Textile membranes are suitable for a wide range of applications due to their user-adjustable properties, which can be modified based on both the textile reinforcement structure and the coating material. Complex dynamic loads are involved in typical usage scenarios for load-bearing components of textile architecture, e.g., unsupported convertible roofs of halls or stadiums, temporary buildings, large-volume consumable media storage and the main sail of sailing boats. It is generally known that particularly in the area of membrane joints, successive degradation of seam strength may occur. This paper addresses the realization of an in situ measurement system for textile surface formation in textile membranes, which is introduced locally in the area of the joining zone and is compatible with the materials as well as the ultrasonic welding process itself. These development efforts are supported by a numerical investigation in terms of the serviceability and residual load-carrying capacity of the joining zone and the textile membrane surface area.