Planning Permission or Building Regulations? Which One Your Job Needs

Somewhere between "we're thinking about a bigger kitchen" and the first skip arriving, everybody has the same slightly panicky conversation about whether they need permission.

The confusion is not really about the rules. It is that there are two sets of them, they are run by different people, they ask different questions and they are both loosely called "getting it signed off". Plenty of extensions have full planning permission and no building regulations approval, which is the worse of the two to be missing.

So before anything else, separate them.

Two systems, two questions

Planning is run by your local planning authority and is about the effect of the building on everybody else. Is it too big, too close, too tall, in front of the building line, out of keeping with a conservation area, blocking somebody's light. A planning officer is not checking whether your beam will hold the roof up.

Building regulations are run by building control, which is either the council's own team or a private registered building control approver. They are about whether the thing is safe and sound: foundations, structure, fire escape, insulation, ventilation, drainage, glazing, electrics.

A garden shed of a modest size usually needs neither. A rear extension usually needs building regulations and often does not need planning permission. Replacing your boiler needs building regulations and never needs planning permission. A change of use with no building work at all can need planning permission and no building regulations.

The two do not talk to each other and one does not imply the other. That is the whole trick.

Permitted development is permission you already have

Permitted development rights are a blanket planning permission granted nationally, so long as you stay inside the limits. You are not escaping the planning system, you are using a permission it already gave you.

For a house in England, roughly:

• A single storey rear extension can go 3 metres deep on a terraced or semi-detached house and 4 metres on a detached one
• The Larger Home Extension route pushes that to 6 metres and 8 metres with prior approval, which means the council notifies your neighbours and waits to see if anybody objects
• The extension cannot be more than 4 metres high, its eaves cannot be higher than the existing eaves and it must not go forward of the principal elevation facing a highway
• Everything you build must not cover more than half the land around the original house, which means as the house was built or as it stood in 1948, not as you bought it
• Loft conversions have a volume allowance, commonly 40 cubic metres for a terrace and 50 for a semi or detached, with nothing extending beyond the roof slope facing the road

Those figures move. A proposal to increase several of them has been consulted on without being implemented, so treat the numbers as the shape of the rules rather than the last word. Your council's planning pages carry the current version.

Building regulations catch far more than planning does

This is the half people underestimate. Building regulations apply to a long list of ordinary jobs, including plenty that never go near a planning officer:

• Extensions, loft conversions and garage conversions
• Removing or altering a load bearing wall, or putting in a steel
• Replacing windows and external doors
• A new boiler, or moving an existing one
• A new consumer unit and electrical work in a kitchen or bathroom
• New or altered drainage
• Underpinning
• Insulating a roof or a cavity wall in most circumstances

Redecorating, replacing like for like fittings and most straightforward repairs do not. A kitchen refit is usually only caught by the parts of it that are electrical, structural or plumbing related, which is generally more of it than people expect.

Who signs it off and what you actually get

There are two routes and the difference matters when you go looking for the paperwork later.

Through building control. You submit full plans or a building notice, an inspector visits at stages and at the end you get a completion certificate. That is the document. Keep it.

Through a competent person scheme. For some trades the installer is registered to certify their own work and notify building control for you. Gas Safe for gas, NICEIC, NAPIT or ELECSA for Part P electrical work, FENSA or Certass for windows and doors, OFTEC for oil, HETAS for solid fuel. You get a compliance certificate, usually by post a few weeks after the job. It is very easy to bin as junk mail.

Two rules follow from that.

Ask before the work starts who is notifying building control. If the answer is a shrug, the answer is you. Nobody finds out until the job is done.

The certificate is the proof, the invoice is not. An invoice shows you paid somebody. It says nothing about whether the work met the standard, which is the question a buyer's solicitor is actually asking. We wrote about that gap in more detail in how to prove work was done on your home.

If the work is already done

For a breach of planning control in England, the enforcement window is now 10 years for anything substantially completed on or after 25 April 2024. It used to be four years for building work, which is why so much informal advice still says four. Older breaches may still fall under the old rule, which is a question for a solicitor rather than a guess.

For building regulations, the council's enforcement window went from two years to 10 years on 1 October 2023.

You have options either way. A retrospective planning application asks for permission after the event. A lawful development certificate asks the council to confirm the thing is lawful, either because it was always within permitted development or because it is now immune. It is the cleaner answer of the two because it produces a document rather than a decision. For building work, building control can issue a regularisation certificate for unauthorised work carried out since 11 November 1985, which usually means opening something up so it can be inspected.

None of that is a disaster. It is a delay, of the kind that turns up at the worst possible moment, which is six weeks into a sale when the buyer's solicitor asks a question nobody can answer.