The evidence base for a nine dwelling greenfield scheme

Nine dwelling planning evidence sits in a useful gap. Nine units is not major development, so the determination period is eight weeks rather than 13, the statutory consultee list is shorter, and several policy thresholds do not engage. What does apply in full is the biodiversity gain condition, and on a greenfield site the ecology and landscape work is the part that governs your programme.

So the evidence base is smaller than a major scheme's and it takes just as long to assemble, because survey seasons do not scale with unit numbers.

Why nine units sits below the major threshold

Major development for residential purposes means ten or more dwellings, or a site area of half a hectare or more where the number of dwellings is not known. Nine units on a site under half a hectare is a minor application on both limbs.

That has concrete effects. The determination period is eight weeks. The lead local flood authority is not a statutory consultee in the way it is for majors, so surface water is handled by the authority's own drainage officer or by an internal consultation. A Statement of Community Involvement is not expected, since the thresholds for community involvement and for transport assessments sit far higher. And environmental impact assessment screening is unlikely to be triggered, because the screening thresholds for urban development projects turn on far larger dwelling numbers, site areas or floorspace figures, unless the site lies in a sensitive area.

The thresholds PlanScope uses to flag reports follow the same pattern: major at ten or more units, a transport assessment at 50 or more units, an affordable housing statement at ten or more units, community involvement at 50 or more. Councils' own validation lists and national policy thresholds take precedence over any tool, so read the list.

Where nine units sits on a site of more than half a hectare, the position changes on the second limb and the application may be treated as major. Check the site area before assuming the shorter route. Contrast this with a scheme that crosses the line, covered in our note on which reports a 12 flat brownfield scheme needs.

Ecology surveys and the seasons that govern them

This is the long pole in the programme, and it is fixed by biology rather than by negotiation.

Start with a Preliminary Ecological Appraisal in the winter before you intend to apply. It can be done in any month, and it tells you which species surveys you need before the season opens.

On a greenfield site with hedgerows, rough margins and any pond within a few hundred metres, expect at least two of these. Great crested newts are the most common programme risk, because the environmental DNA window is only ten weeks long and a negative result still needs to be reported with the effort applied.

Where a licence turns out to be needed, a Protected Species Survey and any European protected species licence require a suitably licensed ecologist under the Conservation of Habitats and Species Regulations 2017, and an AI-assisted draft is a starting point for that professional rather than a substitute for them.

Highways and drainage for a small scheme

Nine dwellings generates a modest number of trips, and the highway evidence should be proportionate to that.

A transport statement rather than a transport assessment is normal at this scale, covering the access design, visibility splays, the trip generation from a recognised source, parking against the adopted standard, cycle parking, and refuse vehicle access. Add a swept path drawing for the largest vehicle that needs to enter, and a tracking drawing for the refuse vehicle if the access is to be adopted. Where the access works affect the public highway, a separate highways agreement is needed, and the timing of that agreement is often the real constraint rather than the planning decision.

For drainage, the sequence is the same as on any site. Establish infiltration potential by testing, then work down the hierarchy. Calculate the greenfield runoff rate for the site, confirm any minimum discharge rate the authority accepts, and size the storage with the current climate change allowance applied, naming the allowance version.

A Drainage Strategy is proportionate at this scale and usually short. Where the site is in Flood Zone 2 or 3, or is a hectare or more, a flood risk assessment is needed as well, and on a greenfield site the arriving overland flow from higher land often matters more than the site's own runoff.

Landscape and settlement edge evidence

A nine unit greenfield scheme is almost always at the edge of a settlement, which makes the landscape case the substance of the application.

What the officer assesses is whether the site reads as part of the settlement or as open countryside, whether the scheme respects the existing pattern of development, and what happens to the new edge. Where the site lies outside a settlement boundary, in a National Landscape, or within a locally designated gap, a landscape and visual assessment prepared to GLVIA3 principles is usually expected, and councils expect a suitably qualified author.

Three pieces of evidence do most of the work. A settlement edge analysis showing how the existing edge is formed and how the scheme continues or changes it. Viewpoints from the routes people actually use, including public rights of way, rather than from the site itself. And a landscape scheme that creates a defensible new boundary rather than leaving a fence against a field.

Trees and hedgerows need their own evidence. A survey to BS 5837:2012 covers trees on and adjacent to the site with root protection areas, and removal of a countryside hedgerow may engage the hedgerow regulations with their own notification procedure and important hedgerow test.

Biodiversity net gain and the small sites route

The biodiversity gain condition has applied to small sites since 2 April 2024, and nine dwellings is a small site: fewer than ten dwellings on a site of less than one hectare.

Check the exemptions first. Self-build and custom housebuilding of no more than nine dwellings on a site no larger than half a hectare is exempt where the housing meets the definition, which is directly relevant at this scale. The de minimis exemption, covering development affecting less than 25 square metres of on-site habitat and less than five metres of hedgerow, will not help on a greenfield field.

Where the condition applies, the small sites metric is available and is simpler than the full statutory metric. It cannot be used in every case: where irreplaceable habitat is present, or where the site contains certain priority habitats or protected species, the full metric applies. That determination comes from the ecological survey, which is another reason to run the appraisal early.

A Biodiversity Net Gain Assessment under the Environment Act 2021 expects the statutory metric to be completed by a competent person, and the biodiversity gain plan is approved by the authority after permission and before works start. On a greenfield site with hedgerows and improved grassland, hitting the ten per cent uplift on-site is often achievable with margins and hedgerow enhancement, and it needs designing into the layout rather than added afterwards.

Affordable housing and local thresholds

National policy generally means affordable housing is not sought from schemes of ten units or fewer that are no larger than 1,000 square metres, which is why nine units is such a common scheme size.

Two qualifications matter. In designated rural areas the threshold can be set lower through the local plan, so a scheme of five or six units in such an area may attract a requirement. And some authorities seek a financial contribution below the unit threshold where their plan and viability evidence support it.

Read the adopted policy rather than the national position. Where a contribution is sought, it may come through a planning obligation, and the negotiation is often the slowest part of the process on an otherwise simple application.

The levy applies separately. Check the charging schedule, submit the additional information form, and claim any self-build exemption before work starts, because the exemption is lost if the claim is late.

Sequencing the surveys against the programme

Work backwards from the submission date and accept that the ecology calendar sets it.

1. Autumn or winter: site appraisal, preliminary ecological appraisal, tree survey, infiltration testing, topographic survey.
2. Winter: confirm which species surveys are needed and book them for specific dates.
3. Spring: great crested newt eDNA between 15 April and 30 June, reptile and botanical surveys as required.
4. Summer: bat emergence surveys where needed, between May and August, with a contingency visit.
5. Summer: archaeological desk-based assessment and any geophysical survey the county archaeologist asks for.
6. Late summer: fix the layout with the biodiversity gain, drainage and landscape constraints resolved.
7. Autumn: write the planning statement last and submit.

The scheme that slips is always the one where the layout was drawn first and the surveys were commissioned to justify it.

Enter your postcode on PlanScope to see which of the 66 reports a nine unit greenfield site is likely to need.

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