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Islington, London

Double-storey extension drawings in Islington

In Islington, two storeys is usually the limit, not the start. Our double-storey extension drawings for Islington homes begin at £1,295 including VAT, and they are shaped by an Urban Design Guide that resists half-width rear additions above two storeys and protects the line of back additions on the terraces.

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

    Islington's rules for double-storey rear extensions

    The Urban Design Guide SPD says half-width rear extensions higher than 2 storeys are normally resisted. Inside a conservation area the line is firmer: extensions above two storeys in total will not normally be permitted.

    That puts the first design question in a new light. On a terrace with an existing back addition, the question is rarely how tall a new rear block can go. It is whether a single half-width upper floor over the existing addition will be accepted at all.

    The guide's answer is conditional. Single half-width upper-floor extensions above existing back additions are often acceptable if a gap is left below the eaves, but extensions above paired additions with consistent rooflines should be avoided. So a matching pair of additions on adjoining houses is where the guide asks for restraint.

    Finished white-rendered rear house extension with large glazed doors

    Local figures for Islington

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Half-width rear extensions higher than two storeys are normally resisted, and in conservation areas extensions above two storeys in total will not normally be permitted.2 storeys—islington.gov.uk, Urban Design Guide SPD, pp.51-52, paras 5.134 and 5.139
    Conservation areas41 named conservation areas published by the council—planning.data.gov.uk
    Listed building entries1,050 list entries (Historic England, within the LPA boundary)—planning.data.gov.uk
    Grade II listed entries1,002 list entries—planning.data.gov.uk
    Households living in a house16.3 % of households living in a house or bungalow (detached, semi-detached or terraced)Census 2021nomisweb.co.uk
    Householder decisions337 decisions1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications granted92.6 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications decided in time98.8 % decided within 8 weeks or an agreed extended period1 July 2025 - 30 June 2026assets.publishing.service.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, para A.2(c)No rear extension of more than one storey under PD on article 2(3) land—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
    Party Wall etc. Act 1996 s3(2)(a)Party structure notice at least 2 months before work—legislation.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 Islington

    Householder applications by street in Islington

    Streets in Islington with the most householder applications, and the share approved
    StreetApplicationsApproved
    Corbyn Street3585%
    Plimsoll Road2893%
    Aberdeen Park2491%
    Thorpedale Road2190%
    Highbury Hill2094%
    Hungerford Road2088%
    Sussex Way18100%
    Avenell Road1585%
    Hemingford Road1579%
    Huddleston Road15100%
    Romilly Road1592%
    Harberton Road14100%
    Offord Road1486%
    St George's Avenue14100%
    Thornhill Road1479%
    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). Islington guidance: 45 degrees (plan and elevation)AB

    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 · Islington guidance
    45 degrees (plan and elevation)

    What this means for your drawings

    We read the back additions on both sides of your house before designing. If the neighbour's addition is lower, a half-width upper floor with a visible gap under the eaves can work. If both sides step up in matching pairs, we show a ground-floor scheme as the lead option and set the upper floor as an alternative for comparison.

    The survey also records window positions on the flank, because a first-floor extension changes the outlook of the house next door. Having that measured on the model makes the officer's questions easier to answer with a drawing than with a letter.

    Heritage land is the rule, not the exception

    Islington has 41 conservation areas and Historic England lists 1,050 entries in the borough, of which 1,002 are Grade II. With so much protected land, every address starts with a constraints check. In a conservation area: No rear extension of more than one storey under PD on article 2(3) land.

    Only 16.3 per cent of Islington households live in a house, and permitted development rights for extensions apply to houses, not flats. For the wider picture see architectural drawings in Islington.

    National limits and the upper floor

    Where permitted development is available, the second-storey rule is: Over one storey: max 3 m beyond the original rear wall and not within 7 m of the rear boundary. Side windows: Upper-floor side windows obscure-glazed and non-opening below 1.7 m above floor. They set the baseline against which the drawings are measured.

    If a basement sits below the proposed extension, the council's Basement Development SPD also applies, and our drawings show the structure from foundation to roof so both documents can be cross-checked.

    Fire safety, party walls and structure

    A new first-floor bedroom needs an escape window: 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. In a terrace the party structure notice also matters: Party structure notice at least 2 months before work. Both belong in the drawings before an application, and they feed into the building regulations drawings in Islington that follow planning.

    Islington's record on householder decisions

    Islington decided 337 householder applications in its latest published year and granted 92.6 per cent, deciding 98.8 per cent on time. The numbers cover all householder work, so we read them as a guide to timing, not an indication of outcome.

    What the set includes and what it costs

    Each Islington set shows floor plans for both levels, the roof in section and the elevations, plus location and block plans. It starts at £1,295 with VAT included. A second chartered technologist checks each sheet before it leaves us, and we redraw free until approval where the council asks for changes.

    Looking at a wider project? Loft conversion drawings in Islington and wraparound extension drawings in Islington cover the other routes. For the same service across the border, see Hackney or Camden.

    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 Islington

    Double-storey extension drawings nearby

    Questions

    Can I extend above a back addition in Islington?

    Often yes, if the extension is a single half-width upper floor and a gap is left below the eaves. The guide says to avoid extensions above paired additions that share a consistent roofline.

    How many storeys can a rear extension have in an Islington conservation area?

    The Urban Design Guide says extensions above 2 storeys in total will not normally be permitted inside a conservation area.

    How many conservation areas does Islington have?

    41, with 1,050 listed building entries across the borough, so we check every address before quoting.

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

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

    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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