Longcross and concrete subcontractor PCE used offsite construction methods to reduce the construction time for a new Volkswagen showroom in west London.
When main contractor Longcross Construction bid for the contract to build the new Volkswagen showroom in Brentford, west London, the company included its concrete subcontractor PCE.
The bid was successful and involved extensive use of precast concrete as opposed to a more traditional in-situ method.
Using the precast concrete solution enabled a three-month reduction in the construction programme, as there is no curing time to consider, less need for temporary supports and the internal fit-out work can begin earlier.
Engineer to engineer
It also means the programme is more stable because the process is not weather-dependent, as the concrete is precast in a controlled factory environment.
“Volkswagen is a company that values innovative engineering solutions, so the management appreciated the solution we provided because it was from one engineer to another”
Jonathan Williams, Longcross
“Volkswagen is a company that values innovative engineering solutions, so the management appreciated the solution we provided because it was from one engineer to another,” says Longcross project manager Jonathan Williams.
“Volkswagen will also benefit from the quicker build time because it means its retail space is open for business more quickly.”
The new four-storey 15,468 sq m development consists of a complete precast frame from ground-floor slab to the roof, designed and built by PCE.
The build time will be 18 weeks, compared with the 30 to 32 weeks it would take using more traditional methods.
The precast reinforced concrete column and beam mainframe supports the pre-stressed concrete flooring, which has an internal span of up to 16 m.
“This was an advantage for the client, as it wanted a high-quality, smooth finish, where the floorslabs aren’t going up and down,” says PCE managing director Nickie Brown.
“You get that in-situ, but we can also offer that with our slabs.
“The dynamics of the unit mean the strand runs along the bottom for tensioning, but it’s reinforced in itself so the tension of the strand gets the distance, and then the reinforcement in the product means it doesn’t need a structural topping on the top.”
Structural stability will come from three precast stair and lift cores complete with flights and landings.
The precast elements are all manufactured offsite in factory-controlled conditions using steel moulds that guarantee the quality and uniformity of concrete finish.
Where the units will be visible, they are finished to a higher standard by hand, which allows for direct decoration.
Using this solution also removed the need for a row of columns down the middle of the building, creating an open, striking space.
“Longcross had to trust us when we said we’ve got products coming from everywhere through just two small gates, in a busy area like this”
Nickie Brown, PCE
“We can start the fit-out much earlier for aspects that aren’t perishable and take a long time to install; we can get started on them now because we opted for this solution,” Mr Williams explains.
Using a construction method that cuts the build time by almost half, reduces the number of workers onsite, is cheaper and safer than a traditional alternative and increases the quality of the build would seem a given.
However, as this method is still relatively new, it was a big decision for Longcross and Volkswagen to go ahead with this solution.
“Longcross had to trust us when we said we have got products coming from everywhere through just two small gates, in a busy area like this,” Mr Brown says.
“They have embraced the system; it takes a lot of guts to try something different.”
Managing the logistics
The project was modelled in building information modelling several times before the team started onsite, and through this process they saw it was vital the logistics were extremely carefully planned and co-ordinated.
“From using BIM modelling on the project, we realised the logistics were one area that had the potential to be disruptive and delaying, meaning the just-in-time deliveries were even more important,” Mr Williams says.
The improvements in health and safety come from the reduced numbers of workers needed onsite, the reduced working at height and because the units were delivered to site precast with the connections for leading edge protection and temporary works systems.
“After the units are delivered to site, the handrailing system is installed while still on the ground and lifted into position, meaning leading edge protection is in place immediately,” Mr Williams says.
Mr Brown attributes his company’s innovations to the fact that he and many of his staff have previously worked onsite and so understand the areas that can be difficult or problematic when working onsite.
“Being in the industry of offsite solutions, it’s very easy to send a product to site and expect them to just get over the problems,” he says.
“That’s why I think we’re different, because so many of our people have come through from the tools and want to make it right onsite.”