Means any change in existing authorised building or change from one use to another use, or a structural  change such as additions to the area or height,  or the removal of part of a building, or a change to the structure such as the construction or cutting into or removal of any wall or part of a wall, partition, column, beam, joist, floor including a mezzanine floor or other support or a change to or closing of any required means of ingress or egress or a change to fixtures or equipment’s, as provided in these regulations. The addition to any existing structure shall only be permitted if it complies with the provisions of regulation No.17.4.