Which roofing material requires a minimum slope of 2 1/2 units in 12?

Clay tiles, often referred to as clay units, are designed for use on roofs that have a minimum slope of 2 1/2 units in 12. This slope is necessary to ensure proper drainage and to prevent water from pooling on the roof, which can lead to leaks and other water-related issues. The construction and weight of clay tiles also require this pitch to ensure they perform effectively over time.

Asphalt shingles can often be used on lower slopes than this, typically as low as 2 units in 12 with special installation techniques. Wood shingles generally require a slope of at least 3 units in 12 to allow for adequate water runoff and to prevent moisture absorption that could lead to decay. Metal shingles can be installed on a variety of slopes, but they are usually effective on roofs with a minimum slope of 3 units in 12 for similar reasons.

Understanding the specific requirements for each roofing material helps ensure proper installation and long-term performance, which is critical in any residential building inspection context.