Mansard Roof Extensions in Lewisham

Which Lewisham postcodes does this mansard roof extension service cover?

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

Which Lewisham neighbourhoods suit a mansard roof extension best?

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

• Deptford (SE8) — mansard roof extension work in Deptford means georgian terraces, post-war estates, new-build. Deptford is Georgian fragments, regenerating quarter. Mansards read as original on Georgian terraces throughout SE8. Lewisham Council decides the Deptford application, and Deptford High Street anchors the Deptford location plan.
• Hither Green (SE13) — a mansard roof extension in Hither Green starts from edwardian terraces, 1930s semi-detached, and Hither Green reads as Edwardian terraces, 1930s semi-detached. Edwardian parapets give a mansard a clean base line in SE13. Lewisham Council assesses Hither Green mansard roof extensions against its own Hither Green character guidance, and the location plan we draw for Hither Green references Mountsfield Park.
• Sydenham (SE26) — a mansard roof extension in Sydenham starts from victorian villas, edwardian terraces, and Sydenham reads as Victorian villas, Edwardian terraces. A mansard on a Victorian terrace almost always needs full planning permission in SE26. Lewisham Council assesses Sydenham mansard roof extensions against its own Sydenham character guidance, and the location plan we draw for Sydenham references Sydenham Wells Park.
• Brockley (SE4) — mansard roof extension work in Brockley means victorian and edwardian terraces. Brockley is Victorian and Edwardian terraces. A mansard on a Victorian terrace almost always needs full planning permission throughout SE4. Lewisham Council decides the Brockley application, and Brockley station anchors the Brockley location plan.
• Forest Hill (SE23) — Victorian villas, Edwardian terraces defines Forest Hill, where victorian villas, edwardian terraces set what a mansard roof extension can do. A mansard on a Victorian terrace almost always needs full planning permission across SE23. Any Forest Hill mansard roof extension is validated by Lewisham Council, with Horniman Museum the usual Forest Hill reference point on the site plan.
• Honor Oak (SE23) — mansard roof extension work in Honor Oak means victorian villas, edwardian terraces. Honor Oak is Victorian villas on the hill. A mansard on a Victorian terrace almost always needs full planning permission throughout SE23. Lewisham Council decides the Honor Oak application, and One Tree Hill anchors the Honor Oak location plan.
• Lewisham (SE13) — mansard roof extension work in Lewisham means victorian terraces, post-war flats. Lewisham is Victorian terraces, post-war centre. A mansard on a Victorian terrace almost always needs full planning permission throughout SE13. Lewisham Council decides the Lewisham application, and Lewisham station anchors the Lewisham location plan.

Does Lewisham planning policy restrict a mansard roof extension?

How designation changes a Lewisham mansard roof extension: Lewisham Council maintains 30 conservation areas, including Lee Green, Blackheath, Deptford High Street. Inside any of them a Lewisham mansard roof extension cannot rely on permitted development, and the route becomes a £548 householder application determined in 8 weeks rather than a £249 prior approval in 6 weeks. Deptford High Street sets the tone for Lewisham casework.

Article 4 and your Lewisham mansard roof extension: Lewisham Council has made no borough-wide direction, so permitted development for a mansard roof extension in Lewisham generally survives outside Lewisham conservation areas and listed curtilages. A Lawful Development Certificate at £274 is how a SE4 owner records that a mansard roof extension was lawful.

The building fabric around Lewisham: Victorian and Edwardian terraces across Brockley, Honor Oak, Forest Hill; 1930s semi-detached in Catford and Hither Green; post-war mixed in Deptford. Generally permissive planning compared to central boroughs; loft conversions and side-return extensions routinely approved under PD. A mansard roof extension in Lewisham 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 Lewisham Council.

Which neighbouring authorities border Lewisham?

• Southwark — cross the Lewisham boundary and Southwark Council takes the mansard roof extension instead, applying 43 conservation areas of its own around SE1. We re-price mansard roof extensions at the Lewisham edge because Southwark policy and Lewisham policy rarely align on mansard roof extension depth.
• Greenwich — the Greenwich boundary runs against Lewisham, so a mansard roof extension a street from Lewisham is decided by Greenwich Council instead. Greenwich runs 20 conservation areas across SE3 and its neighbours, which is why mansard roof extensions priced for Lewisham are re-checked against Greenwich policy whenever the Lewisham address sits on that edge.
• Bromley — cross the Lewisham boundary and Bromley Council takes the mansard roof extension instead, applying 48 conservation areas of its own around BR1. We re-price mansard roof extensions at the Lewisham edge because Bromley policy and Lewisham policy rarely align on mansard roof extension depth.
• Tower Hamlets — cross the Lewisham boundary and Tower Hamlets Council takes the mansard roof extension instead, applying 58 conservation areas of its own around E1. We re-price mansard roof extensions at the Lewisham edge because Tower Hamlets policy and Lewisham policy rarely align on mansard roof extension depth.

Sources for this Lewisham 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.