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Brent, London

Double-storey extension drawings in Brent

Double-storey extension drawings for a Brent house start at £1,295 including VAT. Brent's extension guidance sets the depth of a two-storey rear extension by house type, at 3 m attached; 4 m detached, and adds a sight-line test from your neighbour's window.

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

    Brent's limits for a double-storey extension

    The Residential Extensions and Alterations Supplementary Planning Document gives Brent's depth limit for a two-storey rear extension: 3 m attached; 4 m detached. A detached house is allowed more than an attached one. Where you sit between those two categories, a corner house or a semi with a side passage, we confirm which applies before design.

    Depth is not the only test. A two-storey rear extension must also stay inside a line of 45 degrees taken from the middle of the nearest neighbouring habitable-room window on the original rear wall. We set that line out on the survey, because it depends on where your neighbour's window actually is.

    For a side extension the guidance gives another set of figures: two thirds width; 0.5 m set-back. The upper floor is no higher than the ridge and is not flat-roofed unless the house is. We check the width against the house front, not the plot, before the design is chosen.

    Finished white-rendered rear house extension with large glazed doors

    Local figures for Brent

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Two-storey rear extensions must not be more than 3 metres deep for attached homes or 4 metres for detached homes.3 m attached; 4 m detached—brent.gov.uk, Residential Extensions and Alterations SPD 2025, p.21, paras 3.2.3-3.2.4
    Two-storey rear extensions must not cross the 45-degree line taken from the middle of the nearest neighbouring habitable-room window on the original rear wall.45 degrees—brent.gov.uk, Residential Extensions and Alterations SPD 2025, p.21, para 3.2.5
    Two-storey side extensions must be no more than two thirds of the house width, set back at least 0.5 metres at first floor from the front wall, no higher than the ridge, and not flat-roofed unless the house is.two thirds width; 0.5 m set-back—brent.gov.uk, Residential Extensions and Alterations SPD 2025, p.27, paras 3.4.1-3.4.6
    Article 4 directions39 Article 4 directions published by the council—planning.data.gov.uk
    Conservation areas23 named conservation areas published by the council—planning.data.gov.uk
    Listed building entries93 list entries (Historic England, within the LPA boundary)—planning.data.gov.uk
    Green Belt share of the council area0 % of council area covered by green-belt polygons—planning.data.gov.uk
    Domestic gardens share of land (GLUD 2005)30.3 % of land that is domestic garden (GLUD 2005)2005data.london.gov.uk
    Households living in a house43.3 % of households living in a house or bungalow (detached, semi-detached or terraced)Census 2021nomisweb.co.uk
    Householder decisions879 decisions1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications granted86.6 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications decided in time97.2 % 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 Brent
    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)

    Article 4, conservation areas and listed buildings in Brent

    Brent has 39 Article 4 directions, 23 conservation areas and 93 Historic England list entries. An Article 4 direction can take away rights that apply elsewhere, and 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 0 per cent of Brent, so it is not a factor here. Domestic gardens cover 30.3 per cent of its land, and the depth limits above keep most of a garden open.

    Permitted development or planning permission

    The permitted development limit for a second storey is: Over one storey: max 3 m beyond the original rear wall and not within 7 m of the rear boundary. A design that stays inside Brent's guidance is the route we draw to for a planning application.

    The council's householder fee is £548, paid to the council. Our planning drawings in Brent carry the application. Weighing a single-storey option too? House extension drawings in Brent sets the choices side by side.

    How Brent decides householder applications

    Brent decided 879 householder applications in its latest published year and granted 86.6 per cent. It decided 97.2 per cent within eight weeks or an agreed extension.

    43.3 per cent of Brent households live in a house or bungalow, and only those can use householder rights. The figures cover all household work, and we use them to plan timing, not to forecast a decision. The design is what we control, so the depth, the sight-line and the side width are set out on the plan before you are shown a first option.

    Fire, windows and party walls upstairs

    A new bedroom 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. A side window on the new floor is limited too: Upper-floor side windows obscure-glazed and non-opening below 1.7 m above floor. We draw both, with the stair and steelwork, in the building regulations drawings in Brent.

    A second storey on a shared wall usually needs notice: Party structure notice at least 2 months before work. Foundations near a neighbour's fall under a separate rule, and we can prepare the notices for you.

    Price, process and nearby boroughs

    Double-storey extension drawings start at £1,295 with VAT included, fixed before you commit. We survey both floors, test the sight-line on the model 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. The set shows both floors as existing and proposed, all four elevations, a section through the new roof and the block plan, with the sight-line and depth marked so the case officer can check them at a glance.

    For the borough as a whole, see architectural drawings in Brent. Compare the same rules in Ealing, Harrow and Barnet, 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.
    Two-storey rear extension under construction on a semi-detached house
    Every side considered
    Flick across the turntable to spin it.

    Other services in Brent

    Double-storey extension drawings nearby

    Questions

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

    Brent's guidance gives 3 m attached; 4 m detached. The extension must also stay inside the sight-line of 45 degrees from your neighbour's nearest habitable-room window.

    How wide can a two-storey side extension be in Brent?

    The guidance gives two thirds width; 0.5 m set-back, with the upper floor no higher than the ridge.

    Do I need planning permission for a double-storey extension in Brent?

    Usually yes. Permitted development stops at: Over one storey: max 3 m beyond the original rear wall and not within 7 m of the rear boundary. In one of Brent's 23 conservation areas it does not apply to a rear extension of more than one storey.

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

    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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