This thesis revolves around specifying the problematics concerning hospital retrofits as well as finding solutions for overcoming them. The solutions are constructed with the help of earlier research and thematic expert interviews. Altogether 28 actors, including project managers, architects, engineers and property managers, are interviewed.Due to its old age, the Finnish hospital stock has several problems in addition to the frequent need for adaptation. The problems include structural deterioration, indoor air quality problems and outdated facility designs that reduce the operational efficiency. Versatility of the problems results in large and complex retrofit projects. Complexity of the projects is mainly due to A) technical limitations of the old structures and B) continuous need for unforeseen adaptations.Project complexity and challenges can be alleviated by utilizing different design strategies, including adaptability, which divides change demands into three separate categories: expandability, flexibility and generality.Productive utilization of the strategies can be managed with the help of service modularity. The study proposes five distinct service modules and 16 service components for service providers and hospital property managers. The service modules can be used to construct a modular service that matches the project-specific needs of any hospital retrofit, thus simplifying the design process and improving life cycle costing.