Class R: flexible commercial use of a farm building

Class R lets a farm building change from agricultural use to a flexible commercial use without a full planning application, up to a cumulative limit of 500 square metres across the established agricultural unit. Above 150 square metres the council's prior approval is needed for transport and highways, noise, contamination and flooding. Below that figure the right operates without any prior approval at all, which makes Class R the quietest diversification route in the General Permitted Development Order and the one most often overlooked.

What the right permits and where the cap bites

Class R sits in Part 3 of Schedule 2 to the Town and Country Planning (General Permitted Development) (England) Order 2015. It permits the change of use of a building and any land within its curtilage from agricultural use to a flexible commercial use.

The floorspace limit is cumulative, not per building. Once 500 square metres of the established agricultural unit has changed use under the class, the right is spent, whether that was one large building or three small ones. Keep a written record of what has been converted and when, because the next owner will need it and so will the council if a certificate is ever sought.

The building also has to have been in agricultural use as part of an established agricultural unit on the qualifying date set out in the class, or when it was last in use if it was not in use then. Check the current wording of that condition before you rely on it. Buildings erected under agricultural permitted development rights have their own timing restrictions on later change of use, which catches farms that put up a steel portal frame and tried to convert it two years later.

The uses inside the flexible right

The listed uses have shifted since the Use Classes Order was rewritten in 2020, so read the current text of the class rather than an older summary. In practice the right covers storage and distribution, offices, light industrial and workshop uses, shops, food and drink premises, hotels and assembly and leisure uses, subject to the class as currently drafted.

The point of a flexible use is that the building can move between the permitted uses during the period without a further application. That is useful on a farm where the first tenant is a storage business and the second is a workshop. It is also why the council asks what the initial use will be, since the highways and noise assessment has to be based on something.

Reversion to agricultural use is preserved. A building that has changed under Class R can go back to agriculture, and that flexibility is one of the reasons the route suits buildings you may want back.

When prior approval is required

Where the cumulative floorspace changing use exceeds 150 square metres, apply for prior approval on the four matters the class specifies: transport and highways impacts, noise impacts, contamination risks on the site, and flooding risks. The procedure is the same one used across Part 3, and the mechanics are covered in our explainer on how the prior approval procedure actually works.

The council cannot refuse on matters outside those four. It can and does refuse on any of them where the submission is thin. The commonest failure is a transport section that describes the access as adequate without counting anything.

The evidence each matter needs

For transport and highways, give the vehicle movements the proposed use will generate, the vehicle types, the visibility available at the access measured on site, and the turning and parking arrangements inside the curtilage. Where the access is onto a fast rural road, a speed survey is money well spent. A short Transport Statement is the right format for most Class R schemes, and a full Transport Assessment would be disproportionate.

For noise, identify the nearest residential windows and their distance, describe the hours of operation, list the plant and the activities that make noise, and set out what the mitigation will be. A workshop with an open roller shutter facing a cottage 20 metres away is a different proposition from the same workshop with the shutter on the far elevation.

For contamination, the questions are what the building was used for, whether there are fuel tanks, sheep dip, asbestos sheeting or buried waste, and what the new use means for exposure. Where a risk is identified, the local planning authority will expect a report prepared in accordance with BS 10175 by suitably qualified and experienced persons, so a Contaminated Land Assessment here is a starting point for that professional rather than a finished document.

For flooding, check the Flood Map for Planning and say which zone the building sits in. Commercial uses are classed as less vulnerable, which makes Flood Zone 2 manageable with a Flood Risk Assessment, but Zone 3 needs care and the sequential approach may still be raised.

Where Class R and Class Q collide

Class Q converts agricultural buildings to dwellings. Class R converts them to commercial use. They draw on the same stock of buildings and the two rights interact, so using one can restrict the other on the same holding.

That matters commercially. A building let for storage under Class R may be worth a fraction of the same building converted to a dwelling, and the residential route is the one with the tighter conditions and the shorter list of buildings that qualify. Work out the whole-holding strategy before using either right, and read the current text of both classes, including the amendments made to Class Q, which our note on Class Q barn conversions and the 2024 amendments covers.

Illustrative example: a holding with three buildings totalling 620 square metres. Converting the 180 square metre Dutch barn to workshops under Class R with prior approval leaves 320 square metres of headroom, and the farmer keeps the larger steel building for a possible residential application later. Had all three gone to commercial use, the cap would have been exhausted and the residential option foreclosed.

Conditions, implementation and what to keep

Class R carries conditions, including the requirement to apply for prior approval above the floorspace figure and the restrictions on the building's subsequent use. Read them as part of the right rather than as an afterthought, because a right exercised outside its conditions is not permitted development at all.

Implementation is a question that comes up when a prior approval is about to expire. The safe approach is to make the change of use real and document it: a tenancy agreement, an insurance policy for the new use, photographs of the building in use, and business rates correspondence. Councils tend to accept a coherent bundle of that kind.

If certainty matters, apply for a lawful development certificate under section 192 of the Town and Country Planning Act 1990 before committing to a lease. A certificate is the only formal way to confirm that works or a use are lawful, and an informal email from a planning officer is not one.

Keep three documents on file permanently: the prior approval decision or the confirmation that none was needed, a plan marking the floorspace converted with its area, and evidence of the agricultural use on the qualifying date. Ten years later, that file is worth more than anyone expects.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. Enter the farm postcode on PlanScope to see which supporting documents a Class R prior approval is likely to need.