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House Extension Richmond: Vetted Builders, Matched Quotes

A house extension in Richmond upon Thames costs £65,000-£120,000 for a single-storey rear extension and £110,000-£200,000+ for a double-storey. Richmond has 76 conservation areas and strict design guidance; most extensions require full planning permission. Get 3 matched quotes from vetted Richmond extension specialists.

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House Extension Richmond

How much does a house extension cost in Richmond?

House extension costs in Richmond upon Thames vary by extension type, size, and location within the borough. Richmond (TW9, TW10), Kew, Barnes (SW13), and East Sheen (SW14) sit at inner London rates, typically 20-30% above the London average. Twickenham (TW1, TW2), Teddington (TW11), and Hampton (TW12) run closer to the London average.

Richmond conservation areas: In all 76 of Richmond's conservation areas, Permitted Development rights for extensions are removed. All rear extensions, side returns, wraparounds, and double-storey extensions require full planning permission.
Extension type Typical cost range Planning status Notes
Single-storey rear extension
Single-storey rear extension — outside conservation area (up to 3m depth, terrace/semi) £65,000–£95,000 Permitted Development Building regs Up to 3m rear extension for terraces/semis may be PD outside CAs. Prior Approval scheme allows up to 6m via neighbour consultation. Building regs required.
Single-storey rear extension — inside conservation area £72,000–£110,000 Planning required Building regs All rear extensions in Richmond CAs need full planning. Materials must match existing property. Add £4,000–£7,000 for architect and planning fees. Allow 10–12 weeks for determination.
Single-storey rear extension — large (5–6m depth, open-plan kitchen-diner) £85,000–£130,000 Planning required Building regs Extensions over 3m (terraces/semis) or 4m (detached) require planning outside CAs too. Lantern roof, bi-fold doors, or full-width glazing at higher end of cost range.
Side return extension
Side return extension — outside conservation area £35,000–£55,000 Check PD limits Building regs Side extensions that project beyond the principal elevation require planning in most cases. Check specific PD rules with a planning consultant before assuming no planning is needed.
Side return extension — inside conservation area £38,000–£62,000 Planning required Building regs Planning required in all Richmond CAs. Side return height must not exceed ground-floor eaves. Roof should be flat with concealed parapet — Richmond SPD guidance applies.
Wraparound extension (rear + side return)
Wraparound extension — outside conservation area £85,000–£130,000 Planning required Building regs Wraparound extensions almost always require planning regardless of CA status — the side component typically triggers planning even outside CAs.
Wraparound extension — inside conservation area £92,000–£150,000 Planning required Building regs Most popular high-specification extension type for Richmond terraces. Planning required. Materials and design scrutinised closely in conservation areas. Allow 10–14 months total including planning.
Double-storey extension
Double-storey rear extension — outside conservation area £110,000–£160,000 Planning required Building regs Double-storey extensions are not Permitted Development — full planning required everywhere. Adds a ground-floor room and a first-floor bedroom or bathroom. Better cost per m² than two separate projects.
Double-storey rear extension — inside conservation area £120,000–£200,000+ Planning required Building regs Planning required. Overlooking and privacy assessments apply — Richmond Council scrutinises double-storey rear extensions on all elevations. Most common on larger semis in Ham, Kew, and St Margarets.
Specialist extension types
Glazed orangery or garden room £55,000–£110,000 Planning required (in CA) Building regs Richmond SPD: all-glass frameless extensions not generally accepted in CAs. Brick piers with glazed infill preferred. Outside CAs, may be PD if within size limits. Building regs for glazing energy standards.
Basement extension £3,500–£6,000/m² Planning required Building regs Significant structural and waterproofing works. Requires planning and structural engineer from the outset. Party wall Act almost always triggered. Programme: 24–40 weeks on site. Most common in Richmond Hill, Ham, and Kew.
