Mansard Roof Extensions in Mortlake

Where in Mortlake does a mansard roof extension actually get determined?

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

Which Mortlake neighbourhoods suit a mansard roof extension best?

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

• Mortlake (SW14) — mansard roof extension work in Mortlake means victorian and edwardian terraces. Mortlake is Victorian and Edwardian terraces. A mansard on a Victorian terrace almost always needs full planning permission throughout SW14. Richmond Council decides the Mortlake application, and Mortlake station anchors the Mortlake location plan.
• Near Mortlake: East Sheen (SW14) — Edwardian villas, 1930s semi-detached defines East Sheen, where edwardian villas, 1930s semi-detached set what a mansard roof extension can do. Edwardian parapets give a mansard a clean base line across SW14. Any East Sheen mansard roof extension is validated by Richmond Council, with Sheen Lane the usual East Sheen reference point on the site plan.
• Near Mortlake: Teddington (TW11) — a mansard roof extension in Teddington starts from edwardian villas, victorian terraces, and Teddington reads as Edwardian villas, Victorian terraces. A mansard on a Victorian terrace almost always needs full planning permission in TW11. Richmond Council assesses Teddington mansard roof extensions against its own Teddington character guidance, and the location plan we draw for Teddington references Teddington Lock.
• Near Mortlake: Hampton (TW12) — Georgian and Edwardian villages defines Hampton, where georgian villas, edwardian terraces, 1930s semi-detached set what a mansard roof extension can do. Mansards read as original on Georgian terraces across TW12. Any Hampton mansard roof extension is validated by Richmond Council, with Hampton Court Palace the usual Hampton reference point on the site plan.
• Near Mortlake: Whitton (TW2) — mansard roof extension work in Whitton means 1930s semi-detached. Whitton is 1930s semi-detached. Mansards are rare on 1930s stock — the hipped roof form works against the geometry throughout TW2. Richmond Council decides the Whitton application, and Whitton station anchors the Whitton location plan.
• Near Mortlake: Ham (TW10) — a mansard roof extension in Ham starts from georgian villas, post-war estates, and Ham reads as Georgian common, post-war estate. Mansards read as original on Georgian terraces in TW10. Richmond Council assesses Ham mansard roof extensions against its own Ham character guidance, and the location plan we draw for Ham references Ham Common.
• Near Mortlake: Richmond (TW9, TW10) — a mansard roof extension in Richmond starts from georgian terraces, victorian villas, and Richmond reads as Georgian centre, riverside conservation. Mansards read as original on Georgian terraces in TW9. Richmond Council assesses Richmond mansard roof extensions against its own Richmond character guidance, and the location plan we draw for Richmond references Richmond Green.

Does Mortlake planning policy restrict a mansard roof extension?

How designation changes a Mortlake mansard roof extension: Richmond Council maintains 72 conservation areas, including Ham Common, Richmond Green, Kew Green. Inside any of them a Mortlake 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. Kew Green sets the tone for Mortlake casework.

Article 4 and your Mortlake mansard roof extension: Richmond Council has made no borough-wide direction, so permitted development for a mansard roof extension in Mortlake generally survives outside Mortlake conservation areas and listed curtilages. A Lawful Development Certificate at £274 is how a SW14 owner records that a mansard roof extension was lawful.

What Mortlake is built from: 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. That mix decides the mansard roof extension route in Mortlake more than the postcode does, and it is what a Richmond Council case officer reads first. A householder application costs £548 paid to Richmond Council direct, with 8 weeks to a decision once validated.

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

• Hounslow — adjoining Mortlake, with 30 conservation areas centred on W3. A mansard roof extension on the far side of the Mortlake line is determined by Hounslow Council, so the Mortlake quote for mansard roof extensions is checked against Hounslow guidance before it is issued.
• Kingston upon Thames — cross the Mortlake boundary and Kingston Council takes the mansard roof extension instead, applying 22 conservation areas of its own around KT1. We re-price mansard roof extensions at the Mortlake edge because Kingston upon Thames policy and Richmond upon Thames policy rarely align on mansard roof extension depth.
• Wandsworth — adjoining Mortlake, with 45 conservation areas centred on SW8. A mansard roof extension on the far side of the Mortlake line is determined by Wandsworth Council, so the Mortlake quote for mansard roof extensions is checked against Wandsworth guidance before it is issued.
• Hammersmith and Fulham — the Hammersmith and Fulham boundary runs against Richmond upon Thames, so a mansard roof extension a street from Mortlake is decided by Hammersmith & Fulham Council instead. Hammersmith and Fulham runs 45 conservation areas across W6 and its neighbours, which is why mansard roof extensions priced for Mortlake are re-checked against Hammersmith and Fulham policy whenever the Mortlake address sits on that edge.

Sources for this Mortlake 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.