House Extensions in Mortlake

Mortlake FAQ for house extension drawings

Do I need planning permission for house extension drawings in Mortlake?

Most house extension drawings projects in Mortlake fall under Permitted Development if the property is a house (not a flat), not listed, and not in a conservation area. Richmond upon Thames has no borough-wide Article 4 Direction. We confirm eligibility free at the site survey.

How much does house extension drawings cost in Mortlake?

Drawings: fixed fee from £1,225 (House Extensions). Construction cost is separate and depends on size, finish and structural complexity. For victorian and edwardian terraces (typical of Mortlake), expect £45,000–£85,000 build cost for a standard rear extension or loft, more for mansards or basements.

How long does the house extension drawings process take in Mortlake?

12–14 weeks from first call to Richmond Council planning decision. Site survey week 1, design weeks 2–3, validation 1–2 weeks, statutory 8-week determination.

What property types are common in Mortlake?

Mortlake is characterised by victorian and edwardian terraces. We've delivered house extension drawings for every period represented here — the design choices vary significantly by stock.

Will my application succeed in Mortlake?

Our first-time approval rate in Richmond upon Thames is 98%. Pre-application advice from Richmond Council is built into our process when the case is borderline (conservation area, Article 4, listed).

Where in Mortlake does a house extension actually get determined?

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

Postcode	Area	Dominant stock	What it means for a house extension
SW14	Mortlake / East Sheen	Victorian and Edwardian terraces	A house extension at an SW14 address in Mortlake / East Sheen is determined by Richmond Council under its own Local Plan policies for Mortlake / East Sheen.
TW9	Richmond	Georgian terraces, Victorian villas	Neighbouring Richmond, where house extension work is handled by the same Richmond Council case officers.
TW1	Twickenham	Georgian fragments, Victorian terraces, Edwardian villas	Neighbouring Twickenham, where house extension work is handled by the same Richmond Council case officers.
TW9	Kew	Georgian and Edwardian villas	Neighbouring Kew, where house extension work is handled by the same Richmond Council case officers.
SW13	Barnes	Georgian villas, Edwardian terraces	Neighbouring Barnes, where house extension work is handled by the same Richmond Council case officers.
SW14	East Sheen	Edwardian villas, 1930s semi-detached	Neighbouring East Sheen, where house extension work is handled by the same Richmond Council case officers.
TW11	Teddington	Edwardian villas, Victorian terraces	Neighbouring Teddington, where house extension work is handled by the same Richmond Council case officers.
TW12	Hampton	Georgian villas, Edwardian terraces, 1930s semi-detached	Neighbouring Hampton, where house extension work is handled by the same Richmond Council case officers.
TW2	Whitton	1930s semi-detached	Neighbouring Whitton, where house extension work is handled by the same Richmond Council case officers.
TW10	Ham	Georgian villas, post-war estates	Neighbouring Ham, where house extension work is handled by the same Richmond Council case officers.

What changes about a house extension in each part of Mortlake?

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

Mortlake (SW14) — a house extension in Mortlake starts from victorian and edwardian terraces, and Mortlake reads as Victorian and Edwardian terraces. The side-return infill is the classic move on these Victorian terraces — 3 in SW14. Richmond Council assesses Mortlake house extensions against its own Mortlake character guidance, and the location plan we draw for Mortlake references Mortlake station.
Near Mortlake: Ham (TW10) — house extension work in Ham means georgian villas, post-war estates. Ham is Georgian common, post-war estate. Georgian rear elevations here are usually the listed or locally listed face of throughout TW10. Richmond Council decides the Ham application, and Ham Common anchors the Ham location plan.
Near Mortlake: Richmond (TW9, TW10) — a house extension in Richmond starts from georgian terraces, victorian villas, and Richmond reads as Georgian centre, riverside conservation. Georgian rear elevations here are usually the listed or locally listed face of in TW9. Richmond Council assesses Richmond house extensions against its own Richmond character guidance, and the location plan we draw for Richmond references Richmond Green.
Near Mortlake: Twickenham (TW1, TW2) — house extension work in Twickenham means georgian fragments, victorian terraces, edwardian villas. Twickenham is Georgian and Victorian riverside town. Georgian rear elevations here are usually the listed or locally listed face of throughout TW1. Richmond Council decides the Twickenham application, and Twickenham Stadium anchors the Twickenham location plan.
Near Mortlake: Kew (TW9) — Georgian and Edwardian villas around the green defines Kew, where georgian and edwardian villas set what a house extension can do. Georgian rear elevations here are usually the listed or locally listed face of across TW9. Any Kew house extension is validated by Richmond Council, with Kew Gardens the usual Kew reference point on the site plan.
Near Mortlake: Barnes (SW13) — house extension work in Barnes means georgian villas, edwardian terraces. Barnes is Georgian and Edwardian village. Georgian rear elevations here are usually the listed or locally listed face of throughout SW13. Richmond Council decides the Barnes application, and Barnes Common anchors the Barnes location plan.
Near Mortlake: East Sheen (SW14) — Edwardian villas, 1930s semi-detached defines East Sheen, where edwardian villas, 1930s semi-detached set what a house extension can do. Edwardian plots here are wider across SW14. Any East Sheen house extension is validated by Richmond Council, with Sheen Lane the usual East Sheen reference point on the site plan.

How do conservation areas and Article 4 affect a house extension in Mortlake?

Conservation areas covering Mortlake: Richmond Council runs 72, and Richmond Green, Kew Green, Hampton Wick are the ones Mortlake owners meet most. A house extension inside a Mortlake conservation area loses permitted development, so the Mortlake submission is a householder application at £258 decided in 8 weeks — not a £120 prior approval decided in 6 weeks. In Hampton Wick a house extension is judged on the street elevation first.

No blanket Article 4 over Mortlake: Richmond Council has not withdrawn permitted development across Mortlake, so a house extension outside a Mortlake conservation area usually keeps it. The £129 Lawful Development Certificate is still the document a SW14 owner wants on file.

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 house extension route in Mortlake more than the postcode does. Our fixed fee for house extensions in Mortlake starts at £1,225, against £1,750 for the Complete package that carries a Mortlake scheme through Richmond Council planning and building regulations together.

Which neighbouring authorities border Mortlake?

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

Sources for this Mortlake house 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.