Houses goinarearegoing down

Forget the third bathroom or upstairs parents’ retreat. The latest trend in home renovation is a basement. Welcome to the era of the “iceberg house”.

We all know space is scarce and the cost of land is high so it makes sense to expand a home using its existing footprint – and a basement has obvious benefifits when it comes to protracted council approvals, heritage restrictions and consideration of next-door properties.

Specialist builders are now springing up in cities following the lead of space-poor London, where underground home extensions have become increasingly popular. (One fifirm, London Basement, has done more than 1000 basement conversions since 1994.)

The diffifficulty of excavation will depend on what testing reveals: is the home built on rock, sand or clay? Retaining walls contain the excavated space, the existing structure is underpinned and steel beams pick up the flfloors and walls. In many cases, you can live upstairs during the process.

The trend’s popularity has brought a backlash, with neighbours becoming anxious as the underground works push out to the edges of the property boundaries and the noise and mess of the construction take their toll. There is also the risk of a cave-in, taking the home above with it, as happened to a Georgian house in London in 2015. But the pay- offff, if all goes to plan, could be a subterranean swimming pool, cinema, wine cellar or a true man cave.