How ecofriendly dowel-laminated timber transforms wood waste into structural innovation in construction

Reducing processing steps to make reclaimed timber improve its potential in the wood sector

Each year, large volumes of wood waste are burnt for energy recovery or discarded in landfills. For Mohammad Derikvand, timber engineering researcher at InnoRenew CoE and Assistant Professor at the Slovenian University of Primorska, this ‘waste’ still holds overlooked potential and is too good to be burnt. Through EcoDLT, Mohammad demonstrates how reclaimed timber can gain a second life as dowel-laminated timber (DLT).

A scalable solution

“At the heart of the project is a scalable technique: dowel-laminated timber (DLT),” Mohammad explains. “Instead of gluing, DLT uses wooden dowels to laminate timber into structural floor elements. By integrating low-processed reclaimed timber, instead of new timber, so-called EcoDLT can result in a low-carbon, glue-free system. This can reduce processing steps needed to use reclaimed timber, making it more attractive for the wood sector.” 

In multi-storey buildings, structural floors are critical to overall stability as they must resist a combination of different short-term and long-term loads. Typically constructed from reinforced concrete or steel, these systems are resource and carbon intensive. EcoDLT aims to offer a more environmentally friendly alternative by reusing timber to create a floor system that can satisfy building code requirements. 

Preserving material and cultural value

The project shows that with accessible methods like dowel lamination, reclaimed timber can gain an extended lifecycle. The reclaimed timber used in the project is obtained from the recent renovation of a former Servite Monastery in Koper, Slovenia. This is a centuries-old building that holds deep historical and cultural value for the local community. 

Progress and testing

The project is currently in its first phase: creating a resource inventory of reclaimed timber in Slovenia and characterising the physical and mechanical properties of the reclaimed timber from the monastery site. The next phases will focus on assessing the strength of reclaimed timber. They will also evaluate the short-term and long-term performance of EcoDLT structural floor elements to ensure their safety and reliability over time. In parallel, the team will develop analytical models that can predict how EcoDLT elements will behave based on the properties of the reclaimed timber. “So far, our test results are promising,” Mohammad says. “I think this is due to the simplicity of our methods to process reclaimed timber into EcoDLT elements.”

The EcoDLT research project is currently going through its experimental stages, aiming to reach Technology Readiness Level 5 by the end of the project. The focus remains on developing and validating processing techniques and structural performance models while advancing practical applicability.