This project consisted of the construction of a rooftop extension to the Operating Department which is situated overhead a functioning dialysis unit. In parallel there was an extension to the dialysis unit and a new ventilation system installed there. The location for the works was almost completely surrounded by the live hospital and the project duration was 22 weeks and incorporated 3 phases. The works required extra care and attention because of ‘at risk’ patients and sterile zones within the vicinity of the construction operations.