Planning Permission vs Permitted Development: What You Actually Need

One of the most common questions we get from homeowners is whether their project needs planning permission. The good news is that many extensions and alterations fall under permitted development rights — meaning no formal application is required.

What Is Permitted Development?

Permitted development rights allow certain building works without submitting a planning application. They're granted by Parliament rather than your local council, and they cover most standard domestic extensions, loft conversions, and outbuildings.

Common Projects That Usually Don't Need Planning Permission

Single-storey rear extensions up to 4 metres (detached houses: 8 metres under prior approval) generally fall within permitted development. Loft conversions adding up to 40 cubic metres of space (50 for detached), rear dormer windows, internal alterations, replacement windows, and garden outbuildings under 2.5m at the boundary are typically permitted.

When You Will Need Planning Permission

You'll need a full application if your property is in a conservation area, if it's a listed building, if you're building forward of the principal elevation facing a highway, if the extension exceeds permitted development limits, or if you're converting the use of the building.

The Prior Approval Route

For larger rear extensions (4–8 metres for detached, 3–6 for others), you can apply for prior approval. This is a simplified process where the council notifies your neighbours and assesses impact. It's not full planning permission, but it's not automatic either.

Our Recommendation

Even if your project appears to fall under permitted development, we always recommend getting a Lawful Development Certificate from your council. This costs around £100–£200 and provides written confirmation that your work is lawful. It protects you when selling the property and avoids disputes later.

We handle this paperwork as part of our pre-construction service.