Does a change of use require planning permission? Recent court decisions show the difficulties in answering this question, especially since it depends on the facts and circumstances of the individual case.
The first step is to identify the baseline for assessing whether there has been a change of use. That's referred to as the planning unit, and is generally the unit of occupation.
Taking a shopping centre as an example: there is a single planning permission for the centre, but as each unit within the centre is occupied for the first time, the centre becomes a collection of separate planning units, each with an individual use.
This baseline is crucial: as a rule of thumb, the bigger the unit, the more potential for changes of use not to require planning permission, either because the new use is more likely to be ancillary/ incidental or the change is not material (below).
In a recent Manchester City Council case, an Inspector had said the building as a whole was in mixed use (sui generis) and therefore not imposed a condition restricting permitted uses. However, the Court of Appeal agreed with the Council that there were four separate planning units within the building: a travel agent (class A1), two couriers' offices (class B1) and a therapy/ medical room (class D1) [this pre-dated changes to the Use Classes Order].
The inspector had not identified the 4 units. In turn that meant the wrong use had been identified, and the wrong approach had been taken to the need for any conditions precluding further changes of use.
Ancillary/ incidental use
The character of the use is determined by the primary or main use, and ancillary or incidental uses do not require a new planning permission.
In the "Sharks!" case, it was argued that an artwork on pontoons in the Regent's Canal was ancillary to the permitted B1 use at the site. That was rejected by the court: given the size, scope and location of the artwork, there was a prima facie case that it went beyond ancillary use.
Incidental use to dwellinghouse
There is a specific provision in the Planning Acts that planning permission is not required for the use of any buildings or other land within the curtilage of a dwellinghouse for any purpose incidental to the enjoyment of the dwellinghouse. That flexibility has become more important with the growth of working from home.
The Sage case involved a timber out-building, used in part as a garden shed and in part as a gym. The gym was used for a personal trainer business, for paying clients, who attended at the premises.
The court stated that the number of visitors, the number of days a week, the hours of daily operation of the studio, all as a routine, were the crucial determinants of scale and degree. It agreed that the six day a week use, with 30 or so sessions, in a tight knit residential area, was not incidental or ancillary to the use of a dwelling house as a dwelling house.
The court also indicated concerns about the Secretary of State's Planning Practice Guidance "Do I need planning permission to homework or to run a business from home?". The court criticised the Guidance for ignoring, or blurring badly, the crucial point that a business use in a dwellinghouse may be secondary to the primary residential use, but may still create a material change of use.
The Guidance was also criticised for treating environmental impact as the seemingly crucial issue, whereas the crucial test is whether there has been a change in the character of the use. Environmental impact can be relevant as evidence that a material change has occurred.
Material change of use
Planning permission is only required where the change of use is material. Inevitably that depends on the facts and circumstances.
The inherent uncertainties are shown in the approach taken to short stay commercial visitor accommodation in Scotland.
Holiday accommodation was generally treated as a form of residential use. However, a wave of enforcement cases since 2015 has shown that it can be a material change from residential use. Although it depends on the facts and circumstances, there have been very few cases where appeal reporters have decided there has been no material change of use.
In the Cameron case, the appeal reporter held that limited use for holiday letting was ordinarily incidental to the main residential use, but a material change of use occurred when it ceased to be the main residence and was continually promoted and used as self-catering accommodation for short-stay lets. The court held that it is an issue of fact and degree for the reporter to decide.
To some extent the uncertainty is resolved by the new power for Scottish planning authorities to introduce short-term let control areas. Within those areas, the use of a dwellinghouse for the purpose of providing short-term lets will require planning permission. However, in all other areas, it will remain an issue of fact and degree.