Loft Conversion Richmond: Vetted Builders, Matched Quotes

A loft conversion in Richmond upon Thames costs £28,000-£48,000 for a Velux, £42,000-£70,000 for a dormer, £48,000-£80,000 for a hip-to-gable, and £58,000-£125,000+ for a mansard. Richmond has the highest volume of loft conversion planning applications of any London borough and stricter conservation area rules than most. Get 3 matched quotes from vetted Richmond loft specialists.

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How much does a loft conversion cost in Richmond?

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

Richmond conservation areas: In all 76 of Richmond's conservation areas, roof extensions rooflights, dormers, hip-to-gable conversions, and mansards require planning permission. Permitted Development does not apply to roof works in Richmond conservation areas.
Conversion type Typical cost range Planning status Notes
Velux / Rooflight conversion
Velux conversion — outside conservation area £28,000–£42,000 Permitted Development Building regs No planning needed if outside conservation area and rooflights don't protrude more than 150mm from the roof plane. Building regs required.
Velux conversion — inside conservation area £30,000–£45,000 Planning required Building regs All rooflights in Richmond conservation areas require planning. Conservation-grade flush-fitting rooflights required. Add £2,000–£4,000 for architect fees and planning application.
Velux conversion — rear slope only, outside CA £28,000–£42,000 Permitted Development Building regs Rear rooflights are PD outside conservation areas. Front slope rooflights are never PD — always require planning regardless of CA status.
Dormer conversion
Rear dormer — outside conservation area £42,000–£60,000 Permitted Development Building regs Rear dormers are PD outside CAs for terraces/semis (max 40m³ additional volume) and detached properties (max 50m³). Building regs required.
Rear dormer — inside conservation area £46,000–£68,000 Planning required Building regs All dormers in Richmond conservation areas require full planning. Must be set back from eaves (min 200mm) and party walls (min 300mm). Slate or lead cladding required. Add £3,000–£5,000 for planning fees.
Rear dormer with en-suite bathroom £52,000–£78,000 Planning required (in CA) Building regs Adding an en-suite to the loft adds £6,000–£12,000. Most Richmond loft conversions include at least a shower room. Building regs for plumbing and wet zone electrics.
Hip-to-gable conversion
Hip-to-gable — outside conservation area £48,000–£68,000 Permitted Development Building regs Hip-to-gable is PD for end-of-terrace and semi-detached properties outside CAs. Significantly increases usable loft floor area. Structural work to side wall required.
Hip-to-gable — inside conservation area £52,000–£75,000 Planning required Building regs Always requires planning in conservation areas. Common on Edwardian semis in Richmond Hill, Ham, Kew, and St Margarets. Side elevation visibility means design scrutiny is high.
Hip-to-gable + rear dormer (L-dormer) £58,000–£85,000 Planning required Building regs The maximum floor area option for semis and end-of-terraces. Almost always requires planning. Most common conversion type for Edwardian properties in Richmond.
Mansard conversion
Rear mansard — terraced property £58,000–£95,000 Planning required Building regs Mansard conversions always require planning permission — there is no Permitted Development route. Replaces the entire rear roof slope. Provides the most floor area of any conversion type.
Full mansard (rear + side) — conservation area £75,000–£125,000+ Planning required Building regs High-specification mansard in a conservation area. London stock brick or render to match. Richmond Council scrutinises mansards carefully — appoint an architect with Richmond CA experience.
Professional fees and add-ons
Architect / planning drawings £2,500–£5,000 Required for planning Required for planning applications. Essential in conservation areas — choose an architect with Richmond Council experience. Fee includes planning drawings and application submission.
Structural engineer £800–£1,500 Building regs Required for all loft conversions. Calculates new floor joist specification, steelwork requirements, and roof alterations. Building Control will require structural calculations.
Richmond Council planning fee (householder) £258 Required for planning Standard householder planning application fee. Fixed nationally. Does not include architect fees or any pre-application advice fee Richmond Council may charge.
Party wall surveyor £700–£1,500 per owner Required where applicable Required for structural works on or near shared walls. Most Richmond terrace loft conversions trigger the Party Wall etc. Act 1996. Allow 2–3 months. Cost rises if neighbour appoints own surveyor.
En-suite bathroom addition £6,000–£15,000 No planning Building regs Most Richmond loft conversions include at least a shower room. No additional planning for internal bathroom works. Building regs for drainage, ventilation, and wet zone electrics.
Bespoke staircase £3,000–£8,000 No planning Building regs Building Regulations require minimum 2m headroom at the centre point. A period-appropriate staircase (open-tread timber) costs more than a standard flight but suits Richmond's period stock.
Velux / Rooflight conversion
Velux — outside conservation area £28,000–£42,000
Permitted Development Building regs
No planning if outside CA and rooflights don't protrude more than 150mm.
Velux — inside conservation area £30,000–£45,000
Planning required Building regs
All rooflights in Richmond CAs require planning. Conservation-grade flush-fitting rooflights only.
Dormer conversion
Rear dormer — outside CA £42,000–£60,000
Permitted Development Building regs
PD outside CAs for terraces/semis (max 40m³). Building regs required.
Rear dormer — inside CA £46,000–£68,000
Planning required Building regs
All dormers in Richmond CAs need planning. Set back from eaves and party walls. Slate or lead cladding required.
Dormer with en-suite £52,000–£78,000
Planning required (in CA) Building regs
Most Richmond loft conversions include a shower room. En-suite adds £6,000–£12,000.
Hip-to-gable conversion
Hip-to-gable — outside CA £48,000–£68,000
Permitted Development Building regs
PD for end-of-terrace and semi-detached outside CAs. Significantly increases floor area.
Hip-to-gable — inside CA £52,000–£75,000
Planning required Building regs
Always needs planning in CAs. Common on Edwardian semis in Richmond Hill, Ham, Kew, St Margarets.
Hip-to-gable + rear dormer (L-dormer) £58,000–£85,000
Planning required Building regs
Maximum floor area for semis. Almost always needs planning. Most common for Edwardian properties in Richmond.
Mansard conversion
Rear mansard — terraced property £58,000–£95,000
Planning required Building regs
Always requires planning — no PD route exists for mansard conversions. Most floor area of any conversion type.
Full mansard — conservation area £75,000–£125,000+
Planning required Building regs
High-spec. Richmond Council scrutinises closely — appoint an architect with Richmond CA experience.
Professional fees and add-ons
Architect / planning drawings £2,500–£5,000
Required for planning
Essential in conservation areas. Choose an architect with Richmond Council experience.
Structural engineer £800–£1,500
Building regs
Required for all loft conversions. Building Control requires structural calculations.
Planning fee (householder) £258
Required for planning
Fixed fee for householder applications. Does not include architect fees.
Party wall surveyor £700–£1,500 per owner
Required where applicable
Most Richmond terrace conversions trigger the Party Wall Act. Allow 2–3 months.
En-suite bathroom addition £6,000–£15,000
No planning Building regs
Most Richmond loft conversions include at least a shower room. No planning for internal bathroom works.
Bespoke staircase £3,000–£8,000
No planning Building regs
Building regs require minimum 2m headroom at centre point. Period-appropriate timber staircase recommended for Richmond's period stock.

