The house builders will build to make a profit, make these new houses unsalable is the only answer, tighten up on insurers, tighten up on mortgages, tighten up building standards, and make the conveyancing a lot more onerous
Yup, then you stop building on flood plain. But that doesn’t help because the demand is still there. If flood plain is currently the least stupid place they can build and they can’t build there the planners will have to put slightly more stupid places in Local plans. People aren’t building on flood plain for a laugh, we’re building on flood plain becuase it’s the best available land in those areas. It’s not like there will be better land than people are happy to have developed elsewhere – if there was they wouldn’t be building on flood plain.
This all comes from demand. Unless you fix the demand you’ll need to build houses in dumb places. …and we don’t want to fix demand, so guess what, we’re going to carry on building on land that will be under the sea within 100 years.