Creative Commons by John M
The world's tallest modular prefab is almost complete for the start of the school year at the University of Wolverhampton in the UK.
John M, Creative Commons. Note the concrete core and the modules being stacked on the sides.
The building's cores, which house the central circulation, centralized utilities, fire stairs, and elevators, are site built from slip-formed concrete.
As for the modules, each has its own structural steel frame designed to carry the loads of the modules above it. The modules also include concrete floors, drywall walls and ceilings, and a fire-rated envelope. Prior to shipping, all modules are pre-fitted with plumbing, fixtures, finishes, cabinets, and even furnishings (multiple modules are used to complete each student suite). Once completed, the individual modules made their way from Cork by boat and truck to Wolverhampton.
The modules weigh 21 to 29 tons and are lifted into place by crane. Individual modules are stacked on top of the prior story and attached to the core. Once a module has been set in its final location the frames are spot welded to create a unified structural mosaic.
On the inside, a module's preinstalled electrical and plumbing components are simply joined to the main runs. The modules are then sealed and finished at their mate lines. Outside, a rainscreen façade is applied over factory-installed waterproofing. After the modules are set, the final façade work is applied using a lightweight façade scaffolding system.
Architect Gary East and his team estimated the project would have taken at least 24 months using traditional site-built methods, but modular construction enabled them to top out all three buildings in nine months--well ahead of schedule, Total project completion is set before students arrive for their fall classes this year, fully 10 months ahead of site-built alternatives.
Highrise modular construction always had a fundamental difficulty that the units were never really identical; as you go higher, you are supporting less load and the walls could be thinner. At Moshe Saftie's Habitat 67, the top modules were as strong and heavy as the bottom ones so that they could all come out of the same molds; this made them more expensive than conventional construction.
This project has steel framed modules, which can easily be modified as they are built in the factory to be lighter as they get higher. Going 23 stories is pretty amazing. More in BD&C;