Answer:
(i) Generally, after RC concrete is poured on the roof, there is a process of shaking and crumbling, and the overall surface becomes rough. However, the RC concrete for sloping roofs does not undergo this process, so the surface is prone to unevenness and even sand formation. Additionally, there is a noticeable construction seam at the intersection between the sloping surface and the facade, which is a common cause of future water leakage.
(2) Therefore, before applying the roofing material to waterproof it, it is very important to prepare the base material and reinforce the corners; you must always hire an experienced professional to do this.
(3) The corner areas must first be properly reinforced with resin mortar. The sloping roof must also be prepared by first applying a base material (preferably a hard acrylic resin mortar; avoid using ordinary elastic cement or self-leveling clay series—this will reduce the bonding function with the top waterproof material).
(4) It is best to use a low-spreading elastic waterproof coating (such as PU or modified asphalt) for the formal waterproof layer, and to control its thickness.
(5) If cultural tiles or related surface decorative materials are to be laid on top, it is best to add another layer of modified asphalt waterproof mat (adhesive or oven-baked are both acceptable).