Part 4 Class A: temporary buildings for a development site

Part 4 Class A of the General Permitted Development Order 2015 permits buildings, moveable structures, works, plant and machinery required temporarily in connection with, and for the duration of, operations being carried out on that land or on land adjoining it. That is what allows a site office, welfare cabins, a materials compound, a batching plant and a tower crane to appear without a separate planning application.

It has two limits that catch developers out. The right only exists where the underlying operations have planning permission, or permission is deemed to be granted, so the compound cannot lawfully go in before the consent does. And everything has to come out afterwards, with adjoining land reinstated, as a condition of the right itself.

What Class A actually permits

The wording is broad on purpose. Buildings, moveable structures, works, plant and machinery all fall within it, which covers the full normal apparatus of a construction site: portable offices, drying rooms and canteens, secure stores, fuel bunds, scaffolding and crane bases, temporary haul roads, site hoarding and the plant doing the work.

Two conditions in the Class qualify it. When the operations have been carried out, anything permitted by Class A has to be removed. And any adjoining land on which Class A development was carried out has to be reinstated to its previous condition as soon as reasonably practicable.

So the right is self-terminating. It is not a general permission for a compound, and it does not survive the completion of the works it was serving.

The link to the permitted operations

Class A is parasitic on the main consent. Development is not permitted where the operations in question are mining operations, or where planning permission is required for those operations and has not been granted or deemed to be granted.

Three practical consequences follow.

You cannot establish a compound on the strength of a submitted application. Until permission exists, there are no permitted operations for the temporary buildings to be connected with, and an early compound is unauthorised development in its own right.

Prior approval routes do count. Where development proceeds under a prior approval class, permission is granted by the Order, so Class A attaches to it. That matters on rural conversions, where the structural works allowed under a barn conversion class need somewhere to store materials and park plant, a point that interacts with the limits discussed in Class Q structural works and what is reasonably necessary.

And where the operations are themselves permitted development, Class A follows in the same way.

Required temporarily, and in connection with

These words do more work than they look as though they do. The test is whether the structure is required for carrying out the operations, not whether it is convenient to have on site.

The sales suite is the recurring argument. A marketing suite exists to sell the completed units rather than to carry out the building operations, so relying on Class A for it is a risk. The tidy answer is to include it in the main application with a condition requiring removal by a stated date, which costs nothing at application stage and removes the dispute.

Land adjoining the site

Class A extends to land adjoining the land where the operations are happening, which is why a compound in the neighbouring field can be lawful without its own permission.

Adjoining means touching. Land on the far side of a road, or separated by a strip in other ownership, is not adjoining, and a compound there needs planning permission. Check the title plan rather than the site plan, because the two often disagree about where a boundary runs.

The reinstatement condition bites hardest here. A compound on adjoining agricultural land has to be returned to its previous condition as soon as reasonably practicable, which in practice means removing the stone, breaking up any compaction, reinstating topsoil and reseeding. Price that at the outset and record the pre-existing condition with a photographic survey before anything arrives on site. Without the survey, there is no agreed baseline to reinstate to.

Where another Part applies instead

Part 4 Class A is not the only route, and using the wrong one is a common error.

Hoardings, gates, fences and walls can fall within Part 2 Class A, with its own height limits, independently of any construction operations. Temporary uses of land for a limited number of days a year sit in Part 4 under the separate temporary use classes, which govern things like a car park for an event rather than a construction compound. Mineral exploration and mining-related operations have their own Part. Development by local authorities and by the Crown is dealt with in separate Parts again.

Two general restrictions override all of them. Article 4 directions can remove permitted development rights in a defined area, and the Order does not permit development that is environmental impact assessment development requiring assessment unless the screening position has been resolved. On a major site with a screening opinion outstanding, check that before the compound is mobilised.

Conditions on the main permission take precedence

This is where most of the real disputes happen. Permitted development rights sit alongside the main permission, and a condition on that permission can restrict what the compound does even though Class A would otherwise allow it.

A construction management plan condition typically fixes the compound location, working hours, wheel washing, lorry routing and dust control, and once approved it is enforceable. A condition requiring the approval of a site set-up plan before works start has the same effect. So the sequence is to agree the construction management plan and, where lorry movements are the issue, the construction traffic management plan, and then rely on Class A for the structures within that approved arrangement.

Illustrative example, not a real scheme: a 60 dwelling site with permission granted in March establishes a compound in April on an adjoining paddock in the same ownership, comprising four cabins, a stone hardstanding, a wheel wash and a crane base. All of it sits within Class A because the operations have permission and the paddock adjoins the site. The compound location, hours and routing are controlled by the approved construction management plan condition. In month 26 the cabins come out, the stone is removed, the paddock is reinstated and reseeded, and the photographic baseline taken in April is what proves it was done properly. Had the developer relied on Class A for a sales suite as well, that single element would have been the unauthorised one.

The risk of overstaying

Once operations are complete, the right ends. Leaving a cabin or a hardstanding in place is a breach of the condition attached to Class A, and the structure becomes unauthorised development.

Authorities do pursue these, usually after a neighbour complaint, and the practical remedy demanded is removal. Enforcement time limits for operational development have been the subject of reform under the Levelling-up and Regeneration Act 2023, and the position on when those changes take effect should be checked rather than assumed.

The more common commercial problem is simpler. A developer who wants to keep a compound for the next phase of a multi-phase scheme needs either operations under way on the adjoining phase, or planning permission for the compound. Phasing the permissions so that there is always a live set of operations is a reasonable strategy, and it belongs in the planning statement at the outset rather than being explained to an enforcement officer later.

But the single least costly protection is the photographic survey. Take it before the first cabin arrives.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. A Lawful Development Certificate under section 192 of the Town and Country Planning Act 1990 is the only formal way to confirm that proposed works are lawful without permission.

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