Do You Need Planning Permission to Diversify a Farm Building? A Plain-English Guide
This is the single most common question we get on a first call: it’s already a building, surely you don’t need planning permission just to change what’s happening inside it?
The honest answer is that it depends on what the building is used for now, what you want to use it for next, and how much physical work is involved. Here is how to think it through before spending money on drawings or surveys.
Change of use still counts as development
Under UK planning law, changing what a building is used for counts as development in its own right, even if you are not adding a single brick. Moving from agricultural storage to a holiday let, a workshop-for-hire, or residential accommodation is a change of use. In most cases it needs planning permission, because you are moving the building out of its agricultural use class into a different one entirely.
When permitted development rights can help
Permitted development (PD) rights allow certain changes without a full planning application, but the limits catch a lot of people out.
Class Q allows agricultural buildings to convert to residential use in defined circumstances, subject to size limits, prior approval, and conditions on the building’s structural condition. Class R allows a change from agricultural use to certain flexible commercial uses, such as offices, storage, or some leisure uses, within floor area limits. Class S allows conversion to state-funded schools or nurseries in specific circumstances.
Even where PD rights apply, most schemes still need a prior approval application. It’s a lighter-touch process than full planning permission, but it is still a formal council process, checking things like transport, noise, contamination and design.
One thing that trips people up: PD rights depend on the building already existing and being used for agriculture at a qualifying date, on floor area limits, and on the building being structurally capable of conversion without substantial rebuilding. If a building needs to be largely demolished and reconstructed, it will usually fall outside PD rights and need a full application instead.
When you will need a full application
A full application is usually the right route when the change of use goes beyond what PD rights cover, when the building needs significant structural work, or when the site sits somewhere with extra planning constraints, such as a National Park, Conservation Area, or land next to a listed building.
A full application takes longer and needs more supporting information, but it also gives more flexibility. You are not boxed in by PD floor area limits, and you can make a stronger case for a scheme that might not fit neatly into a permitted development class.
How to check which route applies to your building
The quickest way to find out which route applies is a Lawful Development Certificate application, or a prior approval request, both of which give you a written answer from the council rather than a guess. It is far cheaper to spend a few hundred pounds confirming your route now than to start building and find out later that you needed permission you don’t have.
In practice, most of the diversification projects we work on end up needing at least a prior approval, and quite a few need full planning permission once you look closely at the building’s condition and location. Getting this right at the start saves months later.
If you are weighing up options for a farm building, we can talk through what route fits your site before you commit to drawings.