Timber frame manufacturers are increasingly supplying timber frame systems for high-rise buildings. This material has not traditionally been used for high-rise structures because it was not considered to be as strong and durable as steel or concrete. However, advances in technology mean that wood products are now feasible materials for such projects.
Furthermore, Planning, BIM & Construction Today reports that researchers from the Graz University of Technology (TU Graz) in Austria have developed an innovative timber module system that could make buildings more straightforward to maintain. This will also extend the lifespan of the building, reduce the waste of resources and lower the carbon footprint.
Here’s a closer look at how and why timber frames are used for high-rise buildings.
Why are timber frames now used in high-rise construction projects?
There are a number of reasons for the development, including the following:
Modern engineered wood products
Engineered wood products such as cross-laminated timber (CLT), glue-laminated timber (glulam), and laminated veneer lumber (LVL) are strong enough to support high-rise structures. Tests have shown that these materials have a load-bearing capacity and durability that is equivalent to steel or concrete.
CLT involves layering sheets of timber at right angles to each other, which creates a much stronger material than wood in its original composition. Glulam is made by bonding together three or more timber beams together with weather-resistant adhesives. It is widely used as a building material, and even used for major load-bearing structures such as bridges.
LVL is made from multiple layers of thin wood bonded together with extra strong adhesives. This produces a material that is much stronger and uniform in size and straightness than milled lumber. It performs well as a high-stress building component for beams and columns.
Engineered wood is highly durable and weather resistant, and much less prone to shrinking or warping than conventional timber.
Sustainable construction targets
Governments and developers are keen to encourage the more extensive use of sustainable materials in construction, and the demand for timber is likely to rise steeply in the future. Wood is a renewable resource, and when used instead of non-sustainable materials such as steel or concrete, it helps to lessen the depletion of the earth’s natural resources.
Once constructed, timber buildings store carbon throughout their lifespan, further helping to reduce the environmental footprint.
Faster construction times
Timber frames can be manufactured off-site in controlled factory environments, and are quicker and lighter to work with on-site. This increases the speed of construction and minimises the risk of delays.
Fire resistance
Timber might not traditionally be seen as the most fire resistant of materials. However, when wood-framed structures are correctly designed and constructed, they have an excellent level of fire resistance. Timber is a naturally insulating material, and once the outer surface is charred, it creates a protective layer around the inner core of the building.
Furthermore, engineered wood products such as cross-laminated timber have an even greater level of fire resistance. The frames can additionally be treated with fire-retardant chemicals for an extra layer of protection. All these factors can give firefighters additional time to evacuate buildings, and they also reduce the risk of structural collapse.
TU Graz develop a timber modular system
As previously mentioned, a team from TU Graz have been exploring even more effective ways of using timber in high-rise buildings. They have developed a new modular skeleton system that would allow for the removal and replacement of a damaged section with no risk to the rest of the building.
This means that repair and renovation or conversion work would be much quicker and more straightforward. Currently, it is often simpler to demolish buildings that are no longer fit for purpose, rather than renovate or adapt them. This wastes resources, and significantly contributes to CO2 emissions.
Each prefabricated timber module would be stacked alongside and above the other, up to 24 storeys high. Removing a module would involve disconnecting the utilities and using a lifting cylinder that is inserted between spacers. The structural load would be supported with a shear plate.
A spokesperson for the research team at TU Graz said: “If a property is no longer fit for purpose, it is usually demolished even though it would still be perfectly usable. Even in the event of damage to individual parts of the building, the entire building usually has to make way.”
They added: “That’s why the circular ‘R-strategies’ such as refurbishment, repair or re-use were very important for us in the Mohoho project, in order to develop a building system that offers a CO2-reduced alternative to conventional construction methods in high-rise construction.”
“In Mohoho, we have combined the advantages of modular wood construction, such as the high degree of prefabrication and the short construction time, with the advantages of skeleton construction.”
“The prefabrication of the modules in a production hall under controlled conditions enables higher quality and traceability of the joints compared to on-site assembly and ensures shorter construction times as well as reduced noise and dirt pollution.”
“The repairability and flexibility of the construction system should significantly extend the operating life and life span of the building. During dismantling, the modules can either be reused directly or separated by type. We are already planning a follow-up project in which we want to test and scrutinise all of these things in practice.”
If further development and testing of the module system proves to be positive, then it could be the start of a significantly more efficient and environmentally-friendly approach to the construction of high-rise buildings.
In the future, engineered timber is likely to be at least as widely used as steel or concrete in construction projects, as governments and developers investigate the most effective ways to decarbonise the construction sector and conserve the earth’s natural resources.