Is building control the same as planning permission?

No. They are separate processes run by different departments. Planning permission decides whether your extension is appropriate for the neighbourhood, while building control checks that what you build is structurally safe and energy-efficient. You can need one without the other, but a structural extension almost always needs building control.

What is the difference between a Full Plans application and a Building Notice?

A Full Plans application submits detailed drawings and calculations for formal approval before work starts, so problems are caught on paper. A Building Notice lets work begin within a couple of days with no formal approval document, leaving the inspector to check as you build. Full Plans is the right route for any extension of meaningful size.

Do you need building control approval if you do not need planning permission?

Yes. Permitted development removes the need for planning permission, but it does not remove the need for building regulations approval. Any structural extension still has to pass building control regardless of its planning status.

How long does building control approval take for an extension?

The statutory decision period for a Full Plans application is a matter of weeks once submitted, but the realistic end-to-end timeline is longer once you add document preparation, builder review, and the wait for the council to acknowledge receipt. Plan for a couple of months before you have the green light to start.

What is conditional approval from building control?

Conditional approval means the building control officer is satisfied with your overall design but reserves the right to inspect specific elements on site, such as ground conditions before foundations are poured. It is the normal outcome for extensions and does not mean anything is wrong with your design.

Can you use a private inspector instead of the local council for building control?

Yes. You can submit to your local authority or to a private Registered Building Control Approver. For a standard single-storey extension the local authority is usually the straightforward choice, as private inspectors rarely undercut on cost for smaller projects and councils know local ground conditions well.

Back to Kitchen Extension

Phase 1 · Planning & Permissions · Task 12 of 17

Building Control: How to Apply and What to Expect

Building control is separate from planning permission and costs £300 – £900 for the plan check alone. Here's how to apply, what the documents contain, and realistic timescales.

14 min readUpdated 2026Free with email

Timeline infographic showing the building control application process from document preparation through to conditional approval, with realistic durations at each stage

Prerequisites

Complete these first

Skip building control and you create a defect in your property's title that will surface the day you try to sell. Solicitors check for it. Mortgage lenders require it. And retrospective applications are expensive, stressful, and not guaranteed to succeed. Building control is not optional for any extension, regardless of whether you needed planning permission.

Building Control Is Not Planning Permission

This catches people out. Building control and planning permission are completely separate processes, run by different departments, with different fees and different purposes. Planning permission asks: "Is this appropriate for the neighbourhood?" Building control asks: "Is this safe and energy-efficient?"

You might not need planning permission. You always need building control approval for a structural extension.

Planning checks appearance, parking, and neighbour impact. Building control checks your foundations will hold, your steels will carry the load, your insulation meets thermal targets, your drainage connects properly, and your fire safety is adequate. The two processes run independently. Getting planning approval tells building control nothing, and getting building control approval tells planning nothing.

Do this first

By now you've already confirmed whether you need planning permission or fall under permitted development, and that your architect and structural engineer are appointed. Building control documents can't be prepared without their work.

Two Application Routes

There are two ways to apply for building regulations approval: Full Plans and Building Notice. For any extension of meaningful size, Full Plans is the right choice. Here's why.

Full Plans costs slightly more in some areas and takes longer upfront. But the entire point is that problems are caught on paper before a single brick is laid. A steelwork specification that doesn't quite work is a revised drawing when caught at submission. The same problem caught on site is demolished blockwork, new steel fabrication, and weeks of delay.

Warning

A Building Notice gives you no formal approval document. If you sell the property, your buyer's solicitor will want evidence of building regulations compliance. With Full Plans, you have an approval letter and (eventually) a completion certificate. With a Building Notice, you rely on the completion certificate alone, and if that was never issued, you have a conveyancing problem that can delay or derail a sale.

Building Notice is also not permitted for work near drains shown on the sewer map, for buildings covered by the Regulatory Reform (Fire Safety) Order, or for new buildings fronting private streets. Most extensions in urban or suburban areas will have public sewers nearby, which means Full Plans may be mandatory anyway.

Use Full Plans. The formal approval process catches structural, thermal, and drainage problems on paper, weeks before your builder starts digging. That protects you during the build and protects you again years later when you sell. Your buyer's conveyancing solicitor will ask for evidence of building regulations compliance, and a Full Plans approval letter is the clearest proof you can hand them. The extra few weeks upfront are nothing compared to the cost of fixing problems on site or untangling a conveyancing issue at the point of sale.

What this guide covers

01What the BC Documents Contain
02The Application Process
03What It Costs
04Conditional Approval
05When Things Change Mid-Build
06Local Authority or Private Inspector?
07The Inspection Stages Ahead
08What Happens If You Skip It
09Your Building Control Checklist

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