Powered by the emergence of the Internet of Things, smart homes containing a variety of sensors and actuators are expected to monitor and react to the activities of the residents with the goal of improving convenience, comfort and safety. However, in typical home settings, each human Activity of Daily Living (ADL) generates events from multiple sensors, and each sensor is triggered by multiple ADLs. Consequently, achieving high detection accuracy in these complex environments requires large amounts of training data for every possible multiplexing scenario, making it a complex problem. In this paper, we propose a data driven three-step de-multiplexing approach that simplifies the ADL recognition problem by first segmenting the event stream into periods of interest, before feeding to a classifier. We mine datasets to identify salient features which allow us to achieve a good segmentation. Extensive evaluation on ten public datasets shows that our approach achieves upto 77% segmentation accuracy, and a activity detection accuracy within 91% of the best possible.