• Class Q

Class Q floorspace limits debated

An inspector granted prior approval for the conversion of Hertfordshire barns to four homes after interpreting the cumulative floorspace limitations of Class Q permitted development rights.


The development proposed three units within the ‘larger dwellinghouse’ category as having a floorspace of more than 100 square metres and totalling no more than 465 square metres, and a fourth unit within the ‘smaller dwellinghouse’ category. The floorspace of the larger units would be 417.9 square metres and the smaller unit would be 100 square metres, giving a total floorspace of 517.9 square metres.


The council argued that as the wording in paragraph Q.1.(b)(i)(bb) refers to dwellinghouses in the plural, with no reference to smaller or larger units, the total floorspace of all dwellinghouses must not exceed 465 square metres.


In the absence of any alternative interpretation by the courts, the inspector considered that the limitations set by paragraph Q.1.(b) should be read in a logical way.  Firstly by applying the limitations on larger dwellings, then the limitations on smaller dwellings and, finally the limitations in respect of a combination of both sizes of dwelling. Based on this analysis, a larger dwellinghouses component cannot exceed 465 square metres but does not prevent additional smaller dwellinghouses. The inspector found support in PPG for his interpretation that the 465 square metre cumulative size limitation applies to larger dwellinghouses only and not to the total floorspace of the development, including smaller dwellinghouses. He concluded that the cumulative floorspace of the dwellinghouses proposed would not exceed the limitations set out in Class Q.