Wrap-Around Extension Cost London 2026

Wrap-around extension costs in London, 2026

A wrap-around extension combines a rear extension with a side return infill in one L-shaped structure, wrapping around the back corner of the house. It is the most ambitious and the most expensive single-storey extension type, with a new footprint typically ranging from 40 to 80m².

The totals below include VAT at 20% and a typical allowance for professional fees. They do not include furniture, landscaping or party wall surveyor costs.

Above high specification, architect-designed schemes with luxury finishes and composite glazing run at £4,500–£6,000+/m². These are London figures for 2026, not national averages: labour costs in the capital run 20–30% above the national average. The house extension cost guide for London sets the wrap-around beside rear, side return and double-storey extensions.

What a wrap-around is, and how it compares

Victorian and Edwardian terraced and semi-detached houses have a narrow strip beside the back of the house, typically 1.5–2.5 metres wide, with the wall to the neighbouring property running along it. This is the side return. A side return extension fills that strip; a rear extension builds out into the garden. A wrap-around does both at once, so the new room runs down the side of the house and across the back, usually to make one open-plan kitchen, dining and living space that opens onto the garden.

Wrap-around, side return or rear extension?

Our published mid to high specification ranges:

• Side return extension: 15–25m², £65,000–£130,000. See the Victorian side return extension cost guide.
• Single-storey rear extension: 20–40m², £80,000–£160,000, and the type most likely to qualify as permitted development. See the single-storey rear extension cost guide.
• Wrap-around extension: 40–80m², £190,000–£380,000, and usually a householder planning application.
• Double-storey rear extension: 40–70m², £170,000–£320,000, with bedrooms above. See the double-storey extension cost guide.

If you only need more living space, a single-storey type is the efficient choice. If you also need another bedroom, a double-storey extension almost always makes better financial sense than two separate projects later.

What moves the price within the range

After size, specification moves the price most, and the gap between mid and high specification is mostly glazing, kitchen and finishes.

Steel and the corner

Because a wrap-around wraps around the back corner of the house, the new room meets the existing house along more than one wall, and how much of that wall you take out decides the steel. The larger the opening, the heavier the structural frame, and multi-bay openings need significant steelwork. Removing the entire rear wall for a fully open-plan space needs more steel, and sometimes a goalpost frame, than keeping a section of wall.

As a reference point, removing a full rear wall needs a steel frame and temporary propping, typically adding £8,000–£20,000 depending on span. The structural engineer, typically £800–£2,000, provides the calculations for the steelwork and foundations, and the frame is priced from that design in the itemised quote.

Glazing and rooflights

Glazing is where budgets swing most. Standard bifold doors cost £3,000–£6,000, slim-profile sliding doors £5,000–£10,000 and structural glazing systems £10,000–£25,000+. Bifolds or sliding doors belong to our mid specification; structural glazing to high specification.

Over the side return, the narrow width means natural light from the side is limited, so rooflights are almost always essential. A quality fixed or opening rooflight is £2,500–£8,000 depending on size and specification, and a roof lantern adds £3,000–£8,000.

Roof, ground and drainage

The side return roof is typically a flat roof with internal drainage or a glazed link. The junction with the original house wall is a common point of water ingress if it is not properly detailed, so check how any quote deals with it.

Pockets of made ground, tree roots or inadequate existing foundations can add £3,000–£10,000 to groundworks, and deep excavation below the existing floor level adds £5,000–£15,000 depending on ground conditions. Side returns over shared drains may also need the drainage diverted, which adds cost.

The kitchen

The build price delivers a finished shell ready for the kitchen install. The kitchen itself, meaning units, worktops and appliances, is a separate budget, typically £15,000–£60,000+, and a bespoke or designer kitchen typically runs to £25,000–£60,000+. Changes made once work is on site are the single biggest controllable cause of delay and cost overrun, so fix the kitchen layout before construction begins.

Access and living in

Tight rear access on inner-London terraces adds time and cost to deliveries and waste removal. Conservation area requirements such as matching brick and specific windows can raise the spend, and building while you live in the house takes longer and costs slightly more than working in an empty property.

Planning: one extension, two sets of limits

The planning rules treat a wrap-around as one extension that has to meet the rear limits and the side limits at the same time. To be permitted development, it would need to be:

• no more than 3m beyond the rear wall of the original house on a terraced or semi-detached house, or 4m on a detached house;
• a single storey, no more than 4m high, with eaves no higher than 3m where it comes within 2m of a boundary;
• no more than half the width of the original house in total width;
• laid out so the side return infill extends no more than 3m beyond the rear wall of the main house.

Taken together, these limits mean most wrap-arounds need a householder planning application. It costs £548 and adds 8–12 weeks to the programme. In a conservation area every side extension, including the side return infill of a wrap-around, needs planning permission, whether or not it can be seen from the road. If a smaller scheme does fit within the limits, confirm it with a Lawful Development Certificate before work starts: the fee is £274 and the decision takes up to 8 weeks.

Most applications succeed. London councils approved 88.2% of wraparound extension applications decided between September 2025 and August 2026 (2,550 of 2,890 decisions), against 86.9% for rear extensions and 78.0% for two-storey extensions, and the typical (median) wraparound decision took 8.0 weeks from validation, according to our 2026 London planning approvals study. The borough matters: across all householder applications decided between September 2025 and August 2026, approval rates ran from 69.2% in Barking and Dagenham to 95.1% in Bexley.

