Mansard Roof Extensions · SW13 Barnes
Fixed-fee mansard roof extensions for Barnes, Barnes Village, Castelnau, Little Chelsea in the SW13 postcode, drawn by an MCIAT-chartered architectural technologist and submitted to Richmond Council. Richmond controls Barnes's extensive conservation areas and the Thames frontage; SW13 is an affluent, tightly protected village market.
MCIAT chartered drawings for planning, building regs, lofts and extensions — fixed fees 30% below typical London architects. Tell us what you need and we’ll reply the same working day.
A mansard roof extension adds a full storey behind a new sloping front face — a strong option on SW13's terraces in Barnes where a standard dormer is too small. Richmond Council scrutinises mansards on townscape and precedent, especially within Barnes Green, Castelnau, Barnes riverside, The Terrace; we design to the borough's roof guidance with a Heritage Statement where the setting requires it.
Barnes's most space-efficient loft solution when PD-route dormers are blocked. Our chartered team designs mansards that get approved in Barnes conservation areas — with heritage statements and planning officer negotiation built in.
Across Barnes, Barnes Village, Castelnau, Little Chelsea in SW13, the dominant property is victorian and edwardian terraces and large detached houses around barnes, with riverside houses along the thames and the barnes village core. That stock shapes what mansard roof extensions looks like here: the right approach for a period terrace differs from a mansion-block flat or a new-build, and Richmond Council judges each on design quality and neighbour impact. We survey the specific Barnes property, confirm the planning route — Permitted Development, a Lawful Development Certificate, or full planning — and draw a council-ready set tailored to the SW13 streetscape.
Housing stock in SW13: Victorian and Edwardian terraces and large detached houses around Barnes, with riverside houses along the Thames and the Barnes village core.
Within the district: Barnes, Barnes Village, Castelnau, Little Chelsea.
Streets we know in SW13: the Castelnau villas, the Barnes village streets, Lonsdale Road riverside and the Westmoreland Road terraces. Each road has its own building line, boundary treatment and precedent that Richmond Council weighs when assessing a mansard roof extensions scheme.
Conservation areas: Barnes Green, Castelnau, Barnes riverside, The Terrace. Inside these, most external work needs full planning and a Heritage Statement.
Getting around SW13: Barnes and Barnes Bridge rail to Waterloo, plus the river and bus links to Hammersmith.
Property values: around £600,000 for a flat and £1.3m-£2.5m for a house — a useful gauge of the build value an extension or loft adds in SW13.
Borough 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 Barnes'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 Barnes'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 building-regs submission.
Planning + building regs + structural.
Listed, conservation or complex sites.
Strongly. The Barnes Green, Castelnau and riverside conservation areas, with many attractive period houses and a protected village character, mean external changes need full planning with a Heritage Statement, and Richmond scrutinises materials, boundaries and roofscape closely. We design to that standard for SW13 addresses.
Yes. The Thames frontage along Lonsdale Road and The Terrace sits in the flood zone, so riverside extensions and basements need a flood-risk assessment alongside conservation-area planning. We design within those constraints and produce the survey and heritage drawings required.
Yes. The substantial Castelnau villas suit rear and side extensions and the occasional basement, but they sit in a conservation area, so schemes are designed to match the Italianate detailing and submitted by full planning with a Heritage Statement. We coordinate any structural calculations for the larger schemes.
With SW13 houses around £1.3m-£2.5m, a well-designed extension or loft adds floor area worth well above the build and drawing cost, and Barnes's village appeal keeps demand high. A carefully detailed, conservation-compliant scheme protects both approval and resale, which our fixed fee keeps predictable.
Our fixed fee for mansard roof extensions in Barnes starts at £1,575 — no hourly billing. With Barnes property at around £600,000 for a flat and £1.3m-£2.5m for a house, the professional drawing fee is a small fraction of the value the work adds to SW13's victorian and edwardian terraces and large detached. Richmond Council charges its own statutory application fee on top (currently £258 for a householder planning application, £578 for a full application). We quote the drawings as one fixed price and the free site survey covers every SW13 address.
For a SW13 project across Barnes, Barnes Village, Castelnau, Little Chelsea, expect roughly 3–4 weeks from instruction to submission: week 1 the measured survey, weeks 2–3 the drawings and your revisions, then validation and the statutory determination by Richmond Council (8 weeks for a householder application). We carry the Barnes application through every officer query to the decision.
Barnes (SW13) sits primarily in Richmond upon Thames, so applications are decided by Richmond Council. Article 4 in force in the borough: No. Conservation areas within SW13 include Barnes Green, Castelnau, Barnes riverside, The Terrace, where full planning and a Heritage Statement are required. We confirm the planning route for your exact address before quoting.
Almost always. Any structural work behind mansard roof extensions in Barnes — new openings, steel beams, loft floors, foundations — needs Building Regulations approval covering structure (Part A), fire escape (Part B) and insulation (Part L), submitted to Richmond Council Building Control or an approved inspector. On SW13's typically terraced and semi-detached stock, a Party Wall notice to adjoining neighbours is normally required before the steelwork. We coordinate both as part of the Complete package.
In value terms, yes. With Barnes (SW13) property at around £600,000 for a flat and £1.3m-£2.5m for a house, a well-designed extension or loft typically returns more than it costs in added floor area and sale value, while our fixed drawing fee from £1,575 keeps the professional cost predictable. The bigger risk is an unapproved or non-compliant scheme — which is why council-ready drawings and a clean Building Control sign-off matter on SW13 homes.
From £840.
From £840.
From £1,225.
From £1,225.
From £995.
From £1,950.
From £350.
From £540.
From £450.
From £1,225.
Pick a slot that suits you. No obligation and no sales pressure — just straight answers on your planning route, fixed fee and timescale.
Every SW13 postcode district we draw in, the stock that dominates it and the authority that validates a mansard roof extension there. SW13 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 | Adjoining district to SW13, also inside Richmond upon Thames for mansard roof extension purposes. |
| TW1 | Twickenham | Georgian fragments, Victorian terraces, Edwardian villas | Adjoining district to SW13, also inside Richmond upon Thames for mansard roof extension purposes. |
| TW2 | Twickenham / Whitton | Georgian fragments, Victorian terraces, Edwardian villas | Adjoining district to SW13, also inside Richmond upon Thames for mansard roof extension purposes. |
Roof pitch, wall build-up and plot depth change every few SW13 streets, and each one changes what a mansard roof extension can achieve at that address.
Conservation areas covering SW13 (Barnes): Richmond Council runs 72, and Richmond Green, Kew Green, Hampton Wick are the ones SW13 (Barnes) owners meet most. A mansard roof extension inside a SW13 (Barnes) conservation area loses permitted development, so the SW13 (Barnes) submission is a householder application at £258 decided in 8 weeks — not a £120 prior approval decided in 6 weeks. In Ham Common a mansard roof extension is judged on the street elevation first.
No blanket Article 4 over SW13 (Barnes): Richmond Council has not withdrawn permitted development across SW13 (Barnes), so a mansard roof extension outside a SW13 (Barnes) conservation area usually keeps it. The £129 Lawful Development Certificate is still the document a SW13 owner wants on file.
The building fabric around SW13 (Barnes): 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. A mansard roof extension in SW13 (Barnes) is scoped against that stock first. Our SW13 (Barnes) fixed fee starts at £1,575; the £1,750 Complete package runs the SW13 (Barnes) scheme through Richmond Council planning and building control in one go.
Sources for this SW13 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.
Free fixed quote in 60 seconds. From £1,575. MCIAT chartered.
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