The construction industry has been grappling with the adoption of modular technology for years. It’s long been discussed as one of the ways contractors can get things done faster, safer and at a lower cost – not to mention offering massive improvements to the industry’s productivity.
But as firms consider how best to implement the technology, some contractors and clients are already getting to grips will fully modularised buildings.
One such client is Holiday Inn Express, which has enlisted Bowmer + Kirkland alongside modular contractor CIMC to deliver a 220-bed hotel in Manchester. And B&K has discovered that meticulous planning of both technology and trades has been the crucial to success on a project that will be delivered in just 39 weeks.
The 220-bed Holiday Inn Express, which sits a stone’s throw from Manchester’s EventCity and the Trafford Centre shopping complex, is the first of the client’s ‘generation four’ range of hotels and is intended to be the firm’s brand standard that it will roll out across the country.
B&K started on site in July last year on the 39-week programme that has completion pencilled in for 8 May. On the day of CN’s visit in late November, the progress made is already remarkable. Installation of the modules, which had only begun at the start of that week, is well under way, with half of the building nearing its six-storey height.
The roughly L-shaped building is having its modules installed in two phases to help keep the programme running smoothly and ensure no time is wasted, according to senior site manager Gary Lewis.
He explains that, to prepare for the installation of the modules, B&K has built a transfer structure up to level one, with no concrete or steel frame any higher than this point, aside from the two concrete stair cores at either end of the building.
Gary adds that half of the building goes to its full height, which means follow-on trades can begin working on the interiors while the other phase of the modules are lifted in – ensuring nobody is sitting idle at any point during the project. “The whole thing with modular is that you seem to get everything at the same time,” he says. “Two weeks ago we didn’t have one module installed; now two weeks later we’re releasing cladding, roofing, upper floor corridor works. It’s all about how we then sequence the follow-on trades to make sure we’re straight into the areas we need to be in without any delay.”
He says contractor CIMC, which manufactures the modules in China and installs them on site, had seen main contractors fail to grasp that concept before, leading to problems with programmes and ultimately slowing down what are supposed to be quick-fire projects. “For example, they’ve installedmodules first and then started to line up trades afterwards, but it can’t happen that quickly unless you’ve made all these plans and arrangements weeks and months in advance,” he says. “[CIMC] has come with all manners of lessons learned – and I’d be silly not to listen to them.”
One of these was to understand that the modules can’t simply be dropped on to the slab with little control; B&K had to make sure the modules fitted perfectly to eliminate any problems when it came to lifting and bolting them into place.“All the work is actually in that transfer slab,” Mr Lewis explains. The team had to cast module receiver plates – onto which the modules are bolted – as part of the building’s transfer slab. To do this, B&K boxed out 109 locations on the slab where the receiver plates were going to be positioned and cast the slab with a protective covering of insulation at each position.Mr Lewis says he wanted them to be “precise to the millimetre”. “CIMC has seen these receiver plates floated in like a standard holding down bolt and it’s a recipe for disaster.”
Once the slab started to cure, the insulation – which marks out exactly where there receiver plates need to be cast – was removed, providing an accurate outline for the module installation, rather than them being fitted freehand. This was important as the tolerance on depth is plus zero and minus 5 mm. “Trying to have that control while casting a full slab – things can easily get knocked,” he says. “You’ll do a survey a few days later and all of a sudden you’ll have to break stuff out and reset it because things aren’t in the right place.” Once these receiver plates are cast in place, CIMC then welds a series of plates on top in each corner – meaning that when the modules are lifted in, they fit perfectly. During the module installation, the team had a target of eight per day, with modules coming through the site entrance to be crane-lifted within 10 minutes and fully fixed within the next 10.
Each module contains two rooms and a portion of corridor, with each room fully finished inside, including carpets, wallpaper, decorations and bathrooms. Gary describes the M&E works as “essentially plug and play”, with all cabling and pipework brought into a riser in the corridor. This means no M&E work has to be done in the rooms themselves.
The corridor section includes a floor layer of CFC chipboard, with the ceilings coming with one layer of sealed fire boarding. The only minor works that have be addressed is when two modules adjoin, with a strip of around 120 mm of CFC floor that has to be installed by hand, while the same applies to the plasterboard. “The corridor is just like any traditional [one] thereafter.”
“We still have to install a second layer of plasterboard and put up all the M&E services through the ceiling void space. [Then we] plaster the walls, as well all your usual finishes – joinery, floor finishing and so on. In terms of the upper floors, it’s only the corridors where we have to do any real fit-out, or where we have any real M&E,” said Gary.
Once the modules are installed, the team also has to fully clad the building and get roofing works under way. B&K has taken a similar approach to this as to the module installation, with precise measurements and accurate sequencing needed to keep the programme on schedule. “You can’t come along to the face of the modules and fix brackets anywhere,” Mr Lewis points out. “There’s a real risk if you drill through where you’re not supposed to, you’re going to drill through a bedroom.” Each module has a permitted fixing zone at the top and bottom, marked with a substantial piece of steel. To install the cladding, the team first fixes a series of 3 m vertical brackets in the permitted fixing zones, which span from the top to the bottom of each module, with the process repeated across any given facade. This is followed by insulation, horizontal steel, and finally cladding bolts and the cladding itself.
“You can’t just fix anywhere,” added Gary. “You have to come up with a viable solution that really doesn’t compromise fixing through a finished hotel module.”A similar process applies to the roof level, where B&K is using a timber baton roof, followed by a plywood roof deck. The steel parapets will also be fitted in permitted fixing zones to make sure the installation goes smoothly, without any risk of water damage to the rooms below.As Construction News leaves the site, another module was waiting outside the gates –testament to the speed of the build and how meticulous pre-planning is crucial to making modular construction work, rather than just expecting it to fit together first time.Mr Lewis says this approach has effectively halved the project’s build time from 18 to nine months.
The team is now focusing on the ground floor and stair core fit-out and the furniture, fixtures and equipment works – all of which are being built and installed traditionally – ready for the handover date on 8 May.“Everything, all the way down to knives, forks and spoons [needs to be ready] to make sure they can open the doors and start using it as an operational hotel,” Gary says.“The back end of the job is where all the pressures are to come.”But with the modular stage progressing well and the project’s plan being executed smoothly so far, B&K appears up for the challenge.