Which type of roofing material requires a slope of at least 4:12 for installation?

Slate shingles indeed require a minimum slope of 4:12 for proper installation. This steep slope is essential for slate to perform effectively, as it helps to facilitate adequate water runoff and prevents water from pooling on the surface. Slate, being a natural stone, is heavier and more brittle than other roofing materials, so installing it on a slope ensures that water drains off effectively, reducing the risk of leaks and damage over time. Additionally, the angled surface helps to minimize the potential for ice dam formation in colder climates.

As for the other materials, asphalt shingles can be installed on lower slopes, typically down to about 2:12, while wood shakes can also be used on various slopes, making them more versatile in terms of installation requirements. Concrete tiles often require a slope of at least 3:12 for effective drainage and performance, but they do not necessitate the same steep slope as slate. This highlights the unique characteristics and installation needs of different roofing materials.