A lightweight steel framed floor was tested in a laboratory for eight configurations: continuous/lumped main support, support/unsupported free long sides and concrete/plasterboard as top. The dynamic properties were revealed by modal analysis and subjective evaluations in terms of body perception and perception of vibrating articles. The results showed that the tested parameter that affects the floor most was the top layer. The semi-heavy weight floor with concrete layer was in general judged to be of higher acceptance than the lightweight floor having plaster-boards on the top. Additionally, the lightweight floor was used in a series of experiments where the effect of modified support and the effect of adding line loads of various degree of mechanical connection were tested. This part aims to simulate how the dynamics of a floor stepwise might change going from a bare floor to a floor installed inside a real building. The results show that the line load, mass and stiffness influence the floor in terms of changed natural frequencies. Depending on where on the floor the loads are located, different modes were affected and, depending on how the loads were connected to the floor, the gained stiffness varied slightly