Slate shingles are used only on slopes of what ratio or greater?

Slate shingles are traditionally used on roofs with a slope of 4:12 or greater because this pitch allows for effective water drainage and helps prevent moisture buildup. The steeper angle promotes the natural shedding of rain and snow, reducing the risk of leaks and water infiltration. This minimum slope is important as slate shingles are naturally heavier and can be more prone to issues such as sliding or dislodging if installed on flatter surfaces. Thus, a slope of 4:12 ensures that the roofing system can perform effectively and maintain durability over time.