Techrete were engaged to design, manufacture and install 1,170 precast concrete panels, covering 12,124 square meters of the façade of this prestigious project.
The Paul Marshall Building is located at an important corner of Lincoln’s Inn Fields with the civic prominence to operate at a district wide scale and provide a gateway for the whole School. London School of Economics envisaged the building as a welcoming, public-facing and highly sustainable building that contributes to the life of London.
What makes this project special is that the significant work on the architectural development of the façade completed by our design team using the Tekla model, ultimately defined the envelope of the building. The interlocking nature, the panel geometry, the numerous corners to the multiple elevations and the finishing process to these complex areas could only have been achieved with the expert use of a digital twin to facilitate both the design and construction of this prestigious project.
What were the challenges and what made the project successful?
The architectural detailing of the 'rain screen' façade system is complex, with each elevation presenting a different set of challenges and considerations for our Design Engineers. The North elevation essentially hosts a double façade with large outer fins bearing vertically onto the structure and the inner precast façade. At the higher levels, these double height fins are over-hanging and at the lower levels, they are both splayed and over-hanging, presenting a unique set of challenges in terms of how they are fixed to the structure.
The fins are 75% sitting on the concrete structure and over the 'Atrium' at levels five and eight, 14-metre steel beams support and restrain the fins. Deflections were considered in the design of the units and fixings to allow for the downward movement of the steel beams over time.
Bespoke brackets and fixings were designed in order to accommodate the outer fins, particularly at the corner of the North elevation, where a number of fins are supported and restrained off a relatively small area of the structure.
The bays and panels were rationalised throughout the structure wherever possible to account for panel weights, access to fixings and clashes with the window fixings. Additionally, the rationalised panels weighing up to 10.5 tonnes add to the sustainability of the project in terms of reducing the number of lifts and the time on-site.
The windows, insulation and firestop cavities were all installed in advance of the façade and considerable time and input from an Engineering perspective was dedicated to sequencing, avoiding clashes and ensuring access to fixings was achievable.
There were many design challenges on the project, in particular achieving the architectural visual requirements whilst maintaining the structural integrity of the precast elements. The modelling of the precast units and their associated fixings in Tekla allowed Techrete to communicate the design intent of the precast units to the project design team.
Another major challenge was the co-ordination of the precast system with the curtain walling system. When Techrete were issued a model of the curtain walling system, we were able to design the fixing locations to avoid clashes. Clashes did inevitably occur, but design solutions were agreed upon through the 3D model environment.
Numerous units were non-standard from a handling and installation point of view. Communicating the handling requirements from the Techrete design team to the Techrete installation team was challenging due to the complexity of the units and the variety of different unit types. Trimble Connect enabled pdf design documents to be uploaded and linked to the individual unit in the shared 3D model – this assisted with the successful installation of the units on the project.
What are you most proud of about the project?
We are proud of developing and designing the precast system through all the various stages of the project; from design concept through to the final design. This includes developing the individual units from 3D model to being cast in the factory and finally being erected into their final position on the building.
Creating a digital twin using Tekla empowered us to develop a highly complex façade for our client. It allowed us to run quick reports and discover clash detection, to import/export to different software easily and to navigate the approval process easily.
The project in numbers
- Total gross internal areas 18,000 square meters.
- Early works commenced July 2018 with the main design works commencing August 2019.
- Manufacture began in October 2019 and installation commenced in June 2020.
- Techrete to finish onsite in July 2021
- Estimated to be completed fully by December 2021 and in use by January 2022
- 1,170 precast concrete wall panels, flat panels, fins, beams, copings and soffits installed
- 12,124 square meters of the façade covered
- Panels weighing up to 10.5 tonnes
- Techrete cost approx. £6.2m
