Richmond upon Thames's most space-efficient loft solution when PD-route dormers are blocked. Our chartered team designs mansards that get approved in Richmond upon Thames conservation areas — with heritage statements and planning officer negotiation built in.
A mansard roof extensions package in Richmond upon Thames, where the stock is largely Georgian in Richmond Green and Twickenham; Edwardian villas in Barnes and East Sheen; 1930s semi-detached in Whitton; riverside cottages along the Thames, is the full measured-survey-to-submission drawing set London Borough of Richmond upon Thames needs in order to determine an application: existing and proposed plans, elevations and sections at 1:100 and 1:50, a location and site plan, and the supporting statements the case officer asks for.
Prepared and reviewed by the chartered technologist team at Architectural Drawings London — MCIAT chartered, £2m PI insured.Last reviewed 2026-08-03.
Richmond upon Thames's most space-efficient loft solution when PD-route dormers are blocked. Our chartered team designs mansards that get approved in Richmond upon Thames conservation areas — with heritage statements and planning officer negotiation built in.
Housing stock in Richmond upon Thames: Georgian in Richmond Green and Twickenham; Edwardian villas in Barnes and East Sheen; 1930s semi-detached in Whitton; riverside cottages along the Thames.
Character: Highest conservation area coverage in London; Royal Parks and Thames corridor add heritage layers; design quality heavily scrutinised.
We check against Richmond Council's mansard design guide and design to match the terrace.
Required for Richmond upon Thames's conservation areas — demonstrates the mansard respects character and townscape.
Accurate photomontage showing how the mansard sits alongside neighbours — often decisive at Richmond Council committee.
Mansards invariably trigger Party Wall notices in Richmond upon Thames's dense terraced streets. Structural package includes new ridge, tie beams, floor joists.
Full liaison with Richmond Council planning officer, committee representation if called in.
Part L thermal, Part B fire (critical on mansards), Part E acoustic separation.
Single planning or regs submission.
Planning + building regs + structural.
Listed, conservation, complex sites.
Move the controls for an indicative figure. It anchors your budget — it is not a quote. Every project is priced after a free survey.
Build costs are separate and quoted by your contractor. See our published fees.
Every Richmond upon Thames postcode district we draw in, the stock that dominates it and the authority that validates a mansard roof extension there. Richmond upon Thames fees below are the statutory England rates for 2026, not mansard roof extension estimates.
| Postcode | Area | Dominant stock | What it means for a mansard roof extension |
|---|---|---|---|
| SW13 | Barnes | Georgian villas, Edwardian terraces | SW13 covers Barnes only; Richmond Council handles the mansard roof extension, and Barnes case officers apply the SW13 conservation-area map. |
| SW14 | Mortlake / East Sheen | Edwardian villas, 1930s semi-detached | Mortlake / East Sheen sits wholly inside SW14, so Richmond Council validates every mansard roof extension submitted from an SW14 address. |
| TW1 | Twickenham | Georgian fragments, Victorian terraces, Edwardian villas | A mansard roof extension at an TW1 address in Twickenham is determined by Richmond Council under its own Local Plan policies for Twickenham. |
| TW2 | Twickenham / Whitton | Georgian fragments, Victorian terraces, Edwardian villas | TW2 covers Twickenham / Whitton only; Richmond Council handles the mansard roof extension, and Twickenham / Whitton case officers apply the TW2 conservation-area map. |
| TW9 | Richmond / Kew | Georgian terraces, Victorian villas | Richmond / Kew sits wholly inside TW9, so Richmond Council validates every mansard roof extension submitted from an TW9 address. |
| TW10 | Richmond / Ham | Georgian terraces, Victorian villas | Richmond / Ham sits wholly inside TW10, so Richmond Council validates every mansard roof extension submitted from an TW10 address. |
| TW11 | Teddington | Edwardian villas, Victorian terraces | A mansard roof extension at an TW11 address in Teddington is determined by Richmond Council under its own Local Plan policies for Teddington. |
| TW12 | Hampton / Hampton Hill | Georgian villas, Edwardian terraces, 1930s semi-detached | A mansard roof extension at an TW12 address in Hampton / Hampton Hill is determined by Richmond Council under its own Local Plan policies for Hampton / Hampton Hill. |
Roof pitch, wall build-up and plot depth change every few Richmond upon Thames streets, and each one changes what a mansard roof extension can achieve at that address.
Richmond upon Thames conservation designations: there are 72 across Richmond Council, Kew Green, Hampton Wick, Twickenham Riverside among them. Designation costs a Richmond upon Thames owner the permitted-development route: a mansard roof extension then needs a £548 householder application over 8 weeks, in place of the £249 prior approval route that takes 6 weeks. Twickenham Riverside is the Richmond upon Thames designation that most often changes a mansard roof extension design.
