Extending your home can provide much-needed space and add value to your property. However, before breaking ground, it is important to understand the planning process and the factors that local authorities will consider. Careful preparation can make the difference between approval and refusal as well as an understanding of what is and isn’t permitted.
The Definition of the “Original Dwelling”
This is defined as the house as it stood on 1 July 1948 (the date modern planning controls began), or, if constructed after that date, as it was first built. Any extensions or alterations made since then—whether by you or by previous owners—are not considered part of the “original dwelling.”
Some Councils have restrictive policies as to how much they will allow extension of a property in general and this often relates to “original” – it is therefore key to understand, from the start, what has been done since this point. This is particularly the case in many rural areas and the Green Belt.
Permitted Development Rights
Some extensions can be carried out without formal planning permission under “permitted development rights.” These rights allow householders to make certain changes within specific limits relating to size, height, and location. They do not apply in all circumstances—such as listed buildings, flats, or areas with Article 4 Directions. Even where permitted development applies, it is often wise to seek a “lawful development certificate” from the Council for certainty. In addition, some extensions, whilst permitted development, could still need to go through a notification process (such as for a larger homes extension).
Anything which is not permitted development would be a householder planning application.
Design and Scale
When planning permission is required, the design and scale of the extension are critical. Proposals should respect the proportions of the original dwelling and avoid dominating the existing building or neighbouring properties. Extensions should be clearly subservient to the host dwelling. Local planning authorities will assess whether the extension integrates with the character of the home and surrounding area, using materials and detailing that complement the existing fabric.
Impact on Neighbours
Extensions should not cause undue harm to the amenity of neighbouring properties. Key considerations include loss of light, overlooking, and privacy. Councils may refuse applications that result in an overbearing impact, so thoughtful design and early discussions with neighbours can help smooth the process.
Conclusion
A strong application is supported by accurate drawings, planning statements, and, where relevant, technical assessments. Engaging a planning consultant and architect can help present the proposal in the best light, aligning it with national and local planning policies.
Extending your home involves more than just design ambition—it requires a clear understanding of planning rules, particularly the definition of the “original dwelling” and the limitations it imposes. By considering design, neighbour impacts, and site-specific constraints, and by seeking professional advice where appropriate, homeowners can maximise their chances of securing planning permission and realising a successful extension.