Discovering that your neighbour may have built over the boundary and onto your land is deeply unsettling. What looked like an ordinary extension, garage or garden wall suddenly raises a much more serious question – has somebody actually built on part of your property?
If they have, the legal starting point is fairly clear. A neighbour cannot normally build on your land without your agreement or some other legal right. A wall, extension or other structure that crosses the legal boundary may amount to trespass.
The difficult part is often proving where that boundary lies and deciding what should happen next. A court can order an encroachment to be removed, but removal is not automatic. Depending on the circumstances, the outcome might instead involve damages or a negotiated agreement that allows the structure to remain.
This guide deals specifically with building work that has crossed the legal boundary in England and Wales. If your neighbour is building very close to the boundary but apparently remains on their own land, see my separate guide to how close a neighbour can build to your boundary.
Contents
- Quick answer: What if my neighbour has built on my land?
- First establish where the boundary actually is
- Does planning permission allow a neighbour to build on your land?
- What can count as an encroachment?
- What should you do if the work is still going on?
- What if the building is already finished?
- Can a court make your neighbour remove it?
- What if the encroachment is only a few centimetres?
- What if the building has been there for years?
- Can you remove the encroachment yourself?
- What evidence should you collect?
- Can the dispute be settled without going to court?
- What happens when either property is sold?
- Frequently asked questions
Quick answer: What if my neighbour has built on my land?
If part of your neighbour’s building stands on land that belongs to you, without your consent or another legal right, that will usually amount to trespass.
You may be able to seek an injunction to prevent further work and, in an appropriate case, an order requiring the encroaching structure to be removed. Damages may also be available.
There are two important qualifications. First, you need to establish the legal boundary rather than simply assume that an existing fence marks it. Secondly, even where trespass is proved, the court has a discretion over the remedy it grants. A completed extension will not necessarily be ordered to come down.
If building work is still under way, however, act promptly. A problem spotted while foundations are being dug is usually much easier to resolve than the same problem discovered after the extension has been roofed, plastered and fitted out.
First establish where the boundary actually is
This is where many apparently obvious cases become less obvious.
Your neighbour’s new wall may plainly sit beyond the old fence. That is useful evidence, but it does not necessarily prove that the wall is on your land. The fence itself may never have followed the exact legal boundary.
Nor will the red line on a Land Registry title plan normally answer a dispute about a few centimetres. Most registered titles show only general boundaries. HM Land Registry confirms that there is no standard measurement or tolerance between the red edging on the plan and the exact legal boundary.
You can read the official explanation in HM Land Registry’s guidance on property boundaries.
I have regularly encountered the understandable assumption that a Land Registry plan settled the argument. Often it did not. The real answer could depend on an older conveyance or transfer, its plan, the physical features that existed when the land was divided and other historical evidence.
That is why enlarging a title plan on screen and measuring from the red line can be so misleading. Making the image bigger does not make it more accurate.
If the precise position remains disputed, a surveyor experienced in boundary work may need to compare the documents with an accurate site survey. The surveyor can give an expert opinion, but cannot finally determine a disputed legal boundary simply by measuring it.
For a fuller explanation, see how to establish the legal boundary between two properties.
Does planning permission allow a neighbour to build on your land?
No. Planning permission and private property rights are separate things.
A council decides whether development is acceptable in planning terms. It does not normally decide where the private legal boundary lies and planning permission does not give your neighbour ownership of your land.
The same applies to building regulations approval. Building control deals with matters such as structural safety, fire protection and drainage. It does not authorise trespass.
This can seem surprising. A neighbour may have planning permission for an extension and still be unable lawfully to build it exactly as shown because the design crosses land they do not own.
Equally, a building can remain entirely on the neighbour’s property but breach planning control. It helps to keep the two questions separate.
What can count as an encroachment?
The clearest example is part of an extension, garage or wall physically standing beyond the legal boundary. But an encroachment does not have to involve a whole room or a large piece of garden.
Walls and extensions
If a wall or other permanent structure has been built partly on your side of the boundary without permission or another legal right, that may amount to a continuing trespass.
The fact that only a narrow strip of land is involved does not create a permitted margin. It may, however, make a considerable difference when everyone comes to consider the sensible remedy.
Foundations
Foundations need particular care because the Party Wall etc. Act 1996 creates a limited exception to the ordinary position.
Where somebody is building a new wall wholly on their own land at the line of junction, section 1 of the Act can, once the relevant statutory requirements have been followed, allow necessary projecting footings and foundations to extend beneath the adjoining owner’s land. That is not a general licence to put foundations wherever convenient.
The Act draws an important distinction for “special foundations”, broadly foundations using beams or rods to distribute the load. These cannot be placed beneath adjoining land without the adjoining owner’s written consent.
The Government’s Party Wall Act explanatory booklet explains this distinction.
For the wider statutory rules, see my guide to the Party Wall Act. If work has already begun without a notice that should have been served, there is a separate guide on what to do if your neighbour has ignored the Party Wall Act.
Roofs, eaves and guttering
Property rights are not confined to ground level. An eave, roof edge, gutter or other projection into the lower airspace above your land can also amount to trespass if there is no permission or other legal right for it to be there.
