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

01Lambeth, London

Mansard roof drawings in Lambeth

Lambeth prefers a rear mansard on a double-pitched roof and says it is generally not appropriate on heritage assets or in conservation areas. With 64 conservation areas, that narrows where one can be drawn. Fixed fees from £845 including VAT.

From £845 (VAT included)

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    02The brief

    How Lambeth tests a mansard

    The council's Lambeth Design Guide SPD Part 4: Building Alterations, Extensions and Retrofit sets the geometry. A rear mansard suits a double-pitched roof, not a hipped one, and the ridge must not be altered. There must be 2.1 m of headroom below the existing ridge before the idea works at all.

    For the lower slope the guide gives 70 degrees; 2.3 m: first the pitch, in slate, then the height at which it ends where mansards in a row are to link, with a lead flashing and no fascia or gutter at the junction. We survey the ridge and roof line first, because that decides whether the headroom exists.

    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 Lambeth

    Figures with their unit, period and source
    MeasureValuePeriodSource
    A rear mansard is the preferred option on double-pitched (not hipped) roofs, but generally not appropriate on heritage assets or in conservation areas; ridges must not be altered and 2.1m headroom must exist below the existing ridge.2.1 mNo periodlambeth.gov.uk, Design Guide Part 4, p.40, paras 4.101-4.102
    The rear mansard lower pitch should be 70 degrees in slate, ending at 2.3m height where mansards in a row are to link, with a lead flashing and no fascia or gutter at the junction.70 degrees; 2.3 mNo periodlambeth.gov.uk, Design Guide Part 4, p.40, para 4.102 (2)-(5)
    Replacing a London (butterfly) roof is not acceptable on heritage assets or in conservation areas; elsewhere only a traditional full mansard with two 70 degree lower and two 30 degree upper pitches, 2.1m internal height and party walls set behind the parapets.70 degrees / 30 degreesNo periodlambeth.gov.uk, Design Guide Part 4, pp.42-43, paras 4.106-4.107
    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
    Householder: alterations/extensions to a single dwellinghouse, from 1 Apr 2026548 GBPNo periodribblevalley.gov.uk
    Conservation areas64 named conservation areas published by the councilNo periodplanning.data.gov.uk
    Article 4 directions12 Article 4 directions published by the councilNo periodplanning.data.gov.uk
    Householder applications granted83.4 %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.

    Lambeth7 neighbouring councils
    Councils bordering Lambeth

    04The streets

    Householder applications by street in Lambeth

    Streets in Lambeth with the most householder applications, and the share approved
    StreetApplicationsApproved
    Hydethorpe Road2792%
    The Chase2072%
    Haverhill Road1888%
    Rodenhurst Road1775%
    Clive Road1573%
    Shakespeare Road1571%
    Narbonne Avenue12100%
    Fentiman Road1180%
    Ferndene Road1191%
    St Julian's Farm Road1164%
    Abbeville Road1067%
    Downton Avenue1088%
    Knollys Road10100%
    Lancaster Avenue1078%
    Rosedene Avenue1075%

    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, Lambeth: lower slope: 70 degrees; 2.3 m. B, Lambeth: set-back and parapet: 70 degrees / 30 degrees. C, Permitted development and the eaves: Class B requires the original eaves to be maintained or reinstated, which a parapet-fronted mansard normally removes. D, Additional storeys under permitted development: Class AA additional storeys exclude houses built before 1 Jul 1948 or after 28 Oct 2018. E, 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)ABCDE

    A mansard roof in section

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

    A Lambeth: lower slope
    70 degrees; 2.3 m
    B Lambeth: set-back and parapet
    70 degrees / 30 degrees
    C Permitted development and the eaves
    Class B requires the original eaves to be maintained or reinstated, which a parapet-fronted mansard normally removes
    D Additional storeys under permitted development
    Class AA additional storeys exclude houses built before 1 Jul 1948 or after 28 Oct 2018
    E 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

    Butterfly roofs and heritage assets

    Lambeth is firm about London (butterfly) roofs: replacing one is not acceptable on a heritage asset or in a conservation area. Elsewhere only a traditional full mansard is accepted, with pitches of 70 degrees / 30 degrees and the party walls set behind the parapets.

    Heritage controls here are extensive: 64 conservation areas, 12 Article 4 directions and 953 list entries. A listed roof needs consent too; see listed building consent drawings in Lambeth.

    Permitted development stops short

    Class B requires the original eaves to be maintained or reinstated, which a parapet-fronted mansard normally removes. Class AA is not available on article 2(3) land. Together they leave a householder application as the usual route.

    In the latest year Lambeth decided 595 householder applications and granted 83.4% of them. The council's householder fee is £548, separate from our fee. The Local Plan is the Lambeth Local Plan 2021.

    What the drawing set holds

    From £845 including VAT: existing and proposed plans, sections and elevations of the roof on one datum, with the roofline against both neighbours. Party structure notice at least 2 months before work, so the party wall timing goes in your next-steps pack.

    Around Clapham Common, where Lambeth shares the Common with Wandsworth, see architectural drawings in Clapham. Floors below are covered in basement conversion drawings in Lambeth, and the general route in 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 get a mansard in a Lambeth conservation area?

    Lambeth's guidance says a rear mansard is generally not appropriate on heritage assets or in conservation areas. We confirm the designation for your address in the free constraints check before you spend on design.

    What if my roof is a butterfly roof?

    Replacing a London (butterfly) roof is not acceptable on a heritage asset or in a conservation area. On other houses only a traditional full mansard is considered.

    How much headroom does the council expect?

    2.1 m below the existing ridge, according to the Design Guide. We measure it in the survey.

    Can my mansard join the neighbour's in a row?

    Where mansards in a row are to link, the Design Guide lets the lower slope stop at a set height, with a lead flashing and no fascia or gutter at the junction. It gives the pitch and that height as 70 degrees; 2.3 m, and the survey records the neighbour's roof so the junction is drawn to something real.

    Converted loft bedroom with roof windows and a Juliet balcony

    83.4%

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

    Photograph: Imad Clicks

    09Further reading

    Other services in Lambeth

    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 Lambeth