The advanced off-site manufacturing system, Design for Manufacture and Assembly, was used to build the Cheesegrater in London and is now helping deliver the next generation of UK hospitals faster, safer, and to higher levels of design quality than ever before. Stephen Cousins reports
Main contractor Laing O’Rourke has pumped over £100 million into its proprietary off-site fabrication technology Design for Manufacture and Assembly (DfMA), which has been used to build a range of high profile projects, such as the £340 million Leadenhall Building in the City of London, also known as the “Cheesegrater”, Crossrail’s Custom House overground rail station, and projects for Hong Kong’s Mass Transit Railway. Less well known are the pioneering healthcare projects currently being delivered using DfMA, much faster, safer, and to a higher level of quality, than traditional construction methods. These include the £160 million Cancer Centre at Guy’s Hospital, designed by architects Rogers, Stirk, Harbour + Partners, where over 50 per cent of the structure is being delivered using DfMA. And Liverpool’s £237 million Alder Hey in the Park children’s hospital, designed by BDP, which when handed over in June, is set to become the fastest hospital ever built in the UK, constructed in just two years. DfMA was launched in 2009 and initially focused on pre-fabricating precast concrete components, such as columns, beams and floor plates, but it now includes a range of solutions from fully glazed, sealed and serviced components to modularised M&E systems and facade treatments, all digitally designed in BIM. In 2012 the contractor made DfMA its core delivery methodology and now aims to embed the technology into projects at the earliest design stage. The system offers several benefits to hospital projects: hospital construction programmes are typically very long and DfMA can help to speed delivery, Laing O’Rourke often targets a 30 per cent improvement on programme with over 70 per cent of the structure delivered using DfMA. Hospitals incorporate an array of complex services including data communications, clinical and security equipment, and combining them into modules in a factory helps improve services coordination, quality and reliability.
Leonardo Pelleriti, associate and site architect for the New Cancer Centre at Guy’s at RSHP told ADF:
“At Guy’s Cancer Centre, the main advantages have been around speed of construction and health and safety, particularly on steel work, using prefabricated modules means you don’t have people doing connections at height. On this building, DfMA has eliminated the need for scaffolding, it has also definitely improved quality. It is all about making the construction site more efficient, secure and cost efficient.”
DfMA is typically introduced into hospital design during the bid stages of projects, Laing O’Rourke works in collaboration with design partners, such as BDP, NBBJ and RSHP, to identify how the technology can add value, considering various performance criteria and the geometric constraints. Alder Hey in the Park, a design & build PFI, for client North Staffordshire NHS Trust, was planned to incorporate DfMA from the outset. The hospital is like no other hospital in Europe, located at the centre of a Children’s Health Park designed to improve patient health and wellbeing, it will also features much larger theatres and patient bedrooms than previous schemes. The three main sections of the building reach out like fingers into the parkland, the facades were delivered to site in large bay-sized panels, of up to 20 tonnes each, pre-installed with windows, cladding, insulation and internal plaster boarding. Once delivered, the panels were simply lifted into position by tower crane to quickly create a sealed and weather-tight structure. This approach removed the need for men working at height (panels were fixed from inside building so no scaffolding was required on the job) and the need for large numbers of follow on trades.
“We’re including the same elements you would find in any hospital, but taking processes off-site and automating them in a factory environment,” said Stuart McArthur, health sector leader at Laing O’Rourke. “Hospital guidance includes strict Health Technical Memoranda and Health Building Note requirements for infection control in terms of how buildings are put together, so the key innovation has been finding ways to deliver them in a more productive, efficient and quality controlled way.”
The maximum size of DfMA components is limited by a combination of structural requirements and ease of transport on the British road network. Alder Hey in the Park was designed with a finished floor to floor height of 3.74m, based on the maximum panel size that could be produced, which meant services had to be cleverly designed to fit inside thin ceiling voids. The lower levels of the building are more heavily serviced, incorporating accident and emergency, critical care and surgery departments, so a two-panel system was devised comprising a 3.74m panel stitched to a 0.76m panel to create the deeper floor-to-floor levels required.
