XV International Conference on Durability of Building Materials and Components DBMC 2020, Barcelona C. Serrat, J.R. Casas and V. Gibert (Eds) Are Mineral Toppings of Asphalt Roofing Sufficient to Protect Flat Roofs and Roofing Felt Alone? Tomasz Szkuta 1 and Maria Wesołowska 2 1 Polish Association of Civil Engineers and Technicians (PZITB) Branch in Toruń, Szeroka 34 Str., 87-100 Toruń, Poland, tomszkuta@gmail.com 2 University of Technology and Life Sciences in Bydgoszcz, Al. Prof. S. Kaliskiego 7, 85-796 Bydgoszcz, Poland, Wesolowska.Maria@utp.edu.pl Abstract. Mineral surfaces are an integral part of bituminous roofing felt. Their task is to protect less resistant elements from the destructive effects of the environment. Since the first application in 1897, they have been constantly improved in the direction of better functionality and aesthetics. It often turns out that the intended effect has not been achieved. During the first years of operation, there are signs of roof damages on most facilities. Due to the complex interaction of roofing elements, several causes of damages can be defined. A group of processes taking place in mineral roofing toppings is important for roofing felt. Mineral surfaces are exposed to physical, chemical and biological factors. They cause losses due to the unavoidable breaking of adhesion to the modified asphalt. Pulling out caused by factors occurring on the roof is a long-term process with more effects on the covering, in particular its durability and tightness. In the paper, the reasons for the release of mineral topping from the SBS modified asphalt layer were defined. The analysis shows that as a result of significant degradation and harmful impact of mineral coverage, this layer may lose the ability to protect the roofing paper, and long-term changes threaten the durability of roofing materials. Solutions have been proposed to significantly reduce the phenomenon caused by specific factors. Keywords: Mineral-Surfaced Tar Board, Durability of Roofing Felt, Impact of Environment. 1 Introduction The subject of the work is the problem of top covering roofing felt. It is visible already in the first years of operation of the roofing felt. Depending on the quality of the roofing felt (price), this process takes place faster or slower, but inevitably occurs. Figure.1 This is a comparison of mineral topping on new roofing paper and topping on the same roofing paper after several years of use in adverse conditions (on the right photo a drastic example of a significant loss of granules and exposure of asphalt in a roof depression - a periodic puddle).