Richmond upon Thames permitted development status: there is no borough-wide direction from Richmond Council, so a mansard roof extension at a SW13 address is normally still permitted development. We certify that with a £274 Lawful Development Certificate rather than leaving a Richmond upon Thames sale to argue it later.
Richmond upon Thames housing stock: Georgian in Richmond Green and Twickenham; Edwardian villas in Barnes and East Sheen; 1930s semi-detached in Whitton; riverside cottages along the Thames. Highest conservation area coverage in London; Royal Parks and Thames corridor add heritage layers; design quality heavily scrutinised. Read that before choosing a mansard roof extension route in Richmond upon Thames — construction, not postcode, sets what is achievable. Richmond Council charges £548 for a householder application and has 8 weeks to determine it.
Sources for this Richmond upon Thames mansard roof extension page: borough policies maps and conservation-area registers (2025–26), Royal Mail postcode district boundaries, the Town and Country Planning (Fees for Applications) (England) Regulations, the Town and Country Planning (General Permitted Development) (England) Order 2015 as amended, and the Party Wall etc. Act 1996.
Of 31 listed building and conservation area consent appeals decided in Richmond upon Thames over the window covering appeals decided 2016-2026, Richmond upon Thames was upheld more often than most London councils — only 19.4% of appeals succeeded, against 28.5% across London. 6 were allowed and 23 dismissed, with 2 split. Mansards concentrate on terraces in conservation areas and on listed buildings, where consent runs separately from planning permission. These 31 Richmond upon Thames consent appeals are the contested minority.
Half of those Richmond upon Thames appeals took more than 112 days to decide from the day the appeal started — time added on top of the council's own determination period, which is the argument for getting the application right first. 16.1% of them (5 cases) involved a conservation area, so heritage argument carries real weight in Richmond upon Thames. 12.9% affected the setting of a listed building. 93.5% were decided by written representations rather than a hearing or inquiry, meaning the written case and the drawings were the whole of the evidence.
31 listed building and conservation area consent appeals decided in Richmond upon Thames. Source: Planning Inspectorate casework, OGL v3.0.
Direct answers to the questions Richmond upon Thames homeowners ask every week about mansard roof extensions.
Start a free quote →Mansards in Richmond upon Thames are less common historically — Richmond Council considers each application on its merits. Rear mansards on suitable terraced or semi-detached properties, matching the roofscape, have a reasonable approval rate with the right design and supporting heritage commentary where relevant.
A 70° front slope is typical for Richmond upon Thames mansards — steep enough to maximise floor area while reading as a roof rather than a full additional storey. Front dormers should be small and symmetrical. Richmond Council's design guide (where published) takes precedence on detail.
Often yes, but Richmond Council favours applications supported by wider street precedents. Where mansards already exist nearby in Richmond upon Thames, approval is far more likely. We review street precedents at the feasibility stage.
A Richmond upon Thames mansard carries more design work than a dormer — heritage statement, street-elevation massing and conservation-led detailing on top of planning, building regulations and structural calculations. Build cost then varies with size, roof geometry and site access. Our design fee is fixed before we start; see our fees.
Full-height — typically 2.3–2.5m ceiling from the new floor. Unlike a dormer, which gives partial head height, a mansard provides a complete additional storey within Richmond upon Thames's georgian in Richmond Green and Twickenham terraced context.
We cover all Richmond upon Thames postcodes — SW13, SW14, TW1, TW2, TW9, TW10, TW11, TW12 — and have submitted mansard applications across the borough. Our heritage statement and design-and-access statement are included in every mansard package.
Richmond upon Thames's georgian in Richmond Green and Twickenham terraced stock is the natural context for mansard extensions — they were originally designed for Victorian and Edwardian rows. Feasibility depends on street precedent, conservation area status and party wall implications. We assess all three at the free site visit.
A mansard adds a full upper storey — typically 35–45m² of usable floor space. In Richmond upon Thames this often converts a 3-bed house to 4 or 5 beds. The steep front slope (70°) and flat top read as a roof, not a full floor, which is why Richmond Council accepts them more readily than a simple box extension.
If your property sits on a boundary, here are the neighbouring options.
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Measured surveys across Richmond upon Thames — floor plans, elevations and sections to ±3mm accuracy. Leica Disto laser + BLK360 point-cloud...
End-to-end Party Wall Act 1996 service for Richmond upon Thames — Section 1, 3 and 6 notices, schedule of condition surveys, party wall awar...
London's most popular loft type — the full-width rear dormer. Planning or Permitted Development route assessed for your Richmond upon Thames...
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