Richmond Extensions 2026: Planning Guide, Costs & Permitted Development

Richmond upon Thames: What Kind of Borough Is It?

Richmond upon Thames is unlike any other London borough when it comes to planning. It is consistently rated among the most environmentally sensitive and conservation-active local authorities in England. With 85 designated conservation areas, significant stretches of Green Belt and Metropolitan Open Land, a protected river corridor, and a significant number of listed buildings, it is a borough where planning constraints shape almost every extension project.

The housing stock reflects this character. Richmond town itself has Georgian and Victorian properties set along the Thames and around Richmond Green - some of the most formally composed residential streets in London. Kew and Kew Green have late Georgian terraces and detached houses with generous garden plots. Twickenham offers substantial Edwardian and late Victorian semis alongside the river. Ham and Petersham are dominated by grand detached properties and quiet, village-character streets with little commercial intrusion. East Sheen and Barnes, closer to the South Circular, have large Victorian and Edwardian houses in leafy suburban settings.

Hampton, Hampton Wick, and Teddington - further south and west - shift toward 1930s and post-war housing with more permissive planning conditions and larger garden plots. But even here, conservation area designations and street-specific Article 4 Directions affect a substantial proportion of properties. Understanding which planning regime applies to your specific address is essential before any design work begins.

Richmond's Local Plan and Extensions Policy

The Richmond Local Plan (2024-2039), adopted 7 October 2025, is now the primary planning framework for the borough. It replaces the previous Local Plan (adopted July 2018) and the Twickenham Area Action Plan, and sets out a 15-year strategic vision, place-based strategies covering the whole borough, and thematic policies on climate change, health, heritage, and design quality that apply to residential extensions alongside every other type of development.

For homeowners, the key supporting document is still the House Extensions and External Alterations Supplementary Planning Document (SPD), adopted 1 June 2015 and still in force. It sets out the design principles Richmond applies to residential extensions, and now sits alongside the council's new Biodiversity SPD, adopted 9 June 2026, which adds further requirements on net gain and green infrastructure for development of all sizes.

Core design principles from the Richmond SPD

• Subordinate massing: Extensions must be visually subordinate to the original dwelling in height, width, and bulk - the host building should read as the primary structure
• Complementary or contrasting materials: Materials must either match the original building fabric or be of demonstrably high quality that forms a deliberate contemporary contrast - poorly chosen materials are a common reason for refusal in Richmond
• Neighbour amenity: Loss of light, outlook, and privacy to adjoining properties is assessed carefully - the 45-degree daylight test applies in most cases
• Space between buildings: Richmond places specific emphasis on maintaining gaps between properties - side extensions that would close a gap between houses are generally resisted
• Biodiversity and green infrastructure: Even small-scale extensions are expected to consider biodiversity net gain under the new Biodiversity SPD - swift bricks, bat boxes, and green roofs are increasingly expected in pre-application discussions

Richmond also publishes neighbourhood-level Village Plan SPDs for many of its distinct areas, including Barnes, East Sheen, East Twickenham, Hampton, Hampton Hill, Hampton Wick and Teddington, Kew, Mortlake, Richmond and Richmond Hill, St Margarets, Strawberry Hill, Twickenham, and Whitton and Heathfield. These add local detail on top of the borough-wide guidance, so it is worth checking whether one exists for your area before finalising a design.

Conservation Areas in Richmond upon Thames

Richmond upon Thames currently has 85 designated conservation areas - an extraordinary figure that underscores just how much of the borough is protected. Being inside a conservation area already curtails some permitted development rights automatically under national law. On top of that, the council has applied individual Article 4 Directions to specific streets within many of these areas, removing further rights for external alterations. This means that work which would normally proceed without any planning application - replacing windows, adding a rear extension, re-roofing - can require formal permission, depending on your exact street.

Richmond Hill

The Richmond Hill Conservation Area is one of the most carefully protected in the borough, covering the slopes and terraces leading up to Richmond Hill itself. The view from the Hill has been protected since 1902 by the Richmond, Petersham and Ham Open Spaces Act, one of the few views in England safeguarded by its own Act of Parliament. Extensions here face the highest level of scrutiny in the borough.

The dominant building character is Georgian and Victorian stucco and brick terraces, with formal proportions and well-maintained garden settings. Extensions to properties on the Hill must not compromise the protected view corridor and must maintain the historic roofline and massing of the terrace or street. Pre-application advice is essential before any scheme is designed.

Kew Green and Kew

Kew Green covers the formal green and the historic houses surrounding it - a tight-knit group of Georgian and early Victorian properties, several of which are listed. Extensions here are exceptional; most properties have been fully extended to their limits and further additions face very high design expectations.

