What changes when a scheme reaches 10 dwellings

At ten dwellings your application becomes major development, and almost everything about how the council handles it changes. The determination period stretches from eight weeks to 13. Publicity moves up a gear. Affordable housing policy engages. Biodiversity net gain switches from the small sites version of the metric to the full one. The 10 dwellings major development threshold is set by article 2 of the Town and Country Planning (Development Management Procedure) (England) Order 2015, and it is a bright line, not a judgement call.

Nine houses and ten houses are different animals in procedural terms. Knowing which side of the line you are on before you fix a layout saves months.

Where the ten dwelling line is drawn

Article 2 of the DMPO defines major development for residential schemes as ten or more dwellings. Where the number of dwellings is not known at the point of application, typically an outline with layout reserved, the test switches to site area of 0.5 hectares or more. For non-residential development the equivalent figures are 1,000 m2 of floorspace or a site of one hectare.

Counting is less obvious than it looks. A scheme of eight houses plus two flats above a shop is ten dwellings. A net figure matters too: converting one house into three creates a net gain of two, but the application still describes three dwellings, and councils differ on how they count for policy purposes. Ask the case officer in writing at pre-application stage and keep the answer. But the number on the application form is what validation officers work from, so make the description of development match the count you intend.

Self-contained student accommodation, retirement flats and houses in multiple occupation all have their own counting quirks. None of them are edge cases you want to discover at validation.

The clock changes to 13 weeks

The statutory determination period for a major application is 13 weeks from validation. For anything smaller it is eight weeks. Where the development is subject to environmental impact assessment the period is 16 weeks.

That extra five weeks is not idle time. Statutory consultees have 21 days to respond, and on a major the list is longer: the lead local flood authority, the highway authority, the water and sewerage undertaker, and often the county archaeologist and Natural England. Each of those can generate a holding objection that stalls the file.

In practice, most major applications run past 13 weeks under an agreed extension of time. Refusing to agree one rarely helps. It buys you an appeal against non-determination and loses you the officer's goodwill on a scheme that still needs a recommendation.

Publicity, consultation and who gets notified

Publicity requirements for major development are heavier. The council must publish a site notice or serve neighbour notification, and it must also advertise the application in a local newspaper. Smaller applications need only one of those routes.

More publicity means more representations. On a ten unit scheme in a village, expect the parish council to comment and expect the application to attract enough objections to trigger the council's referral rules for committee determination rather than a delegated decision. That adds weeks to the programme and puts the recommendation in front of members who have not read the technical appendices.

A Statement of Community Involvement is not required by national policy at ten units, though some local validation lists ask for one and early engagement with neighbours often defuses the objections that would otherwise send the application to committee.

Affordable housing enters the conversation

The national policy threshold for seeking affordable housing contributions is ten or more dwellings, or a site of 0.5 hectares or more. Below that, national policy expects contributions not to be sought, subject to the rural exception.

In designated rural areas, including National Landscapes and areas designated under section 157 of the Housing Act 1985, authorities may apply a lower threshold. Check the adopted local plan rather than assuming the national figure, because the rural threshold is where most small developers get caught.

An Affordable Housing Statement should state the tenure split, the transfer arrangement and whether the offer is on-site or a commuted payment. If you are arguing for less than policy requires, that argument belongs in a viability appraisal prepared to the RICS professional statement, not in a covering letter.

The evidence base that appears at ten units

Several documents become either mandatory or effectively unavoidable at the major threshold.

A design and access statement is required for major development under article 9 of the DMPO. Below ten units it is only required in a conservation area or World Heritage Site. A Design and Access Statement that reads as a description of the drawings rather than a justification of them is the most common weak point in a small major application.

Biodiversity net gain applies to major development from 12 February 2024 and to small sites from 2 April 2024, so ten units puts you into the full statutory metric rather than the small sites version. A Biodiversity Net Gain Assessment must be completed by a competent person under the Environment Act 2021 regime, and the biodiversity gain plan needs approval by the local planning authority before development begins. An AI-assisted draft can structure the narrative and the policy references, but the metric calculation itself is a professional task.

Transport evidence scales too. The thresholds PlanScope uses flag a Transport Assessment at 50 or more units, so at ten a transport statement is usually proportionate. Councils' own validation lists take precedence and some ask for more.

Drainage moves from a note on the plan to a strategy. On a site of one hectare or more a flood risk assessment is required regardless of flood zone.

Fees, the planning guarantee and extensions of time

The planning application fee is charged per dwelling with a banded structure and a cap. Fees are indexed annually on 1 April, so quote the current schedule rather than a figure from an old file, and check the fee calculator before you submit.

The planning guarantee still applies. If the council has not determined the application within 26 weeks, and no extension has been agreed, the fee should be refunded. That is a weak remedy and it does not get you a decision, but it is worth knowing when a major application drifts.

Where the scheme is refused, the appeal route is written representations, a hearing or an inquiry, with a six month deadline from the decision notice for a full application. Householder appeals have a shorter window, which does not apply here.

Designing under the threshold, or committing above it

There is nothing improper about designing a scheme of nine dwellings. There is something improper about splitting a site into two applications of nine to avoid affordable housing, and councils treat an artificial split as a single scheme where the land is in the same ownership and the phases are clearly related. Inspectors have taken the same approach on appeal.

The honest calculation runs like this. Nine units keeps you on an eight week clock, out of affordable housing policy in most authorities, and inside the small sites biodiversity metric. Ten units costs you the affordable housing contribution and roughly two extra months, and it may buy you a better layout, a proper access and a workable density.

Run both. If the tenth unit does not pay for the affordable housing contribution, the fee uplift and the extra consultant time, it is not worth having.

Enter your postcode on PlanScope to see which reports a ten unit scheme on your site is likely to need before you commit to a layout.

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.