Building Regulations explained for homeowners

Updated 26 October 2026 · SK Home Improvements

What are Building Regulations?

Building Regulations are legal minimum standards for the design and construction of building work, covering structure, fire safety, damp, ventilation, drainage, energy efficiency, access and safety glazing. They apply whether or not you need planning permission, and both the homeowner and the builder have a stake in making sure work complies.

Each nation sets its own rules and guidance:

Which home improvements need Building Regulations approval?

Most structural, thermal and service work needs approval, while like-for-like repairs and decoration usually do not. Typical work that needs approval or certification includes:

• Extensions, loft conversions and garage conversions.
• Removing or altering load-bearing walls, and making new openings.
• Replacement windows and external doors.
• New or altered drainage, such as a bathroom or kitchen in a new position.
• Installing or replacing a boiler or other heating appliance.
• Certain electrical work, such as new circuits, a new consumer unit, or work in bathrooms.
• Re-covering a large part of a roof or re-rendering a large area of wall, which can trigger insulation upgrades.
• Underpinning, and cavity wall or external wall insulation.

Replacing kitchen units or bathroom fittings in the same place, decorating, flooring and small repairs are usually exempt. In England, a ground-floor porch or conservatory under 30 square metres is often exempt if the existing external door or wall stays in place between it and the house and the glazing meets safety requirements.

How do you get approval in England and Wales?

In England and Wales, you can use the council's building control service or a private building control body, and there are three main routes:

• Full plans application: detailed drawings and calculations are checked and approved before work starts. This is the safest route for extensions, loft conversions and structural work.
• Building notice: you give notice at least two working days before work starts, and the work is inspected as it goes, without plans being approved first. It suits smaller, simpler jobs but is not available for every type of work.
• Regularisation: a retrospective application to the council for work already carried out without approval, which may involve opening up finished work.

Some work can instead be self-certified by an installer registered with a government-authorised competent person scheme, for example replacement windows, boilers and electrical work. The installer notifies building control and you receive a certificate.

How does it work in Scotland?

In Scotland, most building work needs a building warrant from the council's building standards service before work starts, and starting without a warrant where one is needed is an offence. The application includes drawings and specifications showing how the work meets the Technical Handbooks, and the council, acting as verifier, approves it before work begins.

During the work, the council may inspect at key stages set out in a construction compliance and notification plan. When the work is finished, a completion certificate is submitted to the council, which accepts it once it is satisfied the work matches the warrant. Some minor work does not need a warrant but must still meet the building standards. Warrant fees are based on the estimated value of the work.

How does it work in Northern Ireland?

In Northern Ireland, building control is run by the district councils under the Building Regulations (Northern Ireland) 2012, with Technical Booklets giving practical guidance. As in England and Wales, you can usually submit full plans or, for some smaller work, a building notice. The council inspects the work at key stages and issues a completion certificate when it is satisfied. Planning permission, where needed, is a separate application to the same council.

What do building control inspectors check?

Building control inspectors visit at key stages to check work before it is covered up. On a typical extension they will want to see:

1. Foundation trenches before concrete is poured.
2. The damp-proof course and the floor construction.
3. New drains before they are backfilled, sometimes with a test.
4. Steel beams, padstones and the roof structure.
5. Insulation before it is covered by plasterboard.
6. The finished work, with electrical and other certificates, before signing off.

The builder usually books inspections. Missing one can mean opening up finished work later, which is why it helps to have one team managing the whole job.

How much does building control cost?

Building control fees are set by each council or private body, so they vary across the country. As a rough guide, a small structural alteration such as a single steel beam might cost a few hundred pounds, and an extension or loft conversion often costs £800 to £2,000 in fees. In Scotland, building warrant fees follow a national scale based on the value of the work. Regularisation applications usually cost more than applying before work starts.

Structural engineer's calculations, drawings and installer certificates are separate costs. When we quote, we list which approvals your job needs and what is included, and our prices page shows guide ranges for common projects.

What happens if work is done without approval?

If work that needed approval goes ahead without it, the council can require it to be altered or removed, and you may struggle to sell, because buyers' solicitors ask for completion certificates. In England and Wales, regularisation can sometimes put things right, but parts of the work may need to be opened up for inspection, and changes may be needed.

The owner of the building is ultimately responsible for the work complying, even if a builder carried it out. That is why it is worth confirming at the start who is applying for approval and who will hand over the certificates at the end.

Who handles Building Regulations on our jobs?

On jobs that need approval, we arrange building control or a building warrant as part of the work, coordinate structural calculations, book inspections, and hand over the completion certificate and any installer certificates when the job is finished. In England, rules introduced in October 2023 set out duties for clients, designers and contractors on building work; on most domestic jobs the client's duties pass to the contractor or designer.

To see how this applies to a specific project, read our guides on removing a load-bearing wall and planning permission, or get a range from our guide-price tool.

Related services

• Single-storey extensions: guide £35,000–£75,000 inc VAT
• Loft conversions: guide £30,000–£65,000 inc VAT
• Wall removal and steel beams: guide £3,000–£8,000 inc VAT

Figures in this guide are typical UK ranges including VAT where it applies. They are not quotes. Rules on planning and building control differ between England, Wales, Scotland and Northern Ireland and change over time, so we check what applies to your property before quoting.