What's the difference between modern methods of construction, and modern construction methods? Richard Stirling visits Shepherd Construction's £54M St Paul's Scheme to find out how the company is saving time through offsite manufacture and innovative project management.

HALF THE BATTLE to get a project finished on time is to design a structure that suits the client’s criteria and is deliverable within a realistic timespan. The other is knowing what the subcontractors are up to.

From her site hut on Phase 2 of Shepherd Construction’s St Paul’s project to build an eight-storey office block in Liverpool city centre site manager Ann Marie Mooney knows exactly what the project’s subcontractors are doing that day. Around the hut is a wall chart plastered with post it notes stretching across the walls, which is updated with each activity on the site on a daily basis.

The chart behind her maps out the 20th week of the project with the activities of the steel erectors and concrete pourers clearly displayed, so there can be no argument over who’s doing what that day. “It’s about getting the logistics right,” she says. “We have got everybody involved and we can plan exactly what they’re doing.”

The chart represents a pioneering project between Shepherd and the Building Research Establishment (BRE) that might see radical changes in the way the company operates on other sites.

The working relationship between the trades is only one aspect of the scheme that Shepherd has sought to reduce its construction time from the original 104 weeks down to 92. The company has worked with its steel erectors and their suppliers to change the building’s structure for an easier and faster build.

Keeping up appearances

Shepherd is racing to get the project finished before the building’s neighbours move in. The neighbouring eight-storey block was part of Phase 1 of the project, and will be home to solicitors Hill Dickinson, who will help Liverpool host the European Capital of Culture in 2008.

Shepherd is currently constructing the £23m Phase 2 of the project, which was originally designed with five concrete cores.

Shepherd project manager Tim Waters says this design would have taken longer to construct than the client wanted, and the company’s steel contractor recommended using Corefast to reduce the number of cores to three. Corefast is created from Corus’ Bisteel panels, and is a composite of steel and concrete, which the company claims has greater strength than concrete.

A panel made of two layers of steel is erected onsite and the contractor pours concrete in the space between the steel sheets. A rough surface of the steel sheets helps the concrete and steel to bond, and avoids sheering once the panel is in place.

This composite action adds strength to the structure, which has enabled the designers of Phase 2 of St Paul’s to reduce the number of cores in the building and still keep the same lateral restraint.

“We originally established it would be a long programme and would have needed two tower cranes,” explains Waters. “Then Billington Structures came up with the idea of using Bi-steel and we have shaved 12 weeks off the programme. The client gets it for the same price but three months early.”

Changing the structural components from concrete to steel cores also meant steel frame erector Billington was able to get onsite a lot quicker.

“It was very fast,” says Billington operations director Mike Fewster. “The central core took just 21 weeks to build. We were on the job in week two, instead of the eight to 12 weeks minimum it would have taken if we had used a concrete core.”

Using Corefast also meant there wasn’t the tricky business of erecting steel frame around concrete cores.
“You don’t have that interface to manage,” says Waters. “With steel to concrete, someone has to weld a bracket to the shaft. It’s a big headache that’s not there for us anymore. The cores are part of the frame.”

Waters says using offsite fabricated cores introduced a much more rigorous build programme to the scheme. “It has gone like clockwork for us,” he says. “In the first week, we started on the Monday and the first two floors had to be concreted on the Wednesday.”

Building new working practices

If the building’s structure allows Shepherd to run the smooth erection of the building’s cores and steel frame, the company is also trialling a scheme that it hopes will allow the rest of the project to run as well.

Shepherd has worked with the BRE to develop the CLIP scheme, which it hopes will provide transparency to the project and will allow the company and its subcontractors to know what each is doing and how long each element will take.

Site manager Mooney explains: “We generally arrange it so we have a monthly workshop. All the elements such as external works and steel frame are represented. We get all their programmes and put them on the wall, just in case there are any clashes, so at least then we can see what’s going on the following week.”

She says the scheme involves all trades, from structural steel, to ground works, roofers and the company putting up the building envelope. “We have even got the subsubcontractors involved,” she says.

Under the rules of the scheme, no activity is allowed to last longer than four days. “It’s about getting the logistics right on the project,” Mooney says. “In our daily meetings we see if different trades have the space for their activity. If the site is busy they can have priority on another day. Rather than arguing with them, we will get them to work together.”

Working together

White says the transparency that the scheme gives Shepherd and its subcontractors has promoted a greater understanding between the firms working on the project. Or to put it another way, it doesn’t allow subcontractors excuses for running late.

“It makes us sit up and listen to them,” he says, “but they in turn have to look us straight in the eye and explain why they’re late on something. Then there’s the subcontractor sitting opposite them who they have let down and is late, and they have to explain it to them too. I think overall we have achieved a bit of a team spirit through it, where everyone is aware of what’s going on and works together.”

The scheme is run through an external facilitator who visits the site once a month. White says she provides a fresh insight to running a construction project. “She comes in and explains the system to everyone involved with the project,” he says. “She doesn’t have a construction background, so she questions our ways of working and challenges the way we traditionally do things. She asks questions that make people think, and makes us justify what we do because she thinks everything we do is measurable.”

Shepherd has already recouped the cost of bringing in the external facilitator onto the project, says White. “We have worked out the cost of doing it this way, and it costs Shepherd between £500 and £1,000 a day for the facilitator,” he says. “We saved that in the first two sessions, because we got the tower crane down four weeks early.”

Mooney says the scheme has proved very handy for recouping lost time after gale-force winds stopped work earlier this year.

“There has been a stage on the project when we were going to lose one week, which we will able to avoid,” she says. “We will be able to save whatever that was going to cost us. At the moment, we are coming in on Saturday and Sunday to get the work finished. The extra days are planned in to get it back on programme.”

Despite a positive start for the scheme, it is still early days on the project, and too soon to say whether Shepherd will roll it out on other sites around the country. The chart in the St Paul’s site hut is already plastered with post it notes, and White says he anticipates the scheme will get a lot more complex as the project progresses.

“The true test will be when we start doing the little jobs like wiring, plumbing or plastering,” he says. “We could have 100 people onsite doing 50 different jobs.”

If the trial does work out, and Shepherd does give the go-ahead to use the scheme on other sites, it will mark a step forward in the relationship between contractors and their subcontractors and the way they interact onsite.

In a race to get the St Paul’s scheme finished, the company has truly come close to using modern methods of construction. Shepherd has saved time onsite by using offsite manufactured steel panels for the building’s core, and it has got to the core of the building’s construction by defining the roles and working practices of each company on the site.