House Extension Wandsworth: Vetted Builders, Matched Quotes
A house extension in Wandsworth costs £60,000–£120,000 for a single-storey rear extension and £120,000–£280,000 for a wrap-around. Planning permission is required in most cases. Wandsworth’s 30+ conservation areas and widespread Article 4 Directions mean Permitted Development cannot be assumed. Get 3 matched quotes from vetted Wandsworth extension builders.
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How much does a house extension cost in Wandsworth?
A house extension in Wandsworth costs £55,000-£280,000+ depending on type, size, and specification. The table below shows typical all-in costs, including VAT and professional fees.
House Extension Cost Wandsworth 2026
All-in costs including VAT and professional fees. Prices reflect Wandsworth / south London market rates.
| Extension type | Typical size | All-in cost (inc. VAT) | Planning | Best suited to | Notes |
|---|---|---|---|---|---|
| Single-storey extensions | |||||
| Single-storey rear | 15–30m² | £60,000–£120,000 | Usually required | Victorian terrace, semi | Most common extension in Wandsworth. Creates open-plan kitchen-dining space across the rear ground floor. |
| Side return | 10–20m² | £55,000–£100,000 | Usually required | Victorian terrace | Fills the narrow passage beside the house. Specific to Victorian and Edwardian terrace stock. |
| Wrap-around (rear + side return) | 35–65m² | £120,000–£280,000 | Always required | Victorian terrace, semi | Maximum ground-floor footprint. L-shaped structure combining rear and side return in one scheme. |
| Over-structure / garage | 15–30m² | £50,000–£90,000 | Usually required | Detached, semi with garage | Converts garage and adds habitable space above. Lower cost-per-m² than ground-up extension. Common in Putney and Southfields. |
| Double-storey extensions | |||||
| Double-storey rear | 25–45m² | £100,000–£200,000 | Always required | Semi, detached | Adds ground-floor room and upper-floor bedroom/bathroom simultaneously. Lower cost-per-m² than two single-storey schemes. |
| Professional fees and additional costs | |||||
| Architect fees (drawings only) | — | £1,500–£3,500 | — | — | Planning drawings only. Included in all-in estimates above. |
| Architect fees (full service) | — | £3,000–£8,000 | — | — | Design, planning, building regs, and contract administration. Or 5–8% of build cost. |
| Planning application fee | — | £258 | — | — | Fixed Wandsworth Council householder fee (from December 2023). |
| Structural engineer | — | £1,000–£2,500 | — | — | Required for all extensions. Beam and steel calculations, foundation design. |
| Party wall surveyor | — | £1,000–£3,500 | — | — | Per adjoining owner where dissent. Mid-terrace Wandsworth properties have two adjoining owners. |
| Pre-application advice (Wandsworth) | — | £100–£600 | — | — | Recommended for conservation area schemes. Wandsworth Council written advice on householder applications. |
All costs inclusive of VAT and standard professional fees unless noted. Prices reflect Wandsworth / south London market rates for 2026. Actual costs depend on extension type, specification, site conditions, and contractor. Get 3 matched quotes from vetted Wandsworth extension builders at QuoteMyRenovation — free and no-obligation.
Wandsworth extension costs sit in the mid-range of the London market, above outer boroughs such as Bromley or Sutton, broadly in line with Lambeth, Southwark, and Lewisham. High-value streets in Battersea, Putney, and Wandsworth Town carry a modest premium due to parking restrictions, skip permit complexity, and the concentration of conservation area properties.
What drives cost variation in Wandsworth:
– Extension type: a single-storey rear extension costs significantly less than a wrap-around or double-storey
– Size: cost per m² typically falls as the extension gets larger
– Specification: open-plan kitchen-dining extensions with bifold doors and underfloor heating cost more than a simple additional room
– Planning route: conservation area schemes require additional professional input and higher-specification materials
– Structural complexity: chimney stacks, drainage diversions, and load-bearing walls add cost
– Party wall mid-terrace Wandsworth properties often have two adjoining owners, both requiring party wall notices
What type of house extension suits a Wandsworth property?
Most Wandsworth properties are Victorian or Edwardian terraces and semis across Battersea, Balham, Tooting, Earlsfield, Southfields, and Putney. The following extension types are most common:
Type | Typical size | All-in cost (inc. VAT) | Planning | Best suited to
Single-storey rear | 15–30m² | £60,000–£120,000 | Usually required | Terrace, semi
Double-storey rear | 25–45m² | £100,000–£200,000 | Required | Semi, detached
Side return | 10–20m² | £55,000–£100,000 | Usually required | Victorian terrace
Wrap-around (rear + side) | 35–65m² | £120,000–£280,000 | Required | Victorian terrace, semi
Over-structure/garage | 15–30m² | £50,000–£90,000 | Usually required | Detached, semi
Single-storey rear extension: The most common extension in Wandsworth. Creates an open-plan kitchen-dining-living space across the rear of the ground floor. Victorian terraces in SW11, SW12, SW17, and SW18 are the baseline property for this type.
Double-storey rear extension: Adds a ground-floor room and an upper-floor bedroom or bathroom simultaneously. Cost-per-m² is lower than single-storey because the structural cost is shared across two levels. Most common on Wandsworth semis in Putney, Southfields, and Earlsfield.