Professional fees
Architect (planning drawings and Building Regs) £3,000–£8,000 Required for planning Essential in conservation areas. Choose an architect with Richmond Council conservation area experience. Fee covers planning drawings, application submission, and Building Regulations drawings.
Structural engineer £1,000–£2,500 Building regs Required for all structural elements — steelwork calculations, foundation design, and any structural wall removal. Building Control requires signed-off structural calculations.
Richmond Council planning fee (householder) £258 Required for planning Fixed householder application fee. Does not include architect or pre-application advice fees.
Party wall surveyor £700–£1,500 per owner Required where applicable Most Richmond terrace and semi-detached extensions trigger the Party Wall etc. Act 1996. Allow 2–3 months. Costs rise if neighbour appoints own surveyor.
Kitchen fit-out (where extension creates kitchen-diner) £8,000–£25,000+ No planning Building regs Separate cost to the extension structure. Mid-range kitchen £10,000–£18,000; high specification £20,000–£40,000+. Building regs for gas and electrical works.
Single-storey rear extension
Rear extension — outside CA (up to 3m) £65,000–£95,000
Permitted Development Building regs
May be PD outside CAs. Prior Approval allows up to 6m via neighbour consultation.
Rear extension — inside CA £72,000–£110,000
Planning required Building regs
All rear extensions in Richmond CAs need full planning. Materials must match.
Large rear extension (5–6m, open-plan) £85,000–£130,000
Planning required Building regs
Always needs planning over 3m (terraces). Lantern roof/bi-folds at upper end.
Side return extension
Side return — outside CA £35,000–£55,000
Check PD limits Building regs
Check specific PD rules — side extensions often trigger planning even outside CAs.
Side return — inside CA £38,000–£62,000
Planning required Building regs
Planning required. Height not to exceed ground-floor eaves. Flat roof with parapet preferred.
Wraparound extension
Wraparound — outside CA £85,000–£130,000
Planning required Building regs
Almost always needs planning — side component typically triggers it even outside CAs.
Wraparound — inside CA £92,000–£150,000
Planning required Building regs
Most popular high-spec option for Richmond terraces. Allow 10–14 months total.
Double-storey extension
Double-storey — outside CA £110,000–£160,000
Planning required Building regs
Not Permitted Development anywhere. Adds ground-floor room + first-floor bedroom.
Double-storey — inside CA £120,000–£200,000+
Planning required Building regs
Planning required. Overlooking assessments apply. Common on larger semis in Ham, Kew, St Margarets.
Specialist and fees
Glazed orangery / garden room £55,000–£110,000
Planning required (in CA) Building regs
Richmond SPD: frameless glass not accepted in CAs. Brick piers with glazed infill preferred.
Basement extension £3,500–£6,000/m²
Planning required Building regs
Structural and waterproofing works. 24–40 weeks on site. Common in Richmond Hill, Ham, Kew.
Architect (planning + Building Regs) £3,000–£8,000
Required for planning
Choose an architect with Richmond Council conservation area experience.
Structural engineer £1,000–£2,500
Building regs
Required for all structural elements. Building Control requires signed calculations.
Planning fee (householder) £258
Required for planning
Fixed fee. Does not include architect or pre-application advice fees.
Party wall surveyor £700–£1,500 per owner
Required where applicable
Most Richmond terrace extensions trigger the Party Wall Act. Allow 2–3 months.
Kitchen fit-out £8,000–£25,000+
No planning Building regs
Separate to the extension structure. Mid-range £10,000–£18,000; high spec £20,000–£40,000+.

Cost ranges are all-in indicative figures for Richmond upon Thames including VAT, structural engineer, and project management. They exclude planning fees, architect fees, and kitchen fit-out unless stated. Richmond (TW9, TW10), Kew, Barnes (SW13), and East Sheen (SW14) sit at inner London rates — typically 20–30% above the London average. Twickenham (TW1, TW2), Teddington (TW11), and Hampton (TW12) run closer to the London average.

What drives cost variation for Richmond house extensions:

– Extension type – a single-storey rear extension is the most common starting point. A side return fills the gap beside a Victorian or Edwardian terrace. A wraparound combines both. A double-storey adds a first-floor room above.