Cost ranges are indicative for Richmond upon Thames. 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. All costs include VAT. Planning and architect fees apply to all conversions in conservation areas.

What drives cost variation for Richmond loft conversions:

– Conversion type – Velux adds headroom via rooflights only; a dormer extends the roof plane; a mansard replaces the entire roof. Each step up adds high cost and structural complexity.

– Planning requirement – all conversion types in Richmond conservation areas require planning permission (see below). Planning adds professional fees (architect, structural engineer) and 2-4 months to the programme.

– Property type – Victorian and Edwardian terraces (most of Richmond’s period stock) have relatively standard loft structures. Detached Edwardian properties in Richmond Hill, Ham, and Kew often have complex hip roofs that require a hip-to-gable conversion before a dormer can be added.

– Structural complexity – period properties may require additional steel (flitch beams or RSJs) for the loft floor. A structural engineer’s fee of £800-£1,500 applies to all conversions.

– En-suite addition – adding a bathroom to the loft adds £6,000-£15,000 depending on specification. Most Richmond loft conversions include at least a shower room.

– Staircase – a bespoke staircase suited to a period property adds £3,000-£8,000 above a standard straight flight.

Loft Conversion Cost London

Richmond upon Thames has 76 conservation areas, one of the highest counts of any London borough. Unlike some boroughs where rear dormers may be built under Permitted Development, in Richmond’s conservation areas all roof extensions require planning permission. This includes:

– Rooflights (Velux) on the front slope always require planning in conservation areas

– Rooflights on the rear slope – require planning in most Richmond conservation areas

– Rear dormers – require planning in all Richmond conservation areas

– Side dormers – always require planning (not Permitted Development anywhere)

– Hip-to-gable conversions – require planning in conservation areas

– Mansard conversions – always require planning permission (no borough exception)

Richmond Council’s planning approval rate for householder applications is 81%, compared to a national average of 90%. The council applies strict design guidance for conservation area loft conversions:

– Dormers must be set back from the eaves (minimum 200mm) and from the party walls (minimum 300mm)

– Dormer cheeks and roofs must be clad in slate or lead to match the existing roof

– Conservation-grade rooflights must be flush-fitting, low-profile, and set back from the eaves

– Front rooflights are refused in most Richmond conservation areas

– No alteration to the front roof slope is acceptable in most conservation areas

– Mansard conversions in conservation areas must use traditional materials: London stock brick or render to match the existing building

Outside conservation areas, standard Permitted Development rules apply:

– Rear dormers up to 40m³ additional volume (terraces and semis) are Permitted Development

– Rear dormers up to 50m³ (detached) are Permitted Development

– Rooflights on the rear slope are Permitted Development if they do not protrude more than 150mm from the roof plane

Check your property’s conservation area status on the Richmond Council planning portal before commissioning drawings.

Party Wall Agreement London
All 76 Richmond conservation areas remove Permitted Development rights for roof works. Every loft conversion type including Velux rooflights requires a full planning application in all Richmond conservation areas. There are no PD exceptions.

← Scroll to see all columns →

Conservation Area Area / Postcodes Front rooflight Rear rooflight Rear dormer Hip-to-gable Mansard
