Reusing wood from demolition in mass timber products

The Circular Economy Lab exhibited a pilot building that demonstrates new materials developed at UCL.

As part of the UCL Festival of Engineering 2024, London Design Festival 2024 and Futurebuild 2025, the Circular Economy Lab exhibited a pilot building that demonstrates new materials developed at UCL.

Colin Rose at the CLT pavilion talking to a few students

The pilot, known as CascadeUp, brings our bio-based, circular economy research to life. We have sourced timber that would otherwise have entered demolition waste streams and been chipped and incinerated or downcycled. The timber has instead been prepared for reuse and manufactured into ‘glued-laminated secondary timber’ (glulamST), as the building's structural frame, and ‘cross-laminated secondary timber’ (CLST), as wall and floor panels.

Product Passports:

A group of builders installing the CLT pavilion

Materials from demolition, currently treated as waste, present opportunities for new forms of industrial upcycling. CLST and glulamST are examples. Our research was the first to examine this way of reusing timber, and although researchers in various parts of the world are building on the topic, this is, to our knowledge, the first building-scale demonstration.

This innovation provides a low-carbon alternative to structural materials such as concrete, steel and masonry. Retaining timber as a structural building component increases the built environment's capacity as a long-term store for sequestered carbon – whereas incinerating timber releases the carbon captured by trees back into the atmosphere. CLST and glulamST have a fully traceable, local, socially fair supply chain. Implemented at scale, this circular system drives new employment opportunities in reclamation and manufacturing close to cities.

Wood loaded in truck; gloved hand on timber

As well as reusing second-hand materials, the building itself is modular and reusable. During the Festival of Engineering, it was exhibited in the Yard outside UCL Here East, where manufacturing took place, and then at IOE. In September 2024 it was exhibited at the OXO Tower as part of the London Design Festival. In March 2025 it became part of the welcome feature at the entrance to Futurebuild.

Colin Rose delivering a seminar at the CLT pavilion

The timber connections are designed to facilitate future disassembly, upgrade and reuse. Product passports maintain a digital record of key information, stored on Madaster’s platform. We hope to identify a longer-term site for the pilot, where it can continue to inspire conversations about circular construction and find a new practical use. So far it has retained its original form, but it could be upgraded for external use, extended to form e.g. the entrance to a larger building, or taken apart and the components used in a different form. When no further reuse is possible, the timber can still be recycled into panel products (e.g. chipboard or MDF) then finally incinerated for energy.

The project has been carried out in partnership with Portakabin, and with the support of a range of brilliant collaborators. Since 1961, Portakabin has been at the forefront of construction innovation, pioneering modular construction as a smarter way to build. Over the years, the company has changed, adapted, and grown, but always with the aim of making a better future by reusing and repurposing its products and buildings. Now as the world faces enormous climate challenges, Portakabin is preparing to play its part by looking at new and innovative ways to increase circularity in its business model.

In-kind support has been gratefully received from:

Project collaborators:

This work was supported by the Engineering and Physical Sciences Research Council.

