Westminster's most space-efficient loft solution when PD-route dormers are blocked. Our chartered team designs mansards that get approved in Westminster conservation areas — with heritage statements and planning officer negotiation built in.
Westminster's most space-efficient loft solution when PD-route dormers are blocked. Our chartered team designs mansards that get approved in Westminster conservation areas — with heritage statements and planning officer negotiation built in.
Housing stock in Westminster: Grand Georgian and Regency terraces in Belgravia and Pimlico; Victorian and Edwardian mansion blocks; heritage-rich townhouses throughout; very high listed building density.
Character: Heritage-first planning approach; listed buildings on almost every street; basement and rear extension policies particularly strict.
Article 4: Multiple Article 4 Directions — office-to-residential restrictions, HMO conversions, retail to residential in shopping zones.
Basement policy: Westminster basement policy restricts to single-storey, typically under 50% of rear garden footprint; lightwells and rooflights strictly controlled in conservation areas.
We check against Westminster City Council's mansard design guide and design to match the terrace.
Required for Westminster's conservation areas — demonstrates the mansard respects character and townscape.
Accurate photomontage showing how the mansard sits alongside neighbours — often decisive at Westminster City Council committee.
Mansards invariably trigger Party Wall notices in Westminster's dense terraced streets. Structural package includes new ridge, tie beams, floor joists.
Full liaison with Westminster City 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.
Direct answers to the questions Westminster homeowners ask every week about mansard roof extensions.
Start a free quote →Mansards in Westminster are more heavily scrutinised than in outer boroughs. Westminster City Council prioritises heritage and townscape — approvals require exceptional design quality, clear precedents on the street, and a full Heritage Statement. We've delivered mansard approvals in the borough; each application is bespoke.
A 70° front slope is typical for Westminster 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. Westminster City Council's design guide (where published) takes precedence on detail.
Often yes, but Westminster City Council favours applications supported by wider street precedents. Where mansards already exist nearby in Westminster, approval is far more likely. We review street precedents at the feasibility stage.
Our architectural fees for a Westminster mansard start at £1,575 (planning + building regs + structural + heritage statement). Typical Westminster build costs are £90,000–£150,000 depending on size, complexity and access.
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 Westminster's grand Georgian and Regency terraces in Belgravia and Pimlico terraced context.
We cover every London borough with the same fixed-fee approach. If your property sits on a boundary, here are the neighbouring options.
We cover every architectural technology service in Westminster with one chartered team.
From £840. A fixed-fee, end-to-end service — measured survey, scaled drawings, Design & Access Statement where required, Planning P...
From £840. A construction-ready drawing package compliant with every Approved Document — Part A structure, Part B fire, Part L ther...
From £1,225. Every loft type across every {location} roof line — dormer, mansard, hip-to-gable, L-shape, Velux. LDC or full planning ...
From £1,225. The whole spectrum — rear extensions, side returns, wraparounds, double-storey, basement digs. Planning-led design with ...
From £995. Turn your unused {location} garage into a bedroom, home office or open-plan kitchen-diner. Planning route assessment, fu...
From £1,950. Full architectural technology service for basement digs and cellar conversions in {location} — structural underpinning d...
From £350. Chartered structural engineer calculations for every residential intervention in {location} — steel beams, lintels, pad ...
From £450. End-to-end Party Wall Act 1996 service for {location} — Section 1, 3 and 6 notices, schedule of condition surveys, party...
From £1,225. London's most popular loft type — the full-width rear dormer. Planning or Permitted Development route assessed for your ...
Free quote in 60 seconds. Fixed fee from £1,575. MCIAT chartered.
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