The ban on combustible materials in external walls applies to the external walls for residential blocks of flats, student accommodation, care homes, sheltered housing, hospitals and dormitories in boarding schools which are above 18 metres in height. It does not apply to any room in a hostel, hotel or a boarding house, and any commercial buildings.
The ban on combustible materials also applies to buildings where the above building types have balconies, sun shadings and solar panels attached to an external wall. The ban applies to new building work and to existing buildings going through a change of use such as office buildings being converted into apartments, which are above 18 metres in height.