Floor vibrations – Implications of the new EC5? This report presents the design methodology principles for the revised section for the control of vibrations in wooden floors, as well as the proposal for dividing timber floors into performance levels and quality selection, as found in Eurocode 5 With the aim of presenting how different floors commonly used in Sweden performs with respect to the new methodology, the results from a limited parameter study are presented. A total of eight different floor types were examined, including floor structures with load-bearing beams made of structural timber, glulam, LVL, and I-joists. The study also looked at rib joists with T-beams made of glulam combined with an LVL board, as well as floor structures with a load bearing CLT board. The following parameters were varied to study effect on the stiffness of the structures: • the centre distance between beams • the web height of the beam cross-section for rib-floor slabs, • thickness of load bearing CLT board. The maximum span for each floor structure was decided by finding the maximum span for each floor structure which meets the ultimate limit state and the serviceability limit state conditions, both with respect to deformations and vibrations for residential and office buildings set by the new EC5. The stiffness of each floor was then increased to study the effect of stiffness on the performance levels. Response factors were calculated for each case. Note! Direct comparison of the floor structures is not possible since the calculations are based on different span widths for each floor type. Since the calculations are based on each floor type’s unique conditions, it is not possible to compare the floor structures directly. Instead, comparisons must be made based on how a variation in stiffness affects the performance level of each individual floor type. The parameter study shows that for the light floor structures with discrete beams, spacing the beams closer changes the response factor slightly but it typically stays within the values for performance level V, i.e. between 24 and 36. For the other floor structures, rib floor and CLT, increasing the stiffness resulted in a larger change in performance and some floors changed floor performance level. The performance levels and quality choices introduced in the new methodology for checking vibrations in timber floors, makes it easier and clearer for clients and builders to achieve a consensus on what vibration comfort to expect in the finished building. This is an opportunity to reduce the risk of complaints and avoid having to take action to correct a perceived lack of quality. The current advice in the national annex for the Eurocode EKS12 specifies that the deflection for a 1 kN point load is limited to 1.5 mm, which corresponds to the upper deflection limit for performance level V. Performance level V is the worst performance level allowed for the quality choice ‘Economy’ for offices and homes in multi-family buildings. This means that the proposal on quality choice does not provide any tightening compared to the Swedish requirement in EKS12. However, the fact that performance level VI is allowed for dwellings in single-family houses with an upper limit value for deflection of 2.0 mm suggests that the proposal mitigates the requirement contained in EKS12.