Final answer:
When installing underlayment on a roof, it should be lapped over hips and ridges by at least 12 inches on each side to protect against water infiltration.
Step-by-step explanation:
The question refers to the correct method of installing underlayment over hips and ridges in roofing. When installing underlayment, it is essential to lap the material over the hips and ridges to ensure that there is an adequate barrier against water penetration. While specific instructions may vary depending on the type of underlayment and the manufacturer's guidelines, a general rule of thumb is to lap the underlayment at least 12 inches on each side of the hip or ridge. This creates a sufficient overlap to protect the roof from water infiltration and to provide an added layer of protection to these vulnerable areas.