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

Every year, thousands of UK homeowners carry out building work without realising they've needed an approval they didn't get — or conversely, spend weeks waiting for planning permission on a project that never needed it. The confusion typically stems from treating planning permission and building regulations as the same thing. They are not.

This guide explains the fundamental difference between the two regimes, when each applies, when you need both, and what happens when you skip one or the other.

The Fundamental Distinction

Planning permission controls what you build, where you build it, and what it looks like. It is concerned with land use, the visual impact on the surrounding area, and whether a development is appropriate for its location. Planning is administered by your local planning authority (LPA) — typically your district or borough council.

Building regulations control how safely and efficiently it is built. They set minimum standards for structural stability, fire safety, insulation, ventilation, drainage, electrical safety, and energy efficiency. Building regulations are administered by your local authority's Building Control department or by a private Approved Inspector.

A useful way to remember the distinction:

• Planning says "you can (or can't) build that here"
• Building regulations say "if you're going to build it, it must meet these standards"

When Do You Need Planning Permission?

Planning permission is required when you propose a material change of use or when a development goes beyond the limits of permitted development (PD) rights.

Common Triggers for Planning Permission

• Building an extension that exceeds PD limits (e.g., a rear extension deeper than 4m on a detached house, or a side extension on a semi-detached)
• Converting a house into flats (change of use)
• Adding a second storey above an existing single-storey extension
• Building in a conservation area, AONB, or National Park where PD rights are restricted
• Altering the external appearance of a listed building
• Changing commercial premises to residential use (though Class MA permitted development may apply)
• Installing a new outbuilding or extension on a flat (flats have no PD rights under Part 1)
• Two-storey extensions in certain configurations
• Certain changes to the roof that exceed PD volume limits

What Planning Does NOT Control

Planning permission has nothing to do with how safely or structurally soundly work is done. You can receive full planning permission for an extension and still be required to comply with building regulations independently. They run in parallel, not in sequence.

When Do You Need Building Regulations?

Building regulations apply to most structural and material building work, regardless of whether planning permission is needed. The Building Regulations 2010 (as amended) set out which works are notifiable to Building Control.

Common Works Requiring Building Regulations

• Extensions — all extensions, regardless of whether they are permitted development
• Loft conversions — structural changes, fire safety, thermal performance
• New bathroom or en-suite — drainage (Part H), hot water (Part G), ventilation (Part F)
• New electrical circuit — Part P requires notification for new circuits in the home (NICEIC or NAPIT registered electricians can self-certify)
• New or replacement boiler — Gas Safe registered engineers self-certify under the Gas Appliances Competent Person Scheme
• Structural changes — removing a load-bearing wall, creating a new opening
• Garage conversion — change to a habitable room requires compliance with Parts A, C, E, F, L, and P
• Basement conversion — structural works, waterproofing, fire safety
• Replacement windows — if not installed by a FENSA or CERTASS registered company, requires Building Control notification
• Underpinning

Works That Do NOT Require Building Regulations

• Like-for-like repairs and maintenance (re-roofing with the same material, repointing, redecorating)
• Replacing a kitchen (unless new electrical circuits or drainage connections are added)
• Small detached outbuildings under 15m² with no sleeping accommodation
• Porches under 30m² if not heated
• Certain conservatories (if detached from the house by a wall and not provided with heating)

When You Need Both, One, or Neither

Full Plans vs Building Notice Application

When you need Building Regulations approval, there are two main application routes — plus a third option for retrospective regularisation.

Full Plans Application

You submit detailed drawings and a specification to Building Control before work starts. A Building Control surveyor reviews the plans and issues approval (or requests amendments). Inspections are carried out at specified stages during the build, and a Completion Certificate is issued at the end.

Advantages:

• Errors in design are caught before expensive construction begins
• Provides certainty — you know the design complies before work starts
• Lenders and solicitors prefer full plans approval
• The Completion Certificate is the definitive record that work was done to the required standards

Disadvantages:

• Takes longer upfront (typically 5–8 weeks for plan approval)
• Requires complete detailed drawings

Cost: Local authority fees vary but are typically £200–£900+ depending on project size, plus any professional fees for producing drawings.

Building Notice Application

You notify Building Control that you intend to carry out work without submitting full drawings upfront. Work can start 48 hours after the notice is submitted. A Building Control surveyor will make inspection visits to check work complies.

