Waterproof cap

The invention is suitable for the field of building materials, and particularly relates to a waterproof cap which comprises a through pad body. A cap body is connected to the pad body, a concave cavity is formed in the pad body, when a screw is inserted into the through pad body for use and the concave cavity formed in the pad body is extruded by the screw, air in the concave cavity at the contactposition of the pad body and a block material is extruded to form a vacuum state, the pad body can be tightly attached to the block material, the sealing performance after connection is effectively enhanced, then covering with the cap body is carried out, dual waterproof protection is achieved, the waterproof performance of a ceiling is higher, installation screws can be effectively prevented from being affected with damp, the service life of the ceiling is effectively prolonged, and meanwhile, the effect of preventing a panel from being eroded by rain, snow and the like is achieved. 本发明适用于建筑材料领域，具体是一种防水帽，包括呈贯通状的垫体，所