Full Plan Approval vs Building Notice: What’s Best for Your UK House Extension?

If you’re planning a house extension in the UK, one of the key steps is obtaining Building Control approval. This ensures your project complies

with the Building Regulations, covering safety, energy efficiency, and structural integrity. There are two main routes to gaining this approval: Full Plan Approval and Building Notice. Understanding the differences between them can help you choose the right path for your project.

Full Plan Approval

The Full Plan route is the more detailed and thorough approach. It involves submitting a full set of construction drawings, specifications, and structural calculations to your local authority or an approved inspector before work begins.

These documents are carefully checked for compliance, and if they meet regulations, you’ll receive formal approval, often with conditions. Inspections are then carried out during construction to ensure the work matches the approved plans.

Pros:

• You get formal confirmation that your plans comply before building starts.

• Reduces the risk of delays or costly changes during the build.

• Lenders, solicitors, and insurers often prefer this route due to the certainty it provides.

Cons:

• Takes longer to prepare and process.

• May involve additional upfront costs for drawings and structural reports.

Building Notice

A Building Notice is a simpler, quicker option. You notify Building Control of your intention to start work at least 2 working days in advance, without submitting detailed plans up front. The inspector will then assess compliance as the build progresses, through site visits.

Pros:

• Faster to start – no need to wait for plan approval.

• Ideal for minor extensions or alterations by experienced builders.

Cons:

• No formal pre-approval – you risk non-compliance during construction.

• If problems arise, you may need to alter or redo work at extra cost.

• Not suitable for complex projects or work near boundaries or public sewers.

Which Should You Choose?

If your extension is straightforward, being handled by a knowledgeable builder, and you want to get started quickly, a Building Notice can work well. But for larger, more complex, or high-cost projects, Full Plan Approval offers greater peace of mind and control.

Always check with your local Building Control team or an approved inspector before deciding. Getting it right from the start can save you time, money, and stress down the line.