The 4-Year Rule vs. The New 10-Year Rule: Conservatory Planning in 2026

If you are a homeowner in New Milton, Hampshire, or Dorset, you may have heard whispers about changes to planning enforcement. For decades, the 4-year rule was the gold standard for homeowners looking to regularise works that didn’t originally have planning permission.

However, as we move through 2026, the legal landscape has shifted significantly. Whether you are looking to build a new sunroom or you’ve inherited a property with an older structure, understanding the transition from the 4-year rule to the new 10-year rule is essential.

In this guide, the team at Accolade Windows & Conservatories breaks down everything you need to know about conservatory planning permission and how to stay on the right side of the law.

Has the 4-year rule been scrapped?

The short answer is: Yes. As of the enforcement changes brought in by the Levelling-up and Regeneration Act, the traditional 4-year limit for enforcement action regarding unauthorised development in England has been abolished. Previously, if a conservatory was built without permission and the council didn’t notice for four years, it became immune from enforcement.

In 2026, this has been unified into a single 10-year period. This means local authorities in Hampshire and Dorset now have a much longer window to challenge any structures that do not meet planning or building criteria. If your conservatory was completed after the rule change, you are now liable for enforcement for a full decade.

What is the 10-year rule for conservatory planning permission?

The 10-year rule is designed to give local councils more power to manage hidden developments. Under the current 2026 legislation, any breach of planning control, including building a conservatory that exceeds Permitted Development limits, can be challenged at any point within 10 years of the work being “substantially completed.”

For homeowners, this makes professional advice from expert conservatory installers more valuable than ever. Attempting to wait out the council is no longer a viable short-term strategy. If you are selling your home, solicitors will now look for a full 10 years of evidence to ensure the structure is legal.

Do you have to dig foundations for a conservatory?

One of the most common questions we hear at our New Milton showroom is: “Do you have to dig foundations for a conservatory?” From both a structural and a planning perspective, the answer is a resounding yes. While some DIY kits or older structures may have sat on thin concrete pads, modern conservatories built in 2026 require professional-grade foundations—usually at least 1,000mm (1 metre) deep.

Digging proper foundations is crucial for several reasons:

1. Structural Integrity: It prevents the conservatory from pulling away from your main house.

2. Building Regulations: If you ever want to upgrade to a warm roof or tiled roof in the future, the foundations must be strong enough to take the weight.

3. Planning Compliance: Substandard foundations can lead to a structure being deemed unsafe by the council, triggering the very 10-year enforcement rule mentioned above.

Navigating Permitted Development in Hampshire & Dorset

The good news is that many conservatories still fall under Permitted Development. This means you might not need full conservatory planning permission if you stick to certain rules:

• The conservatory does not exceed 50% of the total area of land around the original house.

• It is not higher than the highest part of the roof of the existing house.

• For detached houses, it does not extend beyond the rear wall by more than 4 metres (or 3 metres for semi-detached/terraced).

However, if you live in a Conservation Area, which is fairly common in the New Forest or the coastal areas of Dorset, these rights may be restricted. Always check with a local expert who understands the specific constraints of the New Milton and Christchurch planning departments.

Why Quality Installations Matter More Than Ever

In the era of the 10-year rule, cutting corners is a financial risk. If a local authority issues an enforcement notice because your conservatory was built poorly or without the correct permissions, they can legally force you to demolish the structure at your own expense.

By choosing accredited conservatory installers like Accolade, you ensure that:

• Building Regulations are strictly followed.

• Site surveys determine exactly how deep your foundations need to be.

• All paperwork is in order, making the future sale of your home simple and stress-free.

Enhance Your Hampshire Home With A Conservatory Today

The transition from the 4-year rule to the 10-year rule represents a major shift in UK property law. In 2026, the focus has moved toward longevity, quality, and total transparency.

If you are planning a project in Hampshire or Dorset, don’t leave it to chance. Whether you’re concerned about conservatory planning permission or you’re ready to start digging those foundations, the experts at Accolade Windows & Conservatories are here to help.

Contact our friendly team in New Milton today for a consultation and ensure your home improvement stands the test of time.