PLANNING PERMISSION
Building a home extension is an investment in your property which takes time to plan and perfect to ensure it is exactly how you have envisioned, therefore ensuring that the build is erected within the regulations is key.
The good news is, our standard extension designs are designed to adhere to Permitted Development Rights, however there may be instances where your specific build isn’t possible to construct within the guidelines and therefore may require an application for further planning.
It can be daunting trying to understand the key terms and criteria accepted within either Permitted Development or Planning Permission, therefore we have put together this helpful guide to explain each regulation.
WHAT ARE PERMITTED DEVELOPMENT RIGHTS?
Permitted Development Rights derive from general planning permission granted by Parliament to allow homeowners to make certain types of minor changes to their property, without the need to apply for full Planning Permission.
They are, however, subject to conditions and limitations. For example, in some areas of the country known as ‘designated areas’, Permitted Development Rights are more restricted, such as:
- If you live in a Conservation Area
- A National Park
- An area of Outstanding Natural Beauty
- A World Heritage Site or
- The Norfolk or Suffolk Broads
Please note that this is not the only criteria to be met, and full information can be found on the Planning Portable website here.
WHAT IS THE DIFFERENCE BETWEEN PERMITTED DEVELOPMENT RIGHTS AND PLANNING PERMISSION?
As mentioned, Permitted Development Rights are a set of pre-determined conditions and limitations granted by Parliament that allows homeowners to make minor changes to their property. Planning Permission is formal permission, which you are required to obtain from your local authority to build or alter your home, as the build does not fall within Permitted Development Rights.
WHAT ARE PERMITTED DEVELOPMENT GUIDELINES FOR BUILDING EXTENSIONS?
Permitted development (PD) guidelines for extensions allow some projects to commence without a full planning application, provided they meet strict criteria on size, height, and location.
Key rules include restrictions on rear extension depth (e.g., up to 4m for detached houses, 3m for others), height (max 4m for single-storey), and width (side extensions can't be more than half the original house's width). Some larger extensions require a "prior approval" from the local council before starting, which involves neighbour consultation.
Common Permitted Development Rules:
- Only half the area of land around the "original house"* can be covered by extensions or other buildings.
- Extensions cannot be higher than the highest part of the existing roof; or higher at the eaves than the existing eaves.
- Where the extension comes within two metres of the boundary the height at the eaves cannot exceed three metres.
- Extensions cannot be built forward of the ‘principal elevation’ or, where it fronts a highway, the ‘side elevation’.
- Rear Extensions:
- Single-storey:
- Maximum 4m deep for a detached house; 3m for other types.
- Total height must not exceed 4m.
- Larger single-storey extensions: Can extend up to 8m for a detached house or 6m for other types, but only if you get "prior approval" from the local council.
- Single-storey:
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- Two or more storeys:
- Must not extend beyond the rear wall of the original house by more than 3m.
- Two or more storeys:
- Side extensions:
- Must not be wider than half the width of the original house.
- Must not exceed 4m in height.
- Roof extensions:
- Dormer windows must meet specific size and placement rules, such as being a minimum distance from the ridge, eaves, and sides of the roof.
- Raised ridges or mansard roofs that significantly alter the roof's appearance are generally not allowed.
- Materials:
- The exterior materials must be similar in appearance to the original house.
It is important to note that Permitted Development Rights as explained above apply only to houses and not to flats, maisonettes, converted houses, houses created through Permitted Development Rights to change the use, areas where they may be a planning condition, Article 4 Direction or other restriction that limits Permitted Development Rights.
ARE THERE ANY FURTHER CONDITIONS OR REGULATIONS THAT I NEED TO BE AWARE OF?
All home extensions will need to comply with building regulations. The Building Regulations are intended to protect the health, safety and wellbeing of people in and around buildings, with local councils administering the regulations.
- Structure: Extensions must be structurally sound, with foundations, walls, and roofs built to support the new structure and meet load-bearing requirements.
- Fire safety: You must incorporate fire safety measures, such as fire-resistant materials, smoke alarms, and safe exit routes, especially for multi-story extensions.
- Thermal insulation: Extensions must meet energy efficiency standards for walls, roofs, and floors to prevent heat loss. All new openings (doors, windows) must also be draft-proofed.
- Ventilation: Adequate ventilation is essential to prevent dampness, mold, and poor air quality, particularly in kitchens and bathrooms.
- Drainage: Any plumbing and drainage work must comply with building regulations for both foul water (from sinks, toilets) and surface water.
- Electrical safety: All electrical work must be carried out safely and, ideally, by a registered competent person who can self-certify the work.
- Doors and windows: New doors, windows, and roof lights must be fitted and glazed to meet minimum standards. This includes ensuring they are thermally efficient and that any necessary lintels are correctly installed.
YOUR EXPERIENCE
As mentioned, our standard extensions are designed with Permitted Development Rights in mind and therefore there should be no requirement to apply for further approval from your local council. However, if your build does require full planning permission then we can take care of that for you.
This will be communicated to you during the consultation stage by our friendly team of experts, allowing you to make an informed decision. Whilst it is the responsibility of the homeowner to apply for full Planning Permission/seek Building Regulations approval, our team have over 30 years’ experience combined within the construction sector so can assist you with any questions you may have along the way.
WHAT’S NEXT?
You are equipped with all of the knowledge surrounding Permitted Development Rights, Planning Permission and The Building Regulations, so all that is left to do is start creating your perfect space. Whilst we have lots of best-selling sizes that we can recommend, we understand each customer is different so we will work with you to ensure your needs are met whilst bringing your vision to life! Read about our planning permission services here.
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