The Simple Version
Planning Permission
Does the local planning authority approve of the change to the building? This covers whether you can extend, change use, alter the appearance, or increase the size of a structure. It is a land-use and neighbourhood question.
Building Regulations
Does the construction meet minimum safety, structural and technical standards? This covers how the building is constructed — structural integrity, fire safety, insulation, drainage, ventilation. It is a technical standards question.
Put simply: planning permission deals with what you are building and whether your neighbours and the local authority are broadly in agreement with it. Building Regulations deal with how it is built and whether it is safe, sound and compliant with national technical standards.
Why Both Matter — And Why They Are Often Confused
The confusion arises because they are applied to the same project but are handled by different organisations, at different stages, for completely different reasons.
You can have planning permission without needing Building Regulations (for example, some change-of-use applications). You can need Building Regulations without needing planning permission (most domestic extensions under Permitted Development). And you can need both.
A particularly common mistake: homeowners receive confirmation that their project is Permitted Development — meaning no planning application is required — and assume this means they can build freely. It does not. Building Regulations still apply in almost all cases.
Planning Permission Explained
Planning permission is granted (or refused) by your Local Planning Authority — the planning department of your local council. It controls what changes are made to the built environment, protecting the character of neighbourhoods and managing the impact of development on neighbours and infrastructure.
When you need planning permission typically includes: new buildings, extensions beyond certain dimensions, changes of use (for example converting a house to flats), alterations that materially affect the external appearance in a conservation area, and any work to a listed building.
Permitted Development
Many domestic works fall under Permitted Development (PD) — a set of national rules that grant automatic planning permission for certain types and scales of work, without the need to make a formal application. Common PD works include modest rear extensions, loft conversions within volume limits, and some outbuildings.
However, PD rights are removed or restricted in conservation areas, World Heritage Sites, National Parks and Areas of Outstanding Natural Beauty. They do not apply to listed buildings. They generally do not apply to flats or maisonettes. If in doubt, apply to your council for a Lawful Development Certificate — this is a formal document confirming that a specific project is Permitted Development.
Building Regulations Explained
Building Regulations are national technical standards that construction work must meet. They are enforced by Building Control — which can be your local council's Building Control team or an approved inspector from a private organisation.
The regulations cover a wide range of technical requirements, including:
- Structural integrity — foundations, beams, load-bearing elements
- Fire safety — fire resistance, means of escape, smoke alarms
- Thermal performance and energy efficiency — insulation standards
- Ventilation — adequate fresh air supply
- Drainage and sanitation
- Electrical installations (Part P)
- Gas and heating systems (Gas Safe requirements)
- Damp proofing and weatherproofing
- Accessibility in certain situations
- Conservation of fuel and power
The Completion Certificate
When Building Control is satisfied that the works have been completed to the required standard, they issue a Completion Certificate. This is a critical document — it proves that the works have been inspected and signed off. Without it, you may face problems when you sell the property or remortgage.
Common Points of Confusion — Answered Directly
“I have planning permission. Do I still need Building Control?”
YES — in almost all cases. Planning permission and Building Regulations are separate. Planning permission tells you the local authority is happy with the development. Building Regulations ensure it is built safely and to the correct technical standard. Both are usually required.
“I don't need planning permission (Permitted Development). Do I still need Building Regulations?”
OFTEN YES. Most structural and construction work — extensions, loft conversions, garage conversions, structural alterations — requires Building Regulations approval even if no planning permission is needed. The two are independent requirements.
“Does Permitted Development mean I can just start building?”
No. Permitted Development simply means you do not need to make a formal planning application. Building Regulations still apply. You must still notify Building Control before work starts (or use the Full Plans route). Work without Building Control notification is non-compliant.
What Happens Without a Completion Certificate
Carrying out notifiable works without Building Control involvement — or failing to obtain a Completion Certificate — creates real, practical problems:
Resale complications
Solicitors will ask for evidence of Building Control sign-off. If you cannot produce it, buyers, their solicitors and their lenders may refuse to proceed or require an indemnity insurance policy — which does not resolve the underlying compliance issue.
Mortgage complications
Lenders may decline to lend on a property where significant works were carried out without Building Regulations compliance. Remortgaging can also be affected.
Insurance complications
If a claim arises related to the works — a structural failure, fire — your home insurer may decline to pay if the works were not Building Control compliant.
Enforcement risk
In serious cases, Local Authorities have enforcement powers to require non-compliant works to be corrected or removed — at the owner's cost.
How RCB Handles This
As your principal contractor, RCB coordinates both the planning and Building Regulations routes as a core part of the service — not as an extra you have to manage yourself.
- We assess the correct planning route for your project at the outset — planning application, Permitted Development, or pre-application advice
- We prepare or coordinate the preparation of the required planning documentation, drawings and applications
- We notify Building Control and manage the required stage inspections throughout the build
- We ensure the works are completed to a standard that will achieve a Completion Certificate
- We hand you the Completion Certificate and all required documentation at project handover
Disclaimer: This guide is for general information only. Planning and Building Regulations rules are complex and change. The rules around Permitted Development in particular have been amended several times and can vary depending on location, property type and prior changes. Always verify the specific requirements for your property and project with a qualified professional or by contacting your Local Planning Authority directly.