Side Return Extensions in London
Turn the space beside your kitchen into a wider, brighter room for cooking, dining and everyday life. One accountable point of contact coordinates the design, approvals and build.
- FMB Member
- 10-Year Structural Warranty
- Vetted & Work Inspected
- Fully Insured
- Dedicated Project Manager
- Weekly Updates
What a side return extension is
A side return infills the narrow passage that sits beside the original rear outrigger on many London terraces. It adds width to the ground floor, which is usually what makes a long, thin kitchen work as a room.
It does not automatically add depth. A side-only proposal can leave the rear garden as it is. If the back of the house also moves outwards, that is a wraparound extension, with a different structure, planning route and cost.
Completed project
Widening the ground floor in Isleworth
A wider whole-home renovation that included a side extension, a double-storey rear extension, structural wall removals with new steels, and a loft conversion. It is not a standalone side return project.
The client had secured design and planning before appointing Trovix, and we delivered the construction and coordination through to completion.
It shows the part that matters most on a side return: forming the structural opening, carrying the loads and finishing the widened space properly.
View the Isleworth projectThree decisions that shape a side return
We review these together, whether you are starting with ideas or already have drawings.
- 1
Width and layout
The first measurement is the side passage itself, and what it leaves once walls, insulation and the structural build-up are allowed for. Width decides whether you gain a genuinely usable room or a wider corridor, so we work in circulation and clearances around units, appliances and a table. An island is possible on some plans and not others — it depends on the finished internal width and the run of the kitchen, not on the passage width alone.
- 2
Daylight and roof
Building over the passage usually removes the side windows that lit the original kitchen, so daylight has to be replaced deliberately. Rooflights along the new roof plane, or a glazed section where the new roof meets the house, are the usual answers. The retained middle room is considered at the same time, along with ventilation and, on a sunny elevation, shading and glass specification.
- 3
Boundaries, structure and drainage
Removing the original side wall needs a beam sized for the span, with the new roof junction detailed for weathering and insulation. Foundations are set by ground conditions and by what sits near the boundary, and the soil stack or drain run beside the house is checked early rather than discovered late. Access and neighbour matters are coordinated before work starts.
How much does a side return extension cost in London?
Typical project investment: approximately £55,000-£100,000+ including VAT. Small footprints carry high fixed structural and site costs.
Typical project investment: £55,000 – £100,000+ including VAT
A side return adds a modest amount of floor area, but it still involves a structural opening into the house, groundworks against the boundary and a new roof with glazing. The total scope of work matters far more than the area added, which is why two side returns of the same size can price very differently.
What moves the figure most:
- Internal width achieved and the length of the infill
- The structural opening into the existing kitchen and the steel it needs
- Foundation depth and its position relative to the boundary
- Roof form, rooflights and any glazed roof section
- Drainage or soil stack alterations beside the house
- Planning route and any party wall coordination required
- Access, which on a mid-terrace changes the whole build method
Kitchen units, worktops and appliances are excluded unless specifically agreed for your project. Kitchen installation can be included by prior agreement.
What could your side return extension cost?
Answer two quick questions. No email needed to see the range.
Question 1 of 2 · Property type
Planning and approvals
Some side extensions qualify for permitted development, but only where the property is eligible and every condition and limit is met, including any additions a previous owner has already built. Side extensions are restricted on designated land such as conservation areas, and rights can be removed by an Article 4 direction or a planning condition. Flats and maisonettes follow a different route. We check the address and the proposal before recommending a route.
Party wall notice requirements depend on the work proposed — where a new foundation is excavated close to a neighbour's foundations, or work is carried out to a shared wall, the Party Wall etc. Act 1996 may apply. This is separate from planning, and we coordinate the appropriate specialists. Building regulations approval is a separate process again, and applies whichever planning route your project takes.
The Process
How your side return is delivered
One accountable point of contact coordinates the specialists your project needs, from the first conversation through to handover.
- 01
Discuss your plans
We discuss your property, goals and budget, then arrange a survey or site visit when appropriate.
- 02
Design and approvals
We develop the design or review your existing drawings, coordinating the technical work and approvals your project needs.
- 03
Scope, price and programme
We confirm the construction scope, specification, price and build programme before construction begins.
- 04
Build and handover
Your dedicated project manager coordinates the build, with weekly updates, final checks and handover.
Living through the build
- Occupied rooms, floors and the route through the house are protected before work starts.
- Access, deliveries and waste routes are agreed in advance, including where there is no side gate.
- A temporary kitchen is planned, because a side return usually takes the existing kitchen out of use.
- Your project manager gives a weekly update, so you always know what happens next.
Discuss your side return
We respond within 24 hours, including weekends and holidays.
What happens next
- 01We review your details and respond within 24 hours.
- 02A short call to understand the property, the brief and the budget.
- 03If it looks right for both sides, we arrange a visit and set out the next steps.
Side return questions, answered
Start your side return extension
Tell us about your home and what you want the kitchen to do. We respond within 24 hours.