TL;DR — Key Facts
- Build cost per sqm: £2,500 – £3,800 (inner London borough)
- Council planning fee: £548 (householder application, 2026)
- Typical projects: rear extension, side-return, two-storey, wraparound
- Conservation areas: 45 designated areas in Hammersmith and Fulham
- Permitted Development: Restricted by Article 4 in some areas
What does an extension in Hammersmith and Fulham cost to get approved?
£548 to the council, plus drawings from £1,225. Budget time rather than refusal: the borough approved 96.0% of householder applications, the highest rate in London, but agreed an extension of time on 2,282 of 3,826 decisions and saw 607 applications withdrawn before any decision was issued.
| Measure | Hammersmith and Fulham | London |
|---|---|---|
| Householder approval rate | 96.0% | 83.0% |
| Applications withdrawn before decision | 15.9% | 7.4% |
| Applications with an agreed extension of time | 59.6% | 34.5% |
| Householder decisions made | 1,569 | 77,680 |
| Extension applications in the Datahub | 5,403 | 83% approved |
| Conservation areas | 47 covering 959 ha | 1,141 across London |
Sources: decision figures from MHCLG District Planning Application Statistics (PS1 and PS2), twelve quarters to March 2026; the Datahub row from the Planning London Datahub, retrieved 15 August 2026, phrase-matched and comparable within this borough only; conservation areas from planning.data.gov.uk, retrieved 1 September 2026. Build costs on this page are our own 2026 London range, not a published statistic.
What does an extension cost in Hammersmith and Fulham?
This is the cost picture. The service page for house extensions in Hammersmith and Fulham covers the submission itself.
House extension build costs in Hammersmith and Fulham typically range from £2,500 to £3,800 per square metre, reflecting Hammersmith and Fulham's position as an inner London borough. These figures cover the construction cost only and do not include professional fees, planning fees, or VAT.
On a Fulham or Parsons Green terrace the extension is nearly always the side return, and the cost is set by structure rather than finish. Removing the flank wall of the original back addition means a goalpost frame and careful temporary support, on a party wall shared with a neighbour who has probably done the same thing. The kitchen you put inside it is the cheaper half of the job.
Typical extension costs in Hammersmith and Fulham (build only)
On top of the build cost, you will need architectural drawings. These fees are 30% below typical London architect rates.
What drives the price up here?
Hammersmith and Fulham approves more than nine applications in ten and 92.9% of schemes that create a new dwelling, the highest rate in London (MHCLG planning statistics, retrieved 1 September 2026). The constraint is not consent, it is construction. The two-storey bay-fronted terraces of Fulham and Parsons Green have no side access, and the borough agreed an extension of time on 59.6% of its decisions, so the programme is longer than the statutory target suggests.
Conservation areas
Hammersmith and Fulham has 45 designated conservation areas, including Hammersmith Grove, Brackenbury Village, Fulham Palace Road, Parsons Green, Walham Green. If your property is in a conservation area, Permitted Development rights are restricted, meaning you may need a full planning application (£548 council fee). Conservation area applications also tend to require higher-quality materials and more sympathetic design, which can increase build costs by 10-20%.
Article 4 Directions
Hammersmith and Fulham has Article 4 Directions in place. Article 4 removes PD for HMO conversions; restrictions on ground-floor shop-to-residential in certain streets. Where Article 4 applies, works that would normally be Permitted Development require a full planning application. This adds £548 to the council fee and typically 2-3 months to the project timeline, which can affect overall costs if you are renting alternative accommodation during the build.
Property type
The housing stock in Hammersmith and Fulham is predominantly victorian and edwardian terraces — particularly two-storey bay-fronted terraces south of the river in fulham and parsons green; mansion blocks along main roads. Victorian and Edwardian terraces typically suit side-return and rear extensions, while 1930s semi-detached properties are well suited to two-storey rear extensions. Detached houses offer the most flexibility but often have larger footprints, meaning higher absolute costs even if the per-sqm rate is similar.
