Building regulations explained for homeowners

Building regulations are the minimum standards for how work on a home is built: structure, fire safety, insulation, drainage, ventilation and electrics. In England extensions, loft conversions, replacement windows, new boilers and rewires all need approval, and as the owner you are ultimately responsible for compliance, even when a builder applies. We cover which jobs need it, the ways to apply, who signs it off, the certificate you need to sell, and how Scotland, Wales and Northern Ireland differ.

What building regulations cover

In England the rules are the Building Regulations 2010, a set of minimum standards for how building work is designed and built. They cover structure, fire protection, access, energy performance, sound insulation, protection from falls, drainage, ventilation, damp, ground gases such as radon, and electrical and gas safety.

They deal with how the work performs, not how it looks, and the same standards apply whether a builder does the job or you do it yourself. The regulations themselves are short: a few lines of legal requirement per topic. The detail, such as how well a new wall must be insulated or how steep a loft stair can be, is set out in the Approved Documents, the government's guidance on meeting each part.

Building regulations or planning permission: what is the difference

Planning permission decides whether you can build something at all: its size, its appearance and its effect on neighbours and the street. Building regulations decide whether it is built safely and to standard. A project can need one, both or neither, and knowing whether you need planning permission tells you nothing about the building regulations answer.

A rear extension built under permitted development skips the planning application but still needs building regulations approval. So does every loft conversion, including a dormer that fits the size limits and needs no planning permission for a loft conversion.

Neither regime covers your neighbour's side of a shared wall. Work on or near one has its own notice procedure under the Party Wall Act, and building control approval does not replace it.

Which jobs need building regulations approval

The list runs well past extensions. The government's approval guide names replacement windows and doors, new roof coverings, fixed air conditioning, heating systems and even extra radiators alongside the obvious building work.

Electrics are where the list catches people out. A new socket in the living room is exempt, but any change to the wiring inside the bathroom electrical zones around a bath or shower is notifiable, and so is a new fuse box.

A garage looks like an easy win because the walls and roof already exist. But a garage conversion turns a store into a habitable room, so the new wall where the door was, the insulated floor and walls, the ventilation and the fire safety all need approval.

What you can build without building regulations approval

Exempt work still has to be done properly, but nobody has to approve it first. The exemptions in England cover:

• Most repairs, replacements and maintenance, except work on heating systems, oil tanks, fuse boxes and glazing units
• New power and lighting points, and changes to existing circuits, anywhere except around baths and showers
• Replacing baths, toilets, basins and sinks
• Insulation laid in a loft or under a timber floor
• Some hot water storage systems holding less than 15 litres
• Gutters and downpipes
• External doors where less than half the door is glazed
• Emergency repairs to a boiler or heating system, which need no advance approval but still follow the rules

Garden rooms, sheds and outbuildings

A detached building of up to 15 square metres with no sleeping accommodation is exempt. A single-storey detached building of up to 30 square metres is exempt too, provided nobody sleeps in it and it either sits at least 1 metre from every boundary or is built mostly from non-combustible materials. That covers most sheds, summerhouses, home offices and garden rooms. Add a bedroom, or go over 30 square metres, and the building needs approval like any other.

Porches and conservatories

A porch or conservatory added at ground level with a floor area of up to 30 square metres is exempt, provided its glazing meets the safety glazing rules, it is separated from the house by external-quality walls, doors or windows, and the home's heating system is not extended into it.

Take out the doors between the house and the conservatory, or run a radiator into it, and the exemption goes: it becomes an extension, with the insulation and glazing standards that come with one. None of this settles whether a conservatory needs planning permission, which turns on its size and position on the house.

Full plans, building notice or regularisation

In England you apply before work starts in one of two ways. A third route exists for work that has already been done.

Full plans costs time at the start and buys certainty, because the drawings are checked before anyone digs. A building notice suits a small, simple job such as a new bathroom. Nobody checks a design first, so if the inspector finds an undersized beam or a badly laid drain on site, the fix happens mid-build and the cost lands on the job.

Council building control or a registered building control approver

For most homes you choose who checks the work: your council's building control team or a private registered building control approver, the newer name for what used to be called an approved inspector.

There is no national fee. Each council publishes its own charges, which depend on the type of work, the number of site inspections, the number of homes and the total floor area, so compare the council's figure with one or two approver quotes for the same drawings. Work carried out solely for a person with a disability may carry no fee.

Blocks of flats at least 18 metres or 7 storeys high with 2 or more homes are higher-risk buildings. Work there needs approval from the Building Safety Regulator before it starts, unless it is exempt, done under a competent person scheme or an emergency repair.

Competent person schemes: self-certified work

An installer registered with a competent person scheme can self-certify that the work complies, so you make no application at all. The installer tells the council on your behalf where needed, and you get a certificate within 8 weeks of completion. The certificate shows up in solicitors' searches when you sell, and the schemes carry insurance-backed warranties and complaints procedures.

Windows, boilers and electrics are the usual cases. By law, gas work has to be done by a Gas Safe registered engineer, and the notification for a new boiler comes through that registration. That certificate is a different document from the annual gas safety certificate a landlord needs for appliances already installed.

Electrical paperwork gets mixed up the same way. New wiring comes with an electrical installation certificate plus the scheme's building regulations certificate, while an EICR reports on the condition of wiring that already exists and signs nothing off.

The Approved Documents, part by part

The Approved Documents are the government's guidance on meeting each part of the regulations in England. Following them is the usual way to show compliance; a designer can meet a requirement another way, but then has to prove it to building control.

Inspections and the completion certificate

Building control inspects at key stages rather than watching the whole job. On an extension that usually means the foundation trench before the concrete goes in, the damp-proof course, drains before they are covered, the structure before it is boarded and a final visit. The builder normally books each one, so build them into the order of works before the programme is fixed.

When the final inspection passes, the council issues a completion certificate, usually within 8 weeks of the work finishing on a full plans application. A registered approver issues a final certificate instead. Either way, keep it: it is the document a buyer's solicitor asks for.

Work done without building regulations approval

The person who did the work can be prosecuted and fined, and the council can make you pay to put faulty work right.

The route back is regularisation: a retrospective application to the council, since a registered approver cannot take one on. It only covers work carried out after 11 November 1985. Expect the inspector to ask for finished work to be opened up, such as a trial hole beside a foundation or plasterboard taken off a wall, so budget for the digging and making good as well as the fee.

Building regulations in Scotland, Wales and Northern Ireland

Everything above is the England system. Wales, Scotland and Northern Ireland each set their own technical standards, so a project in Cardiff, Edinburgh or Belfast follows its own nation's rules.

Scotland runs a building warrant system. You need the warrant from the council before work starts, and when the job is done you submit a completion certificate, which the council has to accept. Some smaller work needs no warrant but still has to meet the standards, and the Scottish Government's building standards guidance lists which.

Wales writes its own Approved Documents, so energy and fire requirements can differ from England even where the process looks the same. Registered building control approvers work in Wales too, on a separate Welsh register.

Northern Ireland keeps building control with its district councils, and its technical guidance comes as Technical Booklets rather than Approved Documents.