Requirements engineering is considered a critical phase of the software development life cycle. However, because of the complexity of today's projects, requirements often have a negative impact on each other. Requirements interaction detection is an important activity for the discovery of such unwanted interactions. Commonly used detection processes are oriented towards the telecommunication domain and are done using either human experts or formal approaches. This paper presents IRIS, which stands for Identifying Requirements Interactions using Semi-formal methods. The novelty of IRIS is threefold: First, IRIS uses semi-formal methods for the detection of interactions between requirements. This helps to fill in the gap between the commonly used informal and formal approaches. Secondly, IRIS is a domain independent approach, which means that it is not limited to the telecommunications domain but can be used in any field. Thirdly, IRIS has a basic core as well as extension hooks for future expansion through the creation of new plug-ins that can be attached to the hooks. This paper first presents an overview of IRIS along with its basic core. It then describes the customizability of IRIS through hooks and plug-ins. Finally it presents the customization of IRIS using different plug-ins for different domains as well as a summary of the results obtained from these domains.