Richmond Hill Richmond TW10 Planning req. Planning req. Planning req. Planning req. Planning req.
Richmond Green Richmond TW9 Planning req. Planning req. Planning req. Planning req. Planning req.
Richmond Town Centre Richmond TW9 Planning req. Planning req. Planning req. Planning req. Planning req.
St Margarets St Margarets TW1 Planning req. Planning req. Planning req. Planning req. Planning req.
Twickenham Riverside Twickenham TW1 Planning req. Planning req. Planning req. Planning req. Planning req.
Marble Hill Twickenham / St Margarets TW1 Planning req. Planning req. Planning req. Planning req. Planning req.
Kew Green Kew TW9 Planning req. Planning req. Planning req. Planning req. Planning req.
Kew Road Kew TW9 Planning req. Planning req. Planning req. Planning req. Planning req.
Barnes Village Barnes SW13 Planning req. Planning req. Planning req. Planning req. Planning req.
Castelnau Barnes SW13 Planning req. Planning req. Planning req. Planning req. Planning req.
East Sheen East Sheen SW14 Planning req. Planning req. Planning req. Planning req. Planning req.
Mortlake High Street Mortlake SW14 Planning req. Planning req. Planning req. Planning req. Planning req.
Ham House & Gardens Ham TW10 Planning req. Planning req. Planning req. Planning req. Planning req.
Petersham Petersham TW10 Planning req. Planning req. Planning req. Planning req. Planning req.
Strawberry Hill Strawberry Hill TW1 Planning req. Planning req. Planning req. Planning req. Planning req.
Richmond Hill
Richmond TW10
Front rooflightPlanning req.
Rear rooflightPlanning req.
Rear dormerPlanning req.
Hip-to-gablePlanning req.
MansardPlanning req.
Richmond Green
Richmond TW9
Front rooflightPlanning req.
Rear rooflightPlanning req.
Rear dormerPlanning req.
Hip-to-gablePlanning req.
MansardPlanning req.
Richmond Town Centre
Richmond TW9
Front rooflightPlanning req.
Rear rooflightPlanning req.
Rear dormerPlanning req.
Hip-to-gablePlanning req.
MansardPlanning req.
St Margarets
St Margarets TW1
Front rooflightPlanning req.
Rear rooflightPlanning req.
Rear dormerPlanning req.
Hip-to-gablePlanning req.
MansardPlanning req.
Twickenham Riverside
Twickenham TW1
Front rooflightPlanning req.
Rear rooflightPlanning req.
Rear dormerPlanning req.
Hip-to-gablePlanning req.
MansardPlanning req.
Marble Hill
Twickenham / St Margarets TW1
Front rooflightPlanning req.
Rear rooflightPlanning req.
Rear dormerPlanning req.
Hip-to-gablePlanning req.
MansardPlanning req.
Kew Green
Kew TW9
Front rooflightPlanning req.
Rear rooflightPlanning req.
Rear dormerPlanning req.
Hip-to-gablePlanning req.
MansardPlanning req.
Kew Road
Kew TW9
Front rooflightPlanning req.
Rear rooflightPlanning req.
Rear dormerPlanning req.
Hip-to-gablePlanning req.
MansardPlanning req.
Barnes Village
Barnes SW13
Front rooflightPlanning req.
Rear rooflightPlanning req.
Rear dormerPlanning req.
Hip-to-gablePlanning req.
MansardPlanning req.
Castelnau
Barnes SW13
Front rooflightPlanning req.
Rear rooflightPlanning req.
Rear dormerPlanning req.
Hip-to-gablePlanning req.
MansardPlanning req.
East Sheen
East Sheen SW14
Front rooflightPlanning req.
Rear rooflightPlanning req.
Rear dormerPlanning req.
Hip-to-gablePlanning req.
MansardPlanning req.
Mortlake High Street
Mortlake SW14
Front rooflightPlanning req.
Rear rooflightPlanning req.
Rear dormerPlanning req.
Hip-to-gablePlanning req.
MansardPlanning req.
Ham House & Gardens
Ham TW10
Front rooflightPlanning req.
Rear rooflightPlanning req.
Rear dormerPlanning req.
Hip-to-gablePlanning req.
MansardPlanning req.
Petersham
Petersham TW10
Front rooflightPlanning req.
Rear rooflightPlanning req.
Rear dormerPlanning req.
Hip-to-gablePlanning req.
MansardPlanning req.
Strawberry Hill
Strawberry Hill TW1
Front rooflightPlanning req.
Rear rooflightPlanning req.
Rear dormerPlanning req.
Hip-to-gablePlanning req.
MansardPlanning req.

