Planning an extension can be exciting, but many homeowners run into problems because they don’t realise how strict planning rules can be. Councils assess applications against detailed policies, and small design issues can sometimes lead to a refusal.
Understanding the most common mistakes early can save time, money, and frustration.
1. Extensions That Are Too Large
One of the most common reasons for refusal is simply that an extension is too large for the property or the surrounding area.
Councils will consider whether an extension would:
- Have a harmful impact on neighbouring properties
- Dominate the original house
- Appear overly bulky
- Reduce garden space too much
Even if a large extension seems reasonable to a homeowner, planning policy often limits scale to protect the character of the area.
2. Impact on Neighbouring Properties
Planning officers carefully consider how extensions affect neighbours.
Common concerns include:
- Loss of privacy from new windows
- Overshadowing or loss of daylight
- Overbearing impact on outlook
Designing an extension that respects neighbouring homes is one of the most important factors in gaining approval.
3. Poor Design or Unsympathetic Materials
Extensions should usually reflect the character of the original house.
Applications are sometimes refused because:
- Materials don’t match the existing building
- Roof design conflicts with the original property
- The extension looks visually out of place
Good design does not necessarily mean expensive design, but it does mean the extension should feel like a natural addition to the home.
4. Ignoring Local Planning Policies
Every council has its own planning policies that guide development. These policies cover things like design standards, garden space, parking requirements, and the protection of local character.
Applications that ignore these policies are far more likely to be refused.
5. Assuming Permitted Development Applies
Many homeowners assume their extension will fall under permitted development rights. While this is sometimes true, there are many situations where these rights are restricted or removed.
For example:
- Properties in conservation areas
- Houses with previous extensions or outbuildings
- Location of extension
- Proposed materials
- Homes where planning conditions removed permitted development rights
Checking this early can prevent expensive mistakes.
Planning Advice Before You Start
Before committing to drawings or submitting an application, it’s worth understanding the planning position of your property.
A Home Extension Planning Report provides a clear assessment of:
- What you can build under permitted development
- Planning risks
- The likelihood of approval
Order a Planning Report