University of Roehampton’s new library poses picturesque challenges for Osborne

Construction News features an article on our work at Roehampton University. Read the full article below.
Nestling on the edge of Richmond Park between the London suburbs of Putney and Barnes, the University of Roehampton campus sits well in its surroundings.

Set in beautifully landscaped tree-studded grounds, the institution’s lecture theatres and accommodation blocks are located right alongside various lakes, lawns and fountains.
It’s not the first place you would look to find a £34m construction project, but here, in the dappled light of the campus, main contractor Osborne is busily building a new library for the expanding university. “It is a beautiful site to work on,” says Osborne senior project manager Chris Hickman. “You wouldn’t think you were just a few miles from the centre of London.”

But building a four-storey library to house 350,000 books, as well as provide 1,060 study spaces, group study areas on the ground floor and individual silent study spaces on the fourth floor, comes with an impact.

The project has involved the clearance of 114 trees, although this loss will be mitigated by the planting of more than 100 semi-mature trees around the campus.

Precast concrete frame and hybrid precast/insitu concrete Omnia flooring slabs have been used to create the frame for the new library at the University of Roehampton
“Replanting the same number of trees was the only way we could go really. We tried to work out if we could do anything without having to cut them down but it just wasn’t possible. I think the final scheme will do justice to the landscape,” Mr Hickman says.
“At that sort of depth the London Clay is very hard, very tough”
Built under a NEC3 design and build contract, the Osborne team was given the all-clear that it had won the contract in November 2015 and work started on site just a few weeks later in January 2016.

The frame of the four-storey structure has been designed in precast concrete (see box) supported on 278 CFA piles measuring 450 mm in diameter and augered 28 m through London Clay bedrock. Some of the arisings from the pile installation have been used to bulk-fill beneath the 300 mm-thick reinforced concrete ground-floor slab.
“At that sort of depth the London Clay is very hard, very tough,” Mr Hickman says. “The site slopes 4 m from south to north and we have used some of the arisings as fill. It has cut down on the amount of muck-away we have had to do and helped reduce the amount of site traffic we have had to deal with.”

Busy construction sites can be very noisy so building a new library within a few metres of sleeping students and exam theatres can be a tricky task.

Factor in a build system that requires constant feeding with limited room to make deliveries and the task of organising the project becomes ever more complicated. Planning work with the university was vital.

With two tower cranes – both of which are capable of lifting 9.6 tonnes at a maximum of 40 m – feeding the site, the team has used the unloading bay to its maximum while keeping the university informed of work being carried out and adjusting to suit the college timetable where necessary.
Creagh Concrete Products senior contracts manager Lee Grainger says: “We have always had priority over crane time but we have had to manage that time correctly. Loads would be coming down from Liverpool and pulling into a park-up area near the A3. We know it is an hour run in from there so we can be quite specific about when we allocate crane time.”

The sloping site has seen the team cut the south end with the library building sitting down into the cut. In a move intended to remove any chance of water seepage into the building, the ground-floor slab has been cast using waterproof concrete.
“Because the building is half sunk into the ground we realised there could be a tendency for water to accumulate at the back of the retaining wall. We decided that it would be better to use waterproof concrete to prevent any water ingress,” Mr Hickman says.
Preventing water ingress has been one of the biggest challenges of the project. With the building frame being precast concrete, the Osborne team was keen to get the roof slab in and waterproofed as quickly as possible, enabling the facade, glazing and following trades to get their work carried out in drier conditions.

The facade is a lightweight steel frame system with weatherproof boarding and an outer precast brick-clad skin.

With difficult connection details between the interface of the structural frame, lightweight steel frame and the glazing sections, the team needed to tailor its work process.
Precast concrete frame and hybrid precast/insitu concrete Omnia flooring slabs have been used to create the frame for the new library at the University of Roehampton

This meant closing around the building with installers from precast specialist Creagh Concrete Products placing the slab and columns before the lightweight steel frame and window frames were fitted. Finally the upper precast sections were placed.

Work on the facade, including the outer brick-clad precast skin, is being carried out via a fleet of scissor lifts and MEWPS rather than scaffold, a move that Mr Hickman favours.
“We extended the capping layer 6 m beyond the footprint of the building,” he says. “It gives us a safe, solid base to run the MEWPS and scissor lifts around.”

Two tower cranes service the site, bringing material from the small delivery area that has been set aside. Everything has been brought in through this one point, a detail which makes keeping on top of the deliveries and times vital to the running of the site and university (see box).

Two tower cranes have lifted materials and precast concrete units onto the site. Work on the façade is being carried out using MEWPS and scissor lifts
With most of the external work nearing completion, the team has moved inside with Interserve as mechanical and electrical contractor Interserve works through its package.

Outside there is some landscaping work to be completed and a huge 80,000-gallon water attenuation tank to be placed, but Mr Hickman remains confident he will be able to pass the finished library over to the university in time for the August 2017 deadline.
“We need to get it handed over so that the university can start to bring all its books over to this new facility. They will need plenty of time to do that before the bulk of the students arrive for the start of the new term. We will manage that,” he says.

“It was always going to be a precast concrete frame,” Mr Hickman says, referring to the choice for structural frame material.
“There might have been the odd thought about other systems but really precast was at the fore throughout.”

One of the reasons behind that decision was the ability to get the frame in quickly and the first fix trades working as soon as possible.
“We wanted the cores up first where the surface risers and lifts are, then move up through the frame and get the roof slab in as quickly as possible. Once the roof is in and waterproofed we have a more controlled environment in which to work,” he adds.

For precast concrete producer Creagh Concrete Products, the new library has been a perfect project.
The team at the Northern Ireland-based specialist has been responsible for the design, manufacture, delivery and installation of all members of the precast frame as well as the plate flooring, precast stairs and facade of the new library building.
“It has been a tough project but ultimately hugely successful. We have had two gangs working on site during installation and the finished quality is outstanding,” says Creagh Concrete Products senior contracts manager Lee Grainger.

And that finished quality needs to be outstanding. The design has called for exposed soffits and 450 x 450 mm and 350 x 350 mm square columns to show off the specially pigmented white concrete.

That concrete is mixed at the Toomebridge casting plant in Northern Ireland, where the different sections are manufactured on a 72-hour turnaround from call off, before being shipped over to Liverpool and driven down on a flatbed truck.

“The largest panel we have had to deal with has been 14 tonnes. Installation time has been around an hour to erect a column and half-an-hour for the slabs,” Mr Grainger says.

It is a speed of construction that underlines the attractiveness of using precast concrete systems as a framing material. The amount of repetition suits the process, the project and the site.
“It has been a really quick build. We had five weeks to erect the cores and 13 for the frame itself. The cladding will take another 10 weeks,” Mr Grainger explains.