Which of the following is true regarding skylights?

The statement that skylights should be installed at a slope of 15 degrees or greater is accurate because this angle helps in optimal water drainage, reducing the risk of leaks and condensation that could lead to mold or structural issues. This slope facilitates effective water runoff, preventing pooling and ensuring that the integrity of the building envelope is maintained. Additionally, an appropriate slope can improve thermal performance by reducing heat gain in warmer climates and managing heat loss in cooler ones.

Other considerations such as energy efficiency and orientation also play vital roles in skylight installation; however, they do not strictly dictate the required slope, thus making this guideline specific and crucial for proper skylight implementation.