Question 10

Coal tar built-up roofs shall have a design slope of a minimum of 1/4 unit vertical within 12 units horizontal.

The minimum design slope for coal tar built-up roofs is 1/4 unit vertical for every 12 units horizontal, ensuring proper drainage and preventing water accumulation.

A) 1

Option A is incorrect because a slope of 1 unit vertical within 12 units horizontal exceeds the minimum requirement. While steeper slopes can enhance drainage, they are not necessary to meet the minimum standard.

B) 1/2

Option B is also incorrect as it specifies a slope of 1/2 unit vertical within 12 units horizontal. This slope is steeper than the required minimum and does not reflect the specified standard for coal tar built-up roofs.

C) 1/4

Option C is correct because it accurately states the required minimum slope of 1/4 unit vertical within 12 units horizontal. This slope is essential for effective drainage and compliance with roofing standards.

D) 1/8

Option D is incorrect as it suggests a slope of 1/8 unit vertical within 12 units horizontal, which is below the minimum requirement. A slope this shallow could lead to inadequate drainage and potential water damage.

Conclusion

The correct answer, 1/4 unit vertical within 12 units horizontal, is essential for ensuring effective drainage in coal tar built-up roofs. All other options fail to meet the minimum requirement, either being too steep or insufficiently shallow, which could compromise the roof's integrity and performance.