Class Q Permitted Development

Posted 10th June 2016

Class Q Barn Conversion

Modern barn conversion under Class Q Permitted Development, designed to AECB Silver Standard.

In 2014 the government introduced a new class of permitted development for agricultural buildings allowing them to be converted into residential use subject to compliance with the criteria below:

  1. Development is not permitted where the site was not used solely for an agricultural use, as part of an established agricultural unit on 20/03/13, or if the site was not in use on that date, when it was last in use before that date.
  2. Cumulative floor space of the existing building(s) must not exceed 450m2, and no more than 3 separate dwelling houses can be developed within an established agricultural unit.
  3. Change of use is not permitted if the site is occupied under an agricultural tenancy, unless the express consent of both the landlord and the tenant has been obtained.

Loudon barn is located on a country estate in Ashford, a former straw and cattle barn which had become prone to vandalism due to the construction of a new housing estate nearby and no longer suited the farming activities of the estate.

An ‘application’ was submitted for Prior Approval in 2015, it was refused at the first attempt on the grounds that the access road was too long. Following clarification from the Department of Environment on the Class Q requirements, the application was resubmitted and approved.

Detailed design commenced in October 2015 and tenders issued to 4 contractors.

The barn is constructed from an ‘Atcost’ pre-cast concrete portal frame on pad foundations with asbestos cement cladding.

The client’s brief was for an ultra efficient dwelling using natural materials, something that Conker specialise in, and what we call the Nuthaus approach. We have designed the building using the Passivhaus Planning Package, but to the AECB Silver Standard rather than the full Passivhaus standard. This is due to the fact that the building envelope is not ideal for a Passivhaus, the shape and volume of the building cannot be changed under Class Q permission, the building has a very high volume to surface area which would require uneconomically thick walls and roof insulation to compensate.

Timber I joist construction will be used for walls, floors and roof, triple glazed windows, mechanical ventilation with heat recovery, heating system is still to be reviewed. According to PHPP the peak heating demand will be 2.5kW, this is the maximum output of a heating system in the winter at -1oC, equivalent to a hairdryer.

We started as with all our projects with a thorough survey of the building and surroundings.

Full plans approval was obtained for building regulations via BBS Building Control.