The first and very basic step to waterproofing is application of polymer coating on concrete surface. The thickness of this polymer coating layer is around 2mm. The waterproof polymer coating is available in liquid form like paint. This polymer is mixed with cement and then applied on concrete surface. Roof is an uppermost portion covering a building. Terrace is an occupiable portion of a building above ground level. A flat roof makes the ideal spot for a rooftop garden. … Try arranging potted plants on your flat roof – you could grow flowering plants to attract bees and butterflies, start your own herb garden, or even grow your own fruits and vegetables. Tomatoes and strawberries grow happily in pots and will love the sunshine.