If you’re considering building work in Hertfordshire, whether it’s a new extension, loft conversion or home office in the garden, you’ll likely come across two key terms: planning permission and permitted development.
Understanding the difference is crucial to avoid delays, legal issues, or unnecessary paperwork.
While both routes allow you to make changes to your property, they involve different rules, application processes, and restrictions. So what’s the difference, and how do you know which one applies to your project?
What is Planning Permission?
Planning permission is formal approval from your local council (such as Hertsmere or St Albans City & District) allowing you to carry out certain types of development. It’s typically required when your proposed work:
- Involves major structural changes
- Affects the external appearance of your home significantly
- May impact your neighbours or the local environment
- Includes changes to listed buildings or properties in conservation areas
The application process usually involves submitting architectural drawings, a design and access statement, and paying a fee. Your local planning authority will assess the proposal based on factors like local development plans, visual impact, parking, and privacy concerns.
According to Planning Portal, most planning applications are decided within 8 weeks — or 13 weeks for more complex projects.
Lloyd Dixon Group is an experienced team of property surveyors in London, St Albans, Hertfordshire and Mayfair. To get a quote or speak to us, please call 075 95 534 101.
What is Permitted Development?
Permitted development (PD) rights are a set of national rules that allow homeowners to make certain changes without needing full planning permission. These rights are granted automatically by the government and apply across England — including in Hertfordshire.
Common types of permitted development include:
- Loft conversions with dormer windows
- Single-storey rear extensions
- Garage conversions
- Installation of solar panels
- Building a garden outbuilding or home office
However, these rights come with strict limits on height, size, location, and materials. For example, a rear extension must not extend more than 3 metres (or 6 metres for detached houses, with neighbour consultation).
Key Differences Between Planning Permission and Permitted Development
| Feature | Planning Permission | Permitted Development |
| Requires application? | Yes | No (unless prior approval is required) |
| Council approval needed? | Yes | Sometimes (for prior approval schemes) |
| Limited by property type? | No | Yes (flats, listed buildings often excluded) |
| Typical time to start work | 8–13 weeks (approval required) | Immediate (if compliant) |
| Flexibility of design | High – full architectural freedom | Limited by strict PD rules |
| Common projects | Large extensions, major alterations | Lofts, porches, small extensions, solar |
When You May Need Prior Approval
Some larger projects under permitted development still require prior approval — a simplified version of planning permission. This is common for:
- Large single-storey rear extensions (over 3m but under 6m/8m)
- Change of use (e.g. commercial to residential)
- Building in areas with flood risk or near transport networks
The council won’t assess the whole design, just the specific risks or impacts. Approval must be received before work begins.
How Do You Know Which One Applies?
Here are some common scenarios to help guide you:
- Loft conversion with dormer – Often falls under permitted development
- Two-storey side extension – Likely needs planning permission
- New garage in front garden – Planning permission typically required
- Garden office at rear of property – Usually permitted development if under 2.5m high and not used as living accommodation
- Rear extension on a semi-detached house – May fall under PD if under 3m, but larger extensions require prior approval
Why This Matters for Homeowners
Knowing whether your project needs permission or not can:
- Save you weeks of paperwork and potential rejection
- Help avoid enforcement notices or fines from the council
- Ensure your project stays within legal and design limits
- Prevent issues if you plan to sell the property in the future
We always recommend checking with your local planning authority, even if you think your project qualifies under permitted development. They may have Article 4 Directions in place, which remove PD rights in certain areas (often conservation areas).
Need Expert Support?
Whether you’re planning a small upgrade or a major extension, our team at Lloyd Dixon Group can help guide you through the process. We offer:
- Planning drawings and documentation
- Party Wall surveys
- Defect diagnosis
- Development appraisals and feasibility advice
- Measured surveys and elevation drawings
- Pre-application consultations
- Monitoring your project
We help homeowners and developers across Hertfordshire make confident decisions before they break ground. To get a quote or speak to us, call 075 95 534 101 or visit our contact page.
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