What is a requirement for shower pans in plumbing installations?

Shower pans serve a crucial role in preventing water damage and ensuring proper drainage in plumbing installations. The requirement for shower pans to be turned up on all sides above the threshold is fundamental for effective water containment and to prevent water from escaping the shower enclosure. This design feature helps to funnel water back into the pan and away from areas where it could cause leaks or damage to the building structure.

In addition, having the edges turned up creates a barrier that helps mitigate the risk of water overflow, ensuring that any splashes or spills are retained within the shower area. Proper installation and adherence to this requirement are essential for maintaining the integrity and functionality of the plumbing system in residential and commercial settings.

The other options focus on aspects that are not universally required for shower pans, making them less relevant compared to the critical need for sides above the threshold that ensure water is contained effectively.