Most homeowners starting a building project encounter both terms within the first week. Planning permission. Building regulations. They sound similar, and both involve paperwork and inspections, but they control entirely different things. Getting one does not mean you have the other. Skipping either one creates a legal problem that will follow the property until it is resolved.
What Planning Permission Controls
Planning permission is about land use and appearance. The local planning authority — Hertsmere Borough Council, St Albans City and District Council, Welwyn Hatfield Borough Council, or the London Borough of Barnet, depending on your address — decides whether a proposed structure is acceptable in its location. Their considerations include the impact on neighbouring properties, the character of the street scene, the effect on protected trees or conservation areas, and whether the development is consistent with local planning policy.
Planning permission does not care whether your extension is structurally sound or thermally efficient. It cares whether it should exist at all, and what it looks like from the outside. A planning officer will never ask to see your structural calculations or your insulation specification.
Many common domestic projects fall under permitted development rights, which means planning permission is granted automatically by Parliament rather than requiring a specific application. Single-storey rear extensions within certain dimensions, loft conversions that do not exceed the existing roof height, and internal alterations all typically fall within permitted development. Properties in conservation areas, Article 4 direction areas, or listed buildings have reduced or no permitted development rights.
What Building Regulations Control
Building regulations are about how a structure is built. They set minimum standards for structural integrity, fire safety, thermal performance, ventilation, drainage, electrical installations, and accessibility. The Building Safety Act 2022 and the Building Regulations 2010 (as amended) set the legal framework. Compliance is enforced by a building control body — either the local authority building control team or an approved inspector.
Building regulations apply regardless of whether planning permission was needed. A loft conversion under permitted development still requires building regulations approval. So does a new bathroom, a structural opening through a load-bearing wall, a replacement boiler, and most electrical work. The only projects that typically fall outside building regulations are minor repairs, like-for-like replacements of windows (if using a FENSA-registered installer), and small detached outbuildings under 15 square metres with no sleeping accommodation.
The Two Routes to Building Regulations Approval
There are two ways to obtain building regulations approval for most projects.
Full Plans Application
You submit detailed drawings and specifications before work begins. The building control body reviews them and either approves, approves with conditions, or rejects the plans. Once approved, inspections take place at key stages — foundations, damp-proof course, structural frame, insulation, drainage, and completion.
This is the safer route for structural work. Problems are identified on paper before they become expensive to fix on site. The approval provides legal protection if a dispute arises later.
Building Notice
You submit a notice 48 hours before starting work. No drawings are pre-approved. The building control officer inspects at stages and advises on compliance as the work progresses.
This route is faster to start but carries more risk. If the officer finds non-compliant work during an inspection, you will need to alter or demolish it. A building notice cannot be used for work near a sewer, for certain commercial buildings, or for higher-risk buildings under the Building Safety Act 2022.
Which Projects Need Which Approval?
The table below covers the most common domestic projects in Hertfordshire and North London.
| Project | Planning Permission | Building Regulations |
|---|---|---|
| Single-storey rear extension (within PD limits) | Not required (PD) | Required |
| Single-storey rear extension (exceeding PD limits) | Required | Required |
| Double-storey extension | Required | Required |
| Loft conversion (within PD limits) | Not required (PD) | Required |
| Loft conversion (mansard or exceeding PD) | Required | Required |
| Garage conversion (internal) | Not required (usually) | Required |
| New bathroom | Not required | Required |
| Structural wall removal | Not required | Required |
| New boiler installation | Not required | Required |
| Garden room under 15m² (no sleeping) | Not required | Not required |
| Garden room over 15m² | Not required (usually) | Required |
| New build dwelling | Required | Required |
PD = Permitted Development. Rules vary for conservation areas, Article 4 direction areas, and listed buildings. Always verify with your local planning authority before starting work.
The Planning Application Process
A householder planning application in Hertfordshire follows a standard sequence. Your architect or planning consultant prepares drawings showing the existing and proposed layouts, elevations, and site plan. These are submitted to the local planning authority along with the application form and fee — currently £258 for a householder application in England.
The application is validated, a case officer is assigned, and neighbours are notified. The statutory determination period is 8 weeks for householder applications. Most straightforward applications receive a decision within this period. Applications in conservation areas, those requiring a design and access statement, or those attracting significant neighbour objections can take longer.
Pre-application advice is available from all Hertfordshire local planning authorities. Paying for a pre-application meeting — typically £100–£300 for a householder project — allows you to test your proposals before committing to a full application. Officers will indicate whether the scheme is likely to be supported and what changes might improve the chances of approval.
Permitted Development: What It Covers and What It Does Not
Permitted development rights allow certain types of development without a planning application. The rights are set out in the Town and Country Planning (General Permitted Development) (England) Order 2015, as amended. For householders, the key classes are Class A (extensions), Class B (roof additions), Class C (roof alterations), and Class E (outbuildings).
The limits are specific. A single-storey rear extension on a detached house can extend up to 4 metres from the original rear wall without planning permission. On a semi-detached or terraced house, the limit is 3 metres. Extensions between 4–8 metres (detached) or 3–6 metres (other) can proceed under the Larger Home Extension scheme, which requires prior approval from the local planning authority — a lighter-touch process than a full application, but still a formal step.
