Planning Enforcement Notices: What Happens If You Build Without Permission

Introduction

Carrying out works that require planning permission without obtaining it first is a planning breach — but it is not in itself a criminal offence. Planning enforcement is a discretionary power: the local planning authority may take action against unlawful development, but is not obliged to do so. Understanding how enforcement works — what triggers it, what the formal process is, and what your options are when faced with an enforcement notice — is important for any homeowner in NW3 who has carried out or is considering carrying out works without permission. This guide explains the enforcement process in Camden and Barnet. For related guidance, see our retrospective planning guide, lawful development certificate guide and Camden planning guide.

What Is a Planning Breach?

A planning breach occurs when development that requires planning permission is carried out without it, or when a condition attached to a planning permission is not complied with. Common examples in NW3:

• Building an extension larger than permitted development allows, without a planning application
• Installing windows or altering the front elevation of a property in a conservation area without planning permission
• Using materials not matching the existing building on an external alteration
• Building a side extension in a conservation area without planning permission
• Creating a basement without planning permission where one is required
• Failing to comply with a pre-commencement planning condition (e.g. failing to submit materials details before starting work)

Not all planning breaches are enforced. The planning authority must consider whether it is expedient (in the public interest) to take enforcement action — minor or unnoticeable breaches are often left without action, while prominent breaches in conservation areas are more likely to be pursued.

The Enforcement Process

The formal enforcement process proceeds through several stages:

1. Complaint received / breach discovered: Camden or Barnet's enforcement team is typically alerted by a neighbour complaint, a planning officer observation, or a routine inspection following a permitted development check. The enforcement team investigates whether a breach has occurred.
2. Enforcement investigation: The planning authority requests information from the owner, carries out a site visit, and considers whether the development is lawful (within permitted development or time-expired) or in breach.
3. Planning contravention notice (PCN): The authority may issue a formal PCN requiring the owner to provide information about the nature of the development and whether they have any permission. Failing to respond is a criminal offence.
4. Enforcement notice issued: If the authority decides to take formal action, it issues an Enforcement Notice under Section 172 of the Town and Country Planning Act 1990. The notice specifies: what breach has occurred; the steps required to remedy the breach (typically to demolish, remove or restore); and the compliance period (minimum 28 days, but often 3–12 months for more significant works).
5. Stop notice / temporary stop notice: In urgent cases, the authority can issue a Stop Notice or Temporary Stop Notice requiring construction to cease immediately.

Appealing an Enforcement Notice

A homeowner who receives an enforcement notice has 28 days to appeal to the Planning Inspectorate (PINS). Grounds of appeal include:

• That planning permission ought to be granted for the development as built (the most common substantive ground)
• That the development does not require planning permission (it is permitted development or is not development)
• That the notice has not been correctly issued
• That the steps required to remedy the breach are excessive
• That the compliance period is too short

Filing an appeal suspends the compliance period — you do not need to remedy the breach while the appeal is pending. Appeals can take 6–18 months to determine, providing significant delay while the appeals process runs its course.

Retrospective Planning Applications

In many cases, the most efficient response to an enforcement notice is to submit a retrospective planning application for the works as built. If the application is granted, the enforcement notice falls away. If refused, the enforcement process continues. See our retrospective planning guide.

Submitting a retrospective application does not suspend the compliance period under an enforcement notice (unlike an appeal), but in practice most authorities will not pursue enforcement while a retrospective application is live.

Enforcement Time Limits

Once the enforcement time limits have expired, the planning authority can no longer take enforcement action:

• Operational development (building works): 4 years from substantial completion (note: under review — may change to 10 years under proposed legislation as of 2026)
• Change of use to a dwelling: 4 years from the breach
• Other material changes of use: 10 years from the breach
• Breach of condition: 10 years from the breach

After these periods, a Lawful Development Certificate can be obtained confirming the works are now lawful. See our LDC guide.

Conclusion

Planning enforcement is a real risk for homeowners in NW3 who carry out works without permission — particularly in conservation areas where Camden's enforcement team is active and neighbour complaints are common. The most effective strategy is to get planning permission before starting, or to regularise works promptly through a retrospective application if a breach is identified. An architect who identifies planning requirements at the outset and manages the planning process properly will prevent enforcement issues from arising. If you have already received an enforcement notice, seek professional advice immediately. Use our free matching service to find an architect with Camden planning experience. For project cost guidance, visit hampsteadrenovationcosts.co.uk.