So the question: Why hasn't prefab construction taken over?
Answer: It has, just not all the way.
Modern American construction makes extensive use of prefabricated roof trusses, for large developments it is common to see parts of the framing prefabbed. The drywall interior fixing systems are designed to substantially reduce the amount of on-site work required. Modern plumbing fixtures can often be snapped together or joined with glues/expoxies rather than needing to be soldered. Domestic electrical can come as pre-wired conduit and you better believe that large developments are selecting those sizes carefully to reduce on-site work. Windows and doors arrive as single units which just need to be fitted, again a lot of attention is paid to ease of fitting since they are selling to series building professionals for whom labour time is money. Kitchen cabinetry is supplied fully prefabbed.
Modern flooring is also based on easy-to-assemble systems. Compare the effort required to put in laminate vs old-school parquet, hardwood boards, or marble.
Of course if you just put a whole ground floor together in a few modules in a factory, you will save even more labour time. The question is whether the greater transport costs and reduction in flexibility* will make it worth it in the end.
(*) If your factory isn't mass producing the same product over and over, you're going to lose a lot of the productivity gains from factory production.
Answer: It has, just not all the way.
Modern American construction makes extensive use of prefabricated roof trusses, for large developments it is common to see parts of the framing prefabbed. The drywall interior fixing systems are designed to substantially reduce the amount of on-site work required. Modern plumbing fixtures can often be snapped together or joined with glues/expoxies rather than needing to be soldered. Domestic electrical can come as pre-wired conduit and you better believe that large developments are selecting those sizes carefully to reduce on-site work. Windows and doors arrive as single units which just need to be fitted, again a lot of attention is paid to ease of fitting since they are selling to series building professionals for whom labour time is money. Kitchen cabinetry is supplied fully prefabbed.
Modern flooring is also based on easy-to-assemble systems. Compare the effort required to put in laminate vs old-school parquet, hardwood boards, or marble.
Of course if you just put a whole ground floor together in a few modules in a factory, you will save even more labour time. The question is whether the greater transport costs and reduction in flexibility* will make it worth it in the end.
(*) If your factory isn't mass producing the same product over and over, you're going to lose a lot of the productivity gains from factory production.