020 7864 7245Request a fixed quote

Kensington and Chelsea, London

Side return extension drawings in Kensington and Chelsea

In Kensington and Chelsea a side return is judged by what it does to gaps, views and access, as much as by its size. We draw side return extensions in the borough from £745 including VAT, with the survey and the street context checked before the design is fixed.

From £745 (VAT included)

  • MCIAT chartered
  • £2m PI insured
  • LABC Partnered
  • Fixed fees, VAT included

Request a fixed quote

We use it to check conservation areas and constraints.
Pick the council that decides your application.
A few lines: what you want to build, and anything the council has already said.
Add photos or drawings

Drop files here or choose from your device

PDF, JPG, PNG, DWG · up to 10 files, 90 MB in total

    Architectural model of a four-storey London stucco townhouse in its terrace, with a portico, area railings, sash windows, a cornice and chimney stacks
    The house as it stands: four storeys over a lower ground floor.Existing Proposed worksAn illustrative model, built for this page.

    How we work on side return extension drawings

    Nine steps from first call to approval.

    The same model cut through the middle: every floor, the stair, the chimney breasts, the new mansard, rear extension and basement in section
    Section through the model: every floor on one datum.

    1. Enquiry and constraints check

      We check the property against conservation areas, listed status, Article 4 directions, tree preservation orders, flood zone and planning history. We choose the right route and send a fixed quote.

    2. Measured survey

      We survey the house on one datum: rooms, levels, boundaries, drains, trees and the neighbours' windows that the 45° and 25° tests depend on.

    3. Design options

      We model the house in Revit and show you options in 3D and plan, with the planning strategy and the precedents in your street.

    4. Design frozen

      You choose an option in writing. Nothing changes after this without your say.

    5. Independent check

      A second chartered technologist checks every sheet against the council's validation checklist and the policy. A senior review signs it off before anything is submitted.

    6. Submission

      We prepare the forms, certificates, fee and documents and submit through the Planning Portal.

    7. Officer liaison

      We answer the planning officer and make any amendments within five working days, at no charge until approval.

    8. Building regulations

      Technical drawings are coordinated with the structural engineer's calculations, the drainage and the planning conditions.

    9. Approval and hand-over

      Building control approval, then a next-steps pack covering the commencement notice, party wall timing and CIL.

    Free redraws until approval. Every drawing set is checked independently, and the checker is never the person who drew it.

    Request a fixed quote
    Finished white-rendered rear house extension with large glazed doors

    How the Local Plan tests a side extension in Kensington and Chelsea

    The Local Plan's extensions policy resists an extension that blocks an important or historic gap or view, hides features on a formal flank elevation, or reduces access to the rear of the property or of its neighbours. For a side return, every one of those tests can apply at once.

    Take the gap first. Between two terraces a narrow side alley can be part of the rhythm of the street, and filling it can read as closing a view. The flank test is the next one: on a house with a decorated side wall, a new extension can hide the very feature the council wants kept. Access is the third, because a rear route that serves several houses is not something an extension can close off.

    We photograph the street, draw the flank elevation as it stands, and show on the proposed drawings which of these the scheme avoids. The council also keeps a Basements SPD, which matters if your project digs down as well as out.

    Two-storey rear extension under construction on a semi-detached house

    Local figures for Kensington and Chelsea

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Conservation areas39 named conservation areas published by the council—planning.data.gov.uk
    Article 4 directions84 Article 4 directions published by the council—planning.data.gov.uk
    Listed building entries1,350 list entries (Historic England, within the LPA boundary)—planning.data.gov.uk
    Tree preservation orders4,560 tree preservation orders published by the council—planning.data.gov.uk
    Tree preservation zones41 tree preservation zone polygons published by the council—planning.data.gov.uk
    Householder decisions664 decisions1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications granted93.7 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications decided in time91.9 % decided within 8 weeks or an agreed extended period1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Average price, terraced2,429,086 GBP2026-07publicdata.landregistry.gov.uk
    Supplementary planning documentBasements SPD2016rbkc.gov.uk
    Householder: alterations/extensions to a single dwellinghouse, from 1 Apr 2026548 GBP—ribblevalley.gov.uk

    A blank value means the figure has not been published, not that there are none. Check your own address with the council.

