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 Single Storey Rear 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.

15 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.

What this guide covers

01Building Control Is Not Planning Permission
02Two Application Routes
03What the BC Documents Contain
04The Application Process
05What It Costs
06Conditional Approval
07When Things Change Mid-Build
08Local Authority or Private Inspector?
09The Inspection Stages Ahead
10What Happens If You Skip It
11Your Building Control Checklist

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