Mansard Roof Extensions in Hampstead

Which postcode districts around Hampstead do we cover for mansard roof extension work?

Every Hampstead postcode district we draw in, the stock that dominates it and the authority that validates a mansard roof extension there. Hampstead fees below are the statutory England rates for 2026, not mansard roof extension estimates.

How does a mansard roof extension differ street by street across Hampstead?

Roof pitch, wall build-up and plot depth change every few Hampstead streets, and each one changes what a mansard roof extension can achieve at that address.

• Hampstead (NW3) — a mansard roof extension in Hampstead starts from georgian and victorian villas, listed buildings, and Hampstead reads as affluent, listed Georgian and Victorian villas. Mansards read as original on Georgian terraces in NW3. Camden Council assesses Hampstead mansard roof extensions against its own Hampstead character guidance, and the location plan we draw for Hampstead references Hampstead Heath.
• Near Hampstead: Kentish Town (NW5) — mansard roof extension work in Kentish Town means victorian terraces. Kentish Town is Victorian terraced streets, gentrifying. A mansard on a Victorian terrace almost always needs full planning permission throughout NW5. Camden Council decides the Kentish Town application, and Kentish Town City Farm anchors the Kentish Town location plan.
• Near Hampstead: Belsize Park (NW3) — a mansard roof extension in Belsize Park starts from edwardian mansion blocks, victorian villas, and Belsize Park reads as tree-lined avenues, Edwardian mansion blocks. A mansard on a Victorian terrace almost always needs full planning permission in NW3. Camden Council assesses Belsize Park mansard roof extensions against its own Belsize Park character guidance, and the location plan we draw for Belsize Park references Belsize Park station.
• Near Hampstead: Bloomsbury (WC1) — a mansard roof extension in Bloomsbury starts from georgian terraces, listed buildings, and Bloomsbury reads as Georgian squares, academic. Mansards read as original on Georgian terraces in WC1. Camden Council assesses Bloomsbury mansard roof extensions against its own Bloomsbury character guidance, and the location plan we draw for Bloomsbury references British Museum.
• Near Hampstead: Fitzrovia (W1T) — a mansard roof extension in Fitzrovia starts from georgian terraces, victorian mansion blocks, and Fitzrovia reads as Georgian and Victorian mix, creative quarter. Mansards read as original on Georgian terraces in W1T. Camden Council assesses Fitzrovia mansard roof extensions against its own Fitzrovia character guidance, and the location plan we draw for Fitzrovia references Fitzroy Square.
• Near Hampstead: King's Cross (N1C) — mansard roof extension work in King's Cross means modern apartments, converted warehouses. King's Cross is regenerated quarter, contemporary new-build. Mansards on modern buildings are unusual and generally read as an alien addition throughout N1C. Camden Council decides the King's Cross application, and King's Cross Station anchors the King's Cross location plan.
• Near Hampstead: Highgate (N6) — mansard roof extension work in Highgate means georgian villas, victorian and edwardian semis. Highgate is village character on the hill, Georgian and Victorian. Mansards read as original on Georgian terraces throughout N6. Camden Council decides the Highgate application, and Highgate Cemetery anchors the Highgate location plan.

What local planning policy applies to a mansard roof extension in Hampstead?

Hampstead conservation designations: there are 40 across Camden Council, Bloomsbury, Camden Town, Fitzrovia among them. Designation costs a Hampstead 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. Fitzrovia is the Hampstead designation that most often changes a mansard roof extension design.

What Article 4 removes near Hampstead: Article 4 removes permitted development for HMO conversions (C3 to C4) across the borough, plus restrictions on basement extensions in 12 conservation areas. Before pricing a mansard roof extension we check whether the NW3 address is inside the mapped area, because Camden Council draws the Hampstead boundary street by street rather than across the whole of Hampstead.

Digging below a Hampstead property: Camden's basement policy (Policy A5) restricts single-storey basements to 50% of garden area; double-storey basements generally refused outside commercial zones. Where a mansard roof extension in Hampstead involves excavation that is read beside the Party Wall etc. Act 1996, which needs two months notice for a Hampstead dig within 3 m of a neighbour, and Camden Council expects the NW3 ground conditions addressed in the application.

The building fabric around Hampstead: Victorian and Edwardian terraces, Georgian townhouses in Bloomsbury and Hampstead, post-war mansion blocks, modern developments in King's Cross. Creative, affluent in Hampstead and Primrose Hill; dense mixed-use around Camden Town and Kings Cross; academic character in Bloomsbury. A mansard roof extension in Hampstead is scoped against that stock first, because it decides whether the scheme runs as permitted development, a £274 Lawful Development Certificate, or a full £548 application to Camden Council.

Who decides a mansard roof extension on the edge of Hampstead?

• Brent — the Brent boundary runs against Camden, so a mansard roof extension a street from Hampstead is decided by Brent Council instead. Brent runs 22 conservation areas across NW2 and its neighbours, which is why mansard roof extensions priced for Hampstead are re-checked against Brent policy whenever the Hampstead address sits on that edge.
• City of London — the City of London boundary runs against Camden, so a mansard roof extension a street from Hampstead is decided by City of London Corporation instead. City of London runs 27 conservation areas across EC1 and its neighbours, which is why mansard roof extensions priced for Hampstead are re-checked against City of London policy whenever the Hampstead address sits on that edge.
• Westminster — the Westminster boundary runs against Camden, so a mansard roof extension a street from Hampstead is decided by Westminster City Council instead. Westminster runs 56 conservation areas across SW1 and its neighbours, which is why mansard roof extensions priced for Hampstead are re-checked against Westminster policy whenever the Hampstead address sits on that edge.
• Islington — adjoining Hampstead, with 40 conservation areas centred on N1. A mansard roof extension on the far side of the Hampstead line is determined by Islington Council, so the Hampstead quote for mansard roof extensions is checked against Islington guidance before it is issued.

Sources for this Hampstead 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.