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Merton, London

Flat conversion drawings in Merton

In Merton the levy on new flats roughly halves between Wimbledon and Mitcham, so the postcode of your house changes the sum before design begins. We prepare flat conversion drawings in Merton from £1,195 including VAT, as MCIAT chartered architectural technologists, and we establish the levy area, the plan policies and the local character guidance on your address first.

From £1,195 (VAT included)

  • MCIAT chartered
  • £2m PI insured
  • LABC Partnered
  • Fixed fees, VAT included

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    Architectural model of a four-storey London stucco townhouse in its terrace, with a portico, area railings, sash windows, a cornice and chimney stacks
    The house as it stands: four storeys over a lower ground floor.Existing Proposed worksAn illustrative model, built for this page.

    How we work on flat conversion drawings

    Seven steps from first call to approval.

    The same model cut through the middle: every floor, the stair, the chimney breasts, the new mansard, rear extension and basement in section
    Section through the model: every floor on one datum.

    1. Enquiry and constraints check

      We check the property against conservation areas, listed status, Article 4 directions, tree preservation orders, flood zone and planning history. We choose the right route and send a fixed quote.

    2. Measured survey

      We survey the house on one datum: rooms, levels, boundaries, drains, trees and the neighbours' windows that the 45° and 25° tests depend on.

    3. Design options

      We model the house in Revit and show you options in 3D and plan, with the planning strategy and the precedents in your street.

    4. Design frozen

      You choose an option in writing. Nothing changes after this without your say.

    5. Independent check

      A second chartered technologist checks every sheet against the council's validation checklist and the policy. A senior review signs it off before anything is submitted.

    6. Submission

      We prepare the forms, certificates, fee and documents and submit through the Planning Portal.

    7. Officer liaison

      We answer the planning officer and make any amendments within five working days, at no charge until approval.

    Free redraws until approval. Every drawing set is checked independently, and the checker is never the person who drew it.

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    Red-brick mansion blocks and shopfronts on a street corner

    Merton's two-rate levy and the plan behind it

    The borough levy for homes has two rates. The charging schedule gives £368.20/m² (Colliers Wood, Raynes Park and Wimbledon); £192.47/m² (Mitcham, Morden and West Barnes). Colliers Wood, Raynes Park and Wimbledon pay the higher charge, and Mitcham, Morden and West Barnes the lower one. The table repeats both rates.

    A conversion creates new homes, so the small-extension exemption does not apply. A house of average size split into two flats can therefore carry a very different bill depending on the side of the borough it stands in, and that belongs in the budget at the start. On the Mitcham side the same new floor area attracts roughly half the borough charge, which can be enough to make a marginal scheme worth pursuing.

    The planning policy is the Merton Local Plan 2024. Merton does not publish a single floor-area threshold for conversions that we can quote as a figure, so we do not invent one: the officer reads the scheme against the plan's housing policies, the national space standard and the London Plan. Our flat conversion drawings guide explains the full set we produce.

    Pencil resting on a dimensioned technical drawing beside a scale rule

    Local figures for Merton

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Borough CIL residential rate£368.20/m² (Colliers Wood, Raynes Park and Wimbledon); £192.47/m² (Mitcham, Morden and West Barnes)effective rate for permissions granted in 2026merton.gov.uk
    Minor application decisions206 decisions1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Minor applications granted82.5 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Minor applications decided in time82 % decided within 8 weeks or an agreed extended period1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications granted92.9 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Households living in a house60.4 % of households living in a house or bungalow (detached, semi-detached or terraced)Census 2021nomisweb.co.uk
    Conservation areas28 named conservation areas published by the council—planning.data.gov.uk
    Listed building entries243 list entries (Historic England, within the LPA boundary)—planning.data.gov.uk
    Mayoral CIL charging band2 MCIL2 charging band (1-3)—london.gov.uk
    Mayoral CIL rate (indexed)72.73 £/m² (indexed, permissions granted in 2026)—london.gov.uk
    Change of use of a building to one or more separate dwellinghouses, not more than 10: per dwellinghouse, from 1 Apr 2026610 GBP per dwelling—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 Merton
    Building regulations, layer by layerPart A: structure: Approved Document A: Structure, 2004 edition incorporating 2004, 2010 and 2013 amendments. Part B: fire safety: All dwellings: fire detection and alarm system minimum Grade D2 Category LD3 (BS 5839-6), mains-operated smoke alarms to BS EN 14604. Part L: insulation: New elements in existing dwellings, limiting U-values W/(m²·K): roof 0.15, wall 0.18, floor 0.18, windows 1.4 (or WER Band B), doors 1.4. Part K: stairs: 2.0 m clear headroom over stairs. Full plans application: Building control body must decide a full plans application within 5 weeks, or longer if agreed in writingPart A: structurePart B: fire safetyPart L: insulationPart K: stairsFull plans applicationABCDE

    Building regulations, layer by layer

    The Approved Documents that shape most house projects, from structure to the application itself.

