Boundary Demarcation Agreements: A practical and binding solution

The recent case of White v Alder [2025] EWCA Civ 392 has reaffirmed the legal weight of boundary demarcation agreements, and, importantly, clarified that they are binding not only on the original parties but also on successors in title, regardless of whether they had prior knowledge of the agreement.

What Is a Boundary Demarcation Agreement?

A boundary demarcation agreement is a formal arrangement between neighbouring landowners to fix a shared boundary at a specific, mutually acceptable location. They are used where the exact boundary line is disputed or uncertain. Instead of escalating the matter to litigation or relying on potentially unclear title plans, the parties reach an agreement as to where the boundary should be.

Such agreements are particularly helpful where:

• Title plans are vague or inconsistent
• Physical boundary features (e.g. fences or hedges) do not match legal boundaries
• Encroachments or adverse possession claims are likely
• The parties prefer a negotiated solution over formal dispute proceedings.

These agreements are most often recorded in writing, registered against title (where possible), and can bring clarity and finality to long-standing uncertainty.

The recent case: Successors bound without prior knowledge

• In the case of White v Adler, a new owner sought to challenge the boundary position set out in an agreement entered into by the previous owners of the neighbouring properties. The successor argued they were unaware of the agreement and did not consent to the boundary as marked
• The court dismissed the challenge and held that the demarcation agreement was binding on successors in title, even though they were not parties to it and had no prior knowledge. The agreement had been validly entered into and accurately reflected on the ground; it effectively settled the boundary
• This is consistent with the principle that where adjoining landowners resolve a genuine boundary dispute, the determination is final and binding, not only between them, but also on those who later acquire their interests.

Key legal principles

• Certainty over title: Courts favour the resolution of boundary disputes by agreement to promote clarity and reduce ongoing litigation risk.
• Binding nature: A valid demarcation agreement will usually bind future owners, especially where the boundary line has been acted upon (e.g. through fencing or construction).
• No requirement of notice: Successors can be bound even if unaware of the agreement—there is no general requirement that they must be informed for the agreement to take effect.

Practical advice for landowners

For current owners:

• Where boundary uncertainty exists, consider a demarcation agreement rather than a legal dispute.
• Ensure the agreement is documented clearly, signed, and, where possible, reflected in title records or the land registry.
• Mark the agreed boundary physically (e.g. with fencing) to evidence intent and reduce the likelihood of future disputes.

For prospective purchasers:

• Inspect boundary lines closely and ask whether any agreements or disputes have previously been resolved.
• Consider instructing a property lawyer to carry out thorough due diligence, especially in rural or irregularly shaped plots.

Conclusion

The message from the courts is clear: boundary demarcation agreements are effective, enforceable, and binding, regardless of who owns the land in future. They provide a valuable tool for resolving disputes and securing long-term certainty, but their implications can carry over to unsuspecting buyers.

If you’re considering buying a property or facing a boundary disagreement, our Property Disputes team at Ashtons Legal can help assess your rights and explore appropriate solutions.

Contact our Property Disputes solicitors today

If you have any questions about the points raised in this article, please get in touch with our specialist Property Litigation team by using our online enquiry form or calling 0330 404 0738.