Structural Timber Association – Written evidence (OMC0059)
Perceived advantages of offsite manufacture for construction
The housebuilding sector in the UK had an estimated £24bn of economic output in 2015 (HBF/NLP, 2014 base data), of which the timber frame manufacturers and housebuilders contributed £6.6bn or 27.4% of the total. Offsite manufactured structural timber system contributes circa 5% of all construction GDP and are a key contributor to the circa 750,000 employed in the construction supply chain. In comparison, construction provides more jobs than aerospace - 268,000; automotive - 247,000; chemicals and pharmaceuticals - 658,000.
What the Offsite Structural Timber Sector Offers
• The Government’s number one priority is the provision of housing and the Structural Timber Association, its associates and member companies are ideally placed to deliver the fastest response to this pent-up demand
• The Government has identified offsite manufacture as the solution to building more homes quickly, placing the structural timber sector as the ideal delivery partner
• Structural timber technology is the material of choice to enhance construction schedules, delivering cost and programme certainty, developing airtight and energy efficient buildings at a rapid rate - reducing capital and on-going running costs
• With the emergence of cross laminated timber (CLT) as a key building material, structural timber is now routinely being utilised in buildings of over four storeys and increasingly up to ten storeys with the capability to go beyond
• Current capacity is typically run on a single day shift only; making rapid increases in output by multi-shifting relatively easy to do.
• The timber sector is an engine of economic growth, with a presence in almost all UK counties, improving local economies by providing the wealth necessary to sustain them
• There is a willingness to lay down new manufacturing investment where demand is known
• The Structural timber sector has the capability to exploit the opportunities provided through standardisation and customisation
Architects, designers and engineers have to orchestrate a collaborative design protocol and help to conceive products for a manufacturing process, as well as know how to integrate them into a design. This re-skills rather than de-skills. They set the goals for the components within the design parameters, but offsite construction brings manufacturers and pre-fabricators to the fore. Manufacturers know how the materials and processes they use best come together, how to control waste and quality, and how to learn from previous experience. By understanding the purpose of each component and working collaboratively with the manufacturer, architects can take these virtues from the factory to the building. When architects realise and not all do, how to design for and with manufacturers, they can design buildings that are easier to build, less wasteful of resources, more enjoyable to use and more valuable to their owners.
2. It is often claimed that offsite manufacture can lead to:
• lower costs, faster delivery and increased quality;
• increased productivity;
• improved health and safety;
• greater provision of new, affordable housing.
What is the evidence for this?
Rider Levett Bucknall have just launched the preliminary findings of their Cost Comparison Report for Affordable Housing. The purpose of this report is to gain an appreciation of the comparative costs and establish the basis for a more detailed study. The report compared two build methods – timber Frame and masonry, for a typical affordable two storey housing design. The house type designs were prepared by HTA Architects with structural engineering input by Milner Associates. It is assumed that the foundation design is similar for both build methods. The detailed specification was included, and the drawings issued to four contractors to cost in both masonry and timber frame. The full report can be provided.
Potential barriers to wider use of offsite manufacture
3. What are the drawbacks to offsite manufacture for construction?
The procurement is one of the key challenges for those looking to drive offsite construction forward. The approach taken to the procurement of construction projects in the UK is generally one which follows a tried and tested route from client, to designer, to contractor, to subcontractor, to sub-subcontractor. Each party being seen as a separate part of the process – with little to no engagement taking place with specialist subcontractors or suppliers until much later on in the project. Where offsite construction is concerned, this traditional approach simply doesn’t work.
New procurement strategies focusing on collaborative working between consultants, contractors and manufacturers are vital for offsite construction to be successful and early engagement with the supply chain is paramount. This will no doubt require a change of mind-set for the industry but could bring about significant benefits.
New frameworks are already beginning to appear across England, Wales and Scotland which operate on an alternative ‘design, manufacture, supply and installation’ approach. Integrated design processes like the Design for Manufacturing Assembly (DfMA) model are also being used to demonstrate a new approach which facilitates off-site manufacturing and engages multi-discipline and multi-tier suppliers early in the design process.
4. What re-skilling of the construction workforce is required to facilitate a change to more off-site manufacture for construction?
The Structural Timber Association support the re-structuring of CITB to take into account the new skills required to deliver offsite manufacturing for construction. The work on site becomes more assembly than building and more work is transferred to the factory.
5. Can the benefits of standardisation and factory manufacture be realised without hampering architectural ambition? If so, how?
Yes of course. The best examples come from Ocean Housing in Cornwall who use the same standardised units to produce £3m private housing and terraced affordable homes. Simon Caklais will be able to provide examples.
6. What R&D is needed, and by whom, to realise fully the potential benefits of off-site manufacture?
I’m not best placed to answer this one
Government actions
7. (If published) does the construction sector deal correctly identify the issues faced by the construction industry and the actions that the Government and other stakeholders need to take to address them? What should it contain/what is missing?
If the report published by Construction News is correct, then the Government has got it about right. Construction has landed one of the first sector deals as part of the government’s industrial strategy to boost productivity across the economy.
8. What changes could be made to public procurement processes to encourage more economically and environmentally sustainable practises in the construction industry and facilitate off-site manufacture?
Currently supply chain members have to price first and discover the true extent of the works and the attendant risks later. Their view is that main contractors rarely, if ever, procure supply chain involvement on the basis of the outcomes they want to achieve. Usually procurement is based on ‘price led strategy’ with little understanding, still less communication, of the outcomes wanted, inadequate detailing of the work required and a lack of engagement to discuss what works will be necessary, how they could be carried out more effectively and what the major risks are likely to be. Instead, the assumption appears to be made that those tendering for the relevant works will be able to sort out any gaps, assess the risks and price accordingly.