The wider Kew residential area, with its mix of Edwardian and Victorian terraces and semis, also falls partly within conservation area designations. Proximity to the Royal Botanic Gardens at Kew, a UNESCO World Heritage Site, means that heritage considerations extend beyond the formal conservation area boundaries in practice.

Petersham and Ham

Petersham has one of the most distinct village characters anywhere in London: a genuine rural-feeling settlement of detached houses and cottages set along narrow lanes, with Ham Common and Richmond Park immediately adjacent. Extensions here must maintain the open, uncluttered character of the area and its village scale.

Ham Common is separately designated and covers the formal green and surrounding properties - large Edwardian and late Victorian houses with generous plot sizes. Extensions are possible here on the right properties, but massing and materials are closely scrutinised, and many properties adjoin or back onto Metropolitan Open Land, adding a further layer of constraint.

Twickenham and Twickenham Riverside

Twickenham has several conservation areas, including its riverside and the historic core of the town. Riverside properties in particular - Georgian townhouses and villas on the banks of the Thames - face strict controls, and extensions must not disrupt the historic roofline or skyline when viewed from the river.

East Sheen and Barnes

East Sheen has a number of conservation areas covering its Victorian and Edwardian residential streets. The character here is more suburban than central Richmond - large, detached and semi-detached houses with garden plots - but conservation area designations still apply to a significant proportion of properties. Barnes is similarly well-protected, with its village conservation area covering a mix of Georgian and Victorian properties.

How Richmond's Article 4 Directions Actually Work

It is a common assumption that being in one of Richmond's conservation areas means an entire area has lost its permitted development rights in one go. In practice, most of Richmond's Article 4 Directions for conservation areas operate street by street. The council maintains a public register, running past 80 individual Directions and each tied to a numbered conservation area, naming the specific streets where permitted development rights for extensions, new doors and windows, painting or rendering brickwork, removing chimneys, replacing front gardens, and replacing boundary walls have been formally withdrawn.

Examples from the published register include Ham Street and Ham Gate Avenue in Petersham and Ham, The Green and Priory Road in Kew, Montague Road, The Vineyard and Sydney Road in Richmond, Montpellier Row and Lebanon Park in Twickenham, Ranelagh Avenue and The Crescent in Barnes, and The Mall in East Sheen. These are a small sample of a much longer list covering streets right across the borough, from Hampton and Teddington to Mortlake and St Margaret's.

The practical takeaway: being inside a named conservation area does not automatically mean every permitted development right has been withdrawn on every street within it. It means checking the register for your specific street rather than assuming the position that applied to a neighbouring road, or to a friend's renovation two streets away, applies to yours.

Basements and Richmond's Borough-Wide Article 4 Direction

Richmond's most distinctive planning feature is not a conservation area boundary at all. It is a borough-wide Article 4 Direction covering basement and subterranean development. The council made two directions on 28 February 2017, confirmed on 12 April 2017, and in force from 1 April 2018: one covering land in the borough's greatest flood hazard areas, and a second covering the remainder of the borough not affected by flood risk. Together, they mean that from 1 April 2018, planning permission is required for basement or subterranean development on any residential property in Richmond, with no exceptions for scale.

This is particularly relevant for the Thames-side parts of the borough. Land closest to the river, in Richmond, Twickenham, Petersham, Ham, and parts of Kew, sits within areas the Environment Agency and the council treat as at greater flood hazard, and the flood-hazard variant of the direction applies there specifically. Homeowners considering a basement extension on or near the river should check their flood zone status before committing to a design.

Beyond the planning permission requirement itself, Richmond's Basement Developments guidance sets out a wide range of additional considerations: Building Regulations approval, a Structural Impact Assessment for basement works on listed buildings and buildings of townscape merit, a Construction Management Statement for every basement scheme in the borough, party wall agreements for work within 3 or 6 metres of a neighbour, freeholder consent, and utilities permissions where relevant. Proposals that take up more than half of the front or rear garden are also flagged as a design concern.

If a basement or lower ground floor extension is part of your scheme, budget time for this additional process from the outset. It sits on top of, not instead of, the usual conservation area and Article 4 considerations covered above.

Green Belt and Metropolitan Open Land

Richmond upon Thames contains significant stretches of Green Belt and Metropolitan Open Land (MOL), particularly around Richmond Park, Ham Common, Petersham, and along the Thames. These designations carry important restrictions for extensions.

Green Belt extensions

National planning policy treats the extension or alteration of an existing dwelling as a form of development that is not inappropriate in the Green Belt, provided it does not result in a disproportionate addition over and above the size of the original building. Richmond assesses this against the footprint of the property as it was originally built, not its current footprint if it has already been extended.