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

Note for developer: add a header row note:

“Richmond has 76 conservation areas. In all of them, roof extensions, rooflights,

dormers, hip-to-gable conversions, and mansards require planning permission.

Permitted Development does not apply to roof works in Richmond conservation areas.”

Is my Richmond property suitable for a loft conversion?

Richmond’s period stock is generally well-suited to loft conversion, but suitability depends on roof type, head height, and party wall considerations.

Victorian and Edwardian terraces (common in Twickenham, East Sheen, Mortlake, Barnes)

Most have a standard pitched roof with a ridge height that allows a full dormer or Velux conversion. Head height at the ridge is typically 2.2- 2.8 m on a two-storey terrace, sufficient for a habitable room. The main variable is floor joist depth: Victorian and Edwardian joists are typically 150- 175 mm, which is not sufficient for Building Regulations without sistering (laying new joists alongside the originals). This adds £2,000-£4,000 to the structural package but is routine.

Hip-roofed Edwardian properties (common in Richmond Hill, Ham, Kew, St Margarets)

The detached and semi-detached Edwardian stock in these areas often has a hipped roof on the side elevation. A hip-to-gable conversion fills the triangular void created by the hip, significantly increasing the usable floor area in the loft. It always requires planning in conservation areas and structural work to the side wall. For end-of-terrace and semi-detached properties, a hip-to-gable combined with a rear dormer (sometimes called a “L-dormer”) gives the maximum floor area.

Detached properties in Richmond Hill and Ham

Larger detached properties often have a more complex roof structure with multiple ridges, valleys, and dormers already. A structural engineer’s assessment is essential before committing to a conversion type. Some properties have listed building or curtilage designation; check with Richmond Council before proceeding.

Checking head height:

Measure from the top of the ceiling joists to the underside of the ridge. A minimum of 2.2m is required for a comfortable habitable space; 2.5m+ is ideal. Below 2.2m, a dormer or mansard is likely required to create usable space.

