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Barnet, London

Garden room drawings in Barnet

Garden room drawings in Barnet start at £495 including VAT. Barnet puts numbers on outbuildings, with a footprint cap that depends on the size of your garden, so the drawings can be tested against its own figures before you apply.

From £495 (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 garden room drawings

    Nine 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.

    8. Building regulations

      Technical drawings are coordinated with the structural engineer's calculations, the drainage and the planning conditions.

    9. Approval and hand-over

      Building control approval, then a next-steps pack covering the commencement notice, party wall timing and CIL.

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

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    Two-storey rear extension under construction on a semi-detached house

    Garden room drawings in Barnet: the council's own limits

    Barnet's guidance for garden buildings is in the Sustainable Design and Development Guidance SPD, Part 4: Guidance on residential extensions and alterations. It sits under the Barnet Local Plan 2021-2036, adopted in 2,025. Where an outbuilding needs permission, the footprint limit is 20 sqm (<100 sqm garden); 30 sqm (>100 sqm garden), so a garden under a hundred square metres is held to the lower figure.

    Height has its own rule. In the council's words the figure is 2.5 m within 2 m of boundary; 4 m / 3 m max. Near a neighbour's garden the building must be low and flat-roofed; further down the plot a pitched roof is allowed up to the higher limit.

    The same document says an outbuilding stays single storey and incidental to the house, and the council will add a condition to stop it becoming a self-contained home. We draw the use on the plan so that condition is expected, not argued over.

    House extension under construction with scaffolding, new glazed doors and building materials

    Local figures for Barnet

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Outbuildings needing permission can have a footprint of up to 20 sqm in a garden under 100 sqm, or up to 30 sqm in a garden over 100 sqm.20 sqm (<100 sqm garden); 30 sqm (>100 sqm garden)—barnet.gov.uk, SDDG SPD Part 4 (extensions), p.30, para 4.129
    Within 2 metres of a neighbouring garden an outbuilding should be no more than 2.5 metres high with a flat roof; further away, eaves up to 2.5 metres and a maximum of 4 metres (dual pitch) or 3 metres otherwise.2.5 m within 2 m of boundary; 4 m / 3 m max—barnet.gov.uk, SDDG SPD Part 4 (extensions), p.30, paras 4.132-4.133
    Domestic gardens share of land (GLUD 2005)28.1 % of land that is domestic garden (GLUD 2005)2005data.london.gov.uk
    Green Belt share of the council area28 % of council area covered by green-belt polygons—planning.data.gov.uk
    Tree preservation orders718 tree preservation orders published by the council—planning.data.gov.uk
    Conservation areas16 named conservation areas published by the council—planning.data.gov.uk
    Article 4 directions15 Article 4 directions published by the council—planning.data.gov.uk
    Householder applications granted80.2 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications decided in time95.1 % decided within 8 weeks or an agreed extended period1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder appeals allowed50.6 % of householder appeals alloweddecision dates 1 Jul 2021 to 30 Jun 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.

    Councils bordering Barnet
    Single-storey rear extension: the permitted development limitsDepth beyond the original rear wall: 3 m (attached) / 4 m (detached) beyond the original rear wall, single storey. Maximum height: 4 m. Within the zone near the boundary: Eaves no higher than 3 m where within 2 m of the curtilage boundary. Larger extension under prior approval: 6 m (attached) / 8 m (detached), single storey, height max 4 m; not on article 2(3) land or an SSSIABCD

    Single-storey rear extension: the permitted development limits

    The house in section with a rear extension; the dashed lines mark the zone near the boundary.

    A · Depth beyond the original rear wall
    3 m (attached) / 4 m (detached) beyond the original rear wall, single storey
    B · Maximum height
    4 m
    C · Within the zone near the boundary
    Eaves no higher than 3 m where within 2 m of the curtilage boundary
    D · Larger extension under prior approval
    6 m (attached) / 8 m (detached), single storey, height max 4 m; not on article 2(3) land or an SSSI

    Why garden size matters more here than the building

    Because the footprint cap steps up with the garden, the first job on a Barnet plot is the garden measurement, not the room. A survey gives the true area, and that decides which limit applies. A garden that looks just over the threshold on a map is sometimes just under it on the ground.