– Size – most Richmond single-storey extensions run 20-40m². Cost per m² reduces slightly at larger sizes.

– Conservation area – conservation area extensions require planning permission (adding £3,000-£8,000 in professional fees and 3-5 months to the programme) and often specified materials (brick to match, conservation-grade windows). Budget 10-15% above non-CA rates for materials compliance.

– Structural complexity – removing a rear wall to open up the ground floor adds steelwork costs (£2,000-£6,000). Most single-storey extensions involve at least one RSJ.

– Specification – a glazed kitchen-diner extension with lantern roof and bi-fold doors sits at the higher end. A brick-built utility or garden room sits lower.

– Services – extending a kitchen requires drainage diversion, replumbing, and electrical works. Allow £4,000-£8,000 for services over and above the structure.

House Extension Wandsworth

Do I need planning permission for a house extension in Richmond?

Richmond upon Thames has 76 conservation areas, and most extension work in the borough requires full planning permission. Richmond Council is stricter than average; its approval rate for householder applications is 81% compared to 90% nationally.

In conservation areas: Permitted Development rights for extensions are removed. All rear extensions, side return extensions, wraparound extensions, and double-storey extensions in Richmond conservation areas require a full planning application.

Outside conservation areas: Standard Permitted Development rules apply: a single-storey rear extension of up to 3m depth (for terraces and semis) or 4m (for detached properties) may be built under PD. The Prior Approval (Neighbour Consultation) scheme allows up to 6m for terraces/semis and 8m for detached under a simplified process. Extensions beyond these limits always require full planning.

Richmond Council’s Supplementary Planning Document (SPD): even where PD rights exist, Richmond Council’s SPD sets design standards that many homeowners choose to follow voluntarily. Key SPD guidance:

– Extension materials must match or complement the existing property; no uPVC windows; no render on brick properties in most areas

– Flat roofs with concealed parapets are preferred in conservation areas over pitched roofs that interrupt the roofline

– Side return extensions should not be higher than the ground floor eaves

– Glazed extensions (orangeries, lantern roofs) are subject to specific design guidance in conservation areas; frameless glass is generally not acceptable

Listed buildings: any extension to a listed building (common in Richmond Hill, Ham, and Petersham) requires Listed Building Consent in addition to planning permission. Works affecting the character of a listed building are very tightly controlled.

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House Extension Islington

Richmond Conservation Areas - House extension planning rules

In Richmond's conservation areas, Permitted Development rights for extensions are removed. All extension types single-storey rear, double-storey, side return, wraparound, and orangery require a full planning application. There are no PD exceptions.

