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

01Merton, London

Mansard roof drawings in Merton

Before a mansard is designed in Merton, the route has to be settled. With 28 conservation areas and 243 list entries in the borough, the designations on your house decide how the roof is tested. We draw it from £845 including VAT.

From £845 (VAT included)

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    02The brief

    What Merton says about roof storeys

    Our data records no Merton rule written for mansards or extra storeys, so we do not quote one. The council's published papers include the Borough Character Study SPD and the Merton Local Plan 2024, and we read both for how your street is described. The firm limits come from national rules and from the designations on your house.

    That makes the constraints check the real first step. We place your address against the conservation areas, the list and the Article 4 directions before a roof line is drawn, so you learn the route before you pay for options.

    Brick cottage with a tiled roof, chimneys and a front dormer window
    Upper floors of a large yellow-brick Victorian house in London with chimney pots
    Photograph: Lorenc Memaga

    03The record

    Local figures for Merton

    Figures with their unit, period and source
    MeasureValuePeriodSource
    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(c)Class AA additional storeys exclude houses built before 1 Jul 1948 or after 28 Oct 2018No periodlegislation.gov.uk
    Class AA, para AA.1(b)Class AA is not available on article 2(3) landNo periodlegislation.gov.uk
    Householder: alterations/extensions to a single dwellinghouse, from 1 Apr 2026548 GBPNo periodribblevalley.gov.uk
    Party Wall etc. Act 1996 s3(2)(a)Party structure notice at least 2 months before workNo periodlegislation.gov.uk
    Conservation areas28 named conservation areas published by the councilNo periodplanning.data.gov.uk
    Listed building entries243 list entries (Historic England, within the LPA boundary)No periodplanning.data.gov.uk
    Heritage at Risk entries23 Heritage at Risk Register entries within the LPA boundary (Historic England)No periodplanning.data.gov.uk
    Article 4 direction for HMOs (C3 to C4)YesNo periodmerton.gov.uk
    Householder decisions759 decisions1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications granted92.9 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk

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

    Merton5 neighbouring councils
    Councils bordering Merton

    04The streets

    Householder applications by street in Merton

    Streets in Merton with the most householder applications, and the share approved
    StreetApplicationsApproved
    South Park Road2696%
    Lower Morden Lane2584%
    Coombe Lane2383%
    Pepys Road2377%
    Palmerston Road21100%
    Dorset Road2072%
    Marryat Road2094%
    Mostyn Road2089%
    Springfield Avenue1995%
    Vineyard Hill Road19100%
    Claremont Avenue1888%
    Queen's Road18100%
    Faraday Road1782%
    Gladstone Road1760%
    Stroud Road1794%

    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 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.

    06The detail

    Two national tests that decide the route

    Class B permitted development asks for the original eaves to be kept or put back, and a parapet-fronted mansard normally removes them. Class AA, the upward-extension class, has limits of its own. Class AA additional storeys exclude houses built before 1 Jul 1948 or after 28 Oct 2018. Class AA is not available on article 2(3) land.

    In practice a mansard on a period house in Merton is a householder planning application. The council's fee for it is £548, paid to the council separately from our fixed fee.

    Conservation areas, listing and the register

    Historic England records 243 list entries in Merton, 228 of them Grade II. A listed house needs consent for a roof storey in addition to planning permission, and the roof counts as historic fabric. The consent route is set out under listed building consent drawings in Merton.

    23 entries inside the borough sit on the Heritage at Risk Register. Merton also has an Article 4 direction on HMO conversions (C3 to C4), which governs change of use rather than roofs.

    Householder decisions in the borough

    Merton handled 759 householder decisions in the latest return, and 92.9% were granted. Householder is the ordinary class, so the figure shows how the council treats ordinary home alterations in general, not roof storeys in particular.

    A roof storey in a conservation area is judged against the street first. Wimbledon is the nearest worked example: architectural drawings in Wimbledon lists how Merton divides its conservation areas there.

    What goes on the roof drawings

    We draw plans, sections and elevations of the existing and proposed roof on one surveyed datum, with the roofline shown against both neighbours. A new storey brings its own fire rule: 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 stair needs headroom too: Loft conversions where 2.0 m cannot be achieved: 1.9 m at the centre of the stair, 1.8 m at the side (half width).

    Party structure notice at least 2 months before work, under the Party Wall etc. Act 1996. For the lower floor of the same house, see basement conversion drawings in Merton, and for the general route the mansard roof drawings hub.

    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

    Rear view of brick terraced houses in London with slate roofs and chimney stacks along the shared rooflineParty wall services
    Photograph: Ben Hadfield
    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.

    08Correspondence

    Questions

    Can I add a mansard to my house in Merton without planning permission?

    Rarely. Class B needs the original eaves kept, which a mansard normally removes, and Class AA is not available on article 2(3) land. We confirm which route applies to your address in a free constraints check before quoting.

    Does Merton have its own mansard policy?

    Our records hold none. The Merton Local Plan 2024 and the Borough Character Study SPD describe the borough's character, and we read them for your street, but we do not invent a local limit that the data does not record.

    How much are mansard roof drawings for a Merton house?

    From £845 including VAT, fixed up front. The council fee for a householder application, £548, is paid separately.

    Converted loft bedroom with roof windows and a Juliet balcony

    92.9%

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

    Photograph: Imad Clicks

    09Further reading

    Other services in Merton

    Mansard roof 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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    Mansard roof drawings in Merton: conservation areas