Do I need planning permission in Cornwall?

Cornwall is one of the most beautiful — and most planning-complicated — places to own a home in England. With 145 conservation areas, over 5,000 listed buildings, and land that overlaps multiple Areas of Outstanding Natural Beauty, the rules that apply to your neighbour's extension might not apply to yours. WhatCanIBuild exists precisely for situations like this — where the answer to "do I need permission?" isn't a simple yes or no.

"Permitted development" doesn't mean what most people think

Most homeowners assume that common projects — a rear extension, a loft conversion, a new outbuilding — automatically fall under permitted development and don't need a planning application. Sometimes that's true. But in Cornwall, a significant number of properties sit in locations where those standard rights have been reduced or removed entirely.

If your property is in or near an AONB boundary — the Cornwall, North Devon, or Tamar Valley designations all have presence here — it may sit on what's known as Article 1(5) land. That changes the rulebook. Most homeowners don't realise this until they've already started planning a project.

Conservation areas are everywhere — and the rules are unforgiving

145 conservation areas across Cornwall is a lot. They cover historic town centres, coastal villages, mining landscapes, and rural settlements that don't always look "historic" to the untrained eye. If your property is within one, external alterations that would be fine elsewhere may require a full planning application.

The Cornwall and West Devon Mining Landscape World Heritage Site adds another layer entirely. Properties near those boundaries carry heritage sensitivities that can affect everything from what cladding you use to whether a modest garage conversion triggers a formal application.

The gap between "probably fine" and "definitely fine"

Here's where most Cornish homeowners get caught out. Two houses on the same street can have completely different planning situations — one inside a conservation area boundary, one just outside. One with permitted development rights intact, one where an Article 4 Direction has removed them. The difference between guessing and knowing is the difference between a smooth project and an enforcement notice.

That's before you factor in flood zones, proximity to coastal erosion risk areas, or whether a previous owner already used up certain permitted development allowances on your property.

WhatCanIBuild looks at your specific address and tells you not just what constraints apply, but what's actually been approved and refused for similar projects nearby — including on your street. That's the part that changes how you plan your project.

What does planning permission actually cost in Cornwall?

A householder planning application to Cornwall Council costs £548. The typical decision time is 8 weeks — though that's the target, not the guarantee. If your application is refused and you need to resubmit or appeal, you're looking at months of delay and potentially significant additional cost.

Knowing your odds before you apply — and understanding how your property's specific combination of constraints affects those odds — is the best way to avoid an expensive surprise.

WhatCanIBuild shows you approval patterns for your project type in your area, so you're not walking in blind.