BOROUGH · PROJECT

Basement extension in Richmond upon Thames

Planning permission, real costs and what actually gets approved

Do you need planning permission for a basement extension in Richmond upon Thames?

Yes, almost everywhere. A borough-wide Article 4 direction in force since 1 April 2018 has removed permitted development rights for basement and subterranean development across the borough other than the areas of greatest flood hazard, so a basement needs a full planning application and must meet the council's basement and flood-risk policies. The House Extensions and External Alterations SPD sets design and structural expectations.

A borough-wide Article 4 (since 2018) removes PD for basements except in the greatest flood-hazard areas — every basement here needs planning permission and flood-risk evidence.

Basement control is Richmond's defining householder restriction in the same way it is for Hammersmith and Fulham: the question is not whether permitted development might still apply, but whether the scheme can clear policy, flood risk and structure with full evidence. The national planning-data geometry does not currently hold this direction, so confirm the position on the council's own Article 4 and basement pages as well as any area report. Near the Thames, flood-risk evidence is not optional paperwork — it can decide the scheme.

CHECK

What actually applies in Richmond upon Thames

Conservation areas in Richmond upon Thames

Real · planning.data.gov.uk

Every designated conservation area in Richmond upon Thames from the official dataset — inside one, permitted development narrows and design scrutiny rises.

  • Amyand Park Road
  • Barnes Common
  • Barnes Green
  • Belmont Road
  • Beresford Avenue
  • Blackmore's Grove
  • Broad Street
  • Broom Water
  • Burlington Avenue and West Park Road
  • Bushy Park
  • Bushy Park Gardens
  • Cambridge Park
  • Castelnau
  • Central Richmond
  • Christ Church Road
  • Church Road
  • Cole Park Road
  • Cowley Road
  • Crown Road
  • East Sheen Avenue
  • Fieldend
  • Ham Common
  • Ham House
  • Hamilton Road
  • Hampton Court Green
  • Hampton Court Park
  • Hampton Village
  • Hampton Wick
  • Hanworth Road
  • High Street Hampton Hill
  • High Street Teddington
  • Holmesdale Avenue
  • Joanna Southcott Chapel
  • Kew Foot Road
  • Kew Gardens
  • Kew Green
  • Kew Road
  • King Edwards Grove
  • Lawn Crescent
  • Madrid Road
  • Mallard Place
  • Mays Road
  • Mill Hill
  • Model Cottages
  • Mortlake
  • Mortlake Green
  • Normansfield
  • Oaklands Estate
  • Old Deer Park
  • Park Road (Teddington)
  • Parkleys Estate
  • Petersham
  • Platt's Eyot
  • Pope's Avenue
  • Queen's Road (Mortlake)
  • Queen's Road (Twickenham)
  • Richmond Green
  • Richmond Hill
  • Richmond Park
  • Richmond Riverside

…plus 26 further designated areas.

Source: planning.data.gov.uk · Open Government Licence. Boundaries are checked at address level by the area report.

Article 4 directions in Richmond upon Thames

Real · planning.data.gov.uk

No Article 4 geometry for Richmond appears in the national planning.data.gov.uk dataset, but the borough operates a significant one: a direction made in February 2017 that, from 1 April 2018, removed permitted development rights for basement and subterranean development across the whole borough except the areas of greatest flood hazard — so every basement here needs planning permission. A further direction covers parts of the flood-hazard area. Check the council's Article 4 register and basement pages for the position at a specific address.

Source: planning.data.gov.uk · Open Government Licence. Checked at address level by the area report.

Average house price
£798,928
Annual change
-0.4%

Prices: HM Land Registry UK House Price Index, December 2025 · Open Government Licence.

How often Richmond upon Thames grants householder applications: 81.7% of householder applications decided were granted (1,113 of 1,362) over 2025 Q2 to 2026 Q1 — rank 9 of 33 for lowest grant rate. London average: 85.6%. Householder applications are the class most basement extensions fall under. See the full householder approval-rate league table →
ROUTE

The planning route — PD or permission?

There is no useful permitted development route for basements in practice — assume a full planning application everywhere, with a Basement Impact Assessment covering ground conditions, hydrology, structural methodology and construction management. Camden, Westminster and Islington all limit basements to a single storey in most circumstances and protect listed buildings from excavation almost absolutely.

In a conservation area — which blankets much of prime north-west London, from Hampstead to St John's Wood — there is no permitted-development route to lose, but the visible elements are assessed closely on heritage grounds: lightwells, railings, front-garden changes, rooflights and any external alteration. An Article 4 direction or a listed building can remove the option of excavation altogether.

Party wall procedure is heavier than for any other project: underpinning shared walls triggers awards with detailed method statements on both sides, and neighbour objections — on noise, vibration, structural risk and years of disruption — are the norm rather than the exception. The applications that succeed arrive with the engineering done, not promised.

