Is off-site manufacture the answer?

by Paul Simms

Housing demand in the United Kingdom has risen sharply over recent years. An increasing population coupled with a consistent decline in the rate of occupancy per dwelling means that the government needs to urgently look at ways to increase the output of the house-building industry from 100,000 to over 140,000 homes per year.

A recent report commissioned by the government looks at the feasibility of using off-site manufacture to address the shortfall in housing demand in the UK.

But it isn’t the first time that off-site construction has been on the government’s agenda and there are mixed feelings about whether things will be different this time around.

So what is off-site manufacture? Essentially it is the process of breaking new buildings down into pieces or modules that can be independently manufactured in a factory and then installed on the project site. Of course, we already use off-site manufacture in construction all the time. We frequently specify pre-manufactured doors or windows, for example, but it doesn’t have to stop there. Entire roofs or building segments can be completed in factories and lifted into place on site. It seems that the more we can build in the factory and fit onto each module before they are delivered, the less time will be spent on construction.

Modular pods in construction  Modular pods in construction Modular pods in construction

Although quality, sustainability, waste, and health and safety are also major contributing factors, the primary advantage of off-site manufacture over traditional building methods is speed. Modular construction streamlines the programme by splitting the work between multiple building sites at the same time.

Our Hammersmith Palais project uses off-site manufacture on a large-scale to deliver around 400 student bedrooms. Because we starting manufacturing the bedroom modules in the factory early in the programme whilst simultaneously starting ground works on the project site in Hammersmith, the contractor is on track to realise a three-month saving on the programme compared to using traditional build techniques. Our client’s decision to use off-site manufacture was led by the need to get the building operational in time for the intake of students in autumn.

Modular pods on site

But off-site manufacture isn’t a cheap option and considerable further investment is required. Still in its infancy in this country, this method will require a significant boost to meet future demands, particularly as the availability of traditional building skills is on the decline.

There is a learning curve associated with it that will have its own price tag and there is currently a shortage of firms who have the necessary skills and resources to deliver large volumes of pre-fabricated buildings. It is foreseeable that the economies of scale that off-site manufacture could create may begin to offset the additional cost when applied on a countrywide scale.

An understanding of off-site manufacture needs to be integral to the design process to ensure that our future homes don’t look repetitive and uninspiring. The process of off-site manufacture is well suited to the way that buildings are designed and detailed in digital space. CAD and BIM enable us to design and visualise buildings which can then be “printed” in three dimensions in the factory, so both the design and construction sides of the built environment industry are moving towards this approach.

In order to meet the target set by the Code for Sustainable Homes for all new homes to be zero carbon by 2016, house builders are already being forced to look at alternative ways to design and construct homes over the coming years. Private developers, Registered Social Landlords and other land owners are already factoring in the costs of achieving these codes in the acquisition of sites.

Is the industry ready to tackle these targets? Possibly not. But what is certain is that modular construction will play a significant role in implementing these targets over the coming years.

Follow Make partner’ Paul Simms on Twitter: @prsimms
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3 thoughts on “Is off-site manufacture the answer?

  1. Off Site Manufacture has been around for a long time, and has taken off in some areas where it has been suitable in every aspect of the process for procurement of new buildings.

    The problem is that some areas of the construction industry other factors can make it uneconomic, as I found out when working in rural affordable housing.

    In order to create sufficient volume to be profitable in bulk, OSM relies on a reliable programme of delivery of units, which should be predictably similar.
    In rural affordable housing this is difficult.

    Firstly, the housing need is spread out in small sites of fewer than 50 units, often fewer than 10.

    Then each site has to achieve planning consent separately, which is a long, arduous and drawn out process with many stakeholders. Frequently the position of windows or the layout of a site changes several times as the various parties, politicians, parish councillors, planning officers, all jostle to get what they consider to be policy enacted.

    And then the process of delivering large prefabricated units (anything that has to fit on an oversize flat bed lorry, for example) to relatively remote rural locations, each one different, can also scupper the likelihood of profitability for an industry that needs to invest heavily in advance.

    On the other hand, in easy to access, larger central sites with larger projects such as large units of flats on an urban site next to a major road, none of these problems would be an issue, and so chain hotels routinely use OSM and have been doing so for years.

    So my answer is no, Off Site Manufacture isn’t the answer, at least, not all of the time. Some people (who of course won’t be named) have lost a whole lot of money thinking it was the solution.

  2. Hi Su,

    Very valid points there and we have to agree that off-site manufacture still has a long way to go to make it economically viable and a more practical solution for rural areas, as you say.

    However the speed that off-site manufacture offers along with its quality, sustainability, waste and health & safety advantages means that if the investment comes, it can certainly help in achieving the government’s house-building goals, albeit in more urban areas.

    Overall, it’s just one solution of many that should all be looked at to meet the housing demand.

    Thanks for taking the time to comment!

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