It is one of the most common frustrations in planning. You want to build an extension, convert a property, alter a roof or use a building in a slightly different way. The council raises objections. The plans are criticised. You are told the proposal is too large, poorly designed, harmful to neighbours or contrary to policy. Then you look down the road and see something much worse: a larger extension, an uglier dormer, a more obvious change of use or a building that looks as though it should never have been allowed.
It is natural to ask why someone else appears to have got away with something while your own proposal is being scrutinised so closely. The difficulty is that the built environment is not always a reliable guide to what is lawful, acceptable or likely to be approved. Your neighbour’s development may have planning permission. It may be permitted development. It may be immune from enforcement action because it has been there for many years. Or it may simply be unlawful, but nobody has complained.
Not everything you can see has planning permission
People often assume that, if something has been built, the council must have approved it. That is not always right. There are many reasons why a nearby extension, outbuilding, roof alteration or change of use might exist.
It may have been granted planning permission years ago under different planning policies. It may have been built under permitted development rights, without the need for a full planning application. It may have been approved because the particular site circumstances were different. It may have become lawful through the passage of time. It may also have no permission at all.
A building can be unlawful and still remain in place for many years if nobody complains, if the council does not investigate it or if the council decides that formal enforcement action is not justified. This is why it is risky to rely too heavily on what has happened next door.
There is no automatic inspection after building work
Many people imagine that councils have planning officers patrolling streets looking for unauthorised extensions, loft conversions and garden buildings. In reality, planning enforcement teams are usually complaint-led. They have limited resources and are unlikely to inspect every street looking for possible breaches of planning control.
There is also no general process by which the council checks every completed development against the approved planning drawings. This is sometimes confused with building control, which is a separate regime concerned with matters such as structural safety, fire safety, insulation and drainage. A building control inspection does not mean the works have planning permission, and building control approval does not regularise a planning breach.
This can create a strange situation. One person may build something without permission and never hear from the council. Another person may do something very similar and receive an enforcement letter within weeks, simply because a neighbour complains. That can feel unfair, but it is how the system often works.
Planning enforcement is discretionary
Even where there has been a breach of planning control, the council does not have to take formal action. Planning enforcement is discretionary. The council must consider whether it is expedient to take action, having regard to the development plan and any other material considerations. In plain English, the council should ask whether the breach causes enough planning harm to justify formal action.
This means that not every breach leads to an enforcement notice. A minor technical difference from approved plans may not justify action. A small change in materials, a modest increase in height or a slight repositioning of a structure may be treated differently from a serious unauthorised change of use or a major development causing clear harm. However, that discretion cuts both ways. The fact that the council did not take action against your neighbour does not mean it must take the same approach to you.
Enforcement varies between councils
The difference between councils can be striking. In the third quarter of 2025, 905 enforcement notices were served across England. That figure was spread across 296 local planning authorities. Eighty-four councils served no enforcement notices at all during that period, while 206 served fewer than ten. At the other end of the scale, Westminster and Brent each served 35 notices.
That does not mean some councils ignore breaches altogether. Nor does it mean that every enforcement notice is justified. It does show, however, that planning enforcement is not applied with the same intensity everywhere. Some councils have larger enforcement teams, more political pressure, more complaints, more complex urban development and a stronger appetite for formal action. Others are slower, less well-resourced or more willing to resolve matters informally. This is one reason why copying what someone has done in another borough, or even another street, can be risky.
Why your neighbour’s extension may not help you
Neighbours’ extensions and alterations can sometimes be useful. If there are many similar extensions in the street, they may help show that the character of the area has changed. If the council has recently approved a very similar proposal nearby, that decision may be a material consideration. If a proposal has been allowed at appeal, it may provide a helpful comparison.
But nearby development is not automatically a precedent. The council will still look at the particular site, the particular design, the relationship with neighbouring properties and the current planning policies. Your neighbour’s extension may have been approved under old policies. It may be materially different from your proposal. It may have a different relationship with the boundary, different land levels, different windows or different impacts on adjoining occupiers. It may also be unlawful.
That is why the argument “my neighbour has done the same thing” is rarely enough on its own. A better argument is usually more precise: what was approved, when it was approved, how similar it is, what policies applied and why the same planning judgment should be reached in your case.
The danger of copying what is already there
The real danger is assuming that, because something exists nearby, it must be safe to copy. That assumption can lead to expensive problems. You might build without permission, only to find that a neighbour complains and the council opens an enforcement investigation. You might submit a planning application expecting an easy approval, only to discover that the council regards the nearby example as poor design or an unfortunate historic mistake. You might spend money on drawings and building work without first checking whether permitted development rights actually apply.
The safest course is not to rely on guesswork. Before carrying out development, it is usually worth checking the planning history of the property, the planning history of nearby examples and whether the works might be permitted development. In some cases, the right route is a planning application. In others, it may be a Lawful Development Certificate. In enforcement cases, it may be possible to argue that the development is already lawful because of the passage of time. The correct strategy depends on the facts.
What to do if the council contacts you
If the council has contacted you about an alleged breach of planning control, do not ignore it. An initial enforcement letter or visit does not mean the council will definitely serve an enforcement notice. It may simply be asking for information. It may be possible to explain the position, provide evidence, submit a retrospective application or agree a practical solution.
However, you should be careful about what you say, especially where the issue concerns the use of a property, the number of occupiers, the date when works were completed or whether the development may now be immune from enforcement action. If a formal enforcement notice has already been served, the position is more urgent. There is usually a strict deadline for submitting an appeal, and if that deadline is missed the right of appeal is normally lost.
How Just Planning can help
Just Planning advises homeowners, landlords and small developers on planning enforcement problems, retrospective planning applications and appeals. We can review the council’s letter, the planning history, the approved drawings, nearby examples and the relevant planning policies. We can then advise whether the council’s position is justified, whether a retrospective application is likely to succeed or whether an enforcement appeal should be made.
Nearby development can sometimes help your case, but only if it is understood properly. The fact that your neighbour got away with it is not, by itself, a planning strategy. If you have received an enforcement letter, been contacted by the council or are thinking about copying something built nearby, contact Just Planning for clear, fixed-fee advice on your options.
