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Barnet, London

Double-storey extension drawings in Barnet

Double-storey extension drawings for a Barnet house start at £1,295 including VAT. Barnet writes its two-storey rules down in numbers, for depth, width and distance from the boundary, so we draw against them before you spend anything on design.

From £1,295 (VAT included)

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    House extension under construction with scaffolding, new glazed doors and building materials

    Barnet's numbers for a double-storey extension

    Barnet's rules sit in Sustainable Design and Development Guidance SPD, Part 4: Guidance on residential extensions and alterations. For a two-storey rear extension the guidance asks for no more than half the width of the house, and the figures it gives are: 3 m depth; 1 m / 2 m from boundary. The boundary gap differs depending on whether the neighbouring house is detached or attached, so the neighbour decides part of your design.

    The same guidance asks for a rear extension to be set down from the main ridge, with eaves no higher than the original and a roof that matches the house. Flat roofs are not wanted. So we draw a hipped or pitched roof tucked below the existing ridge.

    A two-storey side extension has its own figures: 1 m gap; 0.5 m set-back; 0.5 m set-down. It should be no more than half the width of the house, and the gap, the set-back from the front wall and the drop from the ridge are what keep the extension from reading as a new building stuck on the side. We test these figures on the model first.

    Brick house being extended, with a wide new opening supported over the ground floor

    Local figures for Barnet

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Two-storey rear extensions should be no more than half the width of the house, usually no deeper than 3 metres, and at least 1 metre from a detached neighbour's boundary or 2 metres from an attached neighbour's boundary.3 m depth; 1 m / 2 m from boundary—barnet.gov.uk, SDDG SPD Part 4 (extensions), p.16, paras 4.53-4.54
    Two-storey side extensions should be no more than half the width of the house, keep a 1 metre gap to the boundary at first floor, be set back at least 0.5 metre from the front wall and set down 0.5 metres from the ridge.1 m gap; 0.5 m set-back; 0.5 m set-down—barnet.gov.uk, SDDG SPD Part 4 (extensions), p.19, paras 4.69-4.74
    Conservation areas16 named conservation areas published by the council—planning.data.gov.uk
    Article 4 directions15 Article 4 directions published by the council—planning.data.gov.uk
    Listed building entries651 list entries (Historic England, within the LPA boundary)—planning.data.gov.uk
    Green Belt share of the council area28 % of council area covered by green-belt polygons—planning.data.gov.uk
    Domestic gardens share of land (GLUD 2005)28.1 % of land that is domestic garden (GLUD 2005)2005data.london.gov.uk
    Householder decisions1,361 decisions1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications granted80.2 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications decided in time95.1 % decided within 8 weeks or an agreed extended period1 July 2025 - 30 June 2026assets.publishing.service.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 Barnet

    Householder applications by street in Barnet

    Streets in Barnet with the most householder applications, and the share approved
    StreetApplicationsApproved
    Wolmer Gardens4282%
    Hampden Way3686%
    Oakleigh Park South3677%
    Marsh Lane3591%
    Millway3493%
    Sturgess Avenue3494%
    Uphill Road3273%
    Chanctonbury Way3190%
    Oakleigh Road North3079%
    Woodlands3076%
    Laurel Way2976%
    Mount Pleasant2880%
    Arlington Road2780%
    Berkeley Crescent27100%
    Longland Drive27100%
    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)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)

    Greenery, heritage and Article 4 in Barnet

    Barnet has 16 conservation areas, 15 Article 4 directions and 651 Historic England list entries. In a conservation area the national rule is: No rear extension of more than one storey under PD on article 2(3) land.

    Green Belt covers 28 per cent of the borough, and domestic gardens cover 28.1 per cent of its land. We check the address against both designations before we suggest a route.

    Permitted development or a householder application

    The permitted development limit for more than one storey is: Over one storey: max 3 m beyond the original rear wall and not within 7 m of the rear boundary. Where a plot cannot meet it, the application is judged against the guidance above.

    The council's householder fee is £548, paid to the council. Our planning drawings in Barnet carry the application. For other shapes of project, see house extension drawings in Barnet, and for the roof option, loft conversion drawings in Barnet.

    How Barnet decides householder applications

    Barnet decided 1,361 householder applications in its latest published year. It granted 80.2 per cent and decided 95.1 per cent within eight weeks or an agreed extension.

    Those figures include every household project and none is specific to two-storey work, so we use them for timetable planning only. For a double-storey scheme the better guide is the guidance itself, which is why we set depth, width and gaps out on the plan before the first option is shown to you.

    Upstairs rules and party walls

    Upper-floor side windows have a rule: Upper-floor side windows obscure-glazed and non-opening below 1.7 m above floor. A bedroom also needs a way out: 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. Both go on the drawings, with the structure, in our building regulations drawings in Barnet.

    The new storey usually bears on a shared wall, so notices are needed: Party structure notice at least 2 months before work.

    Price, process and nearby boroughs

    Double-storey extension drawings start at £1,295 with VAT included, fixed before you commit. We survey the house and both boundaries on one datum, model the options and freeze the design in writing. A second chartered technologist checks every sheet, and if the council asks for changes we redraw at no charge until approval.

    For the borough as a whole, see architectural drawings in Barnet. Compare the same rules in Brent, Camden and Harrow, or read the overview of double-storey extension drawings.

    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.
    Finished white-rendered rear house extension with large glazed doors
    Every side considered
    Flick across the turntable to spin it.

    Other services in Barnet

    Double-storey extension drawings nearby

    Questions

    How deep can a two-storey rear extension be in Barnet?

    Barnet's guidance says no more than half the width of the house and usually no deeper than the figures it gives: 3 m depth; 1 m / 2 m from boundary. We check them against your plot at survey.

    What gap does Barnet want for a two-storey side extension?

    The guidance gives 1 m gap; 0.5 m set-back; 0.5 m set-down, with the extension no more than half the width of the house.

    Does the roof of a two-storey extension have to match the house?

    Barnet's guidance asks for a roof that matches the house, set down from the main ridge, and does not want flat roofs. The national permitted development rule is similar: Roof pitch of a 2+ storey enlargement to match the original house so far as practicable.

    How much do double-storey extension drawings cost in Barnet?

    From £1,295 including VAT, fixed up front. The council's fee of £548 is paid separately to the council.

    Sources and dates

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    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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