1. The flatness of the base wall does not meet the requirements.
2. The wall is too dry. When pasting the insulation board, the base layer is not treated with water. After the rain, the water content of the wall is too large, and the insulation board is pasted before the wall is dry. Because the water content of the wall is too large , causing the glue to sag and lead to the hollowness of the insulation board.
3. Knock, beat and vibrate the board surface during construction, which will cause the glue to fall off, resulting in hollow and virtual sticking of the board surface.