Intensification: when doing more of the same needs consent

Doing more of what you already do lawfully is usually not development. Intensification material change of use is the exception, and the line between the two is whether the character of the use has changed, judged as a matter of fact and degree. A café that serves twice as many coffees is still a café. A café that starts frying at 11pm for a queue on the pavement has probably become something else.

For a business occupier this matters in a specific way. Growth is what you are trying to do, and the planning consequence of growth is rarely considered until a neighbour complains or a council officer arrives.

The statutory definition of development

Section 55(1) of the Town and Country Planning Act 1990 defines development as the carrying out of building, engineering, mining or other operations, or the making of any material change in the use of any buildings or other land.

The word doing the work is material. An increase in the amount of an existing activity is a change in degree. It only becomes development when that change in degree produces a change in the kind of use being carried on.

The courts have put it as a question of whether the intensification results in a change in the character of the use. That formulation comes from the line of authority including Brooks and Burton Ltd v Secretary of State for the Environment, and it has been applied consistently since. There is no percentage, no doubling rule and no threshold. Anyone who tells you that a 50 per cent increase in customers triggers a change of use has invented it.

How intensification can amount to a material change

The situations where it does tend to share features. The activity acquires a new element, or it starts to affect its surroundings in a way that is different in kind rather than simply in volume.

Recognisable patterns:

• A use that was ancillary grows until it is a use in its own right. The classic is the small retail counter inside a workshop that becomes the main business.
• A use spreads outside the building. Storage moves into the yard, seating moves onto the forecourt, deliveries queue on the highway.
• Hours extend into evenings or nights, changing the relationship with residential neighbours entirely.
• The nature of the activity shifts even though its description does not. A gym adding amplified classes, a bar adding live music, a takeaway adding late night delivery riders.
• Numbers of people rise to the point where the traffic and servicing pattern is qualitatively different.

The thing to notice is that most of these involve something arriving, not simply more of something. That is the practical test to apply to your own plans: is anything new happening here, or is there just more of it.

The character of the use as the test

Character is assessed by reference to the planning unit, which is normally the unit of occupation. That means the comparison is between the character of the use of the whole unit before and after, not between the busiest hour before and the busiest hour after.

Officers and inspectors look at a cluster of indicators:

No single indicator decides it. A change in two or three at once, in the same direction, is what produces a finding of material change.

Traffic, hours and noise as evidence

These three carry the most weight in practice, because they are the ones neighbours notice and the ones consultees can measure.

Traffic is the most objective. Where a use generates a materially different pattern of vehicle movements, a Transport Statement is the document that either supports your position or undermines it. Count what actually happens rather than estimating. A business that can show delivery numbers unchanged over three years has a strong answer to an intensification allegation.

Hours are the most decisive. Extending into the evening changes the character of a use more reliably than any increase in daytime throughput, and it is the change most often found to be material. If you are considering it, look first at whether your existing permission contains an hours condition, because if it does the question is a condition question rather than a use question.

Noise and odour are where food and drink businesses get caught. Additional cooking capacity means additional extraction, and new or upgraded extraction is both physical development and evidence of intensification. A Ventilation and Extraction Statement dealing with duct route, termination height, odour control and fan noise is what the environmental health officer will want, and preparing one before installing the kit is much easier than retrofitting to satisfy a complaint.

Where intensification has been found, and where it has not

Without claiming any particular decision as binding, the pattern across decided cases and appeals is reasonably consistent.

Findings of material change have tended to involve a new activity appearing within an existing use, use spilling outdoors, a substantial extension of hours, or a shift from serving a local catchment to serving a regional one.

Findings against have tended to involve growth in turnover or customer numbers with no change in hours, servicing or external effects, seasonal peaks in a use that has always had them, and improvements in efficiency that increase output without changing what happens on site.

Treat appeal decisions as indicative of how inspectors approach the question rather than as precedent. The facts do the work, and two similar businesses can be decided differently because one kept records and the other did not.

Where the increase brings in an activity that has its own classification, the analysis stops being about intensification at all. A use that acquires a sui generis element has changed class, which is a different argument, and conditions attached before the 2020 reforms may still bite in ways that surprise people, as our note on conditions that survived the 2020 use class reforms sets out. Sector specific questions can turn on this, and which use class applies to dog day care and grooming is a good example of how quickly it becomes a classification question.

Conditions, and why they matter more than the case law

This is the part that saves businesses the most money.

Most commercial permissions carry conditions. Hours of opening, numbers of covers, numbers of children at a nursery, numbers of vehicles, restrictions on deliveries, limits on external storage, sometimes a restriction on the use itself. If your growth breaches one of those, the council does not need to prove a material change of use at all. It can serve a breach of condition notice, against which there is no appeal.

So the first document to read is not the Use Classes Order. It is your own decision notice, with every condition on it, and the decision notices for any later permissions or variations.

If a condition is in the way, the route is an application under section 73 of the 1990 Act to vary or remove it. That is determined on the merits of the condition rather than the principle of the use, which is usually a much easier argument to win.

Enforcement exposure and time limits

If intensification has amounted to a material change of use and no permission was obtained, the breach becomes immune from enforcement after ten years of continuous use. Change of use has carried a ten year period for many years, and the Levelling-up and Regeneration Act 2023 brought most other categories of breach into line rather than changing this one.

Ten years is a long time to run a business on an unlawful use. The practical exposure is not usually an enforcement notice. It is the sale, the refinancing or the lease renewal, where a solicitor asks for evidence of the lawful use and there is none.

Breach of a condition is different again, and a condition can be enforced whenever the breach is occurring, which is why condition compliance deserves more attention than it usually gets.

Applying before the change rather than after

Three routes, in ascending order of cost and certainty.

1. A section 73 application to vary the condition that stands in the way. Cheapest where the obstacle is a condition rather than the use itself.
2. A certificate of lawfulness for a proposed use under section 192, which produces a formal determination that what you intend is lawful without needing permission. Useful where you believe the change is not material and want that confirmed.
3. A planning application for the use as you intend to operate it, described accurately, supported by a Planning Statement that deals with hours, servicing, noise and parking directly.

The third is the one businesses resist and the one that most often ends the problem. A permission that describes your actual operation, with conditions you have negotiated rather than inherited, is worth more than years of arguing about whether the character of the use has changed.

Keep records either way. Delivery logs, staff rotas, till counts by hour, photographs of the yard. Evidence of what the use was is the asset that decides these cases, and it is only available to people who kept it.

This is general guidance, not legal advice. Whether a change is material depends on the specific facts, and a certificate of lawful development is the only formal way to confirm that a use is lawful, so check the position with your local planning authority or a qualified professional before relying on it.

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