However because of its difficult lapping, it is easy for a leak to be produced when there are skylights, fans and clearstory etc, at the roof of a building.

• 但是由于其横向搭接困难，故当建筑屋顶有天窗、风机、气楼等突起构造以及需要与采光带等不同材料组合时，容易产生渗漏。