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: 20 designated areas in Greenwich
- Permitted Development: Generally available outside conservation areas
What does Greenwich do with an extension application?
It refuses roughly three in ten. Greenwich approved 70.7% of the householder applications it decided, twelve points below the London figure, refusing 674 of 2,301. It did grant 230 larger-extension prior approvals, at a 52.9% rate on determined cases.
| Measure | Greenwich | London |
|---|---|---|
| Householder approval rate | 70.7% | 83.0% |
| Refused | 674 of 2,301 | — |
| Decided inside eight weeks | 93.8% | — |
| Larger-extension prior approvals granted | 230 | 52.9% of those determined |
| Extension applications in the Datahub | 6,386 | 60% approved |
| Householder appeals allowed after refusal | 39.9% of 571 | 40.8% of 13,067 |
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, comparable within Greenwich only; appeals from Planning Inspectorate casework decided 2016–2026. Build costs on this page are our own 2026 London range, not a published statistic.
What does a Greenwich extension cost in 2026?
Ready to move from budgeting to drawings?
House extension build costs in Greenwich typically range from £2,500 to £3,800 per square metre, reflecting Greenwich's position as an inner London borough. These figures cover the construction cost only and do not include professional fees, planning fees, or VAT.
Two different things push a Greenwich extension upward. In the town centre and its World Heritage setting it is heritage detailing and the evidence needed to support it. In Charlton and parts of East Greenwich it is the ground - the land rises away from the river and a level extension on a sloping plot needs retaining work that a flat Eltham garden does not.
Typical extension costs in Greenwich (build only)
On top of the build cost, you will need architectural drawings. These fees are 30% below typical London architect rates.
What moves the price of a Greenwich extension?
Greenwich contains a UNESCO World Heritage Site, and development affecting the setting of Maritime Greenwich is assessed against its outstanding universal value - a test that has no equivalent in Eltham. On the cost side the borough divides the usual way: Eltham's interwar semis have side access, East Greenwich and Charlton's Victorian terraces do not, and the riverside new-build is flats where the freeholder decides.
Conservation areas
Greenwich has 20 designated conservation areas, including Greenwich Town Centre (World Heritage Site), Blackheath, Charlton, Eltham Park. 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%.
Property type
The housing stock in Greenwich is predominantly georgian in greenwich town centre; victorian terraces in east greenwich, charlton; inter-war semi-detached in eltham; new-build along the riverside. 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
An Eltham semi will normally take plant down the side, which keeps the groundworks conventional. On an East Greenwich or Charlton terrace, spoil is barrowed through the house and the labour reflects it. Greenwich town centre adds a further complication: the streets are historic and narrow, and skip placement and delivery access need arranging rather than assuming.
Our drawing fees for Greenwich extensions
At Architectural Drawings London. No hourly billing, no surprises. Our fees cover everything needed for a valid planning submission to Greenwich Council and for building regulations approval.
Drawing fees for extensions in Greenwich
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 Greenwich Council on your behalf.
We cover all Greenwich postcodes: SE3, SE7, SE9, SE10, SE18, SE28.
Planning or permitted development in Greenwich?
Many house extensions in Greenwich 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).
Twenty conservation areas in Greenwich, concentrated tightly around the town centre. On the Eltham semis the side-extension loss is the practical one. Near the World Heritage Site the materials and cladding restriction matters far more, because what is being protected is the appearance of the built group in views that are themselves designated - and that assessment runs beyond ordinary conservation policy.
Two-storey extensions almost always require full planning permission. Greenwich Council generally expects two-storey extensions to be subordinate to the original dwelling, set in from the side boundary, and designed to avoid unacceptable loss of light or privacy to neighbouring properties.
Greenwich issued 1,228 certificates of lawful development in three years (MHCLG planning statistics, retrieved 1 September 2026). Within the World Heritage Site and its setting the certificate is worth more than the count suggests, because the heritage question can be revisited long after the work is done and the certificate fixes what was lawful at the time. Outside it, the usual conveyancing value applies.
Frequently asked questions
How much does a house extension cost in Greenwich?
Build costs for a house extension in Greenwich typically range from £2,500 to £3,800 per square metre, as Greenwich 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 Greenwich?
Many single-storey rear extensions in Greenwich qualify as Permitted Development, allowing you to build without planning permission. You can extend up to 6 metres from the rear wall for terraced and semi-detached houses, or up to 8 metres for detached houses under Prior Approval. However, properties in Greenwich's 20 conservation areas have more restricted PD rights. We recommend applying for a Lawful Development Certificate (£274) to confirm PD eligibility.
How long does a house extension take in Greenwich?
A typical house extension project in Greenwich 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 Greenwich 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 Greenwich?
Terraced Greenwich property means notice to two adjoining owners; the Eltham semis mean one. Excavation within three metres of a neighbour's foundations at a lower level is the usual trigger on a rear extension, with a month's notice, and work to the shared wall needs two. Neither depends on whether the council is involved.
What experience do you have with extensions in Greenwich?
We prepare extension drawings for properties across all Greenwich postcodes (SE3, SE7, SE9, SE10, SE18, SE28). Our MCIAT chartered architectural technologists understand Greenwich Council's policies, design guides, and local precedents. We have a council-ready drawing review across all 33 London boroughs.
