Prefab housing is coming back, and this time it's permanent
A new wave of off-site construction is bringing new efficiencies to housebuilders' bottom lines by delivering eco-friendly homes in double quick time, as Sean Smith, Director of the Institute for Sustainable Construction at Edinburgh Napier University, explains.
In the late 1950s, more than a decade after the war and not long after the rock and roll explosion, Britain embarked on a house-building programme the like of which we have never seen before or since.
There was suddenly a need for more than a quarter of a million new homes each year as new towns were built to replace the old slums and families sought extra space to accommodate the baby boom. To meet this, large numbers of houses were built in factories and then assembled on location.
These prefabs (“pre-fabrications”) came to be as closely associated with the next few years as Billy Bremner or the Beatles. In truth, this was actually something of an exaggeration, since they never comprised more than 15% of new builds in an era where the high rises were a bigger game changer.
In the early 1970s, prefabs suddenly went out of style, with high rises not far behind. The need for such speedy building had reduced. Insurance companies had begun refusing to insure them as it became clear that there were so many problems with the construction techniques that they would not last nearly as long as people had hoped. Suddenly new homes comprised blocks and bricks and were between two and four storeys in height.
From Langley Park to Motherwell
Yet whisper it, pre-fabrication is making a comeback – though these days it is always known as off-site construction. If the momentum keeps increasing, it is going to come to dominate house building across the UK and possibly elsewhere in a way that never happened in the 1950s and 1960s.
Scotland has been leading the way. Partly this is thanks to timber frame housing, which is much more extensive north of the border. Timber frames became popular in Aberdeenshire in the 1980s to satisfy the nascent oil and gas industry, and then gradually spread to other parts of Scotland.
From the early 2000s, framing companies began merging with other players such as insulators and gradually took advantage of their new strength in depth to move into building kit houses offsite. By the pre-recession peak of 2007, off-site new build had grown from under 10% of all new Scottish houses to between 25% and 30%.
By that year, the total number of new houses being built in the UK was around 200,000. Then it fell to just over 110,000 as demand collapsed. After a few lean years it is on the up again (see image), fuelled by the UK Government’s Help to Buy scheme.
But most experts agree it is going to have to grow much more quickly if we are going to satisfy demand for the future. The UK Government estimates that we will need to build 260,000 houses each year in England and Wales between 2015 and 2031 and 35,000 each year in Scotland.
Housing booms past and future. Edinburgh Napier
Not only are these targets way ahead of what we were building even during the pre-recession peak, there are various other pressures on construction:
replacing skilled workers who have left the industry sector during the recession and are not returning;
high average age in some lines of work, meaning increasing retirement rates;
large amounts of refurbishment to existing housing stock;
delays to utility connections on work sites;
pressure on prices and workers from demand from other sectors such as oil and gas and major infrastructure works for rail, road and power stations.
When building breaks down
Many people believe that offsite is the answer. According to case studies by Build Offsite, the sector body, the savings include a 10% to 15% reduction in the cost of building; and a 40% reduction in vehicle movements.
It also helps with builders’ mounting energy performance requirements. House building has been put under the microscope in recent years to figure out where improvements can be made – for example one recent research area has been improving buildings’ external insulated fabric.
Off-site manufacturing helps with this because it gives builders more control over each stage of the construction process. It also means you can reduce waste and have better control over the types of waste being generated, while implementing techniques popular with other sectors such as just-in-time delivery.
To take advantage of this potential, leading house manufacturers such as Kingspan, CCG and Stewart Milne have been investing heavily in facilities during the recession years.
Kit homes: the comeback
Inspired by the lean construction models of car manufacturers such as Ford and Toyota, plants have emerged or expanded in places like Glasgow, Manchester, Aberdeen, Derby and Motherwell. Off-site now comprises between 15% and 20% of house building in England and Wales, having moved beyond timber frames to various other materials; while in Scotland it is now over 50%.
CCG’s offsite factory near Glasgow. Edinburgh Napier University
With the help of the likes of the future Construction Scotland Innovation Centre, which brings together academics and researchers from 11 universities, these manufacturers are developing increasingly advanced assembly techniques that will include smart technology, intelligent membranes and even nanotech. To reflect these new technologies and systems some believe the the off-site sector may change its name to Advanced Construction.
The proportion of off-site construction is only going to keep growing. It is likely that by 2017, more than 70% of new Scottish homes will be built in this way, while the rest of the UK will show the same upward momentum. Some of the UK’s leading players are also attracting interest from China, Europe, Brazil and Russia, where this segment has yet to take off.
Having got off-site construction so wrong the first time around, this time promises to be very different. Just do the building industry a favour: don’t call it prefab.
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