Building Regulations or planning permission: what differs

Building regulations vs planning permission is the comparison that causes the most expensive misunderstandings on domestic projects. They are separate legal systems with separate applications, separate decision makers, separate fees and separate penalties. Planning permission asks whether your extension should exist. Building control asks whether it will stand up, keep the heat in and let people out in a fire.

You can have one without the other. A loft conversion under permitted development needs no planning permission and always needs building regulations approval. A change of use from a shop to a café needs planning permission and may need very little building control work.

Two systems, two approvals

Planning permission comes from the Town and Country Planning Act 1990. Section 55 defines development as building operations or a material change of use, and section 57 requires permission for development. Your local planning authority decides, with a statutory determination period of eight weeks for a householder or minor application.

Building control comes from the Building Act 1984 and the Building Regulations 2010. The work is checked by a building control body, which is either the local authority building control team or a registered building control approver, the private sector role that replaced approved inspectors following the Building Safety Act 2022 and registration with the Building Safety Regulator.

They do not talk to each other. A planning officer will not check your structural calculations, and a building control surveyor will not tell you that your extension breaches a condition on the permission.

What planning controls and what building control does not

Planning is concerned with the use of land and its effects on other people. Appearance, scale, massing, overlooking, daylight to neighbours, parking, highway safety, drainage impact off site, heritage, trees, ecology and noise breaking out from the site.

Building control is concerned with the performance of the building itself. Structural stability, fire safety, insulation and air tightness, ventilation, drainage within and immediately around the building, stairs and guarding, accessibility, electrical safety, overheating and glazing safety.

The overlaps are narrow and worth knowing:

• Drainage appears in both, in planning as surface water impact off site and in building control as the pipes and soakaways serving the building
• Fire appears in both for larger buildings, where planning fire statements and building control fire strategies sit alongside each other
• Energy appears in both, in planning through local policy on carbon and in building control through Part L
• Access appears in both, in planning through the approach to the building and in building control through Part M inside it

Neither system deals with your neighbour's legal rights. The Party Wall etc. Act 1996, restrictive covenants, rights of light and boundary ownership sit outside both.

Approved documents that matter on a domestic project

The Approved Documents give practical guidance on meeting the requirements. On a typical extension or conversion the ones in play are:

Loft conversions are where Approved Document B surprises people. Converting a two storey house into a three storey one changes the escape strategy, which usually means a protected stair enclosure, fire doors and sometimes a sprinkler system where the stair cannot be protected. That is a building control requirement with no planning equivalent.

Timing and where the two overlap

Planning first, usually. There is no point paying for structural design for a scheme that will be refused on massing.

The exception is where building control requirements will change the design enough to matter at planning stage. A loft conversion that needs a protected stair may need an internal layout that affects window positions. An extension over a public sewer may need to move, and the water undertaker's build over agreement is worth starting early. Insulation thicknesses under current Part L standards affect wall build-ups, which affects the external dimensions on the planning drawings.

Submit the building regulations application once the planning permission is granted and before you order materials. A full plans application gives you a decision on drawings before work starts, which is the safer route on anything structural. A building notice gets you on site faster and puts the risk on you, since nothing is approved in advance and the surveyor can require changes on site.

What happens when you miss each one

The consequences differ in character, and the planning one is better known than it should be.

For planning, the council can serve an enforcement notice requiring the breach to be remedied, which can mean demolition. Time limits give immunity after a period, and the Levelling-up and Regeneration Act 2023 moved the enforcement time limit in England to ten years for all breaches. Which limit applies depends on when the breach occurred, so check the commencement position rather than assuming the older four year rule still applies to your case.

For building control, the local authority can prosecute for contravening the regulations, and it can serve a section 36 notice requiring the work to be altered or removed. The section 36 notice has to be served within twelve months of the work being completed, which is a short window, but the absence of a completion certificate never goes away. It surfaces on every sale, and indemnity insurance is a poor substitute for the certificate.

Unauthorised structural work is the worst outcome of the two, because the risk is physical rather than administrative.

Regularisation and retrospective routes

Both systems have a route back, and both are less comfortable than doing it properly first time.

For planning, a retrospective application under section 73A of the 1990 Act asks the council to grant permission for development already carried out. The council decides it on the same planning merits as any other application, so a well-designed extension built without permission usually gets permission. A poorly designed one usually does not. A Planning Statement explaining the design and the policy position is worth including.

For building control, a regularisation application asks the local authority to certify work carried out without approval since November 1985. The authority will require opening up so it can see foundations, structure and insulation, which means lifting floors and cutting into walls. Where opening up is impractical, a Structural Survey by a chartered engineer supports the application, though it does not replace the regularisation certificate.

Only the local authority can regularise. A registered building control approver cannot, because the work is already done.

A sequence that avoids abortive work

1. Establish the planning position first, using a lawful development certificate if permitted development is being relied on.
2. Get outline structural and Part L advice before the planning drawings are finalised, so wall thicknesses and stair positions are right.
3. Submit the planning application, or the prior approval where the route requires one.
4. Once permission is granted, submit a full plans building regulations application.
5. Serve any party wall notices early enough to absorb the statutory notice periods.
6. Build, with inspections booked at the stages the building control body specifies.
7. Collect the completion certificate and file it with the permission and the approved drawings.

Enter your postcode on PlanScope to see which planning documents your project needs, and browse the full report index for the supporting reports a council may ask for.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.