    Councils bordering Kensington and Chelsea
    The 45-degree test in planTest used in daylight assessments: 45 degrees (plan and elevation)A

    The 45-degree test in plan

    A line from the middle of the neighbour's nearest window: the extension should stay behind it.

    A · Test used in daylight assessments
    45 degrees (plan and elevation)

    Conservation areas, listing and Article 4 in Kensington and Chelsea

    The borough publishes 39 conservation areas, and it has 84 Article 4 directions on the books. In a conservation area permitted development gives no side extension: No side extensions under PD on article 2(3) land (conservation areas etc.).

    Historic England lists 1,350 entries here. Listing changes the whole job: it needs listed building consent alongside planning, and we write that up with the heritage evidence officers expect.

    Trees are the next constraint. The council records 4,560 tree preservation orders across 41 protection zones, so a tree in a rear garden can limit a side extension's footprint and construction access.

    Before drawing, we also walk the street in photographs and look at the neighbouring houses, since the council reads an application in its setting. If a neighbour has already filled their side return, that does not set a precedent for you, but it does show what has been accepted on the road, and we say what we found in the covering note.

    Decisions and market in Kensington and Chelsea

    Kensington and Chelsea decided 664 householder applications in the latest twelve months and granted 93.7 per cent. Only 91.9 per cent met eight weeks or an agreed extension, so we plan the timetable with some slack.

    Just 17 per cent of the borough's households occupy a house, and 31.7 per cent are owner-occupiers. The average terraced house sold for £2,429,086 in the latest figures, so a few extra square metres here carry real value and a well-drawn application matters.

    The permitted limit away from designations is: Side extension: single storey, max 4 m high, max half the width of the original house.

    Party walls, glazing and fees in Kensington and Chelsea

    Side returns sit against a neighbour's flank, often in a house that shares both walls. For a new wall along the boundary line: Line-of-junction (new wall) notice at least 1 month before work. For cutting into the shared wall: Party structure notice at least 2 months before work. Our party wall notices service covers both.

    Approved Document L puts a ceiling on the glazing: Windows, roof windows, rooflights and doors in an extension should not exceed 25% of the extension floor area plus the area of openings removed or covered. Kensington and Chelsea charges the £548 householder fee, and the borough levy is shown as £1,158.30/m² (Zone A); £911.20/m² (Zone B); £664.09/m² (Zone C); £416.99/m² (Zone D); £293.44/m² (Zone E); £169.88/m² (Zone F); Nil (Zones G Earl's Court and H Kensal).

    Structure is part of the design: a new opening in the flank wall needs engineer's sizes, covered by structural calculations in Kensington and Chelsea.

    What the Kensington and Chelsea set includes

    Plans, elevations, sections and location and block plans, with the street photographs and flank elevation described above, for £745 fixed. A second chartered technologist signs off every sheet, and any amendment the Royal Borough asks for is redrawn at our cost.

    The wider picture is at architectural drawings in Kensington and Chelsea, and a deeper rear scheme sits under rear extension drawings in Kensington and Chelsea.

    What you receive

    Planning drawing sheet for a rear extension with plans, elevations and sections
    Sample drawing. Planning drawings for a rear extension: plans, elevations and sections on one sheet set.
    House extension under construction with scaffolding, new glazed doors and building materials
    Every side considered
    Flick across the turntable to spin it.

    Other services in Kensington and Chelsea

    Side return extension drawings nearby

    Questions

    What does Kensington and Chelsea resist in a side extension?

    Extensions that block an important or historic gap or view, hide features on a formal flank elevation, or reduce access to the rear of the property or its neighbours.

    Are there many conservation areas in Kensington and Chelsea?

    There are 39, and inside them the national rule is: No side extensions under PD on article 2(3) land (conservation areas etc.).

    Can a protected tree affect a side return in Kensington and Chelsea?

    They can. The council records 4,560 tree preservation orders.

    What will the council charge to register the application?

    £548, the standard householder fee, which is separate from our price.

    Sources and dates

    City of London skyline glowing at dusk across the Thames under a dramatic orange sky

    Tell us about your property.

    We check the constraints, then send a fixed fee. Messages before 3pm get a reply the same working day.

    Request a fixed quoteCall 020 7864 7245WhatsApp