Consent route for a modular classroom at a school

The modular classroom consent route usually comes down to three questions asked in order. Does the work fit the permitted development right for school buildings in Class M of Part 7 of Schedule 2 to the General Permitted Development Order 2015. If not, is a temporary permission the right application, or does the school need a permanent one. And does the unit sit on a playing field, because that brings a statutory consultee and a separate consent regime with it.

Get the answers in that order and the rest of the pack follows.

Permitted development for school buildings and its limits

Class M of Part 7 permits the erection, extension or alteration of a school building on land used as a school, subject to conditions. The limits are tighter than most people assume, and they are cumulative across everything built since the original buildings.

The floorspace ceiling is the one that bites. The cumulative increase in gross floorspace is capped, calculated as a proportion of the gross floorspace of the original school buildings or an absolute figure, whichever is the lesser, so a school that has already added a hall and a mobile unit may have nothing left. Height is capped, no part may sit within a set distance of the boundary of the curtilage, and the right does not extend to land that is not already in school use.

Read the current order text rather than working from a summary, because Part 7 has been amended more than once and the figures in older guidance are not reliable. Three practical checks save time. Establish the gross floorspace of the original buildings from historic plans, list every addition since, and measure the distance from the proposed unit to the curtilage boundary.

Where the right is available, a prior notification is not required for Class M, but many authorities will accept or even encourage a Lawful Development Certificate application confirming the position. On a school site with a long history of ad hoc additions that certificate is worth having.

Temporary permissions for modular units

Where Class M does not cover the unit, an application follows, and the choice between temporary and permanent matters more than the fee.

A temporary permission for a stated period is granted under the power to impose conditions limiting duration, and it suits genuine short-term need: a bulge cohort, decant accommodation during a rebuild, or a trial of an expanded intake. It is quicker to argue where the unit is visually poor or sits on space the plan protects, because the harm is time-limited and the reinstatement obligation is explicit.

A permanent permission suits a unit that will remain, and it is honest to apply for one where the need is structural rather than temporary. Authorities notice when a three-year consent is renewed twice, and the third renewal is where officers start asking why a building of poor quality is being kept indefinitely on a site with a masterplan.

Two drafting points. State the end date and the reinstatement works the school will carry out, including removal of foundations and hard surfacing and the restoration of any grassed area. And say what happens to the roll if the unit goes, because an officer who suspects the accommodation is permanent in all but name will condition tightly or refuse.

Loss of playing field and the statutory consultation

This is the item that catches schools out. Development affecting a playing field triggers consultation with Sport England as a statutory consultee under the Development Management Procedure Order 2015, and its position carries real weight. The tests it applies are about whether the playing field is surplus, whether equivalent or better replacement is provided, or whether the development is ancillary to the use of the site as a playing field.

Siting a classroom on a corner of a pitch is therefore not a small decision. The application needs a plan showing the extent of playing field affected in square metres, the pitch layout before and after, evidence of current and projected curriculum and community use, and either a replacement proposal or an argument on surplus supported by a playing pitch assessment.

A separate consent applies to disposal or change of use of school playing field land, which requires the Secretary of State's consent under the School Standards and Framework Act 1998. That is a distinct process from planning permission and neither replaces the other.

Where the site has any alternative, put the unit on hard surfacing and accept the loss of some play space instead. Losing 200 m2 of tarmac is a much easier argument than losing a corner of a grass pitch.

An illustrative example. A two-form primary needs a double modular classroom for a bulge cohort of 60 pupils arriving in September. Option one sits it on the edge of the junior grass pitch, removing about 250 m2 of playing field and triggering statutory consultation. Option two sits it on a corner of the hard play area, losing play space that can be partly replaced by remarking the yard. Option two is granted in eight weeks. Option one would have needed replacement provision and a much longer determination. The figures are illustrative.

Daylight, ventilation and internal standards

Modular classrooms are judged internally as well as externally, and the Department for Education area and environmental guidance is the reference point. Area guidelines set out expected teaching area per pupil and the supporting spaces a classroom needs, and the ventilation, thermal comfort and indoor air quality guidance sets performance for air quality, overheating and acoustics.

Three items recur in officer comments. Daylight to the teaching space, where a unit placed tight against an existing building or a boundary fence gets nothing on one elevation. Overheating in a lightweight building with large south-facing glazing, which needs shading, cross-ventilation or mechanical provision designed in. And acoustics, both between the new unit and the classrooms it abuts and from the plant on its roof.

Deal with the plant explicitly. An air source heat pump or air handling unit within a few metres of an existing classroom window needs the same treatment as any other rooftop plant enclosure: position, acoustic screening and a stated sound power level.

Access during construction and safeguarding

A live school is the hardest construction environment a small project can have, and an application that does not address it invites a heavy condition set.

The construction management information should cover the delivery route and hours, avoiding the drop-off and pick-up peaks entirely, a segregated contractor access and compound with its own gate where possible, hoarding lines that keep the compound outside the pupil circulation route, banksman arrangements for every vehicle movement within the site, and a statement that contractors are subject to the school's safeguarding procedures. Where site access shares the pupil entrance, deliveries need to be outside school hours.

A Construction Traffic Management Plan covering these points is normally conditioned in any event, so submitting one with the application removes a pre-start condition from the critical path. That matters when the unit has to be open for September.

Drainage and the surface water calculation

A modular unit adds roof area and usually hard surfacing, and school sites are frequently on drainage systems already at capacity with no as-built records.

The evidence needed is modest but specific. Establish the existing drainage arrangement from a survey rather than from an assumption, calculate the additional impermeable area, and show how the extra runoff is managed, whether by a soakaway if ground conditions allow, permeable surfacing around the unit, attenuation storage, or a restricted connection agreed with the undertaker. Where the unit sits on a playing field, be careful about infiltration features in ground that also has to drain a pitch.

A short Drainage Strategy covering those items is usually enough for a single unit, and the lead local flood authority will only comment in detail on larger schemes.

What to submit for a school building

For a modular unit needing permission, the pack normally runs:

1. Site location and block plans showing the existing curtilage, the unit, and the extent of any playing field or play space affected with areas in square metres.
2. Plans, elevations and sections of the unit with external materials, colour and any ramp, canopy or steps.
3. A Design and Access Statement covering siting, appearance, accessibility, daylight and the relationship to existing buildings.
4. A planning statement covering the consent route considered, pupil need, the temporary or permanent case, and the playing field position.
5. Playing field evidence where relevant: pitch layout before and after, use data and any replacement proposal.
6. A drainage note with the additional impermeable area and the management proposal.
7. Construction management and traffic information written around term-time operation.
8. A tree survey where units sit near mature trees, which on older school sites is common.

One honest uncertainty. Whether an authority treats a series of temporary units as a single cumulative development, or as separate small proposals, varies, and it affects both the Class M calculation and the playing field argument. Ask the case officer how the site's history will be treated before you settle the application strategy.

Browse all 66 report types on PlanScope to see which documents a school building project is likely to need.

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.