I have kept that issue deliberately separate here because it is covered in detail in my guide to a neighbour’s guttering, roof or eaves overhanging your property.
What should you do if the work is still going on?
Do not wait for the builders to finish before raising the issue.
Take clear dated photographs. Preserve older photographs showing the previous fence, wall or other boundary feature. Obtain the title documents and, if possible, the drawings and measurements being used for the construction.
Then raise the problem with your neighbour promptly and in writing. Keep the tone factual. At this stage, the useful question is not “How do I make them knock it down?” but “Has the building actually crossed the legal boundary, and can the problem still be corrected?”
I have seen disputes become vastly harder because everyone argued about principle while the concrete continued to be poured.
If there is good evidence of a significant encroachment and the neighbour intends to continue despite being told about it, urgent legal advice may be required. A court can grant an interim injunction in an appropriate case to preserve the position until the dispute is determined.
An injunction is serious litigation, not a routine stop notice. The applicant will need to satisfy the court that interim relief is justified and may be required to give a cross-undertaking in damages, potentially compensating the other party if the injunction later proves to have been wrongly granted.
Urgency can justify moving quickly, but court proceedings should not normally be the first casual threat in a neighbour disagreement.
What if the building is already finished?
Completion does not make a trespass lawful. Nor can somebody deliberately acquire the right to build on your property simply by finishing the work before you object.
It does, however, change the practical landscape.
If an extension is complete, the cost and consequences of removing part of it may be substantial. The court will have to consider the appropriate remedy, not merely whether an encroachment exists.
This is also the point at which a negotiated solution may become attractive. Depending on the circumstances, the owners might agree that the structure remains in return for payment and a properly documented change to the property arrangements.
Any such agreement needs care. Allowing a structure to remain informally can leave an awkward title problem waiting for the next sale or mortgage.
Can a court make your neighbour remove it?
Yes. The court has power to grant a mandatory injunction requiring an unlawful encroachment to be removed. In a building case, that could mean altering or demolishing part of a completed structure.
But demolition is not automatic.
An injunction is a discretionary remedy. The court may consider the extent and effect of the encroachment, whether damages would provide an adequate remedy, the parties’ conduct and the practical consequences of the order.
Conduct can matter greatly. There is an obvious difference between a genuine surveying mistake and somebody who knows that ownership is disputed, ignores the objection and presses ahead hoping that the expense of demolition will force the neighbour to accept money instead.
Equally, the fact that removing a building would be expensive does not give a developer an automatic right to “buy” somebody else’s land after the event.
Where an injunction is not granted, damages may be awarded. Their assessment is fact-sensitive. Depending on the circumstances, damages may reflect financial loss, the effect on the property or, in an appropriate case, the value of allowing an infringement to continue.
There is no sensible online calculator for this. A two-centimetre projection with no practical effect is not the same problem as an extension occupying a strip of land needed for access or future development.
What if the encroachment is only a few centimetres?
A few centimetres can still matter. There is no general rule allowing a neighbour to build a little way over the boundary because the encroachment is small.
But small does not always mean significant, and significant does not always mean valuable.
A wall that has crossed the boundary by two centimetres may have very little practical effect. The same two centimetres could matter much more if they prevent a gate opening, reduce an already narrow driveway or interfere with your own proposed building work.
This is where neighbour disputes can become painfully disproportionate. Being right about the boundary does not necessarily make £40,000 of litigation a sensible way of dealing with it.
At the same time, simply ignoring the problem may store up trouble. If everyone agrees that a small encroachment can remain, it is usually better to record the arrangement properly than to leave two future buyers trying to reconstruct what the former neighbours intended.
What if the building has been there for years?
Age alone does not make an encroachment lawful. There is no general seven-year rule under which a neighbour automatically acquires land because a building has stood over the boundary for that period.
Long possession can nevertheless become legally important. Adverse possession may eventually arise, and the rules differ significantly according to whether the affected land is registered or unregistered.
For registered land, ten years of qualifying adverse possession can allow an application to HM Land Registry, but that does not mean ownership simply transfers on the tenth anniversary. The registered proprietor is normally notified and the statutory regime contains important safeguards and exceptions.
Different rules apply to unregistered land, where a 12-year period can become relevant.
Rather than repeat those complicated rules here, see my guides to adverse possession of registered land and adverse possession of unregistered land.
Previous agreements can also matter. If a former owner consented to the structure or the neighbours arranged their affairs on the basis of an agreed boundary, the legal position may be more complicated than a straightforward new trespass claim.
Can you remove the encroachment yourself?
I would be extremely cautious about doing this.
Even if you are convinced that part of the structure is on your land, the boundary itself may still be disputed. Removing bricks, cladding, foundations or another structural element could damage the neighbour’s property, create a safety problem and produce a second dispute considerably worse than the first.
There is a world of difference between cutting back a branch that grows over a fence and taking a hammer to somebody’s extension.
If physical removal is genuinely required and the neighbour will not agree, establish the legal position and seek the appropriate order rather than trying to settle the matter by demolition yourself.