Permitted development rights are removed or restricted in conservation areas, Areas of Outstanding Natural Beauty, National Parks, and for listed buildings. Article 4 directions — which Hertsmere, St Albans, and several London boroughs have applied to specific streets — can also remove permitted development rights from individual properties. Checking whether your property is subject to an Article 4 direction before assuming permitted development applies is a necessary step.
A Lawful Development Certificate (LDC) is not legally required to proceed under permitted development, but obtaining one provides formal written confirmation from the local planning authority that your project falls within permitted development rights. It costs £103 for a proposed use and provides protection if the permitted development status is ever challenged — by a neighbour, a buyer's solicitor, or a future planning officer.
What Happens If You Build Without Approval?
Building without planning permission where it was required creates an enforcement risk. Local planning authorities have 4 years to take enforcement action for operational development (building work) and 10 years for changes of use. After these periods, the development becomes immune from enforcement. However, immunity from enforcement does not mean the development is lawful — it cannot be mortgaged or sold without a Certificate of Lawful Use or Development.
Building without building regulations approval where it was required creates a different problem. There is no limitation period for building regulations enforcement. The local authority can require you to open up, alter, or demolish non-compliant work at any time. More practically, the absence of a completion certificate will be identified by a buyer's solicitor during conveyancing. You will need to obtain a regularisation certificate retrospectively, which costs more than the original application and requires the building control officer to inspect exposed structural elements.
Indemnity insurance is sometimes offered as a solution for missing planning permission or building regulations certificates. It covers the legal costs of enforcement action but does not make the work compliant. Mortgage lenders vary in their acceptance of indemnity insurance — some will not lend against properties where structural work was carried out without building regulations approval, regardless of insurance.
Conservation Areas and Listed Buildings
Properties in conservation areas lose most permitted development rights for extensions, roof alterations, and cladding. Any work that would materially affect the external appearance of a dwelling in a conservation area requires planning permission. Hertfordshire has over 130 conservation areas, including large parts of St Albans city centre, Radlett village centre, Shenley, and several streets in Borehamwood.
Listed buildings require listed building consent for any works that affect their character as a building of special architectural or historic interest. This applies to internal as well as external alterations. Listed building consent is separate from planning permission and building regulations — a listed building project may require all three. Carrying out works to a listed building without consent is a criminal offence, not a civil matter.
How TCM Manages the Approval Process
TCM Building & Maintenance works with a network of architects and planning consultants who handle the planning application process for clients. For projects within permitted development, we obtain a Lawful Development Certificate as standard before work begins. For projects requiring building regulations approval, we submit a full plans application and manage all stage inspections through to the completion certificate.
Every project we deliver comes with a complete documentation pack: planning approval or LDC, building regulations completion certificate, structural engineer's calculations, and any specialist certificates (Gas Safe, NICEIC, FENSA). This documentation is what your solicitor will need when you sell, and having it in order from day one avoids delays and additional costs at that stage.
If you are planning a project in Hertfordshire or North London and are unsure which approvals apply, contact TCM for a free initial assessment. We will identify the relevant consents, advise on the timeline, and connect you with the right professionals to manage the process.
Frequently Asked Questions
Do I need both planning permission and building regulations approval?+
Many projects require both, but not always. A loft conversion under permitted development still requires building regulations approval. A garden wall may need planning permission but not building regulations. The two systems are entirely separate. Planning permission controls whether a structure can be built and what it looks like. Building regulations control how it is built and whether it is safe. Your builder or architect should identify which approvals apply to your specific project before work begins.
What happens if I build without building regulations approval?+
Building without required building regulations approval creates a serious problem when you sell. Buyers' solicitors routinely request building regulations completion certificates. Without one, you will need to obtain a regularisation certificate retrospectively, which costs more than the original application and requires the building control officer to inspect exposed work. If the work cannot be inspected without opening up, the cost increases further. Some lenders will not mortgage a property with unregulated structural work.
How long does planning permission take in Hertfordshire?+
Householder planning applications in Hertfordshire typically take 8 weeks from validation to decision. Hertsmere Borough Council, St Albans City and District Council, and Welwyn Hatfield Borough Council all operate within this statutory timeframe for straightforward applications. Complex applications, those requiring consultation with statutory consultees, or applications in conservation areas can take 13 weeks or longer. Pre-application advice from the local planning authority can reduce the risk of refusal and shorten the overall timeline.
Can I start building work before building regulations approval?+
You can start work 48 hours after submitting a building notice, which is a faster route than a full plans application. However, a building notice carries more risk because the building control officer has not pre-approved your drawings. If the officer inspects and finds non-compliant work, you will need to alter or demolish it. For structural work — foundations, beams, load-bearing walls — a full plans application with pre-approval is the safer approach.
Does a single-storey rear extension need planning permission?+
Most single-storey rear extensions on detached and semi-detached houses fall within permitted development rights and do not need planning permission, provided they do not extend beyond 4 metres from the original rear wall for detached houses or 3 metres for semi-detached and terraced houses. Extensions between 4–8 metres (detached) or 3–6 metres (other) require prior approval under the Larger Home Extension scheme. All extensions, regardless of whether they need planning permission, require building regulations approval.
What is a completion certificate and why does it matter?+
A completion certificate is issued by the building control body after the final inspection confirms the work complies with building regulations. It is the legal proof that the construction was inspected and approved. Without it, you cannot demonstrate compliance when selling. Mortgage lenders require it for structural alterations. It also protects you if a dispute arises about the quality of the work, as it confirms the building control officer was satisfied at the time of inspection.
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