DOI: 10.7764/RDLC.18.2.282Activity of static loads and different activities of dynamic loads produced over the structure of a building have a negative effect causing deformations of the materials that form the structure. Reinforced concrete is the most used in building structural material, being deflection its most important deformation that affects bending elements fabricated with this material. This paper presents a new measurement system based on the response of a piezoelectric low cost sensor. Placing the device in the midspan of the beam where maximum deformation is produced, the sensor is able to collect deflection variations according to the loads the element is subjected to, showing produced variations in real time.