City Lifting Building Blocks
As volumetric and modular buildings get taller, as shown here on the 49m Treet Building, tower cranes are playing a greater role in their construction and, although it remains a niche market, ambition in the sector is large. Bernadette Ballantyne reports.
There is nothing new about prefabrication of construction components in buildings. For decades now, contractors and project clients have been pushing to minimise construction time by manufacturing elements in factory environments before delivering them to construction sites at the appropriate time. What is new is the scale of prefabrication and the ambition of the sector. It is not only concrete structural elements that are being prefabricated, whole building units are also being manufactured offsite. From fully fitted-out bathroom pods weighing 12t each in Singapore to 14t timber apartment modules in Norway, the scale of modular construction in building is expanding.
“One of the big benefits is the size of site required, as you can actually develop quite a small site to a high level,” explains Michael Hough, a structural engineer who has been designing volumetric buildings for a decade. His company MJH Structural Engineers has worked on some of the UK’s most leading-edge volumetric schemes from student accommodation to residential projects. “If you think about it, if you can park a truck close to the building with a tower crane in the centre then your lifts are very short,” he says, noting that the location of the arrival site for the modules is very significant.
This is something that Melvin Rogers, operational director of UK crane hire firm City Lifting, knows well, having undertaken a lot of this type of work in London. “The modular stuff is so interesting because projects are getting bigger and bigger but then the actual load handling, and transport to and from site becomes a major consideration. If they are being built offsite, they are a lot greener [in terms of sustainability] but then the manufacturers need to get them to site. If they are 4–5m wide it becomes unachievable. We are working with the built environment; there is only so much you can change,” he adds.
As a result, the transportation requirements generally dictate the width of the modules. Typical modules used for student bedrooms for example would be 3m wide and 6–7m long weighing around 8–10t.