Several regulations and co-property acts allow condominium owners to install hard floor coverings provided that a minimum impact sound isolation rating is achieved. Many construction professionnls recommend such surfaces based on tests performed using the procedures described in ASTM E 492 or ASTM E 1007. During the present study, thirty-five bare concrete slabs with thicknesses ranging from 200 to 250 mm (8 to 10 in.) were randomly tested in different buildings in Montreal using the procedures outlined in ASTM E 1007. The large variations noted in the measured NISPLs and FIIC ratings suggest that the results of tests made in strict conformance with ASTM E 1007 are anecdotal and cannot be used by acousticians and construction professionals to predict the impact noise isolation provided by a floor covering installed on a "typical" 200 mm (8 in.) to 250 mm (10 in.) thick concrete slab. This paper presents the results of these measurements and proposes a statistical approach to predict the probability that a floor installed on a typical 200 to 250 mm thick concrete slab will achieve the noise isolation target set forth in the regulation, or in the co-property act (usually FIIC 55 in Canada and FIIC 50 in USA).