LIMITS

Permitted development limits — basement extension

Permitted developmentNone in practice — assume a full planning application
Required technical evidenceBasement Impact Assessment (ground, hydrology, structure, construction management)
Depth, in most inner-London boroughsSingle storey in most circumstances
Listed buildingsExcavation protected against almost absolutely
Party wall procedureAwards with method statements where underpinning shared walls

Limits summarise the General Permitted Development Order (Schedule 2, Part 1) as it applies in London. In Richmond upon Thames, a conservation area, Article 4 direction or listed status changes the route — the panels above show what is designated, and the address check confirms what applies at your property.

COST

How much does a basement extension cost in Richmond upon Thames?

Cost per m² (low)£6,000
Cost per m² (expected)£8,500
Cost per m² (high — difficult ground / high water table)£12,000+
Typical project (35–50m² single storey)£210,000 – £600,000
Professional and consultant fees (add)15–25% of build

Basements carry the widest cost uncertainty of any project — ground conditions and water management can move budgets six figures. Ranges from real project data; VAT excluded. Never commit on a single quote without a ground investigation.

TIME

Realistic timeline

Feasibility, ground investigation, BIA3–6 months
Planning decision10–16 weeks
Party wall awards (multiple)3–6 months (parallel)
Build8–14 months
WATCH

What catches people out in Richmond upon Thames

Relying only on the national dataset for Article 4 status understates the basement position here. Groundwater, flood risk, party wall awards and multi-month programmes are the other hard realities — this is never a light project.

DISTRICTS

Postcode districts in Richmond upon Thames

TW9 — Richmond & Kew

TW9 covers Central Richmond, Richmond Green and Richmond Riverside, and at Kew the Kew Green and Kew Gardens conservation areas around the Royal Botanic Gardens — a World Heritage Site.

TW9 — Richmond & Kew →
TW10 — Richmond Hill, Petersham & Ham

TW10 runs from Richmond Hill — whose view over the Thames is protected by its own Act of Parliament — through the Petersham, Ham Common and Ham House conservation areas to the edge of Richmond Park.

TW10 — Richmond Hill, Petersham & Ham →
TW1 — Twickenham & St Margaret's

TW1 spans Twickenham Riverside and Twickenham Green, the St Margaret's Estate and Cole Park Road conservation areas, with Strawberry Hill nearby.

TW1 — Twickenham & St Margaret's →
TW11 — Teddington

TW11 is Teddington — the High Street Teddington and Teddington Lock conservation areas and the Broom Water riverside.

TW11 — Teddington →
SW14 — Mortlake & East Sheen

SW14 covers Mortlake and Mortlake Green, the East Sheen Avenue and Sheen Lane conservation areas, and Sheen Common.

SW14 — Mortlake & East Sheen →
SW13 — Barnes

SW13 is Barnes — riverside and common-edge streets in Richmond upon Thames, with extensive conservation coverage.

SW13 — Barnes →
TW2 — Twickenham & Whitton fringe

TW2 covers Twickenham and the Whitton fringe, spanning Richmond and Hounslow.

TW2 — Twickenham & Whitton fringe →
TW12 — Hampton

TW12 is Hampton in Richmond upon Thames — riverside and village streets with substantial conservation coverage.

TW12 — Hampton →
FAQ

Basement extension in Richmond upon Thames, asked straight

01

Do I need planning permission for a basement in Richmond upon Thames?

In practice, yes almost everywhere. The borough-wide basement Article 4 in force since 1 April 2018 removed permitted development rights for subterranean development except in the areas of greatest flood hazard.
02

How much does a basement cost?

Budget £6,000–£12,000+ per m², or roughly £210,000–£600,000 for a typical 35–50m² single-storey basement, before VAT and heavy consultant fees.
03

Why might an online constraint check miss the basement Article 4?

No Article 4 geometry for Richmond appears in the national planning.data.gov.uk dataset this site uses, even though the borough operates a significant basement direction. Confirm basements on the council's own register.
04

What evidence is required?

A full application with structural method, ground conditions and flood-risk evidence where relevant, judged against the House Extensions and External Alterations SPD and basement policy.
05

Are multi-level basements realistic?

They face a harder path across London and should not be assumed acceptable. Treat single-storey under the footprint as the realistic starting ambition unless specialist advice says otherwise.
CHECK

What applies at your address?

Borough-level rules only narrow it down. Enter a Richmond upon Thames postcode for the live constraint check — conservation area, Article 4 and sold-price comparables, cited to source.

Check a Richmond upon Thames address

Need it in writing for one address? A planning permission report for a Richmond upon Thames property — from £59, or surveyor-reviewed from £295.

Planning Permission Checker provides planning and cost intelligence for early feasibility only. It is not legal, planning, valuation, architectural, structural, or surveying advice. All estimates are indicative and must be verified by qualified professionals before purchase, design, planning submission, or construction.

Cost estimates are indicative only — not a quotation. Final price depends on survey, specification, structure, access, party wall matters, VAT, professional fees, and contractor availability.

Planning outcomes are not guaranteed. Local planning authorities make final decisions.

Check an address