Reports needed once a scheme reaches ten units
Ten dwellings makes a scheme major development. Affordable housing evidence, a statutory drainage consultee, biodiversity net gain under the major regime and a thirteen week clock all arrive at once.
At ten dwellings a residential scheme becomes major development, and the application pack changes more between nine units and ten than it does between ten and forty. The reports for a ten unit scheme typically add an Affordable Housing Statement, a drainage strategy that the lead local flood authority will read as a statutory consultee, a biodiversity net gain assessment under the major regime, and enough transport evidence to answer the highway authority. The determination period moves from eight weeks to thirteen. The fee moves too.
Nine units and a modest site area keeps you in the minor world. Ten does not.
What the threshold actually changes
Major development for residential purposes means ten or more dwellings, or a site of 0.5 hectares or more where the number of dwellings is not yet known. That definition sits in the Town and Country Planning (Development Management Procedure) (England) Order 2015, and it drives procedure rather than policy: publicity, consultation, determination period and fee band all follow from it.
Four consequences arrive together. The council must advertise the application in a local newspaper as well as posting a site notice. The lead local flood authority becomes a statutory consultee on surface water drainage. The target determination period becomes thirteen weeks. And the scheme is far more likely to be decided at committee rather than under delegated powers, which adds a cycle of four to six weeks depending on the council's calendar.
Nothing in that list is about design quality. It is all procedure, and it is all predictable, which makes it the easiest part of the programme to plan around.
Affordable housing evidence at ten units
National policy sets the point at which affordable housing contributions are normally sought at ten units, with a lower threshold available in designated rural areas where councils may apply it from five. The current Framework was published on 17 August 2026, so check the wording in that edition rather than an older copy, and read it alongside the adopted local plan policy, which sets the percentage and tenure split.
An Affordable Housing Statement at this scale does four things. It states the policy requirement by reference to the adopted plan. It sets out what the scheme provides, by unit, bedroom count and tenure. It explains how the units are distributed across the site and whether they are tenure blind. And it deals with the delivery mechanism, normally a section 106 agreement with a registered provider clause.
If the scheme cannot meet the policy percentage, the statement should say so plainly and be accompanied by a viability appraisal rather than a paragraph of assertion. Councils refer viability evidence to their own consultant, and a thin appraisal buys a delay rather than a concession.
Thirteen weeks, and what fills them
The longer period is not spare time. It is consumed by the consultation cycle and the officer's need to resolve objections from statutory consultees before writing the report.
A workable sequence looks like this:
- Pre-application advice, ideally with the highway authority and the lead local flood authority present rather than consulted separately.
- Surveys booked against their seasons, because ecology in particular cannot be compressed.
- Draft technical reports issued to the design team for coordination, not straight to the council.
- Validation check against the council's own local list, which will differ from the national list.
- Submission, then a planned response to consultee comments in weeks five to eight.
The last point is where applications are won. Consultee objections that go unanswered until week eleven usually produce either a refusal or an extension of time the applicant is in no position to refuse.
Drainage and highways at major scale
Once the lead local flood authority is a statutory consultee, a two page drainage note stops being enough. The authority will look for the discharge hierarchy applied in order, greenfield or betterment run-off rates justified by calculation, storage volumes for the design events with a climate change allowance, exceedance routes, and a maintenance regime naming who adopts what.
Highways expectations are proportionate to trip generation rather than unit count alone. Ten dwellings in a market town with a constrained junction can attract more scrutiny than ten dwellings on a distributor road. A Transport Statement is usually the right document at this scale, with trip rates drawn from a recognised database, a personal injury collision review covering the surrounding network, and a visibility splay assessment for the access. The full Transport Assessment threshold sits well above ten units in most authorities, but the highway authority can ask for one where local conditions justify it.
Do not assume the drainage and highways work can run in parallel with the layout. Both regularly change the layout.
Biodiversity net gain under the major regime
Mandatory biodiversity net gain applied to major development from 12 February 2024 and to small sites from 2 April 2024, so a ten unit scheme is in the major regime and gets none of the small site transitional treatment. The gain is 10 per cent measured against the statutory metric, with habitats secured for 30 years.
The practical order of work matters more than the arithmetic. Baseline habitat survey first, in a suitable season, then the metric, then the layout, then the Biodiversity Net Gain Assessment that explains the result. Running the metric on a layout that is already fixed tends to produce an on-site shortfall that has to be bought out through off-site units or statutory credits, which is the most expensive way to arrive at the same number.
The Environment Act 2021 regime expects the metric to be completed by a competent person, and the biodiversity gain plan is approved by the council after permission rather than with it. Budget for both stages.
Publicity, consultation and the objection profile
Newspaper advertising and a wider notification radius mean more neighbours see a major application. Objection volume rises, and with it the chance of a committee determination.
Ten units rarely triggers a Statement of Community Involvement as a validation requirement, which most authorities reserve for larger schemes, but there is a case for consulting anyway. A single evening session before submission, with boards and a comment form, gives the officer something to point at when the petition arrives. Record it properly if you do it, because an undocumented consultation carries no weight in the committee report.
Parish and town council comments deserve particular attention at this scale. They are not statutory consultees in most cases, but committee members read them.
Budgeting the evidence base
The cost pattern at ten units is lumpy. The application fee steps up into the major band and is indexed annually on 1 April, so check the current fee schedule rather than last year's figure. Ecology, drainage and transport are the three reports most likely to exceed their quoted fee, usually because a second survey visit or a revised layout was not in the original scope.
Two things reduce the total. Fixing the layout after the constraints work rather than before removes most abortive fees. And producing the narrative documents, the planning statement, design and access statement and affordable housing statement, from structured drafts rather than from scratch turns unbilled writing time into review time. You can see the full set of report types by category and which ones the ten unit threshold tends to pull in.
Enter your postcode on PlanScope to see which reports your site is likely to need at this scale, then take the drafts to the professionals who will sign them.
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. For specialist technical reports, qualified professional input may be required.
Frequently asked questions
What counts as major development for housing?
Ten or more dwellings, or a site of 0.5 hectares or more where the number of dwellings has not been fixed. The definition sits in the Development Management Procedure Order 2015 and controls procedure rather than policy, so it determines publicity, statutory consultation, the determination period and the fee band for the application.
Does a ten unit scheme always need affordable housing?
Not automatically. National policy sets ten units as the point at which contributions are normally sought, with a lower threshold available in designated rural areas, and the adopted local plan sets the percentage and tenure. If the scheme cannot meet the policy figure, submit a viability appraisal rather than an assertion, because councils refer viability evidence to their own consultant.
Is a Transport Assessment required at ten dwellings?
Usually not. A Transport Statement is the proportionate document at this scale, covering trip generation, access visibility and a collision review of the surrounding network. The highway authority can still ask for a full Transport Assessment where the access is constrained or the local network already has capacity or safety problems, so confirm the scope at pre-application stage.
Do the small site biodiversity net gain rules apply at ten units?
No. Mandatory biodiversity net gain applied to major development from 12 February 2024 and to small sites from 2 April 2024, and ten dwellings falls within the major regime. The scheme needs a 10 per cent gain measured on the statutory metric, habitats secured for 30 years, and a biodiversity gain plan approved by the council after permission.
How long does a major application take to decide?
The statutory target is thirteen weeks from validation, or sixteen weeks where an environmental statement is required. In practice many major applications run longer under an agreed extension of time, particularly where a committee date or a section 106 agreement is involved. Plan the response to consultee comments for weeks five to eight rather than leaving it late.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.