Understanding Building Regulations: What Needs Approval in England and Wales

Home improvements are exciting — until you discover you needed approval that you never sought. Building regulations exist not to frustrate homeowners, but to ensure that construction work is structurally sound, safe, and energy-efficient. Yet the rules can be bewildering, with overlapping exemptions, grey areas, and the added confusion between planning permission and building regulations, which are entirely separate processes.

This guide cuts through the jargon and explains, in plain English, what types of work require building regulations approval in England and Wales, what can be done without any formal sign-off, and how to navigate the process when approval is needed.

Planning Permission vs Building Regulations: The Key Distinction

Many homeowners conflate these two, but they are fundamentally different systems with different purposes.

Planning permission is about the appearance and impact of a development — its size, design, effect on neighbours, and whether it fits the character of the area. It is administered by your local planning authority (LPA).

Building regulations are about the quality and safety of the construction work itself — structural integrity, fire safety, insulation standards, electrical safety, drainage, and so on. They are enforced by building control bodies (BCBs), either your local authority's building control department or a private approved inspector.

You can need one, both, neither, or sometimes just one of these. A single-storey rear extension, for example, might fall within permitted development (so no planning permission needed) but still require building regulations approval. Conversely, changing the colour of your front door requires neither.

Work That Almost Always Requires Building Regulations Approval

The following categories of work nearly always need building regulations sign-off, regardless of size or scope:

Extensions and New Buildings

Any extension to a dwelling — rear, side, loft conversion, garage conversion, orangery or conservatory over a certain size — falls under building regulations. The threshold for conservatories was revised in 2022: those under 30m² with a certain level of thermal separation from the main house may be exempt, but this is a narrow exemption. A loft conversion almost always requires approval, covering structural beams, fire escape routes, and insulation to Part L standards.

Structural Alterations

Removing or altering a load-bearing wall, chimney breast removal, underpinning foundations, or any work that affects the structural integrity of the building requires approval. Many homeowners discover this mid-project when a structural engineer is called in — it is far better to establish this before breaking out the sledgehammer. Expect to pay £150–£350 for a structural engineer's report, and around £200–£500 in building regulations fees depending on the scope of work.

Electrical Work (Part P)

Part P of the building regulations covers electrical safety in dwellings. Not all electrical work requires notification to building control — replacing a light fitting or a like-for-like socket replacement does not. However, any work in a kitchen, bathroom, or outdoors (defined as "special locations") does require notification. So does installing a new circuit anywhere in the home, adding a consumer unit, or installing an EV charging point.

The most practical route for most homeowners is to hire a Part P-registered electrician (look for NICEIC, NAPIT, or ELECSA registration). These tradespeople are authorised to self-certify their own work, notifying building control on your behalf without you having to lodge a separate application. Expect to pay £50–£80 for a completion certificate from a registered contractor.

Gas Work

All gas work must be carried out by a Gas Safe registered engineer — this is a legal requirement, not merely a recommendation. Installing or replacing a boiler, fitting a gas fire, extending gas pipework — all of it must be done by a registered professional who will issue a Gas Safe certificate. British Gas, Worcester Bosch, and Vaillant all have networks of registered installers, but independent Gas Safe engineers are often more competitively priced.

Oil and Solid Fuel Appliances

Installing an oil boiler or solid fuel appliance (such as a log burner or multi-fuel stove) also requires building regulations notification. Log burners have seen a surge in popularity, but the regulations around flue design, hearth construction, and proximity to combustible materials are detailed. HETAS-registered installers can self-certify this type of work.

New or Replacement Windows and Doors

Replacing windows or glazed doors triggers building regulations because of the energy efficiency requirements under Part L. However, if you use a FENSA or CERTASS-registered installer, they can self-certify the work, meaning you do not need to make a separate building control application. Always ask for the FENSA certificate — you will need it when you sell your property.

