Mansard Roof Extensions · SW14 Mortlake
Fixed-fee mansard roof extensions for Mortlake, East Sheen, Sheen, North Sheen fringe in the SW14 postcode, drawn by an MCIAT-chartered architectural technologist and submitted to Richmond Council. Richmond controls the Mortlake and East Sheen conservation areas; the former Stag Brewery is a major local redevelopment.
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 SW14's terraces in Mortlake where a standard dormer is too small. Richmond Council scrutinises mansards on townscape and precedent, especially within Mortlake / The Green, East Sheen, Sheen Common; we design to the borough's roof guidance with a Heritage Statement where the setting requires it.
Mortlake's most space-efficient loft solution when PD-route dormers are blocked. Our chartered team designs mansards that get approved in Mortlake conservation areas — with heritage statements and planning officer negotiation built in.
Across Mortlake, East Sheen, Sheen, North Sheen fringe in SW14, the dominant property is edwardian and inter-war terraces and semis around mortlake and east sheen, with larger houses toward richmond park. 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 Mortlake property, confirm the planning route — Permitted Development, a Lawful Development Certificate, or full planning — and draw a council-ready set tailored to the SW14 streetscape.
Housing stock in SW14: Edwardian and inter-war terraces and semis around Mortlake and East Sheen, with larger houses toward Richmond Park.
Within the district: Mortlake, East Sheen, Sheen, North Sheen fringe.
Streets we know in SW14: the East Sheen streets (Christchurch Road, Sheen Lane), the Mortlake riverside and the Palewell streets. Each road has its own building line, boundary treatment and precedent that Richmond Council weighs when assessing a mansard roof extensions scheme.
Conservation areas: Mortlake / The Green, East Sheen, Sheen Common. Inside these, most external work needs full planning and a Heritage Statement.
Getting around SW14: Mortlake and North Sheen rail to Waterloo, plus Richmond nearby for the District line.
Regeneration: Mortlake falls within or beside the Mortlake / Stag Brewery redevelopment, which shapes local planning policy and design expectations.
Property values: around £450,000 for a flat and £900,000-£1.4m for a house — a useful gauge of the build value an extension or loft adds in SW14.
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 Mortlake'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 Mortlake'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.
Yes. The Edwardian and inter-war terraces and semis around Christchurch Road and Sheen Lane suit side-return, rear and loft extensions, much of it within Permitted Development outside the conservation areas, confirmed with a Lawful Development Certificate. We confirm the route and draw to Richmond's checklist.
The former Stag Brewery site at Mortlake is being redeveloped into homes, a school and riverside public space, one of the borough's largest schemes, supporting values across SW14. For a house project the binding controls remain Permitted Development limits and the local conservation area, which we check for your address.
Usually yes on the semis and terraces — a hip-to-gable plus rear dormer within the volume allowance, confirmed by a Lawful Development Certificate, provided you're not in the Mortlake or East Sheen conservation areas. We check the constraints for your road and draw it for Building Control.
With SW14 houses around £900,000-£1.4m and the appeal of Richmond Park on the doorstep, a side-return or loft adds family space worth well above the build and drawing cost. Our fixed fee keeps the professional cost predictable on these Edwardian and inter-war houses.
Our fixed fee for mansard roof extensions in Mortlake starts at £1,575 — no hourly billing. With Mortlake property at around £450,000 for a flat and £900,000-£1.4m for a house, the professional drawing fee is a small fraction of the value the work adds to SW14's edwardian and inter-war terraces and semis around. 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 SW14 address.
For a SW14 project across Mortlake, East Sheen, Sheen, North Sheen fringe, 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 Mortlake application through every officer query to the decision.
Mortlake (SW14) sits primarily in Richmond upon Thames, so applications are decided by Richmond Council. Article 4 in force in the borough: No. Conservation areas within SW14 include Mortlake / The Green, East Sheen, Sheen Common, 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 Mortlake — 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 SW14'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 Mortlake (SW14) property at around £450,000 for a flat and £900,000-£1.4m 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 SW14 homes.
From £840.
From £840.
From £1,225.
From £1,225.
From £995.
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From £350.
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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 SW14 postcode district we draw in, the stock that dominates it and the authority that validates a mansard roof extension there. SW14 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 |
|---|---|---|---|
| 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. |
| SW14 | East Sheen | Edwardian villas, 1930s semi-detached | East Sheen sits inside SW14; mansard roof extension proposals here are determined by Richmond Council. |
| SW14 | Mortlake | Victorian and Edwardian terraces | Mortlake sits inside SW14; mansard roof extension proposals here are determined by Richmond Council. |
| SW13 | Barnes | Georgian villas, Edwardian terraces | Adjoining district to SW14, also inside Richmond upon Thames for mansard roof extension purposes. |
| TW1 | Twickenham | Georgian fragments, Victorian terraces, Edwardian villas | Adjoining district to SW14, also inside Richmond upon Thames for mansard roof extension purposes. |
| TW2 | Twickenham / Whitton | Georgian fragments, Victorian terraces, Edwardian villas | Adjoining district to SW14, also inside Richmond upon Thames for mansard roof extension purposes. |
Roof pitch, wall build-up and plot depth change every few SW14 streets, and each one changes what a mansard roof extension can achieve at that address.
How designation changes a SW14 (Mortlake / East Sheen) mansard roof extension: Richmond Council maintains 72 conservation areas, including Hampton Wick, Twickenham Riverside, Barnes Village. Inside any of them a SW14 (Mortlake / East Sheen) mansard roof extension cannot rely on permitted development, and the route becomes a £258 householder application determined in 8 weeks rather than a £120 prior approval in 6 weeks. Richmond Green sets the tone for SW14 (Mortlake / East Sheen) casework.
No blanket Article 4 over SW14 (Mortlake / East Sheen): Richmond Council has not withdrawn permitted development across SW14 (Mortlake / East Sheen), so a mansard roof extension outside a SW14 (Mortlake / East Sheen) conservation area usually keeps it. The £129 Lawful Development Certificate is still the document a SW14 owner wants on file.
The building fabric around SW14 (Mortlake / East Sheen): 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 SW14 (Mortlake / East Sheen) is scoped against that stock first. Our SW14 (Mortlake / East Sheen) fixed fee starts at £1,575; the £1,750 Complete package runs the SW14 (Mortlake / East Sheen) scheme through Richmond Council planning and building control in one go.
Sources for this SW14 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.
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