One of the first questions homeowners ask is whether an extension needs planning permission. The honest answer is: sometimes. Many smaller extensions fall under 'permitted development', but plenty still need a full planning application — and the rules change depending on your property and where you live. Here's how to think about it.
In short
Many smaller extensions are permitted development and don't need a full planning application — but not all. Size, position, your property type and where you live all matter. We advise on the likely route and prepare the drawings, always confirmed with your local authority.
Not sure which route applies to your property? Send Sean your postcode, a few photos and a short description for an honest first view — with no obligation.
Reviewed by Sean Corser, SC Design & Construction. Sean Corser helps Wirral homeowners with architectural design and drawing packs for extensions, loft conversions, planning and building regulations.
Last reviewed June 2026
Permitted development rights let you carry out certain works without a full planning application, within strict size and position limits. A modest single-storey rear extension on a typical house will often fall within these limits.
However, permitted development does not apply everywhere or to every home. Flats, maisonettes and converted houses usually don't have the same rights, and the limits are tighter on the side and front of a property.
You're more likely to need a full planning application if your extension is large or two-storey, sits forward of the principal elevation, is close to a boundary, or significantly changes the roof.
Where your home sits matters too: conservation areas, Article 4 directions, listed buildings and Areas of Outstanding Natural Beauty all reduce or remove permitted development rights, and the design needs to be handled sensitively.
Wirral has a number of conservation areas — Port Sunlight and parts of Oxton are well-known examples — where permitted development is usually restricted. Whether a specific street is designated must be confirmed with Wirral Council for your address.
Even outside those areas, the position relative to boundaries and neighbouring windows shapes what's achievable. We design with that in mind from the first sketch.
Good architectural design isn't just about how the extension looks — it's about choosing an approach that's realistic for your property and the planning route it's likely to need.
We prepare clear existing and proposed drawings, advise on the likely route, and where a Lawful Development Certificate or full application is the sensible step, we prepare the drawings that support it.
A few details are enough for an honest first view — with no obligation:
External links open in a new tab. Always confirm your specific project with the relevant authority.
Send Sean a few photos and a short description of what you'd like to do. You'll get an honest first view with no obligation.