What evidence should you collect?
Good evidence gathered early can save an enormous amount of argument later.
Keep photographs showing the site before, during and after construction. Save planning drawings, architects’ plans, builder’s drawings and correspondence about the proposed boundary position.
Obtain the title registers and title plans and check for older transfers, conveyances or plans referred to in the register. Historic estate-agent photographs, aerial images and old family photographs can sometimes show a boundary feature that has since disappeared.
If the dispute is really about centimetres, a suitably experienced boundary surveyor may need to inspect the site and provide an expert opinion. Ideally, the expert should consider the documentary evidence rather than merely measure the newest fence.
If litigation becomes likely, avoid commissioning competing reports casually. Expert evidence in court is governed by procedural rules, and duplicated professional costs can quickly become disproportionate.
Can the dispute be settled without going to court?
Very often, yes.
If the mistake is discovered early, the wall or foundation may simply be repositioned. Where a completed structure is to remain, the parties may be able to agree a payment and put the resulting property arrangements on a proper legal footing.
The correct solution depends on what is being agreed. It might involve a transfer of part of the land, an easement, a licence or an agreement recording the boundary. Those are not interchangeable.
In particular, if ownership of a strip of land is actually being transferred, a casual “boundary agreement” is not a substitute for dealing properly with the transfer and Land Registry requirements. A mortgage lender may also need to be involved.
Mediation can be useful where the parties agree about most of the facts but cannot agree what should happen next. It can also deal with practical issues that a judgment may not resolve neatly, such as replacement fencing, future maintenance access and responsibility for professional costs.
Before ordinary civil proceedings are started, the courts generally expect parties to exchange sufficient information to understand each other’s position and to consider settlement and alternative dispute resolution. The official Practice Direction on pre-action conduct explains those expectations.
For the broader practical approach, see my guide to resolving neighbour disputes.
Costs deserve serious thought from the outset. Boundary disputes can involve solicitors, barristers and expert surveyors, and expenditure can quickly bear little relationship to the market value of the strip of land involved. My guide to property litigation costs explains the risks in more detail.
What happens when either property is sold?
An unresolved encroachment can complicate a sale surprisingly quickly.
A buyer may want to know why the building does not appear to correspond with the ownership position, whether there is an existing dispute and whether the structure has a legal right to remain. Their mortgage lender may have the same concerns.
If a dispute has arisen, relevant conveyancing enquiries should be answered accurately. Trying to keep quiet about a known boundary problem can create a different claim after completion.
If the neighbours have reached a sensible settlement, recording it properly while both of them are available is usually far easier than expecting future owners to decipher an informal arrangement years later.
Frequently asked questions
Can my neighbour build on my land if they have planning permission?
No. Planning permission does not give your neighbour ownership of your land or, by itself, a private right to build on it. Planning control and private property rights are separate.
Can I make my neighbour knock down an extension built on my land?
Potentially. A court can grant a mandatory injunction requiring an encroaching structure to be removed. Whether it will do so depends on the circumstances. Damages may sometimes be awarded instead.
What if the extension is only slightly over the boundary?
Even a small encroachment can amount to trespass. There is no automatic tolerance of a few centimetres. The scale and practical effect of the encroachment will, however, be relevant to the remedy and to whether litigation is proportionate.
Can my neighbour’s foundations extend under my land?
In limited circumstances. The Party Wall etc. Act 1996 can allow necessary ordinary projecting foundations beneath adjoining land when a new wall is being built wholly on the building owner’s land at the line of junction. It does not create an unrestricted right, and special foundations require written consent.
Does the Land Registry plan prove that my neighbour has crossed the boundary?
Usually not by itself. Most registered titles show general boundaries. The deeds, plans, historic physical features and other evidence may need to be considered together before the exact legal line can be established.
What if I gave my neighbour permission?
That may change the position. Much depends on exactly what was agreed, whether the agreement was temporary or permanent, what the neighbour did in reliance on it and whether formal documentation was required. A casual conversation should not automatically be treated as either legally irrelevant or as a permanent transfer of property rights.
Can my neighbour eventually acquire the strip of land?
Adverse possession can potentially become relevant after sufficiently long qualifying possession, but the rules are technical and differ between registered and unregistered land. Ownership does not simply pass because a building has stood over the boundary for a particular number of years.
The practical point: Establish the boundary before fighting over the remedy
Finding somebody else’s building on what you believe is your land naturally provokes a strong reaction. But there are really two questions, and they need answering in the right order.
First, has the structure actually crossed the legal boundary? Secondly, if it has, what is the sensible and legally appropriate way to deal with it?
Sometimes removal will be justified. Sometimes the answer will be an alteration while the builders are still on site. In other cases, particularly where a completed structure has crossed the boundary only slightly, a properly documented agreement may be more sensible than years of litigation.
The important thing is not to confuse compromise with surrender. A practical settlement can protect your ownership just as effectively as a court order, provided the legal position is understood and the agreement is recorded properly.
Last legally reviewed: 29 August 2026
This article is based on general principles of English and Welsh law, is intended for informational purposes only, and does not constitute legal advice or establish a professional relationship.
