So-called householder "permitted development" rights are reserved for single dwelling houses only (ie, residential properties that have not been sub-divided in any way). This means that a house converted into flats, a purpose-built block of flats, a pair of maisonettes or even a house in multiple occupation has no planning "privileges" and every alteration or other development must be scrutinised by the local planning authority. There is an obvious reason for this, since a sub-divided property contains a number of separate households, all of whom have rights to privacy, light and outlook, which could very easily be harmed by an unsympathetic alteration. Furthermore, a building covered in numerous satellite dishes is not a pretty sight.