Planning Permission vs Building Regulations: What's the Difference?

Meta title: Planning Permission vs Building Regulations: The Difference Explained | RCB Design & Build

Two Different Systems — Both Matter

When homeowners start thinking about a building project, planning permission and Building Regulations are often conflated into a single "council approval" concept. In reality they are two distinct systems, administered separately, for entirely different purposes.

Understanding the difference matters, because needing one does not automatically mean you need the other — and failing to obtain either when required can cause serious problems when you come to sell the property.

What Is Planning Permission?

Planning permission is about whether a proposed development is acceptable in terms of its impact on the surrounding area, the street scene, the environment, and neighbouring properties.

Planning is administered by the local planning authority (LPA) — typically your borough council. The planning officer's primary question is: does this proposal accord with planning policy, and would it cause unacceptable harm?

Planning permission is concerned with: - The size, scale, and appearance of the proposed works - The visual impact on the street scene and surrounding area - The impact on neighbouring properties (overlooking, overshadowing, loss of light, loss of privacy) - Whether the use of the building is appropriate for the area - Transport, parking, and highways impacts - Environmental and heritage considerations

Planning permission does not tell you whether something is structurally safe, fire safe, or energy efficient. That is the role of Building Regulations.

What Are Building Regulations?

Building Regulations are about whether the proposed works meet minimum standards for structural integrity, fire safety, energy efficiency, drainage, accessibility, ventilation, and a range of other technical matters.

Building Regulations approval (also called Building Control) is administered either by your local authority's Building Control team or by an approved inspector — a private sector alternative.

Building Regulations are concerned with: - Structural integrity and calculations - Fire safety — means of escape, fire detection, compartmentalisation - Thermal performance and energy efficiency - Drainage and plumbing - Electrical safety (for notifiable works) - Ventilation - Accessibility requirements (where applicable) - Sound insulation

Building Regulations do not tell you whether the development is acceptable in planning terms. You could have a project that is entirely compliant with Building Regulations but still requires and lacks planning permission.

When Do You Need Planning Permission?

Many smaller domestic projects benefit from permitted development rights — meaning they do not require a planning application. Common examples of work that can often proceed without planning permission (subject to conditions) include:

Rear extensions up to 3m deep on semi-detached and terraced houses (or 4m on detached)
Loft conversions without altering the roofline at the front
Single-storey outbuildings within the garden
Internal alterations

However, permitted development rights are restricted or removed in conservation areas, for listed buildings, on flats and maisonettes, and in some locations with Article 4 directions. If you're uncertain, apply for a lawful development certificate — a formal confirmation from the LPA that the works are lawful.

For works that do require planning permission, the process involves submitting an application, a period of consultation with neighbours and statutory consultees, and a decision (typically within 8 weeks for householder applications).

When Do You Need Building Regulations?

Building Regulations apply to most structural building works, including:

Extensions of any size
Loft conversions creating habitable rooms
Structural alterations (removing walls, adding steels)
New bathrooms or kitchens where drainage is involved
Electrical installations (where notifiable under Part P)
New boilers, heating systems, and heat pumps
Replacement windows (in some circumstances)

Like-for-like repairs and maintenance — replacing a roof with the same materials, for example — typically do not require Building Regulations approval.

The Building Regulations process involves submitting a full plans application (where drawings and specifications are approved before work starts) or a building notice (where approval is given as work proceeds). Either way, the Building Control officer will inspect the works at key stages — foundations, drainage, structure, and final completion — and issue a completion certificate when satisfied.

The Completion Certificate — Why It Matters

The completion certificate is the document that proves the works were inspected and approved under Building Regulations. When you come to sell the property, your solicitor will be asked about any works carried out and whether Building Control approval was obtained.

Works carried out without Building Control — even if apparently well done — can cause difficulties at the point of sale. Buyers' solicitors may request retrospective approval, which requires opening up the works for inspection and may require remedial work. Or they may insist on indemnity insurance — which signals to buyers that something was done without approval.

For your own peace of mind and the long-term value of your property, always get the proper approvals before starting any notifiable works.

Summary

Planning permission — is this acceptable to the planning authority in terms of appearance and impact on the area?
Building Regulations — does this meet minimum technical standards for safety, structure, and energy efficiency?
You may need planning permission only, Building Regulations only, both, or neither, depending on the nature of the works.
Always check before you start — and always get a completion certificate at the end.

At RCB Design & Build, we manage the planning and Building Regulations process as part of our design-and-build service. If you're uncertain about what approvals your project requires, we're happy to advise.

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