Permitted development rights were extended on 6 April 2014 to allow conversion of agricultural buildings for use as residential dwellings. This became Class MB of the GPDO and covers both change of use and certain building operations. 

This presents an opportunity for the development of underutilised agricultural buildings in rural areas where LPAs may otherwise be reluctant to allow residential developments, but it is not without its hurdles. 

There are several restrictions to the rights. The site must have been used for agriculture on the 20 March 2013, or whenever it was last in use. If it has been brought into agricultural use since that date, the right cannot be used for ten years. The right cannot be used where the land is comprised in an agricultural tenancy, unless both the landlord and tenant agree. 

The floor space converted must not exceed 450 sqm in total, and no more than three dwellings can be created on the site. These are cumulative totals, meaning that if agricultural land has previously been converted under this right, the total residential land cannot exceed these limits. 

There are exclusions for certain land, including sites within article 1(5) land (which includes conservation areas, National Parks and Areas of Outstanding Natural Beauty), Sites of Special Scientific Interest, and listed buildings. 

All potential conversions under this right are subject to prior approval, which requires the developer to submit a written description and a plan to the LPA for determination. The LPA can refuse approval where the application does not comply with the conditions and restrictions set out above. 

The building operations permitted under the right are only those deemed reasonably necessary to enable the property to be occupied as a dwellinghouse. This is limited to the installation or replacement of windows, doors, roofs, exterior walls and work needed to provide essential services including drainage, electricity and gas. It also permits any reasonably necessary partial demolition. 

Dwellings created under this right will not be able to use the residential permitted development rights, for example to erect a garage or small extension, and planning permission would be required for these sorts of development. There is also a restriction which means that where some land in an agricultural unit is converted under this right, the rest of the land will lose the benefit of permitted development under Part 6, for the erection, extension and alteration of agricultural buildings, for a period of ten years. 

It is important to consider the consequences thoroughly and use the rights cautiously, to avoid causing problems for the business in the future, for a gain in the short term.