Over the years we have seen our clients battle with the desire to add space without compromising garden space or they have extended up and out to the greatest extent – leaving ‘down’ as the only way to go.  And with ever increasing property prices, creating a basement storey can be a great option for providing large amounts of additional living space for a growing family, without having to move from a location that may be perfect for schools, commuting etc.

Whereas a loft conversion can add extra bedrooms, a basement is located closer to the main living areas – giving it a much more flexible range of uses such as home cinemas, playrooms, office/home business space, personal gyms and pools.  It is also a great place to relocate practical but not necessarily attractive spaces such as the utility rooms, boiler and storage, freeing up more valuable above-ground space for wow-factor spaces to live and entertain in.


Alternatively, a basement can have its own external entrance and provide a self-contained unit, ideal for use as a home office / business space or annexe. It is important to note, however, that if you want the basement to become an independent separate dwelling (perhaps to sell on), you need express consent.

The financial viability of undertaking a basement storey all depends on the cost of the work relative to local property values.  The market in central London and other sought-after urban areas means that creating a lower ground floor will make much more financial sense than other areas – but in all cases, it is worth seeking the advice from local estate agents as to how much space is worth per square metre in your neighbourhood.   How the space is designed will have a bearing on this – a high quality well-lit basement space, with access directly to the outdoors, is always going to add more value than a dark converted cellar with poor headroom.


As a direct comparison with loft conversions , a straightforward cellar conversion costs about the same per m², but creating a basement from scratch can be twice the amount.  It is often possible to create more usable space with a basement than a loft conversion and as the work should make little difference to a building’s external appearance it can be hard for Local Authorities to find reasonable grounds for refusal.

Planning policy on basements does vary from between Local Authorities (and high profile cases of people creating multi-storey basements means that planning policy is currently under review). HollandGreen will be happy to talk you through the latest guidelines in your area and advise on what is likely to be permissible for your property.

Converting an existing cellar from a storage area to habitable space should not require planning permission and can usually be done under Permitted Development Rights – this is also often possible if property is located in a Conservation Area or other specially designated area.  Some houses on private estates can also be subject to restrictive covenants, which should be checked first.