The long-term deformation behavior of timber-steel hybrid beams was analyzed and tested in specific long-term tests presented at WCTE 2016. The documented reduction of their creeping values in approximately 50% indicates that also some kind of improvement can be expected in the further development of prefabricated timber-steel-concrete ribbed decks. In order to confirm this hypothesis a long-term creeping test under permanent load was designed,aiming to compare the deformation behavior of beams with a timber-steel-concrete and a timber-concrete cross-section.The tests will be performed on down scaled beams of 4 m instead of 6 m span due to a restricted capacity of load implementation and space limitations in the testing laboratory . The creeping beams were designed to have the same stress levels as the real ones in order to ensure the comparability of the results with the actual scope of application.