Waterproofing impassable flat roofs

Impassable roofs, mostly flat shapes, are designed in such a way that their waterproofing cover directly exposed and visible, and in the second variant is protected and loaded. Impassable flat roofs with exposed and visible waterproofing cover technically classify and call exposed impassable flat roofs. Impassable flat roofs where waterproofing is protected by cover and loaded with gravel or other material, called protected or in practice most often - ballast impassable flat roofs.