It intends to meet this target by pulling the benefits of off-site manufacture into one package. "Until the API, we hadn't aggregated all the potential savings and come up with something significant," says Brendan Ritchie, Willmott Dixon's director of innovation. "We decided to go for the big bang – previously we had gone along in small steps." The contractor has therefore attempted to organise the whole design, procurement and project management process around maximising the payoff of using off-site manufacturing.
That sounds good, but also a bit vague. To see if the API is anything more than wishful thinking, Willmott Dixon has teamed up with affordable housing provider Catalyst Housing Group to try out the idea on the construction of 32 affordable houses at Dabbs Hill in Northolt, west London.
How it works
The first stage of the process is finalising the whole design before a single sod is turned on site. This eliminates hold-ups during construction while design decisions are made. "There is a lot of float in traditional programmes because things don't go according to plan. We are stripping that away," says Ritchie. "Historically there is an imperative to get on site as it looks like something is happening," he says. And, of course, "running sites is expensive – the less time spent on site, the more money is saved".
The 12-week lead-in times for the prefabricated system used by Willmott Dixon at Dabbs Hill meant that it was vital to know exactly what was needed in advance. "We have put more staff time into the pre-construction period as you have to put more work in up front, but I would expect them to get out earlier," says Ritchie.
Procuring everything ahead of construction is the second step, and this is now possible because the design has been finalised. Clearly, if materials aren't available then work stops. Willmott Dixon also ensured that specialist contractors were selected early on and fully briefed about what the API is and what was expected of them. Ritchie says some of those who enjoyed long-term partnering relationships with Willmott Dixon were initially unhappy about the API: "Some of the trade contractors were concerned that their work was going to be taken away. It was important to explain to them we were going to be doing 30% more work."
The Dabbs Hill homes have been built with Fusion Building Solutions lightweight steel-framed panel system (for more on this remarkable system, type "John Fleming" into Building's archive search engine). Fusion erects a house up to roof level in two-to-three days. The panels are fully insulated, thereby eliminating another site-based task. Fusion's bathroom pods, or FABS (factory assembled bathrooms), as Willmott Dixon prefers to call them, are being used for the first time at Dabbs Hill to save yet more time. The FABS have an integrated section of floor that simply slots neatly in with the other Fusion cassettes that make up the whole floor.
Changing working practices and processes is the hard bit because you are talking about changing culture. Doing all the design work up front hasn’t been easy
Brendan Ritchie, willmott dixon
Ritchie says Fusion's system enables interior and exterior doorsets to be slotted in, and windows arrive on site fully glazed and decorated, ready for installation. "Because the steel frame is so dimensionally accurate, it allows you to use these types of products with confidence," Ritchie says. Willmott Dixon even fits prefabricated stair balustrades, and plastic plumbing and boilers with integrated hot water stores speed up services installation.
Careful site management is the final strand of the API. The whole construction phase is carefully planned to maximise productivity on site. During the procurement phase, Willmott Dixon agrees how much time each specialist contractor is allotted to complete their part of the job. Part of this is agreeing how many people are sent to site each day to avoid a last-minute rush to complete the job, with the inevitable clashes with other trades. Willmott Dixon's site managers are even taking workers out to social events to get them to buy into the API concept.
Ritchie says the process hasn't been easy because it has meant people having to change the way they do things. "Changing working practices and processes is the hard bit because you are talking about changing culture," says Ritchie. He reckons this is because people simply aren't used to working in that way. "I know we didn't get 100% of the design done in advance but we did significantly more than we would normally have," he says. He adds that the process is worth the pain because company policy is to turn worthwhile innovations into standard practice with the hope that they will then benefit the business in the long term. Ritchie thinks client and supply chains benefit, too, because Willmott Dixon's housing work is done in partnership with repeat clients and suppliers.
So has the API worked? Ritchie says, so far, the Dabbs Hill project is on schedule and the first families are moving into their homes in April.
Improving efficiency the lean wayRiverside Housing, a Liverpool-based housing association decided to build homes faster, with fewer defects, and to give residents more input into the design of their home. It also wanted a method that took care of all the government initiatives it was compelled to adopt. “We recognised we radically needed to reform our development department,” says Mike Rushton, Riverside’s regeneration project manager. “We looked at ‘best value’ and picked up on ‘lean’ - it seemed to hit all the right buttons.”
Lean is a technique commonly used in manufacturing but less frequently in housing. It focuses on driving out waste, cutting inventory levels, shortening production time, increasing quality and reducing cost so that an organisation is able to deliver its core product as efficiently as possible. According to Rushton, his department was crippled by inefficient processes – just paying a bill involved a complex paperchase around the office. “The people who are freed up from this job can now take on a strategic role and look at how we can add value for the customer.”
Rushton says the first step is to identify a strategy to deliver your vision effectively. The next stage is to develop a slimmed down management structure coupled with effective communication. Finally, the lean tools and techniques can pass down through the supply chain. Examples of cutting waste could be something as simple as locating toilets much nearer to where people work. Riverside has just gone through a series of workshops with lean specialists RWD Technologies and are going to try out the ideas in a pilot project partly funded by the Housing Corporation.