重庆邮电学院学生食堂附属工程1000m~2预应力空心板屋面施工中采用了增加一布四油屋面防水层的作法（图1），经5年多使用，该屋面无一处渗漏。其作法如下。（1）屋面施工时注意清理板缝，对落人的杂物（如碎砖块、灰浆等）应认真清理。（2）板缝灌细石混凝土前，必须冲洗干净。 In the construction of the 1000m~2 prestressed hollow slab roof of the student canteen project of Chongqing University of Posts and Telecommunications, the practice of adding a four-oil roof waterproofing layer (Figure 1) was adopted. After 5 years of use, there was no leakage in the roof. Its practice is as follows. (1) Careful attention should be paid to the cleaning of the board joints during the construction of the roof, and the miscellaneous items (such as broken bricks and mortar) should be carefully cleaned. (2) Before the slab seams are stoned with concrete, they must be washed.