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A common floor construction in a lightweight building system is using chipboard plates attached to wooden beams using screws and glue. One drawback with such a system is the propagation of vibrations stemming either from harmonic (washing machines, dishwashers, HiFi-systems) especially at low frequencies and/or transient (Human walking, dropped items, slamming doors) excitations. In order to accurately predict the sound attenuation and the losses of such building systems, computationally accurate and efficient simulation techniques are needed. The main objective of this work is to examine sandwiched floor constructs consisting of one and two layers of chipboards attached to supporting wooden beams. Of special interest are the effects of the discontinuities between adjacent boards and between the boards and beams on the loss of kinetic energy as a consequence of the evanescent wave propagation due to the acoustic attenuation process in the structure and on the phase shift of the waves as they travel past the different types of discontinuities in the floor assembly. The measurements are performed using two-axis accelerometers distributed over the floor and recorded synchronously. The measurements are focused in the low frequency range (10-600Hz) and are also including transient loads.