion masterplanned waterfront precinct built wholly with mass timber. In Australia, timber has been employed to build many medium-rise apartment complexes and is now a key ingredient in mid-rise commercial buildings.
An industry providing innovative ways of construction, including prefabrication, is on the horizon. In certain instances, multi-storey buildings are being constructed totally from timber. In other projects, timber elements are being mixed into conventional concrete and/or steel structures in a hybrid fashion.
At a webinar that will be hosted next week by timber systems supplier Tecbuild, a number of sustainable construction alternatives will be examined. Melbourne University construction management lecturer Chris Jensen will specify the way in which new sustainable building methods will be employed in industry. Phil Gardiner, principal director at WSP in Australia, will examine structural alternatives for sustainable building that include timber, modular and hybrid systems. And Robert DeBrincat, business development manager at Icon Construction, will examine how obstacles facing the adoption of innovative building systems can be conquered.
Gardiner says that hybrid systems are the way of the future.
He says that structures built from 100 percent timber claim a number of benefits. Aside from ecofriendly benefits (wood buildings are ideal for carbon storage, have sound thermal performance and avoid the intensive carbon emissions affiliated with concrete manufacturing, and its light weight makes for low density foundations), the material is also custom made for prefabrication and easy assembly.
Pure timber systems do have a few challenges inherent, in that they employ the use of more and larger columns; a condition that requires a smaller grid and limits floor space.
Pure timber also presents challenges in terms of acoustic and fire protection. Gardiner asserts that hybrid systems can meet these challenges while preserving the benefits common to timber.
In the case of an office building including steel columns and beams mixed with timber flooring systems – cassettes, CLT slabs or timber joists; as opposed to spans measuring nine meters by six meters with pure timber, you might attain nine metres by nine meters with your to 350 mm by 350 mm via the composite. When combined, these measures would facilitate both more floor space and a more sizable grid while keeping the benefits of timber flooring. Also, a concrete screed could be added to enhance fire and acoustic performance.
In regards to concrete, Gardiner discusses the possibilities of inserting large spanning concrete beams with timber between them. These timber beams have additional concrete poured up top.
In these situations, Gardiner says that the concrete need be poured only once. In this case, timber is a component for the formwork but shapes part of the permanent structure and enhances the structural capacity of the slab when the concrete and timber blend. When the timber is in place, the concrete slab and beams are poured together with no need for props.
Gardiners states that this arrangement can also guarantee good acoustic and deflection performance.
The advantages of hybrid structures, according to Gardiner, are that they allow for individual materials to be utilised where they add the most value.
These systems may not match pure timber construction in terms of sustainability performance and aesthetic value.
Building with combos of timber with steel or concrete also presents challenges with the coordination of differing structural trades.
When working with timber, Gardiner says it is vital to comprehend the origins of the wood and connections. Australian hardwoods, not surprisingly, resound in their strength.
Whilst prefabricated structures can be built on site, the automated production process of these buildings means that documentation and workshop drawings must be prepared upfront.
DeBrincat says that we must modernise building processes. These involve the use of engineered wood/mass timber products like cross laminated timber (CLT), glulam, and laminated veneer lumber (LVL), prefabricated timber and light gauge steel frame systems, panelised timber and light gauge steel framed systems to create entire wall panels and floor cassettes, 3-D volumetric modular systems for the construction of hotels, student accommodations, etc. He says that these changes can save time, cost and the planet.