European product standards generally do not specify the qualitative requirements for individual product characteristics. EN 14695:2010, which deals with the waterproofing of concrete bridge decks, is not an exception. Quality requirements for bitumen sheets set the national standard CSN 736242:2010. This standard doesn't take into account in its qualitative requirements the type of the modification of bitumen coating. The aim of this report is to find the limiting value for the flow resistance during high temperatures for reinforced bitumen sheets that are used as the waterproofing of the concrete bridge decks in the Czech Republic. The values for qualitative requirements will be specified due the statistic evaluation of the data taken from laboratory measurements of samples – reinforced bitumen sheets collected in years 2012 - 2016.