    Domestic gardens cover 28.1 per cent of the borough's land in the government's generalised land use database, and about 28 per cent of the borough is Green Belt. In the Green Belt an outbuilding is judged more strictly for its effect on openness.

    If you plan to extend the house as well, our house extension drawings in Barnet and rear extension drawings in Barnet pages cover how the two schemes should be drawn together.

    Trees, heritage and Article 4 on a Barnet plot

    Trees often decide the position of a garden room in Barnet. The council publishes 718 tree preservation orders across 3,219 mapped zones, and a protected tree near the building can fix the footprint or force a raft foundation.

    Heritage is the other filter. There are 16 conservation areas, 15 Article 4 directions covering 48 areas, and 651 list entries. Any of them can switch off the permitted development right for a garden building. We look up the address first, then quote the right route.

    A constraint found after the drawings are done can mean starting again, so the check comes first.

    What Barnet's planning record says about householder schemes

    Barnet decided 1,361 householder applications in its latest published year, granted 80.2 per cent and decided 95.1 per cent in time. Those figures cover every kind of home alteration.

    Appeals show how far officers can be challenged. The Planning Inspectorate decided 413 householder appeals here over the latest five-year period and allowed 50.6 per cent. That is context, not a forecast for your room, but it is a reason to submit a well-evidenced scheme first time.

    The average Barnet home sold for £600,560, with a -4.9 per cent change over the past year. For many owners a garden office or studio is worth more than its cost in working space.

    Using the room: office, studio or guest space

    What the room is for changes the drawings more than its size. A home office needs daylight, power and a data line, and a studio may want a high ceiling. We draw the services route from the house so the electrician and the builder both price the same job.

    Barnet's condition against separate living is the point to plan around. A shower or WC is a normal addition, but a kitchen and a bed together read as a dwelling. If you might want a guest room, tell us at the start so the layout stays on the right side of the line.

    Insulation, a green roof or a deep overhang change the section, so we draw the roof build-up in full. That sheet is also what a kit supplier or joiner quotes from.

    Permitted development, certificate or application

    If the room stays inside the height and use limits and the house has no constraint, it can be built under Class E. For the height test the national order says: Max 2.5 m if within 2 m of a boundary; otherwise 4 m dual-pitched roof or 3 m any other roof. A Lawful Development Certificate in Barnet records that in writing.

    If it falls outside, the route is a householder application. We prepare it as planning drawings in Barnet, and the fee paid to the council for works within the boundary of an existing home is £272.

    Building Regulations are separate. A detached room can be exempt, and the wording for the smaller class is Detached building up to 15 m² with no sleeping accommodation is exempt. Where it is not exempt, our building regulations drawings in Barnet add the technical sheets.

    Your drawing set and what it costs

    You receive a block plan with every distance to the boundary, floor plan, elevations, a roof and floor section and a materials note, from £495 with VAT included. A second chartered technologist checks each sheet, and we redraw free of charge if the council asks for amendments.

    To see how the borough sits in the wider picture, read architectural drawings in Barnet. If you live near the boundary, compare garden room drawings in Brent and Camden, where the numbers differ.

    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.
    Brick house being extended, with a wide new opening supported over the ground floor
    Every side considered
    Flick across the turntable to spin it.

    Other services in Barnet

    Garden room drawings nearby

    Questions

    How big can a garden room be in Barnet?

    Where permission is needed, the council's limit is 20 sqm (<100 sqm garden); 30 sqm (>100 sqm garden). Under permitted development, the national coverage rule applies instead: Buildings may not cover more than 50% of the curtilage (excluding the original house).

    Does a garden room in Barnet need Building Regulations approval?

    Often not. A detached single-storey room can be exempt, but only without sleeping accommodation and within the distance and floor-area limits. A bed in the room removes the exemption.

    Will a protected tree stop my garden room?

    Not necessarily. Barnet publishes 718 tree preservation orders, and a nearby tree usually changes the position or foundation rather than ending the scheme.

    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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