Please turn your device to portrait.
Innovative and sustainable use of reclaimed timber for structural GLT and CLT mass timber construction.
A new initiative led by a team of researchers at London’s UCL has demonstrated the first building-scale prototype of a glue-laminated timber (GLT) and cross-laminated timber (CLT) mass timber structure made entirely from waste timber sourced from demolition sites. This project, part of UCL’s Circular Economy Lab in collaboration with Portakabin and other partners, aims to validate the feasibility of using reclaimed timber for mass timber structural applications. (main pic: Dr Colin Rose from the UCL’s Circular Economy Lab presents the CLT/GLT reclaimed pilot building. Credit: Digby Oldridge/ UCL)
The Prototype
The modular structure, measuring 3.5m high, 2.5m wide, and 2m deep, was designed and manufactured at the UCL Here East campus in London. It features a GLT frame with CLT wall and floor panels, demonstrating a higher-value use of secondary timber, which is typically downcycled, chipped, or incinerated in the UK.
Colin Rose, the lead researcher and co-founder of start-up UK CLT, explained, “The project aims to show how reuse as part of the circular economy can be achieved through a scalable process.” He highlighted that the UK generates four and a half million tonnes of timber waste annually, with two million tonnes originating from construction and demolition. “We need to change attitudes so that people think of it not as waste, but as something that can be reused, and establish more of a market and the infrastructure to handle it,” said Rose.
A Low-Carbon Alternative
Engineered timber is already regarded as a low-carbon alternative to traditional structural materials such as concrete, steel, and masonry. This project further enhances the environmental benefits by using waste timber, thereby increasing the built environment’s capacity to act as a long-term store for sequestered carbon. Official figures indicate that around 56% of waste timber in the UK is incinerated for energy generation, 32% is downcycled, 9% is incinerated without energy recovery, and 3% is exported.
Sourcing and Traceability
All timber in the prototype was sourced from locations in London, including two demolition sites and a site run by Community Wood Recycling. Rose noted, “Overall, we’re trying to source the materials directly from demolition sites because it’s cheaper, and you’re saving timber that would otherwise be going in the skip.” The materials are fully traceable, and Product Passports, stored on the Madaster platform, maintain a digital record of key information. The structure incorporates reusable connections designed to enable future disassembly, upgrade, and reuse, and when no further reuse is possible, the timber can be recycled into panel products such as chipboard or MDF.
Watch the story behind the initiative
Structural Integrity and Feasibility
One challenge of reusing secondary timber for structure is the potential degradation of its mechanical properties. UCL researchers recently carried out structural performance tests, including non-destructive full-scale bending tests, demonstrating secondary timber’s feasibility as a feedstock for CLT production. This aligns with research by Simple Works engineers and Edinburgh Napier University testing glulam, said Rose: “All the results have been encouraging and shown predictable performance.”
Plans for the future
Rose expressed his ambition to work on a large-scale demonstrator project, with the ultimate goal of making it simple for architects and engineers to specify reused timber from a centralised reliable location, including the necessary certification. The UCL prototype was exhibited at two events in July, during the Festival of Engineering, at UCL Here East and at the University’s Bloomsbury Campus on Bedford Way in London.
Reusing Wood from Demolition in Mass Timber Products
As part of the UCL Festival of Engineering 2024, the Circular Economy Lab presented the pilot building demonstrating new materials developed at UCL. The pilot sourced timber that would otherwise have entered demolition waste streams and been chipped and incinerated or downcycled. The timber was instead prepared for reuse and manufactured into ‘glued-laminated secondary timber’ (glulamST) for the building’s structural frame, and ‘cross-laminated secondary timber’ (CLST) for wall and floor panels.
Product Passports and Circular Economy
The use of Product Passports ensures that all materials are fully traceable. Stored on the Madaster platform, these digital records maintain key information about the materials. When no further reuse is possible, the timber can be recycled into panel products and eventually incinerated for energy, completing the circular economy loop.
See: https://ukclt.com/
