How Long Does Planning Permission Last and What To Do if You Missed It!

Are you planning your dream home or a stunning architectural project in London? Have you secured planning permission but are now wondering how long it lasts? Understanding the time limits for planning consent is crucial whether you’re designing a contemporary home extension, reimagining an interior space, or embarking on a full-scale architectural project. You may have received a quote for your project but you need to save up, or there’s an unexpected life event that delays your extension ambitions. We hope this post can help you plan your project and provide key insights on what to do if life doesn’t stick to the plan.

At Open Volume Studio, we know that the clock starts ticking as soon as you get approval. Let’s break down how long planning permission lasts, what happens if it expires, and why staying ahead of deadlines is essential in London’s fast-moving architectural landscape.

What Is Planning Permission? And Why Does It Matter?

Planning permission is the official approval from your local authority that allows you to proceed with certain types of building work. If your project involves significant alterations, such as extensions, new builds, or major refurbishments, you’ll likely need permission before breaking ground. There are also other routes to consent for construction including listed building consent or permitted development. These apply in different circumstances.

For homeowners, planning permission ensures your dream home complies with local policies. For architects and interior designers, it’s the green light to bring creative visions to life. Without it, you risk enforcement action that could halt construction—or worse, require demolition of unauthorized work.

So How Long Does Planning Permission Actually Last?

In most cases, planning permission in the UK is valid for three years from the date of approval. This means you must begin development within that timeframe, or your consent will expire, requiring a new application.

The key word here is “begin.” You don’t need to finish the project within three years, but you must demonstrate that work has meaningfully started. A simple site clearance or digging a trench isn’t enough. There needs to be evidence of genuine progress.

There are different types of planning permission, and each comes with its own set of timelines:

1. Full Planning Permission

This is the most common type, granting approval for a detailed project plan, including architectural designs and specific proposals. It’s valid for three years, so you must begin construction within this period.

2. Outline Planning Permission

Used for larger developments or when full details aren’t yet finalized, outline permission grants approval for the concept of a project. However, you must submit additional details (called “reserved matters”) within three years. Once those are approved, you have an extra two years to start construction—giving you a maximum of five years from the initial consent.

3. Permitted Development Rights

For smaller developments falling under statutory permitted development rights, you may not need to apply at all, however some of these rights require prior consent. This may include larger than normal extensions or works done under specific permitted development classes like Class Q. Once permission is granted you can may find yourself with only 3 years to complete the project, not just start it.

What Happens If Your Planning Permission Expires?

If the deadline passes and work hasn’t begun, the permission becomes void, meaning you’ll need to take action to avoid setbacks. Here are your options:

1. Reapply for Planning Permission

Once expired, the original permission is no longer valid, and you must submit a new application. Keep in mind that planning policies may have changed, so approval isn’t guaranteed—even if you reapply with the exact same plans. This could lead to additional costs or design adjustments to meet new regulations.

2. Apply for a Replacement Permission (Section 73 Application)

Under Section 73 of the Town and Country Planning Act 1990, you can apply to vary or remove conditions tied to the original permission. While this does not extend the original approval, it grants a new permission with revised conditions, potentially allowing you to proceed without a full reapplication. This option is particularly useful if only certain aspects of the original approval need adjusting.

3. Commence Minimal Work Before Expiry

To keep the permission active, you can start development before the expiration date. However, it’s not enough to just clear the site or store materials—your work must constitute meaningful progress. This could involve:

• Laying foundations

• Beginning structural work

• Completing pre-commencement conditions set by the planning authority

If in doubt, consult your architect or planning consultant to ensure that your work qualifies as an official “commencement” under planning law.

Failure to take action before expiry could result in delays, additional costs, and potential refusalof a new application.

Exceptions to the Three-Year Rule

In some cases, your approval notice may specify a different timeframe. For example, certain large-scale developments may have a longer validity period

The Three-Year Rule in UK planning permission requires that work must commence within three years of approval. However, there are exceptions and alternative rules and here a few examples:

1. Outline Planning Permission: For outline permissions, you have three years to submit reserved matters and an additional two years to begin construction, effectively allowing up to five years in total[1][4].

2. 10-Year and 4-Year Rules: These rules apply to unauthorised developments:

   - The 10-Year Rule allows a Certificate of Lawfulness if a building has been used continuously for 10 years without enforcement.

   - The 4-Year Rule applies to breaches involving a dwelling house or operational development completed more than four years ago. Note: this does not apply to listed buildings where there is no statue of limitation on alterations and liability for damage to historic fabric can be transferred as part of ownership.

3. Fraudulent or Concealed Developments: Exceptions exist for fraudulent actions or deliberate concealment of developments, where authorities can withhold lawful status despite the time elapsed.

4. Local Authority Conditions: Some councils may impose specific conditions altering the standard three-year timeframe, which would be stated in the planning notice.

5. Permitted Development Rights and Article 4 Directions: Certain minor works may not require planning permission at all under permitted development rights unless restricted by local Article 4 directions.

These exceptions demonstrate flexibility in planning regulations, but they depend on specific circumstances and local authority decisions. Always check your approval letter to confirm the specific conditions attached to your project.

Why Timing Matters in London’s Planning Landscape

London is a dynamic city where planning policies evolve constantly. With increasing demand for housing, stricter environmental regulations, and ever-changing design trends, delays can be costly. If you let your permission expire, there’s no guarantee a reapplication will be approved under the same conditions.

That’s why timing is everything. Once you get approval, don’t sit on it—start making progress, secure contractors, and work closely with architects who understand the complexities of London’s planning system.

Maximising Your Planning Permission: Key Tips

To ensure your project stays on track, follow these simple but crucial strategies:

1. Work with Experienced Architects

London’s planning rules can be tricky. A skilled architect will help you navigate the process, liaise with local councils, and ensure your project moves forward smoothly.

2. Monitor Your Deadlines

It’s easy to lose track of time, especially with complex projects. Keep a clear record of your planning permission approval date and set reminders well in advance of the expiry.

3. Show Genuine Progress

To keep your permission active, make sure work is properly documented—photos, contractor invoices, and planning reports can help prove that construction has officially started.

4. Stay Flexible with Design Adjustments

If your project timeline is at risk, consider phasing construction. Starting with minor works (such as foundations) can help keep your permission valid while you finalize larger aspects.

5. Plan for the Unexpected

Delays happen—contractor schedules, material shortages, or even council backlogs. Build in a buffer period to ensure you have enough time to get started before the permission runs out.

Final Thoughts: Don’t Let Your Planning Permission Go to Waste!

Once you have planning approval, act fast. The last thing you want is to navigate London’s planning system twice for the same project. One of our first ever projects was a tricky planning permission for an extension to a ground floor flat.  We were so proud of that project early on in our career but sadly it was never built. At Open Volume Studio we tend to take all of our projects from conception to completion and rarely provide a limited service to ensure that continuity and efficiency is maintained.

Whether you’re extending a Victorian terrace in Penge, designing a contemporary loft in Chiswick, or reimagining an entire townhouse in Notting Hill, timing is everything.

Need help bringing your architectural vision to life before the deadline? Get in touch with Open Volume Studio today. Let’s make your dream space a reality—without any last-minute planning headaches.