Sitting comfortably along the south bank of the Thames within the London Borough of Wandsworth, Putney has long been one of South West London's most sought-after residential postcodes. The SW15 area combines excellent transport connections, outstanding schools, and a genuine sense of community — all set against a backdrop of Victorian terraces, Edwardian semis, and larger detached homes spread across the leafy streets between Putney Heath and the river. From the handsome period houses lining Replingham Road and Keswick Road, to the family homes tucked away near East Putney station and the riverside roads approaching Putney Bridge, this is a neighbourhood where homeowners put serious thought into how they live.
For SW15 homeowners, extending rather than relocating has become the natural response to growing space requirements. Putney's property values are consistently strong across the postcode, and additional square footage — whether a ground-floor kitchen extension, a side return conversion, or a double-storey addition at the rear — delivers a meaningful return both in everyday liveability and long-term capital value. This guide is written specifically for Putney homeowners and reflects Buildaway's practical experience delivering extensions across Wandsworth, combining honest 2026 pricing, sound local planning knowledge, and an 18-month labour warranty on every completed project.
How Much Does a House Extension Cost in Putney (2026)?
Putney occupies the upper-mid range of South West London's construction market. Quality builders in SW15 are consistently in demand, and the standard of finish expected across this postcode reflects both the character of the housing stock and the ambitions of local homeowners. Below are realistic 2026 mid-market figures:
Single-Storey Rear Extension
- Build-only: £2,800 – £3,700 per m²
- Fully finished with kitchen: £3,700 – £4,900 per m²
- Example: 25 m² kitchen-diner = £70,000 – £92,500 build-only or £92,500 – £122,500 turnkey.
Double-Storey Rear Extension
- Build-only: £2,600 – £3,500 per m²
- Fully finished: £3,500 – £4,700 per m²
- Example: 40 m² across two floors = £104,000 – £140,000 build-only or £140,000 – £188,000 turnkey.
Side Return & Wrap-Around Extensions
A popular choice for Putney's Victorian and Edwardian terraces: £2,800 – £4,000 per m², depending on structural requirements, roof specification, and glazing choice.
All figures reflect fully compliant, Building Control certified builds meeting Wandsworth's current planning and construction standards.
What Drives the Price Up or Down
- Total floor area — the primary cost variable; a larger extension footprint increases structural, insulation, and finishing expenditure in direct proportion.
- Structural steelwork — load-bearing wall removal is routine across Putney's Victorian and Edwardian terrace stock and typically adds £3,000–£7,000 to the overall project cost.
- Roof type and glazing — flat roofs with quality membranes and rooflights remain the most cost-effective solution; lantern roofs or pitched finishes add cost but can significantly improve the feel of the extended space. Bi-fold or sliding doors add £4,000–£10,000 depending on width and frame specification.
- Conservation area constraints — parts of Putney, including streets within and around the Putney Heath and Huguenot Cemetery conservation areas, are subject to Wandsworth's heritage controls, influencing material choices and design approach.
- Kitchen and bathroom fit-out — kitchens in the Putney market typically range from £12,000 to £32,000+; bathrooms from £7,000 to £16,000.
- Heating and mechanical upgrades — Megaflo unvented cylinders or boiler replacements are commonly required when extensions add bathrooms or floor area: £3,000–£5,500.
- Ground conditions — proximity to the Thames means some SW15 properties sit on alluvial deposits or made ground rather than firm clay, which can affect foundation design and pre-construction investigation requirements.
- Site access and logistics — permit parking zones, residential streets with restricted vehicle access, and skip licensing across Putney's busier roads contribute to site preliminary costs and programme planning.
Planning Permission & Building Control in Putney
- Permitted Development (PD): Smaller single-storey rear extensions often fall within PD rights in Putney, provided they meet Wandsworth's criteria for height, depth, and materials. Properties within conservation areas or those subject to Article 4 Directions require more careful assessment before assuming PD applies.
- Neighbour Consultation Scheme: Extensions beyond standard PD depth limits — up to 6 metres for terraced and semi-detached homes, 8 metres for detached — require formal notification to Wandsworth and neighbouring owners before work begins. Buildaway manages this process on your behalf.
- Full Planning Permission: Required for double-storey extensions, any proposal with street-facing visibility, front alterations, wrap-around designs, and all projects falling outside PD parameters.
- Conservation Areas: Wandsworth's conservation area guidance applies to parts of Putney, where extensions must use materials sympathetic to the original building and the wider streetscape character. Wandsworth's planning officers assess all applications within these zones for visual compatibility.
- Party Wall Act: The density of Putney's terrace and semi-detached housing stock means the Party Wall etc. Act 1996 applies to the majority of extension projects in SW15. Written notices must be served on all affected adjoining owners before structural or excavation works commence.
- Building Control: Mandatory across all extension types — covering structural integrity, thermal performance, drainage, fire safety, and electrical compliance. Buildaway coordinates with Wandsworth's building control department and accredited private inspectors as appropriate.
How Long Will It Take?
- Design and planning preparation: 4–10 weeks
- Technical drawings, approvals, and statutory notices: 3–7 weeks
- On-site construction:
- Single-storey: 10–14 weeks
- Double-storey: 14–20 weeks
- Kitchen installations, bespoke glazing, or conservation area applications may extend the programme by two to four weeks beyond these ranges.
Typical Full Project Budget Breakdown (30 m² Double-Storey)
| Element | Typical Cost |
|---|---|
| Core structure & shell | £82,000 – £102,000 |
| Windows / doors / glazing | £6,000 – £12,000 |
| Kitchen supply & fit | £12,000 – £30,000 |
| Bathroom fit-out | £7,000 – £15,000 |
| Heating / boiler / Megaflo | £3,000 – £5,500 |
| Flooring & decorating | £7,000 – £18,000 |
| Professional fees & permissions | £4,000 – £10,000 |
| Total realistic range: | £122,000 – £175,000 |
(Higher-specification finishes, conservation area requirements, or complex groundworks can push costs beyond £210,000.)
Why Putney Clients Choose Buildaway
- Wandsworth planning knowledge — practical, hands-on familiarity with Wandsworth Council's planning policies, conservation area guidance, and the particular characteristics of Putney's Victorian and Edwardian housing stock.
- Fully transparent pricing — clear, itemised quotations broken down by trade and stage, with no vague provisional sums or unexpected charges introduced once work is underway.
- 18-month labour warranty — providing SW15 homeowners with greater post-completion assurance than the standard defects liability period offered by most comparable contractors.
- Fully accredited and insured — Gas Safe registered, NICEIC certified, and carrying comprehensive public liability insurance on every project without exception.
- Complete project management — Buildaway coordinates architects, structural engineers, Party Wall surveyors, and all specialist trades from first consultation through to final Building Control sign-off, keeping the homeowner fully informed at every stage.