Wood is one of the world’s oldest construction materials. For centuries it has been used in many different ways to shape our homes, industries and cities.
But wood hasn’t always enjoyed the popularity it has today. The Great Chicago Fire of 1871 raged for two days, leaving one third of the city’s population homeless and casting a shadow over the use of mass timber in construction. This historic event – and others like it – led to the introduction of new building codes to improve fire safety and limit the use of wood. It triggered a decline in mass timber construction, sparked new approaches to architecture and construction, and was the catalyst for innovation around other construction materials like brick, concrete and steel.
Modern timber construction
The design sophistication and performance of timber construction has grown considerably in recent years.
Engineering and construction innovation; changes to national and international
building codes; and growing demand for green buildings have rekindled the world’s interest in wood.
Today
plyscrapers are gaining popularity, with wood proving its credentials as a sustainable and cost-effective alternative to steel and concrete. Here we explore some of the benefits of this strong and versatile material.
SUSTAINABILITY
As a renewable material, sustainably sourced timber is considered to be more
eco-friendly and
less carbon intensive to harvest, transport and build with than other materials. Large amounts of carbon can also be stored in the wood used to construct buildings. And the ability to manufacture wood to size and project specification offsite reduces the amount of construction site waste produced by timber buildings.
EFFICIENCY
Engineered, prefabricated timber is proving to be a time and cost effective alternative to concrete and steel. As a strong but relatively lightweight building material, timber construction reduces the need for fixed cranes on site, and reduces foundation requirements. The use of prefabricated timber products speeds up construction time, and improves safety and accuracy during construction. It also allows more trades to work simultaneously on site, shaving more time off construction schedules.
PERFORMANCE
Strength
Wood has an excellent weight to strength ratio. Engineered wood products like cross-laminated timber (CLT) and glue-laminated timber (GLT) perform particularly well as lightweight and strong alternatives to concrete and steel. Unlike steel – which expands and loses strength or collapses in heat, wood dries out and gains strength, improving its performance.
Thermal performance
Wood’s natural insulating properties and the ability to engineer wood to precision for a tight fit, help this building material to achieve strong thermal performance and reduce the energy requirements for heating and cooling. The thermal properties of timber can also help to offset the
warmer temperatures found in city cores, often attributed to steel and concrete construction.
Acoustics
Wood is frequently used in concert halls for its sound absorption properties, which prevent noise and stop echo from travelling. The same acoustic benefits apply to the use of timber in tall commercial and residential buildings.
There are limitations to the use of mass timber in construction too:
Foundations
Just like their steel and concrete counterparts, timber buildings require concrete foundations for stability and to prevent termites and damp from affecting the integrity of the structure above. Concrete foundations are also required to absorb wind loading – which increases along with the height of the tower.
Fire
It is natural for people to have concerns about the fire safety of using timber for multi-storey construction. However, detailed testing has shown that large engineered wood panels actually
burn in a slow and highly predictable way, helping products like CLT to achieve necessary fire resistance times to meet building codes and regulations.
Reaching new heights
At 52 metres,
25 King Street in Brisbane’s CBD is currently Australia’s tallest and largest engineered timber office building (by gross floor area, as of November 2018). Pushing the limits of timber construction, the 18-storey
Mjösa Tower in Norway soars to a staggering 85.4 metres and holds the record for the tallest wooden building ever constructed. And whilst plyscrapers may currently be restricted by building codes, they are certainly not limited by imagination – in Japan an ambitious
350m, 70-floor tower is proposed for completion by 2041.
Does wood feature more prominently in your portfolio today? What benefits does timber bring to your construction projects? Please share your thoughts and feedback via LinkedIn.