Separation layers and their influence on green roof water storage

[EN] This study deals with how adding separation layers to flat roofs improves their design, construction, and sustainability. Better understanding and use of these layers leads to increased durability, lower maintenance, and simpler execution, with potential for material reuse and performance enhancement. Currently, the optional nature of separation layers hinders the overall sustainability of roofing systems, so this research seeks to guide building professionals in selecting suitable separation layers for flat roofs, considering factors like location, function, material composition, and mass. Particularly, it examines the impact of Water Storage layers on self-sustaining green roofs, aiming to enhance thermal performance, especially when water is scarce. Results indicate that installing these layers significantly increases water retention below the drainage layer, primarily in extensive green roofs, where values rise by 17%. Water Storage layers also extend water availability after rainfall, raising maximum daily humidity levels inside the roof by up to 10% on the third day post-rainfall compared to green roofs without such a layer.