Cartwright Pickard Architects has helped create an off-site flatpack system that promises flexibility and super-quick build time.
“This is going to do for housing what Ikea did for furniture,” says James Pickard, partner at Cartwright Pickard Architects. “My dream is that in three years’ time we will be exporting flatpack houses to Sweden. I want to export houses the other way round – that’s my holy grail.” Pickard is clearly optimistic about the launch of his off-site housing system, Optima.
Architects, including Cartwright Pickard, may be used to incorporating off-site manufacturing into their designs, but this is the first time a practice has been so involved in designing the housing system itself. Cartwright Pickard partnered with timber-frame maker the Pace Group to develop Optima, seeing it as the logical next step in a long run of innovative projects involving prefabrication, such as the Peabody Trust’s Murray Grove housing development. “We felt it was about time to put our money where our mouth was,” says Pickard.
But has Cartwright Pickard made the system different and special enough to compete with well-established foreign imports? Darren Richards, the operations director of off-site manufacturing consultant Mtech, was involved in the development of Optima and thinks so. “This is one of the few credible UK closed-panel systems,” he says. Closed panel systems incorporate insulation, windows and doors; the panels are slotted together to build a home. “Unfortunately to get what clients want we have had to go abroad,” says Richards. But Optima has an edge over its foreign competitors. “The collaboration [with Cartwright Pickard] is novel and that will set it apart,” Richards says. “The architect has ensured the system can be applied to a wide range of designs, and it also integrates services and there is more consideration for follow-on trades.” (See “How Optima is built”, page 54).
Optima’s key selling point is flexibility. All internal walls are non-load bearing, meaning that the client has complete freedom to arrange the interior layout to suit its needs, and clients have a wide choice of design routes. Optima is offering the system in the form of three packages: basic, standard and enhanced. With the basic package, the clients design their own scheme; standard consists of 15 Housing Corporation-approved, off-the-shelf designs by Cartwright Pickard; and the enhanced option gives clients a bespoke Cartwright Pickard design. Although the standard designs are pre-planned, Pickard is not precious changing the designs. “The standard designs can be tweaked, they are a starting point for customers to say 'this is interesting' and work from that,” says Pickard. The idea is that housing associations will use Optima’s flexibility to work out styles that can be replicated.
Optima also scores points for arriving on site as a near-complete package, reducing the amount of work done on site. One time-saving trick of the standard designs is the inclusion of a service riser in each home and pre-installed conduit for wiring. “Clients will have to think about M&E much earlier. We will be working with them to work out the M&E, something I see as a great advantage,” says Phil Key, managing director of the Pace Group. He hopes in the future to be able to offer prefabricated homes with preinstalled services.
Another factor that makes the system unique is that it arrives on site with ready-fitted drylined walls. Pace Group already has a specialist drylining division and has used its expertise in this area to remove this job from site, and make it cost effective. “We have already proved we can dryline more cheaply in the factory than on site, and it is factory-controlled as well,” says Key. Workers tape and joint the plasterboard as the house is erected on site ready for decorating. “There will be very little left for the contractor to do,” laughs Pickard.
Contractors will not have to fit out kitchens and bathrooms either. The system is designed to incorporate fully fitted bathroom and kitchen pods – these go next to the service riser for simple connection to services. Pickard is already considering how the pod concept could be developed in the future. “An aspiration for the future would be to pull out the kitchen and bathroom pods and replace them as they only last 10 years,” he says. “Ripping out kitchens and bathrooms is a very big issue for social landlords as it is very expensive.”
So will all the time-saving features of the system appeal to housebuilders? Social housing contractor Willmott Dixon is already using Pace Group’s timber frames for the homes it builds and thinks there is potential for Optima. “It’s a good system they have come up with,” says Brendan Ritchie, Willmott Dixon’s innovations director. “There's a lot in the package that one supplier can give us: the closed frame with insulation, the ready-fitted plasterboard, provision for easy installation of services and the pods. Putting all that in one package with one supplier is a plus.” He says it’s too early to tell how Optima will affect the company financially. “One of the most difficult views to come to is what time savings it will offer on site. It will cost more. The question is, will the increased capital cost offset the time savings on site. It’s not an exact science, you do it a few times and get a sense of what it is going to save you.” He says when the right client with the right type of project comes along the company will try the system out.
Key has no doubts about the likely success of the system. “There is a lot of interest form RSLs and contractors in significant numbers. It sounds a bit strange, but we may have to push people back,” he says. Pace Group, which has exclusive rights over Optima in the UK, has invested considerable sums of money in a new factory to make the system and has high hopes for the future. “As we grow I can see Optima taking over from our standard timber frame business in two to three years,” says Key.
Cartwright Pickard has joint intellectual property rights over the system and will receive a royalty for each unit sold. Pickard says he wants to plough the profits into further research and development to stay ahead of the market. “This will sustain more R&D work as the system will be constantly evolving based on customer feedback, changes within the industry and changes in materials and technology,” explains Pickard. Optima is currently developing the system so it can be used for apartment blocks. In the future there could be solutions for other sectors such as schools and hospitals, and it could be marketed overseas. Perhaps, as Pickard dreams, Optima will even be built in the birthplace of flatpack design.
How Optima is built
The home is supplied and built by Pace Timber Systems on a pre-prepared foundation complete with services positioned in the centre, ready for connection.
The Optima Homes system is a closed panel system, which means whole wall panels are delivered to site complete with insulation and doors and windows fitted. Each panel has a timber framed structure with OSB panels on the outside ready for any type of cladding system, and plasterboard ready for finishing on the inside.
A panel forms a single storey on one side of a house so a typical two-storey detached home would be constructed using eight panels. Designers have the flexibility of being able to have any length of panel up to 3.3 m high.
Prefabricated stairs, kitchen and bathroom pods are craned in as the home is built, and the plasterboard is taped and jointed at the same time ready for decoration.
Floors are supplied as complete cassettes using Pace Timber Systems Posi joist system. This has a metal frame sandwiched between plasterboard on the underside, and a weather-protected composite board on the top. The advantage of the Posi joist system is that floor spans up to 5.4 m can be accommodated, which maximises internal design flexibility. Floor cassettes are supplied with cut-out panels for access to services through the floor; pipes and wires are simply threaded through gaps in the metal frame.
Designers have a choice of three different types of roof. Flat roof panels similar to the floor cassettes can be used either flat or as a mono pitch design. Alternatively preassembled trussed roofs can be used for a more traditional appearance. A preassembled “attic room” design is also available.