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Side extensions in London

The side return extension reclaims the narrow space beside Victorian and Edwardian terraces, and is among the most efficient ways to extend a house.

Ashfield House — side infill and rear extension with white render and timber openings
The brief

A side return extension reclaims the narrow strip beside the rear projection of a Victorian or Edwardian terrace. The added area is modest, but its effect on the plan is considerable, turning a galley kitchen into a room that works for the whole household.

Approach

The design turns on light and proportion: how the new roof admits daylight without overheating the room, how it meets the neighbouring boundary, and how the enlarged space relates to the rest of the ground floor. Side, rear and wrap-around options are compared side by side before a direction is agreed.

Planning and regulation

Side return extensions may fall within permitted development or require a householder application, depending on the house, its setting and its planning history. Party wall notices are almost always required on a terrace and are served early.

Delivery

Feasibility is followed by concept design, planning, technical design and contract administration, with a single director responsible from the first visit to completion.

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 side extension? +
Most side return extensions on London terraces fall within permitted development rights — single storey, under 4m height, within depth limits. If the property is in a conservation area or has an Article 4 direction, you will likely need planning permission. The position of each property is checked before any design work.
How long does a side return extension take? +
Typically 3-4 months for design and consents, then 2-4 months on site. Side returns are quicker to build than rear extensions because the footprint is smaller, but the structural work (building against the party wall, supporting the floor above) requires careful sequencing.
Can a side return be combined with a rear extension? +
Yes — this is called a wrap-around extension. It creates an L-shaped ground floor that is wider (from the side return) and deeper (from the rear extension) in a single build. More expensive but the most complete transformation of a Victorian ground floor. We test both options in the feasibility study so you can compare.

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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