Class Q Permitted Development Rights?

So what do we mean by Class Q permitted development rights?

An exciting topic in the architectural and surveying world but, in layman’s terms, what does this classification actually mean and what does it mean for potential developers.

Class Q classification, came into force circa 2014 and, basically, it’s the granting of permission for the change of use of agricultural buildings. Previously, barn conversions have been predominantly of stone brick or traditional timber construction and, often, part of a traditional farm court yard or stand alone.

But now we can put framed masonry or even poled buildings forward for consideration, subject to certain criteria: Exemptions include areas of outstanding natural beauty, listed buildings and where you are trying to create more than 450 square metres of floor space

They first need to be assessed structurally by a professional (cue our own Nick Matthews) to ensure they can be converted; it is only once the existing structure has been assessed to be strong enough to take the loading which comes with the external works, that they would be considered for the permitted development right.

The subsequent usage of the building may be residential or educational, with size thresholds, limitations and conditions pertinent to each particular case:

Recent case study:
By Nick Matthews


“We have just received approval on a prior notification to convert a large seven bay agricultural barn into three new dwellings on a farm in Wiltshire.

We have worked closely in conjunction with a planning consultant to obtain permission for a Class Q application.

The scheme has been based around an existing substantial steel and concrete portal framed barn which was partially clad with open timber boarding under a concrete profiled roof, and had a disused silage clamp to one side.

The proposal is within the 450m² maximum floor area requirement, with single storey accommodation split between two levels, to take account of the site.  The silage clamp has been removed and the original ground levels restored to invite the countryside up close to the new dwellings.  Part of the process involves a structural assessment of the existing structure to state whether it is indeed capable of being re-used within a conversion.

We have undertaken a number of these structural assessments and this is the second farm building that we have been successfully involved with to achieve approval under Class Q.

I am particularly interested in the conversion of modern barns, having had a long term interest in agriculture from an early age.  The buildings normally offer a clean frame layout, combined with a choice of interesting materials, enabling you to come up with generous open planning living spaces combined with large openings, whilst still retaining their barn origin.

It is a great step forward to not be limited to stone brick structures”