Building regulations explained

Building regulations are the rules that govern how a building is constructed, as opposed to whether you are allowed to build it. They are the most commonly overlooked part of any home project, because people assume that once they have planning permission, or once they have confirmed they do not need it, they are clear to build. They are not. Building regulations are a separate approval, with their own process, and almost every building project needs them.

This guide explains, in plain English, what building regulations are, how they differ from planning permission, the two routes to approval, and the one document at the end that you must not lose. For the precise legal and technical requirements, which change more often than the principles do, this page points you to the official sources rather than restating them, because those are the things you want to read in their current, authoritative form.

Building regulations vs planning permission: the difference that catches everyone

This is the single most useful thing to understand, so it comes first.

• Planning permission is about whether you can build and how it looks: the size, siting, appearance and impact of the work on the area and your neighbours.
• Building regulations are about how it is built: whether the construction is safe and sound. They cover things like structural stability, fire safety, insulation and energy efficiency, drainage, ventilation, and electrical safety.

They are entirely separate systems, run under different laws, assessed by different people. The two consequences that trip homeowners up:

1. You usually need both. Getting planning permission does not deal with building regulations, and vice versa. Most extensions, loft conversions and structural alterations need planning consent (or confirmation it is not required) and building regulations approval.
2. You can need building regulations even when you need no planning permission at all. A great deal of work is permitted development and needs no planning application, yet still has to meet building regulations. "I do not need planning permission" is not the same as "I do not need approval."

If you take one thing from this page: planning and building regs are two different hurdles, and clearing one does not clear the other.

What building regulations actually cover

Rather than a single rulebook, the requirements are set out as a series of official technical standards (the "Approved Documents"), each dealing with a different aspect of construction. In broad terms they cover:

• Structure, that the building will stand up and bear its loads.
• Fire safety, escape routes, fire resistance, alarms.
• Energy efficiency, insulation and heat loss.
• Ventilation and moisture, avoiding damp and condensation, adequate air supply.
• Drainage and waste, foul and surface water handled properly.
• Electrical safety, safe installation of wiring and fittings.
• Accessibility, reasonable access into and within the building.

The specific standards within each of these areas are updated periodically as technology and policy move on, which is why this guide describes what is covered rather than quoting current figures. When you need the exact requirement, read the current Approved Document for that topic (linked at the foot of this page).

A practical note: some common jobs can be signed off by a registered installer under a "competent person" scheme instead of a separate building control application, for example replacement windows, certain electrical work, or a new boiler. The installer self-certifies the work and registers it, and you receive a certificate. If you are using a tradesperson for one of these jobs, ask whether they are registered under the relevant scheme.

Do I need building regulations approval?

As a rule of thumb, you almost certainly do if your project involves any of:

• An extension or new structure
• A loft or garage conversion
• Removing or altering a load-bearing wall
• New or altered drainage
• A new heating system, boiler, or significant electrical work
• New windows and doors (often handled via a competent person scheme, as above)
• Underpinning or foundation work

Minor cosmetic work, like decorating, replacing like-for-like fittings, or most repairs, generally does not. If in doubt, the safe assumption for anything structural or involving services (heat, water, power) is that approval is needed. Your designer or builder will usually tell you, but the legal responsibility to comply rests with you as the building owner, so it is worth confirming rather than assuming.

The two routes to approval

For an ordinary house (a non-higher-risk building), there are two procedural routes, and you can choose.

Full Plans. You submit detailed plans and they are checked for compliance before work starts. You get certainty up front that the design complies, and any problems are caught on paper rather than on site. This is the recommended route for anything beyond the very simplest work.

Building Notice. You notify building control that you are starting, and the work is inspected as it proceeds, without full plans being approved in advance. It is quicker to begin, but riskier: if something does not comply, you may have to undo and redo work that is already built. It is not available for all types of project.

Whichever route, the work is inspected at key stages (typically foundations, drainage, structural elements, insulation, and completion), and your builder should book each inspection at the right moment. Work that gets covered up before it is inspected may have to be opened up again, which is expensive, so proactive booking matters.

