Modern Contemporary Residential Architects

Working In Kent and Sussex

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RIBA Charterd Practice
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Basement - Adding Space Below Ground

Basement Extensions

Not long ago, the word ‘basement’ conjured up images of dank, dark spaces suitable only for storage, the washing machine or possibly a treadmill. Today, beautifully designed basements are increasingly in demand, particularly in elegant London streets and other areas such as Kent and Sussex Greenbelt where land values are high. Contemporary house design often includes basements, as people have realised the value of the ground beneath their feet, and as building engineering technology has advanced. Basements are a great way of adding extra space particularly in Conservation Areas or Areas of Outstanding Natural Beauty and we have successfully obtained planning permission for quite a few.

Contemporary Basement Design

The more expensive the property, the more a basement makes physical and financial sense. Provided the new sunken spaces don’t add up to more than about 25 per cent of the floor area of the house, owners can expect to ratchet up the value of the property by around 20 per cent.

Carefully positioned windows, roof-lights, internal glazed walls, ‘wow’ factor lighting, large sliding doors onto decks and terraces, sunken gardens and internal courtyards are some of the features we use to introduce natural light into subterranean home extensions making them seriously cool, luxurious architectural statements.

Getting Planning Permission For Basements

The planning regime covering the creation of living space in basements is evolving and under review. Converting an existing residential cellar or basement into a living space is in most cases unlikely to require planning permission as long as it is not a separate unit or unless the usage is significantly changed or a light well is added, which alters the external appearance of the property.

Excavating to create a new basement which involves major works, a new separate unit of accommodation and/or alters the external appearance of the house, such as adding a light well, is likely to require planning permission. Sensitive design and thoughtful presentation are key to success. Several of the basements we have designed are in Greenbelt and Conservation Areas or Areas of Outstanding Natural Beauty.

Basements and Listed Buildings

If you want to put a basement under a listed building you will need consent. We haven't done this yet, but there's always a first time! However three current designs position basements next to Listed Buildings


Building Regulations apply and cover areas such as fire escape routes, ventilation, ceiling height, damp proofing, electrical wiring and water supplies. Underpinning and foundation work may also be needed, and the Party Wall Act 1996 needs to be considered if other properties adjoin yours and you share walls.