The concept of green roofs and their importance to the urban landscape is consistent with the concept of sustainable development and management of rainwater. These aspects contribute to the continuous search for solutions in terms of technology these systems. The study assessed the ability of retention model of extensive green roof type based on the profiles of vegetation layer prepared on the basis of expanded clay and perlite. The study was conducted in 2012 on property located in the observatory Agro- and Hydrometeorology Wrocław-Swojec on the type of extensive models of different composition of vegetation layer, which evaluated the effectiveness of retention and reducing the amount of rainwater flowing. Modelling studies have shown that green roofs water retention in the range from 22,9 to 77,8 mm and retention rates ranged from 67 to 98% precipitation. Indicators outflows were relatively small, ranging from 0,5 to 18 mm.