In practice, any extension on a Green Belt property in Richmond should start with a measured survey establishing the original footprint, so that your design team can confirm what headroom remains before drawing up a scheme.

Metropolitan Open Land

Metropolitan Open Land carries equivalent protection to the Green Belt under the London Plan. Properties adjoining or within MOL - particularly in Ham, Petersham, and near Richmond Park - face additional scrutiny on any extension that could affect the openness of the designated land. Extensions on MOL itself are generally resisted; extensions to properties immediately adjacent need careful justification.

Permitted Development in Richmond

Given the extent of conservation area coverage and Article 4 Directions across Richmond, permitted development rights are more restricted here than in most other London boroughs. Properties outside conservation areas - particularly in Hampton, parts of Teddington, and the less-protected parts of Twickenham - can still benefit from the standard national permitted development rules for householders where no conservation area or Article 4 Direction applies.

The Planning Process in Richmond

Standard householder planning applications in Richmond target 8 weeks from validation. Applications in conservation areas or involving listed buildings can take longer, and complex or sensitive cases may be referred to the planning committee rather than decided by officers under delegated powers. A revised Local Validation Checklist took effect on 20 February 2026 and sets out exactly what needs to be submitted with an application, so it is worth checking the current version before you submit.

Pre-application advice

Richmond offers a pre-application advice service for homeowners, with fees set by category. Advice for extensions and alterations to a non-listed dwelling (category 6) costs £190 and is provided as a written response, without a meeting. Advice for a listed building (category 7) costs £660 and includes input from a conservation officer plus a site visit. For conservation area extensions, complex sites, or listed buildings, pre-application advice is strongly advisable: it indicates what materials, massing, and design approach officers are likely to support, reducing the risk of refusal.

For extensions in Richmond Hill, Petersham, Kew Green, and other high-sensitivity conservation areas, pre-application engagement with the council is considered best practice.

Application fees (2026)

• Householder application: £548 (national fee, effective from April 2026 following the annual CPI-linked increase)
• Lawful development certificate: £274
• Listed building consent: No charge (fee-exempt)

Required supporting documents

Richmond requires detailed submissions for conservation area applications. Typically this includes existing and proposed floor plans and elevations at 1:50, elevations of adjacent buildings, full details of proposed materials, and a heritage statement justifying the design approach in the context of the conservation area. Applications without this documentation are likely to be treated as invalid and returned before processing begins.

Applicants are also encouraged to submit an Application Inventory alongside larger or more complex proposals, and must confirm compliance with mandatory biodiversity net gain requirements where applicable.

Extension Costs in Richmond 2026

Richmond sits at the top of the range set out in our London extension costs guide, which puts inner and outer London extensions together at £3,200-£4,600 per m². Build costs in Richmond typically run 10-20% above that London-wide average, reflecting higher labour rates for contractors used to working across the borough's many conservation areas, and the additional design and heritage documentation these schemes usually need. All figures below include VAT at 20% and cover construction cost only (not kitchen fit-out, professional fees, or contingency).

Additional professional and statutory costs

• Design and planning drawings, specification, contract admin: £4,500-£10,000 (higher for complex conservation area schemes)
• Structural engineer: £2,000-£4,000
• Planning application fee (householder): £548
• Lawful development certificate (if applicable): £274
• Pre-application advice (householder): £190 (non-listed) or £660 (listed building)
• Party wall surveyor: £1,500-£3,500 per adjoining owner (particularly relevant for terraced and semi-detached properties in Kew, Twickenham, and East Sheen)
• Building Control: £900-£2,500 depending on project scale
• Heritage statement: £1,500-£3,500 (required for listed buildings and most conservation area applications in Richmond)

Common Extension Types by Neighbourhood

Richmond and Richmond Hill: rear extensions to Georgian and Victorian properties

Properties in and around Richmond town centre are predominantly Georgian and Victorian in character. Extensions are invariably to the rear - front and side elevations are typically protected by conservation area controls and, on many streets, an Article 4 Direction. Rear single-storey kitchen and dining extensions, often with large roof lights and sliding or pivoting glazed doors opening onto the garden, are the most common type. These are typically 3-4m deep and require a planning application. High-quality contemporary design - dark-frame steel glazing, Corten steel, or carefully proportioned brick - is generally supported by officers where it demonstrates design quality.

