A method of retrofitting a smoke extractor system (12) to a building (14) having a plurality of storeys (16) interconnected by a lift shaft, the method comprising providing a mechanical ventilation device (18) to the lift shaft (54). The mechanical ventilation device (18) has an inlet (20) at or adjacent to the lift shaft (54) and an outlet (22) external to the building (14). The method further comprises providing a smoke access path (24) on each storey (16) which couples each storey (16) to the lift shaft (54) and the mechanical ventilation device (18), lift shaft (54) and smoke access path (24) defining a smoke extraction system (10) such that in the event (24) of smoke present on at least one of the plurality of storeys (16), there is a smoke escape pathway. The smoke escape pathway extending from the or each storey (16) through the associated smoke access path (24), via the lift shaft (54) and the mechanical ventilation device (18) to an exterior of the building (14), the mechanical ventilation device (18) providing an airflow through the smoke extraction system (10).