Earlier quoted context omitted.
This is a negative outcome of the Town and Country Planning Act. We've mandated by law that all planning is done upfront and due to the possibility of construction fraud provide detailed designs to building contractors that disallow them from substituting any materials or design choices without it being explicitly requested by the employer. In theory, there can be conversation between individual subcontractors and th…
Building is not a waterfall process because of the Planning act. It's waterfall because of the cost structure of building. Every time you iterate physically, you are throwing a lot of money away in time and materials. So any iteration is pushed back to the paper part of the exercise, in which case it might just as well happen before planning approval. Also, it's possible to request a variation, especially if somethin…
Also it's because of the financial structure. People invest a lot of money in something with a delayed, sometimes for years. Delay increases everyone's risk, increases interest expense, and defers revenue.