Bad weather and an unexpected geotechnical challenge faced contractor MTX Contracts on a north London speed build.
Project: Ashmole Sixth Form Centre
Client: Ashmole Academy
Contract value: £1.3m
Contract type: Design and build
Main contractor: MTX Contracts
Project manager: CGA Project Services
Structural engineer: Alan Wood and Partners
Consultant: Peter Brett Associates
Start date: December 2013
Completion date: May 2014
Ashmole Academy in Southgate, north London, has high standards. The secondary school, which proudly trumpets its Ofsted Outstanding award, has been pumping hard-won capital into the construction of a new sixth form centre.
This finance has come from a combination of community fundraising, lettings of school property and an operating lease for the new building.
“It’s not really modular like a site cabin. We take the concept of a structural steelwork design and we make that work in modular sections”
Andy Leach, MTX Contracts
As head teacher Derrick Brown points out, the number of pupils joining the sixth form has risen 100 per cent, so the school needed new facilities for the around 400 that are currently enrolled.
He says the new two-storey construction, placed at the heart of the school, will contain a cafeteria and relaxation areas on the ground floor with a study centre on the top floor.
But rather than opt for a traditional build, the school has gone for a modular solution, albeit one that main contractor MTX Contracts feels does a lot more than it says on the tin.
“It’s not really modular like a site cabin,” says MTX site manager Andy Leach. “We take the concept of a structural steelwork design and we make that work in modular sections.”
Integra Buildings based in Hull won the contract to manufacture the sections at its offsite factory, with each corresponding to one of the bays that building’s plan has been split into.
Connecting the modular sections
MTX craned in each section separately over three days with what Mr leach describes as a 150-tonne Ainscough “baby” crane doing the heavy lifting.
The reason for the relatively small unit was that MTX Contracts had to keep a vital road open. However, it did offer some benefits.
“We often use a 750-tonne crane but on this site we needed to keep an access road open for emergency services,” Mr Leach says.
“Modular construction does save a great deal of time but it also reduces waste”
Andy Leach, MTX Contracts
“But it worked in our favour on this site because we had a crane that was close to the job, even though it had less reach.”
Site workers then spent another three days screwing it all together and getting it watertight, meaning from first section arriving on site to a connected and watertight stage took just six days.
“Then we start doing the internal bays, which means using wood and plasterboard to seal the bay joints on the inside,” he says.
But Mr Leach is keen to point out that speed is not the only benefit of modular construction.
“It does save a great deal of time,” he says. “But it also reduces waste – and they are guaranteed for 25 years.”
An unwelcome surprise
MTX won the turnkey job with a £1.3m tender and got to work in December last year. But an unexpected delay meant the schedule was almost immediately affected.
As it got into the ground, the contractor encountered a problem that wasn’t recorded in the site investigation it was working from.
“We started here before Christmas but we found old foundations in the ground that we did not expect, so we were put back a month,” Mr Leach explains.
“It was a mud bath with all the rain over Christmas, but it didn’t slow us apart from a couple of days when it was really hammering down”
Andy Leach, MTX Contracts
This meant it was forced to dig out the old foundations and dispose of them while bringing in fill material to make good, before it could get to work putting in its own speedily redesigned foundations.
The new design comprised 35 300 mm-diameter piles installed into the London Clay to depths ranging from 11 m to 23 m. These connect to ring beams and a floor slab that together required 186 cu m of concrete.
Getting this onto a working school was always going to pose a challenge.
“The building is being built at an existing [educational] site with school children on it and so MTX has had to tie in with certain timings – like, for example, when you have 24 concrete deliveries coming through an entrance used by school children,” says Ashmole’s finance director Daniel Powell.
It wasn’t just the surprise of existing foundations that hit the team at that time. “It was a mud bath with all the rain over Christmas,” My Leach recalls.
“But it didn’t slow us apart from a couple of days when it was really hammering down.”
The project’s BREEAM Very Good rating is partly due to features such as daylight detection lighting and a heat recovery system for the air conditioning system.
But MTX also proposed a PV option for the roof, which the client can still take up retrospectively and which the contractor says will make the building almost carbon-neutral.
With decorators and finishing and fit-out work still to come, he says it is still well on track to meet the 23 May handover.
Mr Leach’s faith will be rewarded once a satisfied client can open the new facility to Ashmole’s current crop of sixth formers.
Be that as it may, Mr Powell is happy with the relationship it has with its main contractor. “We have been pleased with MTX and would recommend its services,” he says.
A return to Ashmole
Ashmole’s ambition hasn’t ended with the sixth form centre.
It has an application with the Department for Education for a brand new primary school on the same site, though the school needs to raise the money for this project as being able to demonstrate that there is sufficient interest to fill the school.
“We will certainly be tendering for that, once we’ve demonstrated that this modular build is just as good as a traditional one,” Mr Leach says.
Rapid operating theatre delivery
Mr Leach says that although MTX has been building using modular construction for almost 10 years, the real changes are in the amount of additions that are being crammed in.
“Now we are putting as much as possible into the modules, such as M&E ducting,” he says.
This approach gets really put to the test in the new-build operating theatre environments that MTX often works within.
He says that a recent operating theatre job took just 16 weeks from the contract signature to the first operation taking place.
“People will be booked in for surgery that has to take place three days after we’ve finished,” he says.
The most recent job at the Queen Elizabeth Hospital in Kings Lynn saw the contractor complete an A&E extension in six weeks from when the sections were delivered to site.
“That was the tightest we’ve done and it was a real challenge,” Mr Leach admits.