    A · Part A: structure
    Approved Document A: Structure, 2004 edition incorporating 2004, 2010 and 2013 amendments
    B · Part B: fire safety
    All dwellings: fire detection and alarm system minimum Grade D2 Category LD3 (BS 5839-6), mains-operated smoke alarms to BS EN 14604
    C · Part L: insulation
    New elements in existing dwellings, limiting U-values W/(m²·K): roof 0.15, wall 0.18, floor 0.18, windows 1.4 (or WER Band B), doors 1.4
    D · Part K: stairs
    2.0 m clear headroom over stairs
    E · Full plans application
    Building control body must decide a full plans application within 5 weeks, or longer if agreed in writing

    Merton's supplementary guidance

    Three supplementary documents shape the detail. The Borough Character Study SPD describes the character of each part of the borough, the Small sites toolkit SPD deals with modest plots, and the Basement and subterranean SPD applies where a lower floor is to be used for a home.

    The character study is the most useful for a conversion, because the new front door, bin store and window changes are judged against the pattern of the street. We draw the existing elevation beside the proposed one so the officer can compare them quickly.

    Where the change is internal only, as it often is in a conversion, the drawings put their weight on layouts, areas and amenity space. We schedule the area of each flat against the national standard and show how the garden is divided or shared.

    How quickly Merton decides smaller schemes

    A conversion into two or three flats is a minor application. Over the latest twelve months Merton decided 206 of them and granted 82.5 per cent, but only 82 per cent were decided within eight weeks or an agreed extension.

    That in-time figure is the one to plan around. For householder work the council decided 759 cases, granted 92.9 per cent and decided 85.2 per cent in time, so a conversion is the slower route here.

    We advise building an extension of time into your programme and answering officer questions within five working days, which keeps a scheme moving if the statutory period runs out. 60.4 per cent of Merton households live in a house, so the council sees many of these cases.

    Heritage, directions and what a flat is worth

    Merton lists 28 conservation areas and 243 listed building entries. In a conservation area the front elevation is judged more closely, so the doors, windows and bin store need careful drawing.

    The Mayor's levy is in band 2 with an indexed rate of £72.73 per square metre. The planning fee is £610 for each flat created. A terraced house averages about £686,591 and a flat about £405,123, with the twelve-month price change at -0.9 per cent.

    We check whether your street is in one before the front elevation is drawn. See the Merton area page for the wider constraints.

    What the Merton set contains

    Each flat is also tested for height and sound. The London Plan asks for 2.5 m floor-to-ceiling across most of the flat, and the floor build-up that meets the sound targets between flats takes depth from the room below, so we resolve both on the section drawings before the layout is fixed. The set contains existing and proposed floor plans, elevations, sections, a block plan and a schedule of areas by flat, with the height and sound build-ups drawn on the sections. Approved schemes continue to building regulations drawings. For a neighbouring borough, see flat conversion drawings in Sutton.

    What you receive

    Building regulations section drawing showing the construction build-up
    Sample drawing. Building regulations section showing construction build-up for a building control check.
    Rear view of brick terraced houses in London with slate roofs and chimney stacks along the shared roofline
    Unit by unit
    Move up and down — the nearest units slide out.

    Other services in Merton

    Flat conversion drawings nearby

    Questions

    Why does the levy differ across Merton?

    The borough's charging schedule sets a higher rate for Colliers Wood, Raynes Park and Wimbledon and a lower one for Mitcham, Morden and West Barnes.

    Is a Merton conversion decided within eight weeks?

    Only 82 per cent of minor applications were decided in time, so allow for an agreed extension.

    Does Merton publish a minimum house size for conversions?

    We have not found a figure we can quote, so we test the layout against the plan, the national space standard and the London Plan.

    What is the planning fee for two flats?

    It is £610 for each flat created, so twice that figure for two.

    Sources and dates

    City of London skyline glowing at dusk across the Thames under a dramatic orange sky

    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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