Why are basement conversions so popular in London?

Apr 28, 2023 | Property News

Space is at a premium in the capital, and for those that are looking to find more space in their current property, a basement conversion has become a popular choice.

Twenty years ago, basements were mostly the preserve of wealthy elites and oligarchs, who wanted to excavate down to add swimming pools, gyms, and other luxury rooms to their London property. Today, however, the majority of basement conversions are constructed for professionals looking to extend their home with an extra bedroom, playroom, or home office.

In a report titled Bunkering down? The geography of elite residential basement development in London, researchers looked at the 7,328 basement construction projects approved by the City of London or one of the capital’s 32 boroughs and found that the vast majority of the projects (80%) were for “standard” single-storey basements. These basements were generally made up of one to three rooms, and built in areas such as Hackney, Hammersmith and Fulham.

Professor Roger Burrows, who lead the study, told the Guardian that booming house prices over the last decade had made basement developments a logical choice for affluent Londoners who wanted to maximise the value of their property.

“What we’ve seen is a normalisation of single-storey basements as the 21st-century version of the loft conversion,” he said.

Meanwhile, the researchers found that a further 18.3% of the basement developments were classed as “large basements”, which are large enough to fit a swimming pool or other luxuries, and 2.3% were “mega-basements” which consisted of multiple stories and extended under the garden. These larger basement construction projects were most commonly completed in Kensington, Chelsea, and Westminster.

The authors of the research paper estimated that over the course of a decade London property owners have excavated more than 1.782 million cubic metres of earth to create these basements, which would fill St Paul’s Cathedral 12 times over. Basement construction has become an aspirational home improvement project for those that have already converted their attic for an extra bedroom and now face a choice between moving further into the suburbs where they could afford a couple of extra rooms, or staying where they are and digging down to create a basement.

Basement conversion vs attic conversion

Attic conversions are generally lower cost, but not all properties have a loft with enough headroom to create a full-sized room, or the property may have a flat roof and any extension towards the sky would require planning permission and additional expense.

If your property already has a cellar, converting that space into a home office or a couple of extra bedrooms can also be completed within a reasonable budget. Costs will rapidly increase if excavation is required, but for many people converting an existing cellar will provide all the additional floor-space they are looking to create.

Critically, however, many of the homeowners choosing to build basements have not chosen a basement conversion instead of a loft conversion – they have already converted their loft space and are looking to build further space by extending downwards.

More space without the costs of moving

In theory, people would only buy a property that has the space they need at the time, and then move to a larger property when children are added into the equation or an elderly relative needs to move in. Moving house will always be a hassle, but stamp duty (SDLT) also makes it an expensive exercise, where homeowners need to live in a property for a minimum of five years to claw back some of the costs.

The increase to stamp duty introduced by George Osborne for more expensive properties adds to the troubles of homeowners in London, where house prices are significantly more expensive. Now, with house prices stagnant, it will take even longer to recoup the expense of moving house, and so those looking for more space will be tempted to dig down instead of move out.

Additional floorspace adds value

Whether you decide to convert your attic into an extra bedroom or excavate a new basement, adding additional floorspace to a property adds value. Estate agents generally treat the value of floorspace in a converted basement as the same as anywhere else in the property, which means across much of London each additional square foot of floorspace could add £1,000 to £2,000 to the value of your home. If you can convert and renovate your basement for less than £1,000 per square foot, then when it comes time to sell your home that money will have been a good investment.

How to build a basement conversion

If you are looking to add space to your property by converting an existing cellar or excavating a brand new basement, then it is time to contact the experts at Good London Builders. We can help you decide on the right construction project to improve your home, and guide you through the process from start to finish. Contact us today on 0207 978 5097 or via our contact form.

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