It’s been a long time coming but offsite construction methods and, by extension, timber construction, is being brought into the public arena thanks to media coverage of the government’s focus on solving the UK housing shortage.
BBC News, for example, has run a series of reports into offsite manufacture and modular construction, including a look at the Treet multi-storey apartment building in Bergen, Norway and an interview with architect and structural timber aficionado Andrew Waugh.
In December, the BBC and other media organisations reported on the news that the China National Building Material Company has formed a joint venture with housing association Your Housing Group and renewable energy specialist WElink to build six offsite factories around the UK. The £2.5bn deal, which the government helped broker, is set to deliver 25,000 “prefabricated” homes over the next five years.
Reports suggest these will be steel-framed but the move does at least indicate the government’s intention to bring offsite construction into the mainstream.
UK housing minister Gavin Barwell (appointed only last July) has thus come into pole position at a key time. A housing white paper has just been unveiled and will be the policy blueprint for how the government is going to be meet the housing demand. It follows last year’s Farmer Review, which identified offsite manufactured housing as a way to help meet the demand for new housing.
The UK construction sector suffered a sharp fall in the immediate aftermath of the Brexit vote in June but while some parts of it remain flat, by the early autumn housebuilding had recovered. Construction data provider Barbour ABI reported that the residential sector in October “unexpectedly reached a massive £2.3bn-worth of construction contracts on the month” – an increase of 34%.
Taylor Wimpey and Persimmon both reported growth in their order books, with the latter reporting a 19% sales rate increase. In November, housebuilder Redrow noted that housing was up 8.7% in the third quarter, when compared with the same period in 2015 and its chief executive officer, John Tutte, said the year-on-year figures revealed a “much-improving picture for housing”. Market analyst IHS Markit also hailed a strong rebound in construction output during the final quarter of 2016, noting that housebuilding remained a key engine of growth. It said the latest upturn was the fastest growth for almost a year.
This comes as no surprise to Andrew Carpenter, chief executive of the Structural Timber Association (STA), and, as timber construction methods continue to gain market share, is encouraging news.
The STA’s recently published “Annual survey of UK structural timber markets”, prepared by Egan Consulting, reveals strong growth in 2015. Key findings were that UK housing starts overall were up 8.1% to 176,690 and that timber frame’s share rose to 27.6%.
The survey also forecast that housing starts would rise to 183,850 in 2016 (up 4.1%), with 56,500 of those being of timber construction (up 16.5%). Those figures are expected to rise this year and the prediction for 2018 is 201,300 house starts, of which 65,300 will be of timber construction. Market share is predicted to reach 32.4% by 2018.
The figures are significant, said Mr Carpenter and indicate the direction of travel the industry and the government is now taking.
“The government’s priority is housebuilding and using offsite manufacturing and that really puts us in the shop window because 85% of all offsite housing is timber frame.
“I have been in the construction industry for 40 years and I have never known a situation like this where everyone is singing from the same hymn sheet and saying that the solution to the huge housing deficit has to come from offsite construction.” STA’s survey highlighted the relative lack of new social housing in comparison to private developments – the public sector registered a 3.8% increase (1,200 units) in 2015 over the previous year, while the private sector registered an 8.6% increase (11,500 units) – but Mr Carpenter believes social housing will see “a significant upturn” over the next couple of years.
“For example, I know that some of the providers are looking to work with L&G Homes and when it comes into the sector it will have a really disruptive influence because it is looking to deliver 7,500 homes from its new factory in Leeds. If L&G is prepared to invest in the UK housing sector, it must see an opportunity here.”
Offsite construction specialist Stewart Milne Timber Systems has seen “significant growth”, according to Stewart Dalgarno, director of product development at Stewart Milne Group. He added that some of this growth had come from product substitution as developers moved away from traditional bricks and mortar while some was derived from constructors seeking cost effective and time efficient solutions. He also said that the re-emergence of local authorities as developers of affordable, low-cost housing presented a real opportunity for timber.
“The benefits of timber frame offsite construction are significant in today’s market where there is such a demand for volume housing.”
Another new and emerging market for Stewart Milne Timber Systems is in the private rental sector (PRS), with companies building large developments as rental propositions. “This type of project suits offsite as you are looking at longevity and whole life cycle costs,” said Mr Dalgarno.
“Speed is a key factor in the building of PRS developments, so timber frame and offsite construction suit this type of project.” Sales of the company’s Sigma II Build System have increased and there has been “a definite move towards closed panel systems and a particular drive towards pre-insulated and closed panel formats,” said Mr Dalgarno.
“We expect a push towards factory fitting windows and are developing this capacity, which we will offer within the next year. This is about vertical integration and suppliers working together. Buying a timber frame which is insulated and has a window fitted means it can be erected with the crane in one go and saves three separate processes.”