What does a loft conversion in Richmond include?

A full loft conversion programme in Richmond typically involves:

1. Planning application (if required, almost always in Richmond CAs): architect drawings, structural engineer’s input, Richmond Council application fee (£258 for a householder application). Allow 8-12 weeks for determination. Richmond’s 81% approval rate means refusals do happen; appoint an architect with Richmond conservation area experience.

2. Structural works: new loft floor (joists sistered or replaced), steelwork (RSJ or flitch beams to carry the new floor load), and structural alteration to the roof where a dormer or hip-to-gable is included.

3. Party wall notice (if applicable): required for structural works within 3-6 metres of a neighbouring property’s foundations, and for any work on a shared wall. Most Richmond terrace loft conversions trigger the Party Wall etc. Act 1996. Allow 2-3 months for the party wall process.

4. Roofing works: dormer frame and cladding (slate, lead, or zinc), new rooflights (conservation-grade in conservation areas), waterproofing.

5. First fix services: new loft floor electrical and any plumbing for en-suite.

6. Insulation: between and below rafters – Building Regulations require a minimum U-value of 0.18 W/m²K.

7. Staircase: new staircase from first floor to loft. Building Regulations require a minimum 2m headroom at the centre point of the staircase (1.9m at the side).

8. Fire safety: 30-minute fire-rated doors to all habitable rooms on the escape route, mains-wired smoke alarms, and (for a 3-storey property) an emergency egress window in the loft.

9. Second fix and fit-out: plastering, flooring, decoration, and en-suite bathroom fit-out.

10. Building Regulations sign-off: final inspection and completion certificate from Richmond Council’s Building Control.

How long does a loft conversion take in Richmond?

Planning (where required): 8-12 weeks for determination. Richmond Council is slower than the national average; allow 10-12 weeks and factor in the possibility of requests for further information.

Party wall process (where required): 2–3 months, running concurrently with the planning process.

On site:

– Velux conversion (no structural extension): 4-6 weeks

– Dormer conversion: 6-10 weeks

– Hip-to-gable + dormer: 8-12 weeks

– Mansard conversion: 10-16 weeks

Total from decision to completion:

– Velux in a conservation area (planning required): 4-6 months

– Dormer in a conservation area: 6-8 months

– Mansard: 8-12 months

Most of the time is planning and party wall, not the build itself.

How do I find a vetted loft conversion specialist in Richmond?

Richmond has more loft conversion planning applications than any other London borough. That means experienced contractors are working in the area, but it also means demand is high and availability is competitive.

What to look for when choosing a Richmond loft conversion specialist:

1. Conservation area experience – has the contractor completed dormer or mansard conversions in Richmond conservation areas specifically? Ask for planning approval letters and addresses.

2. Architect relationships – the best Richmond loft contractors work with architects who know Richmond Council’s planning officers. Ask whom they use.

3. Itemised quotes – structural package, roofing, services, staircase, fit-out, and planning/architect fees should all be broken out separately.

4. Programme realism – any contractor quoting 4 weeks for a dormer in a conservation area hasn’t accounted for planning. Programme should include planning, party wall, and build phases.

5. Party wall experience – most Richmond terrace loft conversions trigger the Act. A contractor who hasn’t handled party wall notices before is a risk.

QuoteMyRenovation matches Richmond homeowners with vetted loft conversion specialists who have recent, verifiable 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 Loft Conversion Richmond

    Questions homeowners ask us most often before submitting their brief.

    Do I need planning permission for a loft conversion in Richmond?

    Almost certainly yes. Richmond upon Thames has 76 conservation areas, and in all of them roof extensions, rooflights, dormers, hip-to-gable conversions, and mansards require planning permission. Permitted Development does not apply to roof works in Richmond conservation areas. Even properties outside conservation areas should check Article 4 directions and Permitted Development limits before assuming planning isn't needed. Check your property's status on the Richmond Council planning portal.

    How much does a loft conversion cost in Richmond?

    How long does a loft conversion take in Richmond?

    Is my Richmond property suitable for a loft conversion?

    What is the difference between a dormer and a mansard loft conversion in Richmond?

    Does a loft conversion add value in Richmond?

    Do I need a party wall agreement for a loft conversion in Richmond?

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