Who carries out building control

You also have a choice of who provides the building control service for an ordinary home:

• Your local authority's building control service, the council route.
• A private-sector provider, now formally called a Registered Building Control Approver (RBCA). This is the role that used to be known as an "approved inspector"; the name changed under building safety reforms, but for a normal house the service is broadly equivalent to the council route.

Both are legitimate, and both end in the same place: inspection against the regulations and, on success, a completion certificate. Private providers are sometimes faster but can cost more. (Higher-risk buildings, such as tall residential blocks, follow a different, stricter regime overseen by the national regulator, but that does not affect ordinary householder work.)

The completion certificate, and why it matters years later

When all the work is done and the final inspection is passed, you receive a completion certificate (sometimes a "final certificate" from a private provider). This is the document that proves the work was approved as compliant.

Keep it safe, and store it with your property documents. Its importance shows up at a moment most people are not thinking about during the build: when you sell. A buyer's solicitor will ask for building regulations certificates for any work done to the property. Missing or absent certificates are a common cause of delay and friction in a sale, because they leave the buyer (and their lender) unable to confirm the work was done properly.

This is also why building regulations history is part of the picture when you are assessing a property: unconfirmed or unauthorised work is a real-world fact about a home that can affect both its safety and its sale, not just a paperwork formality.

What if work was done in the past without approval?

It is common to discover, often when buying or selling, that previous work to a house was never signed off under building regulations. Where that happens, it may be possible to put it right after the fact by applying to the council for a regularisation certificate: the council assesses the existing work (sometimes requiring parts to be opened up for inspection) and, if it is satisfactory, certifies it retrospectively.

Regularisation is not always straightforward, and not all work can be regularised easily, but it is the recognised route for resolving historic unauthorised work, and is usually far better than leaving a gap in the record. If you are dealing with this, the council's building control team is the place to start; the official guidance is linked below.

The points that catch most people out

1. Planning permission is not building regulations approval. Clearing one hurdle does not clear the other. You usually need both.
2. Permitted development still needs building regs. "No planning permission required" does not mean "no approval required."
3. The legal duty to comply is yours. Not your builder's. Confirm, do not assume.
4. Uninspected work is a liability. Anything covered up before inspection may have to be exposed again.
5. Losing the completion certificate causes problems at sale. It is a legal record a buyer's solicitor will demand.
6. Standards change. The principles are stable, but the specific technical requirements are updated over time, so always check the current Approved Document rather than relying on an old figure or an out-of-date guide.

Frequently asked questions

In short

Building regulations are the "is it built safely?" half of any project, separate from the "are you allowed to build it?" half that planning permission deals with. Most work needs both, permitted development still needs building regs, and the completion certificate at the end is a document you will be very glad to have when you come to sell. The principles here are stable; the precise technical standards change, so for those, go to the official sources below and read the current version.

If you are at the earlier stage of working out what you can build in the first place, that is a different question, and one specific to your property. Our build process guide walks the whole journey from idea to sign-off, and a property check will tell you what your own home can actually get. Check your property →

Sources and further reading

• Building regulations overview and approval (GOV.UK): gov.uk/building-regulations-approval
• The Approved Documents (current technical standards), GOV.UK: gov.uk/government/collections/approved-documents
• Building control and the application routes (Planning Portal): planningportal.co.uk
• Completion certificates and regularisation of unauthorised work: start at your council's building control pages, or GOV.UK building regulations approval (above).
• Find or check a registered building control professional (Building Safety Regulator register): register-building-inspector.service.gov.uk
• Competent person schemes (self-certification by registered installers), GOV.UK: gov.uk/building-regulations-approval/use-an-approved-contractor

Always read the current version of an official source; the standards are updated periodically.

Related guides

• The planning and build process — what to expect from first idea to finished work.
• Permitted development rights — what you can build without a full planning application.
• Do I need planning permission? — when permission is required, and when it isn't.
• Planning permission costs — application, professional and building costs, with current figures.