Post-tensioned timber frame construction using hardwood

Post-tensioned timber frame construction using hardwood

An attractive alternative to concrete frames

Post-tensioned timber frames construction using hardwood (PTTF) is an attractive and eco-friendly alternative to traditional concrete and steel frames. PTTF is quick and easy to assemble, resulting in cost savings for builders.

The production of cement for concrete and steel reinforcing uses a large amount of energy. PTTF offers the following environmental advantages:

·      Increased use of wood, a renewable material, for building projects

·      Storage of CO2 for the lifetime of the building

·      Wide availability of material in local forests

““This innovative construction method offers multiple benefits. The high degree of prefabrication means quick, easy assembly on site. The skeleton design provides more flexibility when it comes to dividing up the available space and allows for a façade with a large surface area.” ”
Häring & Co. AG (Source: company website)

A game changer: cost-effective and eco-friendly

Researchers at ETH Zurich, who developed PTTF, believe it could be a game changer for the building industry, transforming the way that frames have been built for the past century.

The PTTF consists of ash glulam (glued-laminated timber) columns, and hybrid beams made of ash and spruce glulam. A steel cable within the timber beam connects the beams to the columns, and is tightened to pull the elements together. The current system does not require additional steel elements or a concrete core: the system is stiff and efficient in case of wind loads or earthquakes.
The main advantages to building with PTTF include:

·      High quality due to prefabrication

·      No heavy machinery required

·      Quick to assemble, resulting in cost savings

·      Suitable for adding additional storeys to existing buildings or for new buildings

·      Light construction due to timber

·      Skeleton design provides greater flexibility in terms of dividing up available space or creating a facade with a large surface area

PTTF was used as the load-bearing structure at the ETH House of Natural Resources (HoNR), a Living Lab. It is an extremely efficient system: it took just four days and two people to build one storey of the Living Lab.

A material for the future

Cement is used to produce the most common construction material: concrete. However, the cement industry is a leading source of greenhouse gas emissions due to the energy-intensive production process. Hence, replacing concrete with timber, a renewable and more eco-friendly material, can significantly reduce carbon emissions.

The construction of timber buildings typically uses less energy than those made of concrete or steel. Timber buildings also store CO2.  As a result, timber buildings generate 58% to 71% less greenhouse gas emissions than buildings built with traditional materials such as steel and concrete, according to the Austrian wood industry association proHolz.

Did you know?

1m3 of timber binds 1 ton of CO2

Contact details

Prof. Dr. Andrea Frangi

Institute of Structural Engineering

ETH Zürich

+41 44 633 26 40


Published 20 February 2018

About BTA

Building Technologies Accelerator (BTA) is a programme by EIT Climate-KIC: the EU’s largest public private partnership addressing climate change through innovation to build a zero carbon economy.