Final answer:
Wood shakes should be used on roof slopes that are 3 units vertical in 12 units horizontal (3:12 slope) or greater, as required by roofing construction standards for proper water drainage.
Step-by-step explanation:
The question relates to the roofing construction standards for the installation of wood shakes, which is an aspect of building construction and engineering. Wood shakes, a type of roofing material, should only be used on roof slopes that are 3 units vertical in 12 units horizontal (3:12 slope) or greater. This requirement ensures that the slope is steep enough for proper water drainage, which is critical to prevent water penetration and to protect the integrity of the roof and the structure it covers. When installing wood shakes, it is vital to adhere to these specifications to ensure a durable and safe roofing system. The steeper the slope, the more effectively the roof will shed water and debris, reducing the risk of leaks and extending the lifespan of the roofing material.