Basement Extensions, London
Expert Residential Basement Extension Builders London.
Expert Residential Basement Extension Builders
A basement extension is one of the most effective ways to significantly increase the floor area of a London property without compromising its garden, altering its roofline or changing its street appearance.
By extending outwards beneath the garden, side return or front forecourt – or combining a new basement with an existing cellar space – it is possible to create substantial additional accommodation that adds significant value to your home.
Advantage Basements & Renovations has designed and built basement extensions for London's most prestigious residential properties for over 25 years. Our integrated service – from architectural design and planning through to construction and interior finishing – ensures that your extension is delivered to the highest standard with a single point of accountability.
“Time and again the team contributed with ideas and suggestions for refinements (large and small) to add an extra gloss to the finished home. No surprise then, that the work finished on time, on budget and beyond even our expectations as to the result.”
— Former Customer
Planning and Design Considerations for Basement Extensions in London
Planning requirements for basement extensions vary across London boroughs, and some authorities have specific policies that address the scale, design and impact of basement works. Our planning team's detailed knowledge of borough-specific requirements ensures your application is prepared with a thorough understanding of the likely planning approach, improving the prospects of approval and avoiding unnecessary redesign.
Our architects design basement extensions that respond sensitively to the character and context of your property, maximising usable space and creating a coherent architectural relationship between the new basement and the existing house above.
Basement Services
Begin Your Basement Extension Project
Contact Advantage Basements & Renovations to discuss a basement extension for your London property. Our team will advise on the possibilities, timescales and costs specific to your home.
We will provide clear, expert advice on the scope of works required and the most effective way to achieve your vision.
FAQs
Can I extend my basement under a garden in London?
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Yes, garden basement extensions are one of our core specialisms and one of the most popular forms of basement development in London. Extending beneath your garden creates substantial additional floor area without consuming any of your garden space at ground level – the garden is typically reinstated above the new basement once construction is complete.
Garden basements are accessed from the house via new openings in the rear basement wall, via a glazed lightwell and stair that also brings natural light into the space or via a discrete entrance structure at garden level.
Planning requirements for garden basements vary between boroughs, and some authorities limit the proportion of garden that can be excavated. Our architectural and planning team advises on the requirements specific to your property and location.
How far can I extend my basement forward or to the side in London?
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The extent to which you can extend a basement forward, sideways or rearward depends on several factors. Planning policy varies between different parts of London. Some areas limit basement footprints to a percentage of the total plot area. Others have specific policies regarding the extent of basements beneath front gardens or side returns.
Structural considerations, including proximity to adjacent properties, the depth of neighbouring foundations and ground conditions, also affect what is achievable. Practical construction logistics – access for excavation plant, removal of excavated material and construction of the extended structure – must also be considered. Our feasibility assessments examine all of these factors and advise on the maximum practical and approvable extent of extension for your specific property.
Do basement extensions in London require party wall agreements?
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Yes, almost all basement extensions will trigger the Party Wall Act requirements. Excavating within three to six metres of a neighbouring property, where the excavation will go deeper than the neighbour's foundations, requires party wall notices to be served and, typically, a Party Wall Award to be agreed.
Even where excavation does not extend close to boundaries, works to shared party walls to create openings between existing and new basement areas will trigger the Act. Our project management service includes full management of the party wall process, ensuring that all necessary notices are served, surveyors are appointed and awards are agreed before construction commences.