Advantages:

• Faster to start — no waiting for plan approval
• Lower initial fee
• Simpler administration for smaller projects

Disadvantages:

• No advance certainty — if the surveyor inspects and finds non-compliance, you may have to demolish and redo expensive work
• Cannot be used for dwellings involving fire safety systems, buildings over 18 metres, or certain other categories
• No Completion Certificate is issued — only a Building Notice completion notice, which provides less certainty for future buyers and lenders

Cost: Typically slightly lower than full plans, but the risk of remedial work makes full plans preferable for significant projects.

Regularisation (Retrospective Approval)

If building work has already been carried out without Building Regulations approval, you can apply for a Regularisation Certificate retrospectively. Building Control will inspect the work (and may require opening up to inspect concealed elements) and issue a certificate if the work meets the required standards.

Fee: typically £200–£600+ depending on the project. This does not apply to work completed before 11 November 1985 (which pre-dates modern building regs).

The Completion Certificate: Why It Matters

A Completion Certificate (issued under a Full Plans application) or a Certificate of Compliance (for Approved Inspectors) is the documentary proof that your building work has been inspected and meets Building Regulations requirements.

Why it matters:

Selling the property: When you sell, your solicitor will provide a Property Information Form (TA6). Any alterations to the property must be disclosed. If you can't produce a Completion Certificate for an extension or conversion, the buyer's solicitor will raise an enquiry. This can delay or kill a sale.

Remortgaging: Mortgage lenders may ask for evidence of Building Regulations compliance for any structural work. Without a Completion Certificate, some lenders will decline to lend against the property.

Insurance: Buildings insurance policies often require that work was carried out to Building Regulations standards. Unregularised work may affect a claim if it can be shown the work contributed to the damage.

Safety: Building Regulations exist to protect occupants from structural failure, fire, and other hazards. Unregularised work creates genuine safety risk as well as legal and financial risk.

What to do if you don't have one: Apply for regularisation if the work is recent, or instruct your solicitor to arrange indemnity insurance if the work is old and unlikely to be challenged. Indemnity insurance (typically £150–£500) protects the buyer and their lender against enforcement action but does not guarantee the work is safe.

Common Mistakes

1. Assuming planning permission covers building regulations. They are entirely separate. You can have planning permission and still need Building Regulations approval. Always check both.

2. Not booking inspections at the right stage. Building Control must inspect work at specified stages — foundations before concrete is poured, for example. If you miss an inspection stage and cover up the work, Building Control may require you to open it up again.

3. Using a non-registered tradesperson for notifiable work. Unregistered electricians, gas engineers, or window installers cannot self-certify — you must notify Building Control yourself and pay the applicable fee.

4. Failing to get a Completion Certificate. Even if inspections were carried out, the Completion Certificate is only issued when you request it and all work is satisfactorily complete. Some homeowners never collect it — and then can't find it when they sell years later.

5. Assuming old work doesn't matter. Pre-2000 extensions without Building Regulations approval are common and often acceptable to lenders — but only if indemnity insurance is in place. Speak to your solicitor before marketing your property.

Key Takeaways

• Planning permission controls what you build and where — administered by the local planning authority
• Building regulations control how safely it is built — administered by Building Control
• Most structural building work requires building regulations regardless of whether planning permission is needed
• Routine maintenance, like-for-like repairs, and most installations by registered competent person scheme members do not require building regulations notification
• Full plans application gives more certainty and results in a Completion Certificate; building notice is faster to start but riskier
• The Completion Certificate is critical for selling, remortgaging, and insurance — always collect it
• If work was done without building regs, apply for regularisation (if recent) or arrange indemnity insurance (if old)

Related Guides

• Building Regulations: Full Plans vs Building Notice vs Regularisation — deep dive into the three Building Regs routes, fee comparison, all 10 inspection stages, and why the Completion Certificate matters
• Permitted Development Rights UK: The Complete Homeowners Guide — all Part 1 PD classes with limits, Prior Approval explained, and the Lawful Development Certificate process
• Permitted Development Rights: The Complete UK Homeowner's Guide — the GPDO 2015 in full: Classes A through H, Prior Approval vs full planning, and the most common invalidating mistakes
• Building Regs Completion Certificate UK — why the Completion Certificate matters for selling and remortgaging, and how to obtain one retrospectively
• Planning Permission for a House Extension UK — when you need full planning: application types, fees, drawings, and timescales
• How to Find and Manage Tradespeople for a UK Renovation — ensuring your contractors handle Building Control notifications correctly