Research papers

Rose, C.M., Breidenbach, J., Quinn, P., Stegemann, J.A., 2025, Pilot project: Modular construction with secondary materials in a circular economy, in: 14th World Conference on Timber Engineering 2025 (WCTE 2025), Brisbane, Australia. pp. 3789-3798. https://doi.org/10.52202/080513-0463.
Godina, M., Gowler, P., Rose C.M., Wiegand, E., Mills, H., Koronaki, A., Ramage, M., Shah, D., 2025, Strategies for salvaging and repurposing timber elements from existing buildings in the UK. Journal of Cleaner Production. https://doi.org/10.1016/j.jclepro.2024.144629.
Dong, W., Rose, C.M., Stegemann, J.A., 2024, Cross-Laminated Secondary Timber: Validation of Non-destructive Assessment of Structural Properties by Full-scale Bending Tests. Engineering Structures. https://doi.org/10.1016/j.engstruct.2023.117029.
Breidenbach, J., Rose, C.M., Quinn, P., Stegemann, J.A., 2024, CascadeUp: Extending the life of reclaimed solid wood through reuse in the manufacture of mass timber products, in: 20th Annual Meeting of the Northern European Network for Wood Science and Engineering, Edinburgh, Scotland. Available from: https://wsenetwork.org/cascadeup-extending-the-life-of-reclaimed-solid-wood-through-reuse-in-the-manufacture-of-mass-timber-products/.
Romero, A., Rose, C.M., Stegemann, J.A., 2020, Quantification of material stocks in existing buildings using secondary data—A case study for timber in a London Borough. Resources, Conservation & Recycling: https://doi.org/10.1016/j.rcrx.2019.100027.
Rose, C.M., Stegemann, J.A., 2019, Feasibility of Cross-Laminated Secondary Timber, in: Claisse, P., Ganjian, E., Naik, T. (Eds.), Fifth International Conference on Sustainable Construction Materials and Technologies (SCMT5), Coventry, UK: Vol. 1, pp. 495-507. https://doi.org/10.18552/2019/IDSCMT5053.
Rose, C.M., Bergsagel, D., Dufresne, T., Unubreme, E., Lyu, T., Duffour, P., Stegemann, J.A., 2018, Cross-Laminated Secondary Timber: Experimental Testing and Modelling the Effect of Defects and Reduced Feedstock Properties. Sustainability. https://doi.org/10.3390/su10114118.

Other publications

Rose, C.M., Isaac, P., 2024, Reusing wood from demolition in mass timber products, in: The Structural Engineer: 102, 6, 36-38, https://doi.org/10.56330/XBQF7968.
Morales Rapallo, A.C., Doostdar, M., Rose, C.M., et al., 2024, D4.2 Achieved reuse, refurbishment and recycling quota energy and resource balances and cost analyses for the demonstrator cases. Available from: https://www.circuit-project.eu/post/latest-circuit-reports-and-publications (accessed 12 July 2024).
Rose, C.M., 2024, Ask the expert: Timber reuse, in: Architecture Today. May/June, 78. Available from: https://architecturetoday.co.uk/ask-the-expert-timber-reuse/ (accessed 12 July 2024).
Rose, C.M., 2020. Waste wood project promises greener CLT, in: RIBA Journal, Products in Practice, 16 September. Available from: https://www.ribaj.com/products/clt-from-waste-wood-ucl-reusing-secondary-timber-colin-rose (accessed 12 July 2024).

Featured in

Jervis, J., 2025, Why is secondary timber still secondary? In: RIBA Journal, 11 June. Available from: https://www.ribaj.com/intelligence/circular-economy-biomaterials-cross-laminated-secondary-timber-uk-clt?utm_source=linkedin&utm_medium=social&UTM_campaign=70967f82-bb6c-4093-9f2c-577ed25deb88
Mass Timber Group Show, 2025, UK CLT: Cross-Laminated Secondary Timber Pioneers, on Sustainable Building Experts Podcast, 24 April. Available from: https://www.buzzsprout.com/2203045/episodes/17028544
Cousins, S., 2024, Structural timber prototype uses 100% waste from demolition, in: RIBA Journal, 26 July. Available from: https://www.ribaj.com/products/structural-timber-prototype-uses-waste-from-demolition-ucl-circular-economy.
Ramsay, G., 2024, New Ways to Use Timber, in: Structural Timber Magazine, Autumn. Available from: https://issuu.com/radarcommunications/docs/st_mag_issue_37_autumn_2024_web.
Wolf, J.R., 2024, Mass Timber Prototype Demonstrates Value of Demolition Materials, in: Green Building Advisor, 17 December. Available from: https://www.greenbuildingadvisor.com/article/mass-timber-prototype-demonstrates-value-of-demolition-materials.
World Green Building Council, 2023, The Circular Built Environment Playbook. Available from: https://worldgbc.org/wp-content/uploads/2023/05/Circularity-Accelerator-Playbook_2023.pdf (accessed 12 July 2024).
Cheshire, D., 2021, The Handbook to Building a Circular Economy, RIBA Publishing, 2nd edition.
Institution of Civil Engineers, 2020, Material gains, in UN75: Sustainable Engineering in Action, Artifice Press.