Estimation of acoustic insulation between rooms on the example of a monolithic reinforced concrete ceiling on lost formwork made of trapezoidal sheet metal

The article presents the results of field measurements of airborne and impact sound insulation of a reinforced concrete ceiling on a permanent formwork made of trapezoidal sheet metal. The measurement results were compared with the results of the calculations carried out using the available methods and with the standard requirements.The measurement and calculation results differ significantly. In the case of the R’_A,1 index, the difference was 5 dB and in the case of the L’_n,w index, as much as 12 dB using formulas according to standards [1; 2]. Calculations carried out using PN-EN 15037-1:2011 [3] gave results that differ even more from the measurement result. The reason for the above situation is the lack of an appropriate calculation model that allows determining the acoustic insulation of the ceiling on the permanent formwork made of trapezoidal sheet metal, which is an unusual solution. A positive aspect of the comparison is the results of the fact that the calculation differ from the calculation result in a “safe” direction, so the use of this method at the design stage results in introducing an additional safety margin.