Access and logistics
On a Fulham or Parsons Green terrace the side return is the extension, which means the working space and the access route are the same strip of ground. Everything comes through the house until the new opening is formed. It is a well-understood sequence on this stock and builders here price it routinely - but it is not comparable to an outer-London semi, and quotes should not be compared across that line.
Our drawing fees for Hammersmith and Fulham extensions
At Architectural Drawings London. No hourly billing, no surprises. Our fees cover everything needed for a valid planning submission to Hammersmith & Fulham Council and for building regulations approval.
Drawing fees for extensions in Hammersmith and Fulham
Every package includes a measured survey of your existing property, existing floor plans and elevations, proposed floor plans and elevations, a site plan, and a design and access statement where required. Our MCIAT chartered architectural technologists handle the full process from survey to submission, and we liaise with Hammersmith & Fulham Council on your behalf.
We cover all Hammersmith and Fulham postcodes: W6, W12, W14, SW6, SW10.
Planning or permitted development?
Many house extensions in Hammersmith and Fulham can be built under Permitted Development (PD) rights without needing a planning application. Under PD, single-storey rear extensions can extend up to 6 metres from the original rear wall for terraced and semi-detached houses, or 8 metres for detached houses (under the Prior Approval process). However, Hammersmith and Fulham has Article 4 Directions that may remove some PD rights. Article 4 removes PD for HMO conversions; restrictions on ground-floor shop-to-residential in certain streets.
Across this borough's 45 conservation areas the side-extension restriction has almost nothing to act on, because the Fulham and Parsons Green stock is continuous terrace. The rule with force is the one on cladding and materials, applied to rear elevations that repeat identically along a street. A scheme is judged on whether it matches that rhythm or interrupts it.
Two-storey extensions need an application, though this is among the more receptive boroughs to receive one - 96.0% of householder applications were approved over three years, the highest rate in London (MHCLG planning statistics, retrieved 1 September 2026). On the bay-fronted Fulham terraces the constraint is uniformity rather than principle: the rear elevations repeat along the whole street, and a scheme that matches the established rhythm has a straightforward path.
The council granted 260 certificates of lawfulness over three years (MHCLG planning statistics, retrieved 1 September 2026), the fourth-lowest count in London, which follows from an Article 4 Direction and 45 conservation areas covering most of the residential borough. If your address is one of the few where permitted development survives, that certificate is a genuinely distinguishing document at sale.
Frequently asked questions
How much does a house extension cost in Hammersmith and Fulham?
Build costs for a house extension in Hammersmith and Fulham typically range from £2,500 to £3,800 per square metre, as Hammersmith and Fulham is an inner London borough. A typical single-storey rear extension of 15-20 sqm would cost between £37,500 and £76,000 for the build alone. On top of build costs.
Can I extend under Permitted Development in Hammersmith and Fulham?
In this borough's 45 conservation areas the restriction with real force is the one on materials and on anything that breaks the rhythm of a repeated terrace. The rear elevations of the Fulham and Parsons Green terraces are as consistent as their fronts, and a side-return extension is judged on whether it reads as part of that pattern or as an interruption to it.
How long does a house extension take in Hammersmith and Fulham?
A typical house extension project in Hammersmith and Fulham takes 5-8 months from initial instruction to completion. This breaks down as: 2-3 weeks for measured survey and drawing preparation, 8 weeks for planning determination by Hammersmith & Fulham Council (if required), 2-4 weeks for building regulations approval, and 8-16 weeks for construction depending on the size and complexity of the extension.
Do I need a Party Wall Agreement for an extension in Hammersmith and Fulham?
A side-return extension on a mid-terrace here typically builds off or up to the boundary wall on one side and excavates within three metres of the neighbour on the other, so both limbs of the Party Wall etc. Act 1996 are engaged and both adjoining owners need notice. On streets where most houses have already done it, neighbours generally know the process.
What experience do you have with extensions in Hammersmith and Fulham?
We prepare extension drawings for properties across all Hammersmith and Fulham postcodes (W6, W12, W14, SW6, SW10). Our MCIAT chartered architectural technologists understand Hammersmith & Fulham Council's policies, design guides, and local precedents. We have a council-ready drawing review across all 33 London boroughs.
