Case Study - Recovering Steel for Reuse at 20 Giltspur Street
Project summary
The redevelopment of 20 Giltspur Street in London, managed by Deconstruct UK, represents a pioneering approach in sustainable construction. This ambitious project includes structural modifications to the existing building and the addition of new features, aiming to maximise net usable space while significantly reducing the carbon footprint. The renovation retains two-thirds of the original structure, preserving much of the existing fabric, and introduces advanced construction techniques such as floor jacking, steel reuse, and composite floor slabs.
Building background
Constructed in the late 1990s, the original six-storey building featured a steel frame and metal deck structure, including a ground floor, basement, and a rooftop plant room. It was designed for commercial use by the Bank of America. Planning restrictions due to its location near St Paul’s Cathedral and the presence of a section of the London Wall, a scheduled ancient monument in the basement, limited conventional options for expanding the building’s footprint or height. This unique context prompted a creative redevelopment strategy.
Structural alterations and innovative techniques
The redevelopment sought to capitalise on the building’s high ceilings (5 metres) across the first three floors, creating a seventh storey by jacking up the existing floor slabs. The process involved lifting the first and second floors by approximately 1.5 metres each to become the new second and third floors. The floor jacking process utilised 75 hydraulic jacks to raise each floor incrementally by 250 mm, ensuring a controlled lift and smooth transition. The lifting took around three days per floor, followed by three weeks for securing and reconnecting with new perimeter beams. Deconstruct UK has invested in jacking equipment, indicating plans to employ this technique in future projects.
Project information
Project name | 20 Giltspur Street |
Location | London |
Project type | Commercial |
Amount of steel recovered for reuse | 50 tonnes |
| Client | Simten |
| Structural Engineer | Elliott Wood |
| Architect | Buckley Gray Yoeman |
| Demolition contractor | Deconstruct UK |
| Steel Stockholder | EMRÂ |
Recovering steel for reuse
The reuse of steel was integral to the project’s sustainability goals. The following outlines the approach taken for steel recovery:
Pre-demolition planning and identification
Before commencing demolition, Deconstruct UK, along with Elliot Wood, conducted an audit to identify steel sections suitable for reuse. This helped set realistic targets for reclaimed steel and ensured alignment with sustainability goals. There was no existing building information, so a point cloud survey was undertaken and then input into the Tekla system. This proved to be very accurate, with a tolerance of 5mm, and an invaluable tool in undertaking the work.
Steel removal process
Steel sections were recovered by cutting at the ends with oxy-gas torches and lifted using manual chains or cranes where feasible. The use of tower cranes was limited due to space constraints, and positioning a spider crane within the site would have been difficult and time-consuming. As a result, most of the steel handling was carried out manually using chains for lifting. The tower crane was used only for the two-storey extension, which serves as a plant room.
The process of reusing the steel did not require any additional labour, as the building would have been demolished regardless, nor did it necessitate extra equipment. Manual methods were used throughout the project due to the restrictions of the floors above, which limited full crane access.
Cleaning and preperation for reuse
Shear studs were removed using grinders to prepare the steel for reuse. Some sections were transported to EMR for further reprocessing, such as length adjustments and the removal of remaining shear studs. The steel was then blasted, which was a labour intensive process. Afterwards, it was primed, and intumescent paint was applied for fire protection. Service holes were plasma-cut as needed, with additional holes cut during installation to accommodate changes in services, although this could impact future reuse potential.
Logistical considerations
Temporary on-site storage was arranged to hold the steel until it was ready for transport to EMR. The steel was stored until a full lorry load (approximately 18-20 tonnes) could be accumulated, which helped minimise transportation costs and ensured the efficient management of the reclaimed materials.
Amount of steel recovered and reused
Around 140 tonnes were recovered for reuse, with 50 tonnes reused on the same site and 90 tonnes sent to EMR for reuse in other projects and recycling.
Early engagement and coordination with key stakeholders
Early collaboration was essential, with Deconstruct UK working closely with Elliot Wood to determine the feasibility and scope of steel reuse. This partnership involved developing the jacking scheme and discussing the reuse approach during the tender process. Regular coordination meetings ensured that the project stayed on track, with progress monitored, material conditions assessed, and decisions made on processing and reinstallation steps. Early engagement with suppliers and contractors was also instrumental in maximising reuse opportunities and efficient implementation.
Procurement and setting realistic targets
Procurement is a key factor in reuse, especially in minimising logistics and storage. It is important to decide early whether reclamation and reuse are feasible, and to set some initial targets. The necessary supply chain should be appointed as early as possible to support these efforts. Reuse targets were set based on a pre-demolition audit, which helped establish achievable goals for the amount of steel to be reused.
Retaining and reusing additional materials
Approximately 80% of the original steel frame and 70% of the concrete were retained in the renovation. The retention of these materials resulted in a substantial reduction in embodied carbon, compared to a traditional demolition and rebuild approach. Portland stone was reclaimed for future use, following assessment using ground-penetrating radar. Plans to incorporate brick rubble into terrazzo flooring were considered, although final decisions on quantity and supplier need to be confirmed.
Economic and environmental impact
By retaining much of the original structure and incorporating innovative construction techniques, the project achieved significant environmental and economic benefits. The project avoided the need for off-site dismantling and refabrication, thus reducing transportation emissions, noise, and dust. This approach also achieved savings of £2 million and 30 weeks in the construction programme. Furthermore, there is an uplift of reusing steel in comparison with recycling. The average price for reclaimed steel was £320 per tonne, compared to £270 per tonne for scrap.
Lessons learnt and recommendations
- Deconstruct UK noted that all their clients are now requesting steel reuse, a trend that was previously driven by architects and engineers but is now increasingly client-driven.
- Given the rising client demand for reclamation and reuse, setting clear and measurable targets for material reuse should become standard practice across projects.
- It is crucial to establish achievable targets for reclaimed materials. In some cases, targets have been set too high, making reuse impractical due to factors such as material grade or availability. Flexibility is essential to adapt to these limitations.
- Early engagement with the supply chain is vital for maximising reuse opportunities and ensuring that reclaimed materials are available when needed.
- For more efficient material flow, consultants need to improve their ability to match reclaimed materials between different projects. Engineers should also deepen their understanding of the materials present in the buildings they work on to identify more reuse opportunities effectively.