Engineered timber solutions provider Pasquill has also noted the growth in offsite construction and managing director Ross Baxter believes this will gain momentum over the next two or three years. Efforts are being made by Pasquill to promote the systems approach, he said.
The company offers several panellised roof solutions, for example – its own Pas-Roof, MiTek’s X-Rafter, James Jones’s JJIIntelliroof and a bespoke “Your-roof”.
“We have seen that some of the nationals are moving towards panellised roofs for two-and-a-half bed houses,” said Mr Baxter, adding that while it’s a growing part of Pasquill’s business it is still relatively small.
The company’s I-joist and metal-web joist offerings are commonly used in floor and roof solutions but less frequently in wall systems. One recent example of the latter, however, was in the first project in the UK to be built to “Multi-Comfort” standards – a concept launched in the UK at Ecobuild 2015.
JJI-joists were used in the roof of the new building at a Worcestershire school and also formed the stud walls, creating the ideal wall depth required for the insulation required to help the building achieve both Passivhaus and Multi-Comfort standards.
Jonathan Fellingham, managing director at Donaldson Timber Engineering (DTE), agrees there has been more interest in the offsite manufacturing and systems approach in the last couple of years, citing the skills shortage in the construction sector as a major driver. However, he says there are still barriers.
“Builders need to make a decision right at the planning stage whether they are going to use a traditional system or an offsite system,” he said. “At the moment developers will specify something that they then have to make timber frame fit. If they changed their approach and attitude at the outset [and specified timber frame] they would gain more benefits from the offsite solution. It’s probably a cultural thing – they are so used to doing brick and block.”
This cultural issue – which is something Andrew Carpenter also cites as a possible barrier – does put a slight question mark over the sustainability of any increase in offsite timber construction.
“There is still a resistance [to offsite timber solutions] and the approach by the majority of housebuilders seems to be that if their output is low it will all be brick and block and when output is high they want to prop it up with offsite solutions,” said Mr Fellingham. “It’s very cyclical. The government is certainly pushing it and if they can get the funding into the right areas then it can become more sustainable, but the fact that [housebuilders] can switch it on and off again creates cash flow issues within the sector.”
The cyclical nature of this business is reflected in DTE’s floor and roof cassette offerings. “When the timber frame kit manufacturers are really busy and maxed out on their own capacity they will sub some of it out, but when they aren’t busy they won’t – so we don’t rely on it.”
DTE’s I-joist and metal-web joists (Posi-Joists) are most commonly used in floor systems, said Mr Fellingham, with little or no uptake in wall systems. Metsä Wood tells a similar story that floors are still the biggest market for its Finnjoists and said the company’s SoundBar system, which incorporates the Finnjoist, was proving to be a very successful party floor solution in timber framed apartments, care homes and student accommodation.
He added that the use of Finnjoists in roofs was also increasing year on year as builders capitalized on the long spans that are possible.
“We have made joists as deep as 500mm, which not only span a long distance but also give a very deep insulation zone,” said sales director Matt Collins.
“There are projects coming through using I-beams in walls,” he added. “These tend to be more specialist Passivhaus-type builds, which require a high level of technical expertise and that we can offer on a project-by-project basis.”
Software and timber component provider MiTek Industries said sales of its Posi-Joist metal-web have grown by 50% in the last two years. The majority of this growth has been from its use in floor systems but its use in roof systems is also on the increase.
“A lot of this is down to Part L [airtightness] and Part F [ventilation] of the Building Regulations because more and more new houses will be built to the new regs,” said Roy Troman, sales and marketing director.
He added that customers’ reaction to MiTek’s PAMIR roof design tool had been “fantastic” and that, as announced in the company’s latest newsletter, the software program suite now incorporates Posi-Joist. Fellow software and component provider Wolf Systems has also seen demand for its design software increase, particularly its Horizon timber frame software.
“It’s the only timber frame software currently available that makes use of Autodesk’s Revit platform,” said Karl Foster, sales and marketing director. “Revit is really starting to gain traction in the construction industry.”
Mr Foster said that Wolf Systems would update customers on the development of its next generation truss and easi-joist design software “Fusion” this year. And, on the subject of easi-joist, he added that the company had launched an improved easijoist web – the WS250X.
“It features a redesigned profile with additional barbed nails giving an increase of over 20% in compressive and tensile strengths,” said Mr Foster.
“There was definitely a little wobble immediately after the EU referendum result but overall figures for this year and projected into next are very encouraging. In fact, 2016 was a record year in terms of production and sales of both nailplates and easi-joist for Wolf Systems.
“Buoyed up by the overwhelming demand for a greater number of homes, our customers – and their customers – remain very positive about the future.”
