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Southwark, London

Double-storey extension drawings in Southwark

Double-storey extension drawings in Southwark start at £1,295 including VAT. The council's Householder SPD does not encourage two-storey side extensions, so the scheme to aim for is often a rear addition, or one that keeps the gap between houses visible. We establish which of those routes your address allows before any plan is drawn.

From £1,295 (VAT included)

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  • Fixed fees, VAT included

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    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 double-storey 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.

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    Finished white-rendered rear house extension with large glazed doors

    Southwark's stance on upper-floor side extensions

    Most councils set a number for the first floor. Southwark sets an attitude. Its Householder development SPD, which sits under the Southwark Plan 2022 adopted in 2,022, says that two-storey side extensions are not encouraged. Where one is acceptable it must avoid a terracing effect, match the existing roof and, in a conservation area, keep the gap between buildings open.

    That wording has a practical meaning. A design that fills the side passage at both floors is the likeliest to be refused, while one that stops at the ground floor, or sets the upper storey well back, has a case. We draw the side elevation twice when the choice is close, once with the gap closed and once with it kept, so you can see what is lost.

    The guidance quoted above is about side extensions, so many owners look at putting the new bedroom over a rear ground-floor extension instead. The comparison is on our rear extension drawings in Southwark page.

    When the side gap cannot be spared, the roof is the other place to find a room. Loft conversion drawings in Southwark show whether a dormer could deliver a bedroom without touching the passage, and the two routes can be priced side by side before you commit to either.

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

    Local figures for Southwark

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Supplementary planning documentHouseholder development SPD2025southwark.gov.uk
    Conservation areas53 named conservation areas published by the council—planning.data.gov.uk
    Listed building entries919 list entries (Historic England, within the LPA boundary)—planning.data.gov.uk
    Tree preservation zones724 tree preservation zone polygons published by the council—planning.data.gov.uk
    Householder decisions558 decisions1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications granted94.8 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications decided in time95.3 % decided within 8 weeks or an agreed extended period1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Average price, terraced838,160 GBP2026-07publicdata.landregistry.gov.uk
    Class A, para A.1(h)Over one storey: max 3 m beyond the original rear wall and not within 7 m of the rear boundary—legislation.gov.uk
    Class A, condition A.3(b); Class B, condition B.2(c)Upper-floor side windows obscure-glazed and non-opening below 1.7 m above floor—legislation.gov.uk
    Approved Document B Vol 1, 2019 ed. incl. 2026 amendments, para 2.10Escape window: unobstructed openable area at least 0.33 m², at least 450 mm high and 450 mm wide, bottom of opening no more than 1100 mm above floor—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 Southwark

    Householder applications by street in Southwark

    Streets in Southwark with the most householder applications, and the share approved
    StreetApplicationsApproved
    Ivydale Road6098%
    Upland Road5192%
    Friern Road4695%
    Underhill Road3293%
    Landells Road2996%
    Crystal Palace Road2587%
    Melbourne Grove2491%
    Dunstans Road2391%
    Burbage Road2291%
    Turney Road22100%
    Hollydale Road21100%
    Court Lane1994%
    Harlescott Road19100%
    Henslowe Road19100%
    Barry Road18100%
    Counts of householder applications by street; no individual applications are shown. Streets with fewer than five applications are left out.Source: GLA Planning London Datahub, householder applications, all years held. Contains public sector information licensed under the Open Government Licence v3.0. Contains OS data © Crown copyright and database right 2026.
    The 45-degree test in planTest used in daylight assessments: 45 degrees (plan and elevation). Southwark guidance: 45 degrees / 25 degreesAB

    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)
    B · Southwark guidance
    45 degrees / 25 degrees

    A borough of flats, with pockets of houses

    Only 21.8 per cent of households live in a house or bungalow, and just 28.9 per cent own their home. Where houses do stand, they are often in terraces, and terraces are where guidance on gaps and rooflines matters most.

    Houses are valuable. The average terraced home sold for £838,160 and the average semi-detached for £1,229,706, which gives owners a reason to extend. Domestic gardens made up 17.6 per cent of the land in the national land-use database, a figure that shows how little private garden many plots have to spare.

    Designations that change what you can draw

    Southwark has 53 conservation areas and 919 listed buildings. The council also records 724 tree preservation zones, so the root protection area of a garden tree can decide where the new footing goes. In conservation areas the national rule is: No rear extension of more than one storey under PD on article 2(3) land.

    Outside them the permitted development line is: Over one storey: max 3 m beyond the original rear wall and not within 7 m of the rear boundary. In this borough the debate is mostly about neighbours, daylight and the character of the street.

    What Southwark's householder figures show

    Over its latest twelve months Southwark decided 558 householder applications, granted 94.8 per cent and decided 95.3 per cent in time. The grant rate is high, but it is a total across every kind of small scheme, and most are modest.

    Southwark also decided only a handful of larger home extension prior approvals in its latest four quarters, granting 7 and refusing 2. Most house extensions here therefore go through the full householder route, which is where well-argued drawings do their work.

    Windows, fire and the structure under a new floor

    Upper side windows are a flashpoint on narrow plots. The permitted development condition, which councils echo in their decisions, is: Upper-floor side windows obscure-glazed and non-opening below 1.7 m above floor. For the roof: Roof pitch of a 2+ storey enlargement to match the original house so far as practicable.

    A bedroom over the extension needs an escape window under Approved Document B: Escape window: unobstructed openable area at least 0.33 m², at least 450 mm high and 450 mm wide, bottom of opening no more than 1100 mm above floor. The new floor also puts load on old brick walls, so our structural calculations service coordinates the steel before the drawings are issued. Where the wall is shared, the notice rule is: Party structure notice at least 2 months before work.

    Fee, deliverables and nearby boroughs

    The fee is £1,295 including VAT, fixed before you commit, and Southwark's householder fee of £548 goes to the council. You receive floor plans, elevations, sections and location and block plans, every sheet checked by a second MCIAT chartered technologist. If the council asks for amendments we redraw free of charge.

    To see other options for the same house, read about house extension drawings in Southwark. Next door, Lambeth and Lewisham apply their own tests, and the full local picture is on architectural drawings in Southwark.

    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 Southwark

    Double-storey extension drawings nearby

    Questions

    Does Southwark allow two-storey side extensions?

    They are not encouraged. The Householder SPD asks that they avoid a terracing effect and match the existing roof, and in conservation areas that the gap between buildings is kept.

    Can I extend upwards at the back of my house in Southwark?

    Often, yes, subject to neighbour impact. The permitted development limit is: Over one storey: max 3 m beyond the original rear wall and not within 7 m of the rear boundary. Anything larger needs a householder application.

    How many conservation areas does Southwark have?

    53. In those areas permitted development rights for two-storey rear extensions do not apply.

    What do double-storey extension drawings cost in Southwark?

    From £1,295 including VAT, fixed up front. The council's householder fee is separate.

    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.

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