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Slate-clad roof extension on a yellow-brick London terraced house
Photograph: Daniel Sikpi

01City of London, London

Mansard roof drawings in the City of London

Few City addresses are houses: 2% of households live in a house or bungalow, so the first question on a mansard here is usually who owns the roof. We answer it with the survey, then draw the set from £845 including VAT.

From £845 (VAT included)

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    Write to us before 3pm and we reply the same working day. Redraws are free until approval.

    02The brief

    Who owns the roof

    A City flat rarely owns the roof above it. The freeholder has to agree before a planning application is worth making, and that conversation shapes the brief more than any design rule.

    Where the roof structure is shared with a neighbour, the Party Wall etc. Act 1996 applies too: Party structure notice at least 2 months before work. The survey records each shared wall so the notices can be prepared.

    Rear view of brick terraced houses in London with slate roofs and chimney stacks along the shared roofline
    Brick cottage with a tiled roof, chimneys and a front dormer window
    Photograph: Tanya Barrow

    03The record

    Local figures for City of London

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Conservation areas28 named conservation areas published by the councilNo periodplanning.data.gov.uk
    Households living in a house2 % of households living in a house or bungalow (detached, semi-detached or terraced)Census 2021nomisweb.co.uk
    Listed building entries637 list entries (Historic England, within the LPA boundary)No periodplanning.data.gov.uk
    Householder decisions1 decisions1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications granted100 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Class B, condition B.2(b)(i)(aa)Class B requires the original eaves to be maintained or reinstated, which a parapet-fronted mansard normally removesNo periodlegislation.gov.uk
    Class AA, para AA.1(b)Class AA is not available on article 2(3) landNo periodlegislation.gov.uk
    Class AA, para AA.1(c)Class AA additional storeys exclude houses built before 1 Jul 1948 or after 28 Oct 2018No periodlegislation.gov.uk
    Party Wall etc. Act 1996 s3(2)(a)Party structure notice at least 2 months before workNo periodlegislation.gov.uk
    Householder: alterations/extensions to a single dwellinghouse, from 1 Apr 2026548 GBPNo periodribblevalley.gov.uk

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

    City of London7 neighbouring councils
    Councils bordering City of London

    04The drawing

    A mansard roof in sectionA, Permitted development and the eaves: Class B requires the original eaves to be maintained or reinstated, which a parapet-fronted mansard normally removes. B, Additional storeys under permitted development: Class AA additional storeys exclude houses built before 1 Jul 1948 or after 28 Oct 2018. C, Fire protection to the stair: New storey above 4.5 m by loft conversion: protect the full escape route with fire-resisting doors (min E 20) and partitions (min REI 30)ABC

    A mansard roof in section

    A London terrace with a mansard behind the parapet. The lettered marks show the limits the legend gives.

    A Permitted development and the eaves
    Class B requires the original eaves to be maintained or reinstated, which a parapet-fronted mansard normally removes
    B Additional storeys under permitted development
    Class AA additional storeys exclude houses built before 1 Jul 1948 or after 28 Oct 2018
    C Fire protection to the stair
    New storey above 4.5 m by loft conversion: protect the full escape route with fire-resisting doors (min E 20) and partitions (min REI 30)
    The mansard in three dimensions3D
    Scroll the page: the model turns with it.

    05The detail

    Where a house does exist

    A City house sits among 28 conservation areas, and Class AA is not available on article 2(3) land, which closes the upward-extension route for many addresses. The rule carries a date limit as well: Class AA additional storeys exclude houses built before 1 Jul 1948 or after 28 Oct 2018. Class B requires the original eaves to be maintained or reinstated, which a parapet-fronted mansard normally removes.

    Our records hold no City rule written for mansard roofs, so we quote no local limit. We read the council's local plan, City of London Local Plan 2015, against your street.

    How few decisions there are

    Householder decisions over the twelve months of the statistics numbered 1, with 100% granted. It recorded 0 upward-extension prior approvals granted and 0 refused. With numbers this small, the figures describe volume and not odds.

    Our drawing fee sits on top of the council's own £548 householder charge, which you pay to the council.

    Heritage around a City roof

    Historic England records 637 list entries within the boundary, and work to the roof of a listed building can need consent as well as permission. Listed building consent drawings in the City of London covers that second application, including the council's guidance for the Barbican.

    The Article 4 count here is 1, and 5 entries sit on the Heritage at Risk register. We check both at the address before any roof is drawn. The mansard roof hub shows the full route, and Westminster's mansard rules show a borough that sets numbers.

    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.

    06The papers

    What the drawings rest on

    Converted loft bedroom with roof windows and a Juliet balconyLoft conversions
    Photograph: Imad Clicks
    Loft floor plan marked up in an independent review, with three critical issues clouded and explained
    Sample drawing. A loft plan with the reviewer’s mark-up: stair pitch, dormer cheeks and roof ventilation.

    07Correspondence

    Questions

    Can I add a mansard to a City flat?

    A flat rarely owns the roof above it, so the freeholder's agreement comes first. Tell us the address and we say which application, if any, fits.

    Does the Barbican have its own guidance for roof work?

    The council's guidance for the estate is the Barbican Estate Listed Building Management Guidelines: Volume I Introduction and Volume II Residential (SPD). Because the estate is managed as a listed building, a roof question there starts with listed building consent.

    Is Class AA open to a City house?

    Not on conservation land: Class AA is not available on article 2(3) land, and the City publishes 28 conservation areas. We check your address before ruling the route in or out.

    Upper floors of a large yellow-brick Victorian house in London with chimney pots

    100%

    Householder applications granted, City of London, 1 July 2025 - 30 June 2026. Source: assets.publishing.service.gov.uk

    Photograph: Lorenc Memaga

    08Further reading

    Other services in City of London

    Mansard roof drawings nearby

    09Sources

    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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    Mansard roof drawings in the City of London