First we built up into the attic, now we're going down under the ground. Emma Cullinanon digging deep to create extra space

WE'VE EXTENDED out, we've created living spaces in attics and now people are extending their homes underground.

It's not an entirely new concept, as many of us have experience of either visiting or living in Georgian basements with 'light wells' twixt front room and road. But there is a growing group of people extending houses beneath their gardens and Crean Salley Architects is responsible for nestling plenty of clients into the terra firma of Dublin 4.

The practice has already built about seven underground extensions and is in the process of creating more of them.

They are typically used to house livingrooms, guest bedrooms, gyms and band rehearsal spaces and one client has even created an at-home leisure facility that includes a cinema, sauna, steam room and bar, beneath a glass roof, all tucked under his garden.

In many cases, when one person on a street builds an extension it sets off a sort of reverse-domino effect with rows of extensions going up, as neighbours follow suit.

That is the case on a leafy Dublin 4 road of Edwardian houses, where one resident built a traditional-style extension that starts above ground and then plunges beneath the grass.

As Crean Salley proceeded with this job the next-door neighbours decided that they would like something similar, although they opted for an extension that didn't ape the original house style and also wanted a decked garden with sunken patio.

So while neighbour number one has a lawn with a light well to one side bringing natural light into their subterranean space, neighbour two has a large light well in the middle of their garden.

Anyone passing the original house here would think that all was idyllic in this pretty Edwardian redbrick home at a des-address but there were problems with the configuration of space. The front livingroom faced north-west and so was rather gloomy.

There was another livingroom, and a kitchen, to the rear with a small extension housing a study. On the two floors above were bedrooms. To stretch the restrained living space the client asked for a larger kitchen and a spill-out play area where people could chill and play drums and keyboards (one advantage of going underground is the sound-proofing afforded by metres of earth).