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Barnet, London

Biodiversity net gain plans in Barnet

In Barnet, a biodiversity net gain plan matters when you build a new home or a larger scheme, and almost never for an extension or loft. The borough has no rule of its own on the subject that we could verify, so the national figure of 10 per cent applies. What sets Barnet apart is its trees: the council publishes 718 tree preservation orders. We quote a fixed price after a free constraints check.

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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 biodiversity net gain plans

    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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    Pencil resting on a dimensioned technical drawing beside a scale rule

    The Barnet position on biodiversity net gain

    We searched Barnet's published planning guidance for a local biodiversity net gain rule that carries a value, and found none that we can cite. That is useful in itself. It means the statutory metric and the statutory gain apply as written, with no borough uplift to design for.

    The council's own policy framework is the Barnet Local Plan 2021-2036, adopted in 2,025, read together with the Sustainable Design and Development Guidance SPD, Part 4: Guidance on residential extensions and alterations. Neither asks for more than the law does on gain, but both shape what you may build on a plot, and the habitat that remains after that is what the plan measures.

    Our biodiversity net gain service page sets out the national rules. This page is about how they meet a borough where trees and open land are the real constraints.

    Rows of brick terraced houses and gardens on a residential street

    Local figures for Barnet

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Tree preservation orders718 tree preservation orders published by the council—planning.data.gov.uk
    Tree preservation zones3,219 tree preservation zone polygons published by the council—planning.data.gov.uk
    Green Belt share of the council area28 % of council area covered by green-belt polygons—planning.data.gov.uk
    Domestic gardens share of land (GLUD 2005)28.1 % of land that is domestic garden (GLUD 2005)2005data.london.gov.uk
    Larger home extension prior approvals granted18 decisions2025 Q2 to 2026 Q1 (1 Apr 2025 to 31 Mar 2026)assets.publishing.service.gov.uk
    Larger home extension prior approvals refused103 decisions2025 Q2 to 2026 Q1 (1 Apr 2025 to 31 Mar 2026)assets.publishing.service.gov.uk
    Local plan adopted2,025—barnet.gov.uk
    Environment Act 2021 Sch 14 para 2, inserting Sch 7A TCPA 1990: 'relevant percentage' 10%10 %—legislation.gov.uk
    'Developments of 0.2 hectares or below': from 6 August 2026 BNG does not apply where the site area within the red line boundary is 0.2 ha or below0.2 ha—gov.uk
    Sch 7A para 9(3) as inserted: enhancement maintained for at least 30 years after completion30 years—legislation.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
    Which application your project needsLawful Development Certificate decision: 8 weeks. Prior approval decision: 42 days. Householder decision: 8 weeksYour projectWithin permitted development?Lawful Development CertificatePrior approvalHouseholder applicationYesLarger rear extensionNoABC

    Which application your project needs

    The usual route for a house; flats and listed buildings follow other rules.

    A · Lawful Development Certificate decision
    8 weeks
    B · Prior approval decision
    42 days
    C · Householder decision
    8 weeks

    Trees come first in Barnet

    Barnet publishes 718 tree preservation orders and 3,219 mapped protection zones. In a net gain assessment, a mature tree is not a minor feature. Individual trees are scored by size and condition and can carry a large share of a site's baseline value, so removing one can create a deficit that is expensive to repay.

    That is why we ask three questions before anything else. Is there a protected tree on or beside the plot? Would the building footprint, the access or the drainage run into its root area? And could the design shift a few metres to keep it? A tree kept costs nothing in the calculation, and a tree lost may need a lot of new planting to compensate.

    Please do not clear or prune before you have spoken to us. A tree or hedge left in place keeps the design options open, and one removed cannot be put back.

    Green Belt, gardens and the edge of the borough

    About 28 per cent of Barnet is covered by Green Belt, and domestic gardens account for 28.1 per cent of the land. Sites on the Green Belt edge need the closest look in the survey, because open land beside a plot can hold habitats the metric values highly.

    Further in, the typical site is a suburban garden. Lawn and mixed borders have modest value on the metric, so a well-designed scheme can often meet the gain with new native hedging, a few trees and a green roof, without needing off-site units.

    Which Barnet projects are caught

    Householder applications are exempt, and so is development granted under a development order. That covers most of what owners ask for, including the larger home extensions that Barnet's prior approval process handles. In the latest returns the council granted 18 of these and refused 103. A householder application for the same extension is also exempt.

    Sites of 0.2 hectares or below are exempt, and the de minimis rule excludes impacts below 25 square metres of habitat. A new house in a large rear garden, a block of flats or a conversion with major landscaping can still be caught.

    For schemes of that kind, see our new build drawings, which include the landscape layout the plan relies on.

    Timing, price and next step

    When a gain condition applies, the plan must be approved before work begins. We prepare it with the planning set so that the condition can be discharged straight away. For the wider application strategy, our planning consultant service covers the sequence.

    There is no list price, because the cost follows the number of habitat parcels and the trees involved. You receive a fixed quote after a free constraints check. See all our services on the Barnet area page.

    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.
    Georgian brick terrace with sash windows, arched fanlight doorways, stone steps and iron railings in London
    The street around you
    Move across the plinth — the blocks rise around the pointer.

    Other services in Barnet

    Biodiversity net gain plans nearby

    Questions

    Does Barnet ask for more than the national net gain figure?

    We found no Barnet rule with a value that goes beyond the statutory 10 per cent.

    Does a protected tree change my plan?

    Yes. Barnet publishes 718 tree preservation orders, and a protected tree is scored in the baseline, so removing it can be costly in the calculation.

    Does a loft conversion in Barnet need a plan?

    No. Loft conversions and extensions are householder development and are exempt, but the application form must still say so.

    How long does the gain last?

    It must be maintained for at least 30 years after completion.

    Sources and dates

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    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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