← Scroll to see all columns →

Conservation Area Area / Postcodes Single-storey rear Double-storey Side return Notes
Richmond Hill Richmond TW10 Planning req. Planning req. Planning req. Many listed buildings — LBC may also be required
Richmond Green Richmond TW9 Planning req. Planning req. Planning req. —
Richmond Town Centre Richmond TW9 Planning req. Planning req. Planning req. —
St Margarets St Margarets TW1 Planning req. Planning req. Planning req. —
Twickenham Riverside Twickenham TW1 Planning req. Planning req. Planning req. —
Marble Hill Twickenham / St Margarets TW1 Planning req. Planning req. Planning req. Registered park setting — stricter assessment
Kew Green Kew TW9 Planning req. Planning req. Planning req. Adjacent to Kew Gardens WHS buffer zone
Kew Road Kew TW9 Planning req. Planning req. Planning req. —
Barnes Village Barnes SW13 Planning req. Planning req. Planning req. —
Castelnau Barnes SW13 Planning req. Planning req. Planning req. —
East Sheen East Sheen SW14 Planning req. Planning req. Planning req. —
Mortlake High Street Mortlake SW14 Planning req. Planning req. Planning req. —
Ham House & Gardens Ham TW10 Planning req. Planning req. Planning req. Historic England registered park — pre-app advice recommended
Petersham Petersham TW10 Planning req. Planning req. Planning req. Historic village — conservation officer pre-app recommended
Strawberry Hill Strawberry Hill TW1 Planning req. Planning req. Planning req. —
Richmond Hill
Richmond TW10
Single-storey rearPlanning req.
Double-storeyPlanning req.
Side returnPlanning req.
Many listed buildings — Listed Building Consent may also be required.
Richmond Green
Richmond TW9
Single-storey rearPlanning req.
Double-storeyPlanning req.
Side returnPlanning req.
Richmond Town Centre
Richmond TW9
Single-storey rearPlanning req.
Double-storeyPlanning req.
Side returnPlanning req.
St Margarets
St Margarets TW1
Single-storey rearPlanning req.
Double-storeyPlanning req.
Side returnPlanning req.
Twickenham Riverside
Twickenham TW1
Single-storey rearPlanning req.
Double-storeyPlanning req.
Side returnPlanning req.
Marble Hill
Twickenham / St Margarets TW1
Single-storey rearPlanning req.
Double-storeyPlanning req.
Side returnPlanning req.
Registered park setting — stricter assessment applies.
Kew Green
Kew TW9
Single-storey rearPlanning req.
Double-storeyPlanning req.
Side returnPlanning req.
Adjacent to Kew Gardens World Heritage Site buffer zone.
Kew Road
Kew TW9
Single-storey rearPlanning req.
Double-storeyPlanning req.
Side returnPlanning req.
Barnes Village
Barnes SW13
Single-storey rearPlanning req.
Double-storeyPlanning req.
Side returnPlanning req.
Castelnau
Barnes SW13
Single-storey rearPlanning req.
Double-storeyPlanning req.
Side returnPlanning req.
East Sheen
East Sheen SW14
Single-storey rearPlanning req.
Double-storeyPlanning req.
Side returnPlanning req.
Mortlake High Street
Mortlake SW14
Single-storey rearPlanning req.
Double-storeyPlanning req.
Side returnPlanning req.
Ham House & Gardens
Ham TW10
Single-storey rearPlanning req.
Double-storeyPlanning req.
Side returnPlanning req.
Historic England registered park — pre-application advice recommended.
Petersham
Petersham TW10
Single-storey rearPlanning req.
Double-storeyPlanning req.
Side returnPlanning req.
Historic village setting — conservation officer pre-application advice recommended.
Strawberry Hill
Strawberry Hill TW1
Single-storey rearPlanning req.
Double-storeyPlanning req.
Side returnPlanning req.

15 of Richmond upon Thames's 76 conservation areas are shown above. All 76 remove Permitted Development rights for extensions. Check your property's conservation area status on the Richmond Council planning portal.

What type of extension suits a Richmond property?

Richmond’s period stock predominantly consists of Victorian terraces in Twickenham, East Sheen, and Mortlake, and Edwardian properties across Richmond Hill, Ham, Kew, and St Margarets suits different extension types depending on the property’s layout and plot.

Rear Extension (most common)

Extends the back of the property. On a Victorian or Edwardian terrace with a narrow rear, a single-storey rear extension of 3-5m creates a larger ground-floor kitchen-diner and better connection to the garden. The most popular configuration in Richmond is a full-width rear extension with a glazed roof lantern or flat roof with rooflights.

Side Return Extension

Victorian and Edwardian terraces in Twickenham, East Sheen, and Barnes typically have a narrow side return passage alongside the kitchen. Infilling this passage (usually 1- 2 m wide, 4- 8 m long) adds valuable kitchen floor area without touching the rear garden. A side return alone is modest in size but transformative in a narrow terrace kitchen, typically 6- 15 m².

Wraparound Extension (rear + side return)

Combines the side return with a full-width rear extension to create the maximum ground-floor footprint on a terrace plot. The most common high-specification extension type in Richmond’s inner areas. Planning is always required in conservation areas.

