1 June 2022 · By Fran Williams

Source: McGregor White Architects/AHR

Source: McGregor White Architects/AHR

Source: McGregor White Architects/AHR

Source: McGregor White Architects/AHR

Source: McGregor White Architects/AHR

Source: McGregor White Architects/AHR

Source: McGregor White Architects/AHR

Source: McGregor White Architects/AHR

Source: McGregor White Architects/AHR

Source: McGregor White Architects/AHR

Steve White, director of McGregor White Architects, and Wai Lun Ho, director of AHR, discuss their AJ Retrofit Award-winning project – Chris Payne House, which they moved across London in June 2020

In recent years there has been a growth in the development of modular homes that have been designed from the outset to be relocatable to a new site – particularly for the provision of affordable homes. There are many determining factors at play: from shortages of skilled labour, efficiencies of production time, quality assurance, to considerations of sustainability and the circular economy.

But the case of Chris Payne House set a new precedent: its disassembly in one London borough and relocation in another demonstrate various instructive lessons that could be applied to a new wave of re-usable modular homes.

The original building, designed by AHR for registered provider Hyde Housing, was completed in 2005 on land leased from the London Borough of Southwark. The building used volumetric and modular construction techniques to provide flexible, demountable and relocatable affordable homes. The modules were constructed by BUMA, a fabricator based in Poland.

In 2018, Southwark required the land back, as the lease was ending. Hyde had the options of either demolishing the building, moving it to a new location, or selling it on to a new owner. Fortuitously, the London Borough of Ealing at this time had several potential locations for such a project and was interested in purchasing the building to be used as temporary accommodation for families in emergency need.

AHR was once again commissioned to initiate a planning application for the relocated homes, which were renamed in honour of a former Ealing councillor who died in 2014. McGregor White Architects was then appointed for post-contract services and as contract administrator for the disassembly and relocation 12 miles away in Hanwell, as well as executing the refurbishment and adaptation of the scheme from 18 one and two-bedroom apartments into 16 one, two, and four-bedroom apartments.

The re-use of Chris Payne House sets a precedent in preserving the embodied carbon of original construction and providing a flexible solution to housing on meanwhile sites before being transferred to alternative locations when required.

But what happens when the time comes for those buildings to be relocated? Is it practical and what are the challenges in the design, planning and logistics of re-siting an existing building on a new site?

There was no playbook to follow … the team had to develop the plan from first principles

As far as we could ascertain, a residential apartment building like this had not been relocated before. There was no playbook to follow in how to deliver this type of project, so the team had to develop the plan from first principles.

To design and plan the move, members of the team which delivered the build in 2005 were called upon to join the new project team and, luckily, all were available and willing to accept the challenge, including the original QS, who came out of retirement to be part of the project. This enthusiasm and commitment proved essential, as there was much retained knowledge and nuggets of information that were not communicated in the ‘as built’ drawings. It demonstrated the importance of having access to reliable building information for future relocation projects.

Designing the building to be as flexible as possible, and seeing policy or building regulations as a base line to be exceeded, rather than a target to be met, certainly helped the project, too.

This flexibility helped address the question of whether the relocated building should be treated as a new build, or a retrofit project. When dealing with Building Control, planning and various other stakeholders, this question had the potential to become a troubling grey area.

The enhanced standards the building was already designed to, and its adaptability, helped minimise the uncertainty and the stakeholders were able to negotiate appropriate approaches. In the event the building was treated as a mixture of new build and existing, and agreeing this approach early on was the key to successfully helping to define the brief.

Transporting an entire building on the back of lorries 12 miles across London was a complex logistical operation. The project team included logistics experts and hauliers to ensure it was completed safely and efficiently. The building modules needed to arrive on the site in Ealing in the correct order, which wasn’t necessarily the order they had to be dismantled in. The team also had to think about maintaining the building’s stability through disassembly and reassembly, in addition to factoring in the weather and London’s traffic.

It all amounted to a huge juggling exercise. After months of planning, the demounting, transportation, and reassembly of the building took 18 days from start to finish. The subsequent refurbishment took a further four months.

Within days of handing over the building, families began to move into their new homes. The London Borough of Ealing was extremely satisfied with the speedy delivery of the project, which took less than half the time of delivering an equivalent new building.

The relocation and refurbishment saved 219.5 tonnes of embodied carbon compared with a new equivalent building

Relocation of modular homes is certainly something to consider in future from a sustainability point of view. More than 95 per cent of the material in the original building was re-used in the relocated building. Our calculations showed that the relocation and refurbishment saved 219.5 tonnes of embodied carbon compared with the construction of a new equivalent building on the same site – even when factoring in disassembly, transport and the new concrete foundations.

The refurbishment and retrofit of the homes also included new and upgraded heating and hot water systems, low-energy lighting and electric fittings, and a solar PV installation, which together reduced in-use CO 2 emissions by 53 per cent. The cost for the client was considerably less than that of a new build, estimated at just 40 per cent of the cost of an equivalent, as well as being delivered in half the time.

Chris Payne House has already borne fruit with a successor project. McGregor White Architects is now working with the Pan-London Accommodation Collaborative Enterprise (PLACE), a development company owned and supported by four London boroughs, to develop relocatable modular homes for temporary accommodation for use on meanwhile sites.

And AHR continues to develop and advance BIM workflows to aid in the design and modelling of prefabricated building modules and elements, most recently demonstrated in its Gillender Street housing project for Mount Anvil in Tower Hamlets.

Tags chris payne house In practice McGregor White Architects Prefabricated housing

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