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Basement conversions in London

Basement conversions in London demand exact coordination of structure, waterproofing and party wall matters from the first day of design.

Contemporary basement living space with natural light from above
The brief

A basement conversion creates new accommodation below the house, and is among the most technically demanding forms of residential work in London.

Approach

Structure, waterproofing, drainage, daylight and ventilation are resolved together from the outset. The studio coordinates the architectural design with structural engineering and specialist consultants so that the construction method is established before planning is sought.

Planning and regulation

Most basement proposals in London require planning permission, and many boroughs apply specific basement policies covering depth, extent, drainage and construction management. Party wall matters are significant and are addressed at the start of the project.

Delivery

Feasibility, planning, technical design and construction are managed as one coordinated process, with a director responsible throughout.

Fees

Fees are fixed for each stage and confirmed in writing once the scope is agreed. Construction cost depends on the site, the specification and the procurement route, and is established through an indicative cost plan at feasibility stage.

Frequently asked questions

How are fees and construction costs established? +
Fees are fixed for each stage and confirmed in writing once the scope is agreed. Construction cost depends on the site, the specification and the procurement route, and is established through an indicative cost plan at feasibility stage.
Is planning permission required for a basement in London? +
Almost always yes in London. Most boroughs now require planning permission for basement excavations. Some (Camden, RBKC, Westminster) have specific basement policies limiting size, depth and garden coverage. We navigate these borough-specific requirements as part of the service.
How long does a basement conversion take? +
6-12 months for design, planning and coordination, then 6-12 months on site. Basements are the longest residential project type — the excavation and underpinning alone can take 3-4 months. We give you a detailed programme at appointment.
Is a basement conversion financially viable? +
In outer London, the economics are harder to justify. We can give you a rough value-added estimate during feasibility based on comparable sales in your area.

Who we work with

  1. 01Homeowners
  2. 02Families
  3. 03Landlords
  4. 04Self-builders
  5. 05Property developers
  6. 06Investors
  7. 07Businesses

Why clients choose us

01Fixed fees

Fees are fixed at each stage and confirmed in writing, so that cost is known before design begins.

02Director-led

A director leads each project from the first conversation to completion, giving continuity at every stage.

03Response

Every enquiry is answered by a director within one working day, and progress is reported at every stage.

04Independent advice

Advice follows the evidence, including where it departs from the initial brief.

05Design quality

Design is resolved in detail before it reaches site, so that the quality of the idea is carried into the built work.

Related services

Services that usually sit alongside this appointment. Fixed fees, staged, with a director leading the work.

Discuss a project with the studio

Provide the site address and a summary of the requirement. A director will respond within one working day.

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