Busting the myths on timber buildings

Timber is one of our most sustainable building materials

Due to a tree’s ability to store carbon until it rots, decays or burns, designing and constructing buildings using timber significantly reduces potential greenhouse gas emissions. Particularly if sourced from sustainably-managed forests, timber building products are an environmentally friendly choice.

Mass engineered timber (MET), which is comprised of engineered wood products to create a strong and durable building material, is increasingly being used in high-rise commercial and residential projects. It includes such products as cross laminated timber (CLT), whereby layers of wood are stacked crossways and bonded with adhesives, predominantly used for walls, floors and roofs; and glue-laminated timber (GLULAM), similar to CLT but with the grain running in the same direction and mostly used for columns, beams and trusses.

Mass engineered timber is lightweight yet strong; allows for precise off-site prefabrication, which is faster, safer, quieter and produces less waste; and it requires less carbon dioxide to manufacture, as compared to steel and concrete. On average, producing a product from steel requires 19 times more energy than from timber; 45 times more to produce a plastic product and 85 times more to make an aluminium product (Timber NSW).

Using timber in workplaces and other buildings is also associated with a greater sense of wellbeing and productivity due to the practice of biophilic design, which involves increasing occupant connectivity with nature by using natural elements indoors.

As we need to build 10,000+ buildings a day to cater for a 10 billion world population by 2050, and building and construction represent almost 40 per cent of all carbon emissions, there is a clear case for using timber in greater proportions.

Debunking myths about timber buildings

However, even though mass engineered timber is a highly sustainable building material that enables a greater sense of wellbeing for building occupants, questions still exist about its inherent benefits as a construction material.

Watch this video! Aurecon senior structural engineers debunk some of the myths on timber buildings – from them not being fire resistant, to being susceptible to termites!

Video summary: Aurecon engineers bust the myths on timber buildings

Aurecon senior structural engineers debunk the myths on timber buildings – from them not being fire resistant, to being susceptible to termites.

There is a growing trend towards using mass engineered timber (MET) for commercial as well as residential buildings, including high-rise, as a highly sustainable material that is good for the environment as well as the health and wellbeing of occupants. Using timber as a major construction material achieves a lower carbon footprint and enables a sense of wellbeing through biophilic design, that is, increasing occupant connectivity to the natural environment.

However, myths still exist about timber’s inherent benefits. In this video, Aurecon busts the myths on timber buildings:

Myth 1 – Timber isn’t fire resistant – one of the key properties of massive timber is that it is difficult to ignite and will char in a fire but leave sound timber underneath. It also burns at a predictable rate, allowing for the design of timber for a given fire event.

Myth 2 – Timber buildings aren’t termite resistant – large timber buildings are usually constructed on a concrete podium to create separation from the ground and no concealed entries to allow termites to enter. Timber can also be treated against insect attack and this is a key part of any strategy, and is in fact mandatory in some parts of the world.

Myth 3 – Timber isn’t sustainable – timber has a lower carbon footprint than traditional building materials. Trees actively sequester carbon from the atmosphere while growing, and when they are cut down for use as building materials, the carbon is ‘trapped’, unable to escape into the atmosphere as carbon emissions. Mass engineered timber can and should be sourced from sustainably-managed forests.

Myth 4 – Timber isn’t structurally sound – when the natural shrinkage and expansion of timber is appropriately considered in the design, timber performs well as a structural system. Where buildings are designed with timber cores (usually the main lateral load resisting system), diagonal timber bracing can be implemented to resist lateral loads while also providing an architectural feature.

All your questions about Mass Engineered Timber (MET) answered

Is timber fire resistant?

There is a misconception that timber is an unsafe building material, however, timber contains some inherent qualities that make it safe in a fire event. For instance, timber is an excellent insulation material, meaning that it doesn't easily allow heat to pass through it. Massive timber is difficult to ignite (think about how hard it is to light a large log on a fire!).

Also, timber chars from the outside, leaving an insulating layer of charcoal and sound timber underneath that maintains its integrity. This also means that it burns slowly, making it a very predictable material in a fire event, allowing time for evacuation. Australia's Nation Construction Code sets Performance Requirements for timber that ensures buildings constructed with timber are safe in the event of a fire.

Is timber resistant to termites?

Large timber buildings are usually constructed with reinforced concrete groundworks to create separation between the timber and the ground and with no concealed entries that allow termites to enter. This is the case with 25 King, Australia’s tallest commercial timber building, which is constructed on a concrete podium.

Timber can also be treated against insect attack and this is a key part of any strategy, and is in fact mandatory in some parts of the world.

Is timber sustainable?

Timber has a lower carbon footprint than traditional building materials. Trees actively sequester carbon from the atmosphere while growing, and when they are cut down for use as building materials, the carbon is ‘trapped’, unable to escape into the atmosphere as carbon emissions.

Mass engineered timber can and should be sourced from sustainably-managed forests, which actually improves a forest’s carbon sequestration rate, as opposed to allowing forests to decay or burn naturally, releasing carbon into the atmosphere.

Is timber structurally strong?

Mass engineered timber products are strong; some structural load-bearing elements have a higher strength to weight ratio than typical concrete mixes. When the natural shrinkage and expansion of timber is appropriately considered in the design, timber performs well as a structural system. Where buildings are designed with timber cores (usually the main lateral load resisting system), diagonal timber bracing can be implemented to resist lateral loads while also providing an architectural feature.

Are timber buildings difficult to construct?

Mass engineered timber construction is faster, safer, quieter and creates less waste as it uses precise off-site prefabrication. As off-site prefabrication occurs in the controlled environment of a factory, with modules delivered to site, this can decrease construction time by up to 50 per cent and improve safety on site.

It also reduces site noise and waste. MET construction also lends itself to the use of automated construction techniques, which many argue could be the future of construction.

Do timber buildings require more maintenance than traditional buildings?

Maintenance needs to be considered in the design of any building. Often a high cost material has lower maintenance costs and vice versa so decisions need to be made about the balance between upfront capital cost and ongoing maintenance costs. The key to the durability of timber is moisture, so generally enclosed timber elements within a building will last for the accepted design life of any building, which is typically 50 years.

Are timber buildings more at risk of water damage?

Large timber buildings are usually constructed on a concrete podium and the external façade is clad in glass or other material so the timber is not exposed. Any external timber elements can be protected by an additional layer of non-porous material.

Are timber buildings soundproof?

Timber consists of a network of interlocking cells that convert sound energy into heat energy, meaning that timber has a greater sound dampening ability than many other building materials. While concrete walls bounce sound, creating an echo, timber tends to 'absorb' sound which is why it is often used to clad walls and ceilings in public buildings. The Sydney Opera House, whose theatres are lined in timber acoustic panels, is a great example of the acoustic performance of timber.

Raised floors and floor coverings can further reduce any potential impact of noise, particularly in office buildings.

Timber building design experience is key

Timber is a different material to concrete and steel and has its own unique properties. Experience in designing and building with timber is important to ensure serviceable and durable buildings.

Aurecon has amassed an enviable track record in successful timber design over the past 35 years, including designing Australia's tallest commercial timber building, 25 King, Australia's tallest residential timber building, Monterey Apartments and one of the world's largest timber buildings, Nanyang Technological University Academic Building South in Singapore.

Learn more about our thinking below.

Into the woods: how a resurgence in timber could redefine the construction industry

Aurecon’s Major Projects Director, Built Environment Ralph Belperio explains the potential of timber in replacing concrete as the material of choice in construction.