Double-Storey Extension

Adds a first-floor room (typically a bedroom or bathroom) above a single-storey rear extension. Better cost per m² than two separate projects. Most common on larger semi-detached or detached properties in Ham, Kew, and Richmond Hill. Requires planning in conservation areas; also subject to overlooking and privacy assessments from Richmond Council.

Orangery or Garden Room

A glazed or part-glazed structure extending from the rear. Popular in Richmond’s larger Edwardian and detached properties. Richmond Council’s SPD has specific design guidance for glazed extensions in conservation areas; all-glass frameless structures are generally not accepted; brick piers with glazed infill are the preferred form.

Basement Extension

Increasingly common in Richmond Hill, Ham, and Kew where properties sit on larger plots with good ground conditions. Costs £3,500-£6,000+/m², significantly more than a ground-level extension. Requires planning and structural engineer involvement from the outset. Party wall notices are almost always required.

How long does a house extension in Richmond take?

Planning (where required): 8-12 weeks for Richmond Council to determine a householder application. Richmond is slower than the national average. Allow 10-12 weeks and factor in the possibility of a request for further information or committee referral for larger or more sensitive applications.

Party wall process: 2-3 months, running concurrently with planning where possible. Most Richmond terrace extensions trigger the Party Wall etc. Act 1996.

Design and tender: appointing an architect, producing planning and working drawings, tendering to contractors: 2-3 months.

On site:

– Single-storey rear extension: 10-16 weeks

– Side return extension: 8-12 weeks

– Wraparound extension: 14-20 weeks

– Double-storey extension: 16-24 weeks

– Basement extension: 24-40 weeks

Total from decision to completion (including planning):

– Single-storey in conservation area: 8-12 months

– Double-storey in conservation area: 10-14 months

– Basement: 14-20 months

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How do I find a vetted house extension specialist in Richmond?

Richmond’s planning environment means a house extension is not just a building project; it’s a planning project first. The contractor you choose needs to have experience with Richmond Council’s design requirements, know which architects produce drawings that get approved, and understand the borough’s conservation area SPD.

What to look for when choosing a Richmond extension specialist:

1. Conservation area track record: Ask for planning approval letters and completed project addresses in Richmond specifically. An approval at planning stage means the contractor and architect know the council’s requirements.

2. Architect relationship: The best Richmond extension contractors work with local architects who have pre-application experience with Richmond planning officers. Ask whom they use and whether they’ve worked together before.

3. Itemised quotes: Structure, steelwork, roofing, glazing, services, kitchen fit-out, and decoration should all appear separately. Lump-sum quotes cannot be compared.

4. Party wall experience: Most Richmond terrace extensions trigger the Act. A contractor who hasn’t coordinated party wall agreements before is a risk on a terrace project.

5. Programme clarity: The programme should show planning, party wall, and construction phases separately. Be cautious of any quote that doesn’t account for planning time.

QuoteMyRenovation matches Richmond homeowners with vetted house extension specialist contractors with recent, verifiable extension projects in the borough. Submit one brief and receive up to 3 matched quotes from specialists who have reviewed your project.

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    COMMON QUESTIONS

    Frequently Asked Questions About House Extension Richmond

    Questions homeowners ask us most often before submitting their brief.

    Do I need planning permission for a house extension in Richmond?

    Almost certainly yes if you are in a conservation area. Richmond has 76 conservation areas, and in all of them, Permitted Development rights for extensions are removed; all extensions require full planning permission. Outside conservation areas, standard Permitted Development rules apply: a single-storey rear extension of up to 3m (terraces and semis) or 4m (detached) may not need planning. Check your property's conservation area status on the Richmond Council planning portal before proceeding.

    How much does a house extension cost in Richmond?

    How long does a house extension take in Richmond?

    What extension type suits my Richmond Victorian or Edwardian terrace?

    Can I build a glazed orangery extension in Richmond?

    Do I need a party wall agreement for a house extension in Richmond?

    What materials does Richmond Council require for a conservation area extension?

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