Drainage and Plumbing

Any work on drainage (Part H) that involves the installation, extension, or alteration of drains, sewers, or soil pipes requires approval. New bathrooms, WC installations, and certain plumbing alterations fall within this. Replacing like-for-like fittings (a new toilet in the same position, for example) generally does not.

Work That Does Not Require Building Regulations Approval

Not everything needs sign-off. Common examples of exempt work include:

• Redecorating — painting, wallpapering, laying carpet or floor tiles
• Replacing kitchen and bathroom fittings in the same position (unless involving new drainage runs)
• Like-for-like roof tile replacement (not adding insulation or structure)
• Garden structures such as sheds and summerhouses under 15m² or certain size thresholds
• Most paving and driveways (although permeable surfaces and drainage are governed separately)
• Internal non-structural partition walls
• Replacing a boiler in the same location on a back-to-back basis — however, the new boiler must still be fitted by a Gas Safe engineer who will certify the work

The Approval Process: Full Plans vs Building Notice

When building regulations approval is required and no self-certification scheme applies, you have two main routes:

Full Plans Application

You submit detailed drawings and specifications before work begins. Building control checks the plans and approves them in principle. An inspector then visits at key stages during construction — foundations, damp-proof course, structural elements, insulation. At the end, you receive a completion certificate. This is the recommended route for larger projects such as extensions, loft conversions, and structural alterations.

Fees for a full plans application typically start around £200–£250 for minor work, rising to £800–£1,500+ for substantial extensions. Your local authority's website will have a fee calculator.

Building Notice

A simpler application where you notify building control before work starts, without submitting full plans. An inspector visits as the work progresses. This suits smaller, straightforward projects but offers less certainty upfront — if the inspector is not satisfied, you may need to redo work. It is not suitable for larger extensions or work near public sewers.

Retrospective Approval (Regularisation)

If work was done without the required approval — often discovered when selling a property — you can apply for a regularisation certificate. The inspector will assess the completed work, and you may need to expose certain elements for inspection. Fees are typically higher than a standard application. A solicitor's indemnity insurance policy is an alternative sometimes used in conveyancing, but it does not guarantee the work is compliant.

Common Pitfalls and What to Watch For

Selling Your Home

Building regulations compliance (or the lack of it) almost always surfaces during the conveyancing process. Solicitors will ask about any work done in the last ten years and request copies of certificates. Missing certificates can delay or even derail a sale. Keep every certificate you receive — file them with your property documents immediately.

Listed Buildings and Conservation Areas

If your home is a listed building, the rules are stricter — you will need listed building consent for many changes, in addition to any building regulations requirements. Homes in conservation areas also have additional restrictions, particularly on external changes visible from the street. Check with your local planning authority before undertaking any work.

Permitted Development Rights

Permitted development (PD) rights allow certain works without planning permission, but this does not mean building regulations are waived. The two systems operate independently. Many homeowners — and some tradespeople — incorrectly assume that PD rights mean "no approvals needed". Always check both.

Party Walls

The Party Wall etc. Act 1996 is a third, separate legal framework. If you are carrying out work near or on a shared wall, excavating near a neighbour's foundations, or building a new wall on the boundary, you may need to serve a party wall notice. This is not a building regulations matter, but it is another legal requirement that homeowners often overlook.

Getting Advice Before You Start

When in doubt, contact your local authority's building control department — they are there to advise, not simply to enforce. Most will give informal guidance free of charge. The Planning Portal (planningportal.co.uk) is also an excellent resource with interactive tools to help you determine whether your project needs approval.

For larger projects, engaging an architect, architectural technician, or structural engineer early will help you navigate the requirements correctly. The fee you pay for professional advice upfront is almost always cheaper than the cost of putting things right — or losing a sale — further down the line.

Building regulations can feel like bureaucratic red tape, but they exist because poorly executed structural work, inadequate fire protection, and substandard electrical installation cause real harm. Understanding the system — and working within it — protects you, your family, and the future owners of your home.