The clincher could be the land question.A combination of strict planning rules and “landbanking” – developers’ habit of buying but not building on land – is driving up prices in many parts of the UK.By contrast, floodplain land is cheap. One of the ways to make your home float on water is to build it on boats and have a building that is always floating. Amphibious houses cost about 20% more to build than a conventional design. Doors and windows will need to be flood proof.