Part 7 Class M: extensions at schools and colleges

School extension permitted development runs through Class M of Part 7 of Schedule 2 to the Town and Country Planning (General Permitted Development) (England) Order 2015, and the allowance is smaller than most governing bodies expect: the cumulative floorspace of new building, extension or alteration cannot exceed 25 per cent of the gross floor space of the original building or 100 m², whichever is the lesser. On a large secondary school, that means 100 m². One classroom and a corridor.

Used well, it still earns its place. A prior approval determination on transport and highways runs in weeks rather than the months a full application takes, which is why the class matters for summer works.

Which buildings the class covers

Class M applies to the erection, extension or alteration of a school, college, university or hospital building. The development has to be within the curtilage of the existing establishment and used as part of it, or for a purpose incidental to it.

Two consequences follow immediately. A nursery operating independently on a school site is not automatically covered, since the test is the use of the establishment rather than the presence of children. And a building for a use that would not be incidental to the school, such as a commercial letting or a separate community facility with its own access and hours, falls outside the class even where it sits inside the fence.

Alterations are included alongside extensions, which is more useful than it sounds. Re-roofing, replacing a curtain wall or reconfiguring an entrance can all be alterations, provided the limits are met and the materials condition is satisfied.

The floorspace limit

The figure is cumulative, measured against the original buildings, and taken as the lesser of 25 per cent and 100 m².

Original means the buildings as they stood when first erected, or as at 1 July 1948 for older establishments, so a post-war school that has already gained two mobile-replacement blocks has spent part of its allowance. Cumulative also means across the whole site rather than per building, and across time rather than per project. Three 40 m² additions over five years exhaust it.

Keep a record. The single most useful document an estates team can hold is a plan of the site marked with every addition made under permitted development, with the date and the area. Where no such record exists, reconstruct it from historic mapping, the council's planning history and any building control files before planning the next scheme.

Where the allowance has gone, the route is a full planning application. A short Planning Statement setting out the educational need, the site constraints and the alternatives considered does most of the work, and national policy has for some years given weight to the provision of new and improved school places.

Height and the 5 metre boundary standoff

Two spatial limits apply alongside the floorspace figure.

No part of the development may be within 5 metres of a boundary of the curtilage of the premises. On a tight urban site, that alone removes most of the buildable area, since school sites are frequently bounded on three sides by residential gardens.

Height is capped at 5 metres. That accommodates a single storey building comfortably and a two storey one not at all, which is the practical reason Class M is used for classroom extensions, sports stores and dining halls rather than for teaching blocks.

Development within the curtilage of a listed building is excluded from the class. Where the school occupies a Victorian board school or a country house campus, check the listing entry and the extent of the curtilage before assuming anything, and expect listed building consent to be needed for works affecting character.

Parking, turning and the limit that stops schemes

Class M does not permit development that would reduce the space available for the parking or turning of vehicles on the site.

This is the limit that catches good schemes late. A new classroom block sited on the edge of the staff car park, or a dining extension that clips the coach turning circle, fails the class outright regardless of floorspace. The prohibition is absolute, not a matter of degree, and it is not cured by proposing replacement parking elsewhere unless that space really does remain available.

Survey the existing parking and turning provision properly before siting anything. Mark the bays, the manoeuvring space and the swept paths for the largest vehicle that regularly attends, which on most school sites is a refuse vehicle or a coach rather than a delivery van.

Prior approval for transport and highways

Before development under Class M begins, the developer must apply to the council for a determination as to whether its prior approval will be required for the transport and highways impacts of the development.

The scope is narrow, which is the attraction. The council is not assessing the design, the appearance or the effect on neighbours. It is assessing transport and highways impacts, and it must reach a view within the period the Order allows or the development may proceed in accordance with the details submitted.

What to send: the description of development, a site plan, a plan showing the parking and turning arrangements before and after, and a short transport note. On anything beyond the smallest addition, a Transport Statement covering the change in pupil or staff numbers, the trip generation, the existing arrival and departure arrangements and the effect on the surrounding network answers the question before it is asked.

Construction traffic is a separate question and often the more contentious one on a school site. A Construction Traffic Management Plan covering routing, delivery timing around the school day, wheel washing and pedestrian segregation is worth submitting even where it is not required, because it is the document local residents will ask about.

Playing fields and Sport England

Playing field land carries its own protections, and they sit outside the General Permitted Development Order.

Sport England is a statutory consultee on planning applications affecting playing fields, and it applies published policy to objections and to the exceptions it will accept. Separately, school playing field land is subject to statutory controls on disposal and change of use, and academy and maintained school land can be subject to further restrictions in its funding or transfer agreements.

The practical position for an estates team is that any proposal touching a marked pitch, a former pitch or land used for outdoor sport within the last five years needs checking against all three regimes before the design is fixed. Establish the status of the land first. It is the question that most often turns a summer project into a two year one.

Fitting the work into a term-time programme

Schools build in the summer, and the consent programme has to be built backwards from that.

A workable sequence starts in the autumn term: confirm the permitted development allowance remaining, survey parking and turning, establish the status of any playing field land, and settle the scheme in outline. Submit the prior approval application in the spring term with the transport material complete. Use the determination period to procure, and start on site the week the pupils leave.

The failure mode is submitting in June. A prior approval determination is quick by planning standards and still not quick enough to absorb a request for more transport information three weeks before the contractor arrives. Where the works also need building regulations approval, that runs on its own timetable alongside. Other Part 7 classes follow a similar pattern for other building types, and Part 7 Class H for industrial and warehouse extensions works the same way.

This is general guidance, not legal advice. A lawful development certificate is the only formal way to confirm that works are lawful, so 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.