Reds10 claims its modular scheme in the heart of a new residential quarter in Reading has made big cost saving compared with traditional methods.
Scheme: Green Park Village Primary School, Reading
Main contractor: Reds10
Client: St Edwards / Berkeley Group
Contract type: Design and Build (lump sum)
Contract value: £6.1m
Engineer: Considine, Maidstone
Architect: Sense of Space Architects, Ilkley
Start date: January 2019
Completion date: October 2019
The Berkshire town of Reading has grown markedly over the past 20 years. Its close proximity to London and great transport links by train and the M4 motorway has prompted its population to swell by more than 45,000 during that time.
Taking just 25 minutes to get to on the mainline rail service from London Paddington, Reading is a popular place to live among commuters into the capital. But with international companies also centred in the town, including Microsoft and Oracle, as well as a major research university, there are plenty of good careers available locally, too.
The hike in population has inevitably led to greater demand for homes. To help sate that demand, developer Berkeley Group is building hundreds of houses and apartments, via its St Edward business, on a site to the south of the city alongside the Green Park business centre.
A key part of the 1,700-home Green Park Village development will be the new primary school that is currently under construction.
Beating tier ones to the job.
The school is being built by Wimbledon-based contractor Reds10, which beat a handful of major tier one contractors to land the contract, a fact that delights operations director Duncan Purvis.
"This project is perfect for us," he says. "We offer a full modular-construction design-and-build service and have plenty of experience in the education sector.
"The Green Park Village developer, Berkeley Group, is a great supporter of modern methods of construction - including modular building - so we're obviously very happy to be in the position we are."
The Reds10 team managed to find its way onto the tender list for the project in May 2018. Through its determination to provide the best solution for the construction of the 420-pupil-capacity primary school, it was awarded the contract in December under a £6.1m lump-sum deal.
"We are a very dynamic company," Mr Purvis says. "We have our own labour force that carries out the work at our manufacturing facility in Hull; the same with the onsite team.
"Traditional tier one contractors don't have that vertical integration and have to cover their costs - and build in profit margins - with every subcontractor.
"It means that tier ones find it difficult to compete on projects like this using traditional construction techniques. Their margins are too tight.
"As an estimate, I would think that we have saved around £1m using modular construction methods against traditional, without any compromise on quality; in fact, the opposite."
Public sector boost for MMC
It's no secret that the government is determined that the industry embraces modern methods of construction, encourages innovation and improves project-delivery efficiency.
The introduction of 'MMC1' – a framework to be set up by the Department for Education for the offsite delivery of schools, and design for manufacture and assembly methods – is being planned.
Although it will focus on the introduction of this work in the education sector, other areas, such as healthcare and the Armed Forces, are also on the government's radar. It is clear that this is an area of business that is attractive to the Reds10 team.
"We are a design and build contractor," Mr Purvis states. "We design buildings to the same specification, using the same materials as those using traditional methods of construction.
"We want to be vying with the tier one contractors for projects like this and a place on frameworks. We believe we have the skills and quality available to do that."
He also points to the development of a series of standardised designs by the DfE, which can be easily applied to modular building techniques and then rolled out to suit larger or smaller projects.
"These are standardised models that can be dressed up to suit local planning or educational requirements and site layouts. They are ideal for modular construction solutions," Mr Purvis says.
On the Green Park Village Primary School site, work is going on apace. Like all modular building schemes, the project is notable for the orderliness of the site itself.
With relatively little construction work carried out on site once the piling and groundworks have been completed (see box), there is precious little waste and no need to stockpile materials.
Groundwork key to building success
At Green Park Village Primary School, Duncan Purvis is proud of the 85 per cent pre-manufactured value (PMV) – the percentage of the over project value that is built off site or prefabricated – score the project has hit. It is, he believes, about the optimum level for this project. "Perhaps we could grab an extra percentage or two, but really, I think the 85 per cent value is fantastic. There is always going to be some work you have to do on site, so that figure is close to the best you can expect," he says.
Of the remaining 15 per cent, much is taken up by the piling and groundwork regime. There is a 1.8 m layer of engineered fill that covers the site, but the Reds10 team wanted to be sure of its bearing capacity, and after a raft of California Bearing Ratio tests indicated it would need improvement, the team called in subcontractor Roger Bullivant.
The firm used a series of 510 vibro displacement stone column piles to depths of up to 7 m to stabilise and consolidate the site before strip and pad foundations were placed.
A pinpoint-accurate survey of the foundations is taken to make sure they tally with the design for the building before the units are brought down to site and lifted directly into position.
"We take a 3D survey of the foundations and of the connection points in the factory as the units are being manufactured," explains Mr Purvis. "If we are aware of potential issues early enough, we can work on them before they become major problems."
Pretty much everything that is needed to add the finishing touches to the building – sections of plasterboard or skirting, for example – is placed in each separate section of building units at the East Yorkshire manufacturing facility before being lifted onto the back of a low-loader for the long trip south.
Even where holes have been cut through installed plasterboard at connection points, the resulting 'plug' of board has been helpfully taped to the wall alongside, making the repair easier for the onsite team. There are 72 of these units in total.
"Our teams will preassemble all our buildings before they are sent out to site," Mr Purvis says.
"This enables us to get any of the quality issues sorted before the units leave the factory. If someone is paying more than £6m for a building, it should be right."
Perhaps that is the best lesson to be learnt from a school build such as this.
A school design for the future
As one of the keystones of the new Green Park Village development, the new school will be pivotal in helping to create the community it is set to serve. Facilities include a two-storey building that caters for children with special educational needs, as well as 3G artificial sports pitches that will be available for use by the local community.
With an entrance facing onto the village's new Market Square, the secure school reception, offices, classrooms and changing rooms will be situated to the right with, the double-height main sports/dining hall and catering facilities located to the left.
"The building was at RIBA stage 3 of the design process when we were awarded the project in December 2018," Mr Purvis says, adding: "We had just six weeks to move it on to stage 4. It took a lot of buy-in and effort from everyone involved in the project."
That sharp turnaround for the design team focused everyone's minds and the BIM level 2 project was cleared through for fabrication at the beginning of the year.
"The manufacturing team worked on a 15-week timescale. We had 12 weeks for the manufacturing, but with a three-week stagger built in to avoid any clash of trades as they work through each unit. It helps improve efficiency in the factory," explains Mr Purvis.
He made sure he spent five months working at the factory in Hull to fully understood the manufacturing process – a learning he describes as "invaluable".
The units are brought down from East Yorkshire each night and held at Reading services so that the site team can hit its eight-to-10 units-per-day average and still comply with the strict 7.30am to 9am and 4.30pm to 6.30pm delivery-exclusion zone.
"All major projects have logistical challenges and this is no different, but by careful management we can work around them," he says.
Once brought onto site, a mobile crane lifts the units onto the concrete pads where they are teased into their final position.
The units are then welded together using small 50 mm square plates spaced equidistant along the unit edge to help stop any independent movement of each unit and any potential cracking of the preinstalled concrete floor.
"Its belt-and-braces, really. We probably don't need to do that, but we want to make sure the building looks and performs as well as possible," he says.
"If that weld means the difference between there being an unsightly crack in the concrete or not, then I think its better that we do it."
Various facade finishes, including brick slips, bronze cladding, architectural fins and curtain walling, can then be installed.
"It's the architectural add-ons that make the difference with a modular building," says Mr Purvis. "That's when they can really be individualised."