Kew: rear extensions and loft conversions to Edwardian semis

Kew's residential streets, away from Kew Green itself, are predominantly Edwardian semis and Victorian terraces with good garden depth. Rear extensions and dormer loft conversions are the most common projects. Conservation area coverage is extensive, and the proximity to the World Heritage Site at Kew Gardens adds an additional layer of sensitivity to anything visible from public viewpoints. Side return extensions are popular where the property has a usable side passage, typically filling the narrow gap between the house and the boundary wall to create an enlarged kitchen-dining room on the ground floor.

Twickenham: extensions to substantial Victorian and Edwardian houses

Twickenham has some of the largest Victorian and Edwardian properties in the borough - substantial semis and detached houses on generous plots, particularly in the streets around Twickenham Green and St Margaret's. These properties often lend themselves to two-storey rear extensions or side extensions. However, conservation area coverage and street-specific Article 4 Directions across much of Twickenham mean that planning permission is required for most external alterations. The generous plot sizes mean there is often scope for extensions of meaningful scale, subject to design quality.

Ham and Petersham: limited opportunities, high design scrutiny

Ham and Petersham present some of the most restricted extension environments in the borough. The village character of Petersham, the adjacency to Richmond Park and Ham Common, and the prevalence of listed buildings mean that extensions here face exceptional scrutiny. Where extensions are possible - typically modest single-storey rear additions - they must be designed with extreme sensitivity to the existing building and its setting. Pre-application advice is essential.

East Sheen and Barnes: Victorian and Edwardian suburban extensions

East Sheen and Barnes offer slightly more flexibility than the central Richmond areas, with larger Victorian and Edwardian detached and semi-detached houses on generous plots. Rear extensions, typically 3-5m deep single-storey additions, and side extensions are common. Conservation area coverage is still substantial, meaning planning permission is usually required. The character of these areas - well-maintained suburban streets with consistent building lines - means that design quality and material selection remain important.

Hampton and Teddington: more permissive outer suburban areas

Hampton, Hampton Wick, and Teddington - further from the river and central Richmond - have more varied housing stock, including 1930s and post-war semis alongside Victorian terraces. Conservation area coverage is less extensive here, and some streets retain full permitted development rights. Single-storey rear extensions up to 4m deep may proceed without planning permission on detached properties in these areas (or up to 8m via prior approval), subject to the standard height and materials conditions. Always verify your specific address before assuming.

Planning Tips for Richmond Extensions

• Use pre-application advice for all conservation area schemes. Richmond has 85 conservation areas and officers are experienced with the specific design expectations of each. A pre-application conversation, from £190 for a householder scheme, significantly reduces the risk of refusal on materials, scale, or design approach.
• Check the Article 4 register at street level, not area level. Richmond's Article 4 Directions for conservation areas are recorded street by street. Look up your specific street on the council's register rather than assuming that because a neighbouring road is unaffected, or affected, the same applies to yours.
• Factor in the basement Article 4 Direction if a lower ground floor is part of the scheme. Planning permission is required for basement and subterranean development anywhere in the borough, with additional flood-hazard considerations for Thames-side properties. Read the council's basement guidance before committing to a design.
• Never assume permitted development applies. With 85 conservation areas and a large street-level Article 4 register, the majority of properties in Richmond are subject to some form of planning constraint that removes or restricts permitted development rights. Use Richmond's online planning map or our free checker to verify your specific address before starting any design.
• Budget for a heritage statement in conservation areas. Richmond officers typically expect a written heritage statement justifying the design of any extension in a conservation area, particularly for listed buildings or properties in the most sensitive areas such as Richmond Hill, Kew Green, and Petersham.
• Party wall notices are essential for all semi-detached and terraced properties. The Victorian and Edwardian semis and terraces that dominate most of Richmond's conservation areas all have shared party walls. Serve notice on adjoining owners before beginning any excavation or structural work to a shared wall, and allow 2-4 months if neighbours appoint their own surveyor.
• Check for trees before commissioning any design. Richmond has an exceptional number of protected trees, both TPO-protected and those in conservation areas that require council consent before works. Mature trees can significantly constrain extension design, particularly foundations and drainage.

Summary

Richmond upon Thames is one of the most tightly controlled planning environments in London. Between 85 conservation areas, a growing street-level Article 4 register, a borough-wide basement direction, and significant Green Belt and Metropolitan Open Land coverage, very few extension projects in the borough proceed without some form of planning application.

That said, a well-prepared scheme with good pre-application engagement, a heritage statement where needed, and materials that respect the host building generally fares well with Richmond's officers. The first step for any project is always the same: confirm your conservation area status, check the street-level Article 4 register, and establish whether Green Belt, Metropolitan Open Land, or listed building status also applies, before any design work begins.

For a wider look at costs across London, see our London extension costs guide, and for extension design more broadly, our rear extension guide.