Assembling vs. building skyscrapers

I just watched an interesting documentary about the construction of the Leadenhall Building in London. One of the claims made in the documentary is that the skyscraper construction was innovative in being built mostly off-site (due to space constraints), with workers doing mostly “assembly” at the site of the building. For example, instead of having cement workers pouring concrete floors on-site, whole sections of floors were trucked to the location and craned into the frame. They also built entire bathrooms offsite and, again, simply craned them into location.

Is there any reason this method isn’t more widely used? It would seem like building parts at a specialized factory would result in economy of scale and thus less cost. Obviously this method is not used, so there must be more to this. :confused:

it might be more expensive but the only choice for that location.

This is a YouTube video showing a thirty-story building constructed in fifteen days, by a Chinese company called Broad Group. They’re proposing to use the same technology to build the tallest building in the world in seven months. Their approach uses prefab blocks that are stacked. So one criticism I read is that no interior space is going to be larger than the size of the prefab blocks. (So no wide open floors or atrium spaces.)

I think it would be more expensive. A lot of the times bathrooms a little different on many of the floors, so an assembly line approach would not be particle. Also it would take very large cranes that can handle bulk to get them onto the building.

Weren’t the twin towers built from modular components built off site? I seem to recall big panels of the “grating” that was so prominent in the wreckage being delivered and hoisted into place.

The top of the Chrysler building was a modular assembly built (more or less at the last minute) within the upper floors of the originally-planned building, then hoisted into place and assembled. IIRC, it was a late addition designed to add height and keep the building from being reduced in “tallest” standings before it was even completed.

Also, that building was made of steel trusses, which were light enough to lift into place with the building crane. US developers seem to prefer concrete floors, and I doubt those would be light enough to lift into place with a crane. The current slip-form technology seems to be fast enough, and the concrete is lifted into place bit by bit with a pump.

The documentary I linked to shows the crew lifting *sections *of concrete floors by crane to each floor, where they are bolted into place.

It’s usually only a single floor, but tilt-slab construction is probably the way 90% of industrial-park buildings are built. The slabs used to be poured right at the tilt-up position but it’s increasingly common to have them trucked in.

This is a cramped location within the medieval street pattern of the City of London (drove past it this morning). Very likely the City Corporation only agreed to green light it if they did it this way.
Not sure if the 20 Fenchurch St development a few streets away is doing the same thing.