Stretching across the SW6 postcode within the London Borough of Hammersmith and Fulham, Fulham occupies a compelling position in London's property landscape — affluent, well-connected, and home to some of the capital's most attractive Victorian and Edwardian residential streets. From the elegant garden squares near Parsons Green and the riverside roads approaching Bishops Park, to the period terraces lining Munster Road, Hurlingham Road, and the quieter backstreets off Fulham Broadway, this is a neighbourhood where homeowners invest seriously in their properties.
Extending your Fulham home rather than upsizing to a new property is a decision more and more SW6 homeowners are making — and for good reason. With strong capital values across the postcode and a growing family demographic, additional square footage delivers both quality of life and meaningful long-term return. This guide is written specifically for Fulham homeowners and draws on Buildaway's practical experience delivering extensions across the borough — combining straightforward pricing, detailed project communication, and an 18-month labour warranty on every completed build.
How Much Does a House Extension Cost in Fulham (2026)?
Fulham sits in the upper-mid to premium tier of London's construction cost spectrum. Demand for quality builders in SW6 is consistently high, and the standard of finish expected across this postcode reflects that. Below are realistic 2026 mid-market figures:
Single-Storey Rear Extension
- Build-only: £2,900 – £3,800 per m²
- Fully finished with kitchen: £3,800 – £5,000 per m²
- Example: 25 m² kitchen-diner = £72,500 – £95,000 build-only or £95,000 – £125,000 turnkey.
Double-Storey Rear Extension
- Build-only: £2,700 – £3,600 per m²
- Fully finished: £3,600 – £4,800 per m²
- Example: 40 m² across two floors = £108,000 – £144,000 build-only or £144,000 – £192,000 turnkey.
Side Return & Wrap-Around Extensions
A particularly popular choice for Fulham's Victorian mid-terraces: £2,900 – £4,200 per m², depending on roof specification, glazing, and the degree of structural alteration required.
All figures reflect mid-market rates for fully compliant, certified builds meeting current Building Regulations standards.
What Drives the Price Up or Down
- Extension size and layout — overall floor area remains the primary cost driver; open-plan designs with fewer internal walls tend to be more cost-efficient structurally.
- Structural steelwork — load-bearing walls are common in Fulham's Victorian terraces; their removal typically adds £3,000–£7,000 to the overall project cost.
- Roof specification — a flat roof with quality membrane and rooflights is the most affordable option; a pitched or lantern-style roof adds cost but can transform the internal feel of the space.
- Glazing and doors — bi-fold or sliding doors opening onto a Fulham garden are a popular choice; budget £4,000–£11,000 depending on frame specification and opening width.
- Conservation and heritage constraints — certain streets in Fulham, particularly around Eel Brook Common and the Peterborough Estate, sit within or adjacent to conservation zones where material choices are subject to LBHF approval.
- Kitchen and bathroom fit-out — quality kitchens in the Fulham market typically range from £12,000 to £35,000+; bathrooms from £7,000 to £18,000.
- Heating upgrades — if an extension adds bathrooms or significantly increases floor area, a Megaflo unvented cylinder or boiler upgrade is often necessary: £3,000–£5,500.
- Site logistics — permit zone parking, skip licensing, and the constraints of Fulham's busier residential roads can marginally affect programme and preliminary costs.
- Drainage and substructure — proximity to the Thames means ground conditions in some SW6 locations may require deeper foundations or drainage surveys prior to commencing construction.
Planning Permission & Building Control in Fulham
- Permitted Development (PD): Single-storey rear extensions within LBHF's PD limits — typically up to 3–4 metres for terraced properties — can proceed without a formal planning application, subject to height, materials, and boundary compliance.
- Neighbour Consultation Scheme: Extensions under the larger homes allowance (up to 6m for terraced, 8m for detached) require neighbour notification through LBHF before work starts. Buildaway manages this process on your behalf.
- Full Planning Permission: Required for double-storey extensions, additions visible from the street, wrap-around designs, and any proposal falling outside PD parameters.
- Conservation Areas: Parts of Fulham — including sections of the Peterborough Estate and roads near Eel Brook Common — fall within designated conservation areas. Extensions here must demonstrate visual compatibility with the existing streetscape and the character of the original building.
- Party Wall Act: The vast majority of Fulham extensions will engage the Party Wall etc. Act 1996, requiring formal notice to be served on adjoining owners before construction begins.
- Building Control: Mandatory across all extension types — covering structural integrity, thermal performance, fire safety, drainage, and electrical compliance. Buildaway works with both LBHF's own inspectors and accredited private building control bodies.
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 fitting, specialist glazing, or bespoke joinery may extend the overall programme by two to four weeks.
Typical Full Project Budget Breakdown (30 m² Double-Storey)
| Element | Typical Cost |
|---|---|
| Core structure & shell | £80,000 – £100,000 |
| 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: | £120,000 – £170,000 |
(Higher-specification finishes or basement-level work can push costs beyond £200,000.)
Why Fulham Clients Choose Buildaway
- Genuine SW6 expertise — extensive hands-on knowledge of Fulham's Victorian terrace stock, LBHF planning requirements, and the practical realities of building in a dense inner-London residential setting.
- Clear, itemised pricing — every quote sets out costs by trade and stage, with no ambiguous allowances or charges emerging mid-build.
- 18-month labour warranty — providing Fulham homeowners with greater peace of mind than the standard defects period offered by most comparable contractors.
- Fully accredited and insured — Gas Safe registered, NICEIC certified, and carrying comprehensive public liability insurance throughout every project.
- Complete project coordination — Buildaway manages architects, structural engineers, Party Wall surveyors, and all specialist trades, keeping the homeowner informed at every stage without the stress of juggling multiple contractors.