Reports needed for a scheme at the ten unit major threshold

At ten dwellings a residential scheme becomes major development, and the document bundle changes more than the unit count suggests. The determination period moves from eight weeks to 13. The lead local flood authority becomes a statutory consultee on surface water drainage. Affordable housing policy engages in most authorities. A design and access statement stops being optional. Biodiversity net gain moves from the small sites route to the full statutory metric. Plan for all of that at nine units, because deciding to add a tenth after the design is fixed is an expensive way to find out.

The threshold itself is procedural, set by the Development Management Procedure Order 2015.

What the major threshold changes

Major development for residential purposes means ten or more dwellings, or, where the number is not known, a site area of half a hectare or more. For other development the test is 1,000 m² of floorspace or a site of one hectare or more.

Crossing it changes five things at once.

The fee also moves into a different band and is indexed annually, so take the figure from the current national fee schedule rather than from a previous application.

Affordable housing evidence at ten units

National policy sets the threshold above which affordable housing contributions are normally sought at ten dwellings or 1,000 m², with a lower threshold available in designated rural areas. Most adopted local plans mirror it, and a scheme of exactly ten units lands on the line.

Three documents follow. An affordable housing statement setting out the tenure mix, the unit sizes, the distribution across the site and how the affordable homes will be managed. A draft set of heads of terms for the planning obligation. And, where the scheme cannot carry the policy-compliant provision, a viability assessment with the evidence to support it.

Two practical points. Councils increasingly ask for the affordable units to be shown on the layout rather than described, with the tenure indicated, because pepper-potting commitments made in writing tend to disappear at reserved matters. And a scheme proposing nine units on a site plainly capable of ten will attract a question about deliberate avoidance, so if the constraint is real, evidence it.

Statutory consultees that arrive at major scale

The consultee list lengthens and each addition brings a document with it.

• The lead local flood authority, on surface water drainage, requiring a drainage strategy with calculations rather than a statement of intent
• The local highway authority, at a level of scrutiny that usually means a transport statement or assessment depending on trip generation
• Natural England, where a designated site, protected species or a nutrient catchment is engaged
• The Environment Agency, where any part of the site is in Flood Zone 2 or 3 or where there is a contamination or groundwater issue
• Historic England, where a designated heritage asset of the relevant grade or a scheduled monument is affected
• The water and sewerage undertaker, on foul capacity and connections
• Active Travel England, on larger majors, with the current threshold worth checking before assuming it applies

Each of those consultees has 21 days to respond and each can hold a determination. The way to keep the clock moving is to give them what they need at validation rather than after the first round of comments.

Drainage and the lead local flood authority

This is the change that catches developers moving up from minor schemes. On a nine-unit scheme the drainage evidence is often a page in the planning statement. On a ten-unit scheme it goes to a statutory consultee who reviews calculations.

Expect to provide an infiltration test result or a justification for discounting infiltration, greenfield or existing runoff rates with the method shown, attenuation volumes for the design events including the climate change allowance, exceedance routing for events beyond the design standard, and a maintenance and adoption proposal for the drainage components.

A drainage strategy that omits the maintenance arrangement is the most common reason for a holding objection, because the authority cannot condition something with no responsible party attached to it.

Biodiversity net gain on a major site

Mandatory biodiversity net gain applied to major development from 12 February 2024 and to small sites from 2 April 2024. At ten units the scheme is major, so the small sites metric is unavailable and the full statutory biodiversity metric applies.

That has three consequences. The baseline habitat survey needs to be to the standard the full metric expects, which means a competent ecologist walking the site and classifying habitats rather than a desk exercise. The ten per cent gain has to be secured for 30 years, on site through a condition or off site through a legal agreement or purchased units. And the biodiversity gain plan has to be approved by the authority before development begins, which is a pre-commencement step with a real lead time.

The statutory metric must be completed by a competent person under the Environment Act 2021 regime. A drafted biodiversity net gain assessment is a starting point for that professional rather than a substitute for them.

Compare the position with a slightly larger brownfield proposal, where the evidence base for a 12 flat scheme shares most of this list but starts from different habitat baselines and a different policy footing.

The clock, publicity and committee

Thirteen weeks is the statutory period, and extensions of time are routine on majors. Agree one in writing rather than letting the period expire, because an expired period without agreement gives an appeal route that most developers would rather not need and leaves the authority free to refuse.

Publicity for a major application requires a site notice and a notice in a local newspaper, with 21 days for representations. Many authorities have a scheme of delegation that sends majors, or majors attracting a set number of objections, to planning committee. Find out which applies at pre-application, because a committee date is a fixed point in the programme and committee cycles do not move for applicants.

Where the authority expects pre-application community engagement, a record of it belongs in the submission even below the threshold at which a formal statement of community involvement is required.

Assembling the pack in the right order

Sequence the work so that survey results inform the design rather than describing it.

1. Constraints check and pre-application advice, including a written question about the local validation list for majors.
2. Ecology walkover and habitat baseline, early enough to catch seasonal survey windows.
3. Ground investigation and infiltration testing, before the layout fixes the drainage.
4. Transport scoping with the highway authority to settle whether a statement or an assessment is needed.
5. Design development, with the affordable units and the drainage features on the layout.
6. Technical reports: drainage strategy, biodiversity metric, transport, arboriculture, heritage where relevant.
7. Written statements last, drawing on the technical findings.
8. Draft heads of terms circulated to the authority's legal team before submission.

Step eight saves more time than any of the others. Section 106 drafting is routinely the reason a resolution to grant sits unissued for months, and starting it at submission rather than after committee removes that delay entirely.

To see which of the report types a ten-unit site is likely to need, browse the full list by category and start from the constraints.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.