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Bright finished basement room with a glass-balustrade staircase, high windows and a built-in desk
Photograph: Point3D Commercial Imaging Ltd.

01Southwark, London

Basement conversion drawings for houses in Southwark

Southwark limits a basement to a single storey, measures its reach from the rear wall with a smaller allowance towards the front, and asks for a Basement Impact Assessment with the application. We draw to those limits from £1,995 including VAT, and coordinate the structural work behind them.

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    02The brief

    The envelope in the householder SPD

    The Householder development SPD sets the envelope in one line: 1 storey; 50% rear; 30% front. Read in full, that is a single storey, reaching no further than half the garden depth from the rear wall and a smaller distance towards the front, with a Basement Impact Assessment submitted alongside.

    Lightwells follow a separate rule. They are permitted only where they are already a common feature of the street, and otherwise may be placed discreetly at the rear. On a street without them the front is closed to a lightwell.

    Georgian brick terrace with sash windows, arched fanlight doorways, stone steps and iron railings in London
    Rear view of brick terraced houses in London with slate roofs and chimney stacks along the shared roofline
    Photograph: Ben Hadfield

    03The record

    Local figures for Southwark

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Basements must be single storey, extend no more than 50% of the garden depth from the rear wall and no more than 30% to the front, and need a Basement Impact Assessment.1 storey; 50% rear; 30% frontNo periodsouthwark.gov.uk, Householder SPD 2025, p.82, section 3.8
    Supplementary planning documentHouseholder development SPD2025southwark.gov.uk
    Domestic gardens share of land (GLUD 2005)17.6 % of land that is domestic garden (GLUD 2005)2005data.london.gov.uk
    Party Wall etc. Act 1996 s6(1), s6(2), s6(5)Adjacent excavation notice at least 1 month before work: within 3 m and deeper than the neighbour's foundations, or within 6 m and cutting a 45° line from their foundationsNo periodlegislation.gov.uk
    Approved Document B Vol 1, para 2.16Basement storeys with habitable rooms need an escape window or external door, or a protected stair to a final exitNo periodgov.uk
    Householder: alterations/extensions to a single dwellinghouse, from 1 Apr 2026548 GBPNo periodribblevalley.gov.uk
    Conservation areas53 named conservation areas published by the councilNo periodplanning.data.gov.uk
    Article 4 directions480 Article 4 directions published by the councilNo periodplanning.data.gov.uk

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

    Southwark7 neighbouring councils
    Councils bordering Southwark

    04The streets

    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.

    GLA Planning London Datahub, householder applications

    05The drawing

    A basement in sectionA, Southwark: depth and garden share: 1 storey; 50% rear; 30% front. B, Party wall notice for excavation: Adjacent excavation notice at least 1 month before work: within 3 m and deeper than the neighbour's foundations, or within 6 m and cutting a 45° line from their foundations. C, Escape from basement rooms: Basement storeys with habitable rooms need an escape window or external door, or a protected stair to a final exitABC

    A basement in section

    A house and garden over a single-storey basement. The lettered marks show the limits the legend gives.

    A Southwark: depth and garden share
    1 storey; 50% rear; 30% front
    B Party wall notice for excavation
    Adjacent excavation notice at least 1 month before work: within 3 m and deeper than the neighbour's foundations, or within 6 m and cutting a 45° line from their foundations
    C Escape from basement rooms
    Basement storeys with habitable rooms need an escape window or external door, or a protected stair to a final exit
    The basement in three dimensions3D
    Scroll the page: the model turns with it.

    06The detail

    Gardens and the measurements that matter

    Domestic gardens cover 17.6% of Southwark's land in the national land-use survey. The rear-wall measure is taken from your own plot, so the survey records the true garden depth, the boundaries and the trees before the first option is drawn.

    Neighbours, escape and fire detection

    Digging beside a neighbour brings in the Party Wall etc. Act 1996. Adjacent excavation notice at least 1 month before work: within 3 m and deeper than the neighbour's foundations, or within 6 m and cutting a 45° line from their foundations. A dispute arises if the adjoining owner does not consent within 14 days of the notice.

    Building Regulations add escape and detection. Basement storeys with habitable rooms need an escape window or external door, or a protected stair to a final exit. All dwellings: fire detection and alarm system minimum Grade D2 Category LD3 (BS 5839-6), mains-operated smoke alarms to BS EN 14604. The council's householder fee is £548, paid separately.

    Designations above a Southwark basement

    The borough has 53 conservation areas and planning data lists 480 Article 4 direction records, which can add permission requirements. In Dulwich, Southwark publishes Article 4 directions for the Sunray Estate Conservation Area. The Dulwich neighbourhood guide lists the others.

    Historic England records 919 list entries here, and a basement under one needs consent as well as permission. See listed building consent drawings in Southwark before you commission a survey.

    Planning sheet for a single-storey rear extension: proposed ground floor plan and rear elevation, with the Property Architecture title block
    Sample drawing. Proposed plan and rear elevation from a planning application set, sheet 03 at 1:50.

    07The papers

    What the drawings rest on

    Brick house being extended, with a wide new opening supported over the ground floorStructural calculations
    Photograph: Brett Jordan
    Structural calculation sheet for a steel beam over a new rear opening, with the load diagram, loading table and section checks
    Sample drawing. Beam B1 over a new rear opening: loading, bending moment and section checks.

    08Correspondence

    Questions

    How deep can a basement be in Southwark?

    The householder SPD allows a single storey. Its full limit, as we record it, is 1 storey; 50% rear; 30% front, covering depth and the reach from the rear and front walls.

    Do I need a Basement Impact Assessment in Southwark?

    The SPD says a basement needs one with the application. We coordinate the structural calculations that sit behind it and draw the basement to match.

    Where can a lightwell go on a Southwark house?

    At the front only where lightwells are already a common feature of the street. Otherwise the SPD allows a discreet one at the rear.

    What do the drawings cost?

    Basement drawings start at £1,995 including VAT. Council fees are separate, and a party wall notice is £45 per adjoining owner.

    Rows of brick terraced houses and gardens on a residential street

    17.6%

    of land that is domestic garden (GLUD 2005)

    Domestic gardens share of land (GLUD 2005), Southwark, 2005. Source: data.london.gov.uk

    Photograph: Altaf Shah

    09Further reading

    Other services in Southwark

    Basement conversion drawings nearby

    10Sources

    Sources and dates

    Licences

    Kensington street lined with brick townhouses and lit streetlamps beneath an orange dusk sky

    Send us the address of your house.

    We look up the conservation area, listing and Article 4 position, then reply with a fixed fee. A message before 3pm is answered the same working day.

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    Basement conversion drawings in Southwark