“When this project was designed, DfMA had never been used in healthcare to such a great extent before,” said Ged Couser, architect director and healthcare leader at BDP.
“All the wet and dry M&E services were prefabricated in the factory , delivered in five to ten metre-long modules and plugged together on site, which massively speeded up the process.”
The Cancer Centre at Guy’s Hospital is an ambitious 14-storey building designed to bring together the majority of the hospital’s cancer care and research estate under one roof. It comprises a number of stacked ‘care villages’, each one relating to a particular patient need, such as chemotherapy, radiotherapy or the one-stop clinic, and with its own distinct identity. Breaking the building up into two-, three- or four-storey chunks is intended to introduce a human scale, making orientation easier. Each village centres on a ‘square’, a non clinical space including a planted external balcony and informal seating and relaxation areas for patients. Most of the building’s structural and non-structural elements are being fabricated off-site, including the main structural external shear walls, known as “twin walls”, which are delivered to site pre-installed with insulation and precast concrete with a high quality concrete finish. Engineering Excellence Group, Laing O’Rourke’s in-house team of experts set up to innovate new construction methodologies, developed several structures for the hospital including the E6 floor slab, which comes to site pre-installed with reinforcement, requiring no in situ concrete pours. In addition, a 12-storey steel frame plant tower, located on the back of building, is being assembled in sections off-site pre-installed with all the services. The finished building will feature a large amount of exposed concrete, making pre-cast the ideal solution for a quality finish.
“This building is comparable to “Lego” construction and the innovation was in resolving very complex structural concrete details at the joints between different components,” said Leonardo Pelleriti at RSHP.
Off-site modular construction has been criticised in the past for limiting the creative options available to architects. But recent hospital projects completed using DfMA challenge the traditional notion that pre-fabrication must stand for bland repetition and monotony. Alderhey in the Park is geometrically very complex, featuring numerous curved walls and flowing green roofs that cascade down toward the park like waves on a beach. BDP wanted the building to appear as if it had emerged from the ground and designed the facades to mimic the rock strata that can be seen in the train tunnels when entering Liverpool Lime Street station. To create this effect, Explore Industrial Park, Laing O’Rourke’s manufacturing facility in Steetley, Nottinghamshire, used just three different concrete moulds, set in different orientations to create 1,200 different panels in four shades of sandstone red. Only 18 facade panels across the entire project are identical.
“BDP found it a hugely enjoyable process looking at the differences of texture that can be achieved with a limited number of moulds, and how spinning or flipping them, you get what appears to be a random pattern, but retain the efficiency of a repeating design,” says McArthur at Laing O’Rourke. “The architects we work with are not interested in people trying to constrain their creativity, they want hospital buildings to have a civic presence and a feel of quality in the way the facades relate to the environment.”
Similarly, at the New Cancer Centre at Guy’s Hospital, DfMA prefabrication helped RSHP create cut backs and external terraces that bring in light and allow people to sit outside, which also helped articulate the building and make it less institutional from an architectural perspective. Many of the DfMA innovations introduced at Guy’s and Alder Hey hospitals will be taken on a stage further on future healthcare projects awarded to Laing O’Rourke and it’s consortium partners.
“We’re currently developing designs for the 19,000 sq m Clatterbridge Cancer Centre in Liverpool, due to start on site in June 2016,” said McArthur.
“This will include extensive DfMA, but developing the technology and moving it on. The urban site is driving us more towards a completely unitized approach, to avoid disruption on the roads and complete construction within the two-year timeframe. In addition, we plan to use Smartwall, Laing O’Rourke’s fully prefabricated internal partition wall solution, for the first time on a UK hospital.”
In addition, DfMA will be implemented on a £270 million acute district general hospital for NHS Dumfries and Galloway. High Wood Health, a consortium that includes Laing O’Rourke and design partners Ryder Architects and NBBJ, was awarded the construction contract in March this year.