In order to comply with the new safety regulations a significant number of Spanish dam spillways must be upgraded. In this scenario and with the aim of increasing the discharge capacity with a reduced investment innovative designs become interesting solutions. One of these innovative designs are the labyrinth weirs. Project POLILAB is carrying out with the objective of optimize the design of labyrinth weirs, physical and numerical tests exposed in this article were developed within this framework. The most relevant results are related with the discharge capacity, the flow pattern and the structural reinforcement achieved by the implementation of a polyhedral bottom.