Side return extension fills the narrow passage running alongside the house between the main body and the garden boundary. Specific to Victorian and Edwardian terraces. Adds 10–20m² to the ground floor and, when combined with a rear extension, creates a full L-shaped or T-shaped open-plan layout. Very common on Wandsworth terrace stock.
Wrap-around extension combines the side return and rear extension into a single L-shaped structure. The most space-efficient extension for a Victorian terrace. Almost always requires full planning permission.
Over-structure / garage conversion with extension above converts an integral or attached garage and adds habitable space above. Lower cost-per-m² than a ground-up extension. Common in Putney and Southfields where detached and semi-detached properties with garages are more frequent.
Usually yes. Most house extensions in Wandsworth require planning permission. Permitted Development rights allow some single-storey rear extensions to proceed without a planning application, but those rights are removed or restricted across large parts of Wandsworth.
Permitted Development applies when ALL of the following are true:
1. The property is a house (not a flat, maisonette, or listed building)
2. PD rights have not been removed by an Article 4 Direction
3. The property is not in a conservation area (or the works meet conservation area conditions)
4. The rear extension does not exceed 3m depth (terraced or semi-detached) or 4m (detached)
5. Under the Neighbour Consultation Scheme (Prior Approval), depth limits extend to 6m (terraced/semi) or 8m (detached)
6. The extension does not exceed 4m in height and does not project beyond the principal elevation
Planning permission is required when:
– The property is in one of Wandsworth’s conservation areas
– An Article 4 Direction has removed PD rights from the property
– The extension exceeds PD size limits
– The extension is double-storey
– A wrap-around or side return extension is proposed
– The property is a flat, maisonette, or listed building
Always check Wandsworth Council’s planning portal at planning.wandsworth.gov.uk before commissioning drawings.
Wandsworth has more than 30 designated conservation areas. Extensions in conservation areas face additional controls on materials, scale, and design. Timber cladding, zinc roofing, and full-width glazing that would be acceptable elsewhere are often refused.
Key conservation areas affecting house extensions in Wandsworth:
Area | Postcodes/neighbourhoods affected
Battersea conservation areas | SW11 – Lavender Hill, Clapham Junction, Battersea Park Road |
Wandsworth Town | SW18 – West Hill, Old York Road
Tooting Bec | SW17 – Tooting Bec Road, Balham Hill
Balham | SW12 – Bedford Hill, Balham High Road
Nightingale Triangle | SW12 – between Clapham South and Balham
Earlsfield | SW18 – Magdalen Road, Garratt Lane environs
Putney | SW15 – Upper Richmond Road, Putney Heath
Southfields | SW18 – parts of Replingham Road
Streatham Park | SW16 – boundary with Merton
In conservation areas, Wandsworth Council typically requires extensions to use matching stock brick, hidden gutters, and flat or lean-to rooflines rather than pitched roofs. Pre-application advice is strongly recommended before commissioning drawings.
How long does a house extension take in Wandsworth?
Works on site for a standard single-storey rear extension take 10-16 weeks. The full programme from decision to completion is longer:
1. Architect appointment and measured survey 1–2 weeks
2. Planning drawings produced 4–8 weeks
3. Planning application submitted and validated 1–2 weeks
4. Planning decision (statutory 8 weeks from validation): 8–12 weeks
5. Building regulations application submitted in parallel with planning
6. Party wall notices served: 2 months minimum (run concurrently with planning)
7. Contractor tendering and appointment: 3–6 weeks
8. Works on site 10–16 weeks (single-storey); 14–22 weeks (double-storey or wrap-around)
Total from decision to completion: 7–10 months for a single-storey with planning permission. 10–14 months for a double-storey or wrap-around.
Party wall notices are required for most Wandsworth terrace extensions. Rear extensions almost always involve the party wall foundations (excavation within 3m) and often the party wall itself (cutting in for steels). Mid-terrace properties have two adjoining owners, both requiring notices.
How do I find a vetted house extension builder in Wandsworth?
Most Wandsworth homeowners receive extension quotes that vary by £20,000-£50,000 with no explanation of different scopes, different assumptions, different inclusions. Comparing them is nearly impossible without an identical written specification.
To get useful quotes:
1. Agree on your brief extension type, approximate size, specification level, and whether you want an architect or design-and-build
2. Confirm planning status before approaching builders; know whether you need planning permission and whether you’re in a conservation area
3. Request itemised quotes for groundworks, structure, roof, windows, internal fit-out, and professional fees listed separately
4. Confirm whether quotes include VAT, planning fees, architect fees, party wall costs, and building regulations
5. Check that each builder has recent, verifiable extension projects in Wandsworth or adjacent south London boroughs
QuoteMyRenovation matches Wandsworth homeowners with vetted extension specialist builders with recent, verifiable project history in SW11, SW12, SW15, SW17, SW18, and SW19. Submit one brief and receive up to 3 matched quotes. Free and no-obligation.
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COMMON QUESTIONS
Frequently Asked Questions AboutHouse Extension Wandsworth
Questions homeowners ask us most often before submitting their brief.
How much does a house extension cost in Wandsworth?
Do I need planning permission for a house extension in Wandsworth?
How long does a house extension take in Wandsworth?
Do I need a party wall agreement for a house extension in Wandsworth?
Which Wandsworth conservation areas affect house extensions?
How do I get matched extension quotes in Wandsworth?
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