It is difficult to design and operate a Wireless Sensor Network (WSN) that ensures timely data delivery. Hence, few time-critical WSNs are nowadays in operation despite numerous application scenarios that would benefit from such a system. This paper presents a novel dimensioning framework that can be used to efficiently construct WSNs for time-critical applications. The framework employs the Sensor Network Calculus (SNC) as an analytical method for network dimensioning. A medium access control (MAC) protocol called SNC-MAC is used to ensure that this dimensioning process is reflected accurately in a subsequent deployment. The proposed framework is evaluated using both simulations and measurements in an experimental WSN deployment. The evaluation shows that observed message transfer delays in the deployment never exceed delay bounds determined during network dimensioning. Therefore, the framework can be used to implement WSNs requiring transmission delay guarantees.