Question 4

A coal-tar, built-up roof should typically have a minimum slope of 1/8 inch per foot to ensure adequate drainage.

A roof designed with a slope of 1/8 inch per foot is generally sufficient to facilitate proper drainage, preventing water pooling and potential damage.

A) 1/8 inch per foot.

This option is correct as it represents the minimum slope recommended for coal-tar, built-up roofs. A slope of 1/8 inch per foot is considered adequate to ensure that water drains effectively, reducing the risk of leaks and structural issues.

B) 1/2 inch per foot.

While a slope of 1/2 inch per foot would provide good drainage, it exceeds the minimum requirement for coal-tar, built-up roofs. Therefore, it is not the correct answer to the question, as the minimum slope needed is less than this.

C) 1 inch per foot.

This option is incorrect because a slope of 1 inch per foot is significantly steeper than the minimum requirement. Such a steep slope may not be necessary for adequate drainage and could lead to complications in construction and maintenance.

D) 2 inches per foot.

A slope of 2 inches per foot is excessively steep for a coal-tar, built-up roof. This option is incorrect as it far exceeds the minimum slope needed for effective drainage, making it impractical for standard roofing applications.

Conclusion

The minimum slope of 1/8 inch per foot is essential for ensuring effective drainage in coal-tar, built-up roofs. Options B, C, and D, while providing adequate drainage, do not meet the specified minimum requirement, making them incorrect. Therefore, option A is the only appropriate choice, aligning with industry standards for roofing design.