What Are Your Permitted Development Rights Really Worth in 2026?

 

Think of permitted development rights as a hidden asset attached to your house. They let you add serious space without ever applying for planning permission, and most homeowners have no idea how much that freedom is actually worth in pounds. Understanding your permitted development rights before you plan anything can save months of waiting, hundreds in fees, and unlock tens of thousands in value.

What they actually let you build

Permitted development rights are a national grant of planning permission from central government, written into the Town and Country Planning Order 2015. They let you carry out defined works on a house without asking your local council.

The core allowances in 2026 are generous. A single-storey rear extension of 3 metres on a terrace or semi, or 4 metres on a detached house. A loft conversion of up to 40 cubic metres on a terrace or 50 cubic metres on a semi or detached. And outbuildings covering up to half your garden. Each of these adds real, usable space.

The bigger extensions people miss

Here's the part that surprises homeowners most. You can go considerably further without a full planning application through the prior approval route.

The Larger Home Extension scheme, made permanent in May 2024, allows single-storey rear extensions up to 6 metres on a terrace or semi, and 8 metres on a detached house. It involves notifying the council and a 21-day neighbour consultation, but it is not a full planning application. That's a substantial extension, the kind that transforms a ground floor, achieved without entering the planning system properly.

Putting a number on the value

So what's it worth? Consider a garden office built under permitted development, which typically costs £15,000 to £40,000 and adds both usable space and property value.

Scale that up to a loft conversion or a 6-metre rear extension and the numbers grow fast. A well-executed extension commonly adds 10 to 15 percent to a home's value, often more than covering its build cost. The permitted development route delivers that uplift while saving you the roughly £258 planning fee and, more importantly, the eight weeks of waiting a full application takes. The time saved alone can be worth thousands in a moving chain.

The 2026 rules haven't actually changed

There's been a lot of noise about permitted development expanding, so it's worth being clear. Despite proposals to increase extension depths and scrap loft caps, no permitted development rules have actually changed in 2026.

A House of Lords private member's bill and a 2024 government consultation both suggested bigger allowances, but neither has become law, and the Planning and Infrastructure Act 2025 doesn't alter householder rights. So the limits above are the real ones today. Don't design to proposed rules that haven't passed, because building beyond the current limits without permission is a genuine enforcement risk.

Where the rights disappear

Your permitted development rights aren't guaranteed, and this is where their value can quietly vanish. They apply to houses only, so flats and maisonettes have none for external work.

They're removed or reduced in conservation areas, National Parks and other designated land, where side extensions, cladding and roof changes usually need permission. An Article 4 direction on your street can strip them out entirely. And a condition on the original planning permission, common on newer estates, may have removed them when the house was built. Any of these can turn your assumed free extension into a full application.

The allowance you may have already spent

One more trap that catches people out. Permitted development allowances belong to the house, not to you, and they're measured from the original building.

If a previous owner already added a rear extension, converted the loft or built outbuildings, that work counts against your total. Loft volume allowances in particular are cumulative, so a house that's been extended twice may have little or no permitted development left, even though nothing about it looks maxed out. Always establish what's already been used before assuming you have a full allowance.

Cashing in the asset safely

To use your rights with confidence, get a Lawful Development Certificate. It's the council's formal written confirmation that your work was lawful and didn't need planning permission.

You don't legally need one to build, but your buyer's solicitor will almost certainly ask for it when you sell, and it defeats any later enforcement question. Applying for it also forces the checks above to be done properly, so you discover a hidden Article 4 or a spent allowance before you build, not after. Treat your permitted development rights as the valuable, and losable, asset they are: confirm exactly what your specific house still has, then use it to add space and value the fast, cheap way.