We advise taking a pre-application view from the council before committing to a wrap-around design, particularly in boroughs with Article 4 directions on side extensions. Our in-house architectural team prepares the drawings and manages the application, and we use the Full Plans route for building regulations as standard, so the technical drawings are approved before construction starts.

Party wall: one neighbour or both

A wrap-around typically involves work next to one or both neighbours, so party wall notices are almost certainly required. A side return extension almost always triggers the Party Wall etc. Act 1996, and the rear part triggers it where it sits on a boundary, or where its foundations are within 3m of a neighbour's structure and go deeper than that neighbour's foundations.

Work to an existing party or garden wall needs a Party Structure notice, served at least 2 months before the proposed start; a new wall on the boundary or an adjacent excavation needs 1 month. Each neighbour has 14 days to respond. If they consent in writing, no surveyor is needed, and work can start when the notice period ends, or earlier if they also agree to that in writing. If they dissent or do not reply, surveyors agree a Party Wall Award before work starts.

The building owner usually pays all reasonable surveyor costs; strictly, the surveyors decide who pays. Expect £800–£1,500 with a single agreed surveyor, or £800–£3,500 per neighbour where each side appoints its own. These costs are not in the ranges above. We prepare and serve the notices alongside the planning work, so they do not hold up the start; the party wall agreement cost guide has the detail.

How long a wrap-around extension takes

Allow 16–22 weeks on site, against 12–16 weeks for a single-storey rear extension and 18–24 weeks for a double-storey. We have delivered complex double-storey and wrap-around projects within 22 weeks on site.

1. Design and drawings. A wrap-around takes slightly longer to design than a straightforward rear extension, which typically needs 4–8 weeks. Our in-house architectural team carries out the measured survey and prepares the drawings and 3D visualisations.
2. Planning and party wall. 8–12 weeks for the householder application. Building regulations drawings run alongside, and party wall notices are best served when the planning application is submitted; where surveyors are appointed, the Award typically takes 4–8 weeks.
3. Pre-construction. Typically 2–4 weeks to confirm selections and order long-lead items; large roof lanterns and steel-framed bi-fold doors can have lead times of 6–12 weeks.
4. Build. 16–22 weeks on site, from groundworks and steel to a weathertight roof, then first fix, plastering, second fix and finishes.
5. Sign-off. After snagging, Building Control carries out the final inspection and issues the Completion Certificate, which we obtain for you.

In most cases you can stay in the house. Expect 1–2 weeks of higher disruption during the structural openings, and kitchen use may be disrupted for several weeks. The extension timeline guide covers each stage.

What the price includes, and what to budget separately

One contract covers the work from survey to sign-off:

• In-house architectural drawings, planning application and building regulations approval
• Structural engineering calculations
• Party wall notices prepared and served
• Demolition, excavation, foundations and drainage connections
• Steelwork, padstones and temporary propping during the opening-up
• Cavity walls to match or complement the house
• Flat roof with warm roof insulation, membrane and rooflights
• Bifold doors, sliding doors or fixed glazing
• Insulation to current Building Regulations Part L standards
• Electrics, plumbing and heating, with underfloor heating where specified
• Plastering, screed, floor finish and decoration
• Project management, and our 10-year workmanship warranty

Not included: the fitted kitchen, bathroom suites and tiling (usually quoted separately or as a variation), furniture, blinds, curtains, landscaping and party wall surveyor costs. The individual fees to check against any quote:

• Architect and design: £3,000–£8,000, or 5–8% of build cost for a full design and planning service
• Structural engineer: £800–£2,000
• Householder planning application: £548
• Building regulations: £1,000–£3,000 in building control plan check and inspection fees
• Party wall surveyor: £800–£3,500 per neighbour, where needed
• VAT: 20%; extensions are standard-rated

Is a wrap-around worth it?

Of the single-storey types we price, a wrap-around adds the most floor area: 40–80m², against 20–40m² for a rear extension and 15–25m² for a side return. In inner-London boroughs, open-plan kitchen-diners are the single most sought-after feature among family buyers, and that is the room a wrap-around is designed to create.

Whether the value it adds covers the cost depends on your street. The ceiling price for your street sets the limit on how much value any project can add, and building beyond it rarely pays back, so check it before the design is fixed. If you need a bedroom as well, compare the double-storey figures: a 40–70m² double-storey rear extension costs £170,000–£230,000 at mid specification.

How we price a wrap-around extension

We design and build wrap-around extensions across London, and we do not give a ballpark figure and adjust it once work is underway. After a consultation, our in-house architectural team prepares the drawings, or we work from your architect's. With the structural engineer's input on the key elements, we issue a fully itemised quotation broken down by trade, so you know what each element costs before you sign.

The contract is the JCT Minor Works Building Contract: a fixed price for the agreed scope, a defined programme and written variation instructions, with any extra cost confirmed before the work is done. Our 10-year workmanship warranty starts at practical completion, and we hold £10M public liability insurance.

Comparing quotes? We will go through a competitor's quote with you and explain any differences in scope or specification. Send drawings or photos through the contact form, which takes PDF, JPG, PNG, HEIC and DWG files, or call 020 8080 8240. Our house extensions service explains how a project runs from first drawings to building control sign-off.

Frequently Asked Questions

Prices shown are indicative ranges based on London market data for 2026. Actual costs depend on the existing structure, specification and programme. All figures include VAT at 20% unless otherwise stated. Your own price is fixed in a written, itemised quote.