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 name and one way to contact you for an honest first view — with no obligation. A postcode, a few photos and a short description help if you have them, but aren't required to start.
Reviewed by Sean Corser, SC Design Wirral. 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.
You don't need a full brief or drawings to get started — just your name and one way to contact you. The rest is optional, and you can send more whenever it suits you.
External links open in a new tab. Always confirm your specific project with the relevant authority.
All you need to start is your name and one way to contact you. A short description, postcode or a few photos help if you have them — but they're not required.