What does a roof system encompass?

A roof system encompasses all the various components that work together to protect the building from weather elements and ensure its structural integrity. By focusing on roof components designed to weatherproof, this option accurately describes the comprehensive nature of a roof system.

This includes not only the visible elements like shingles but also essential parts such as underlayment, flashing, and drainage systems. Each of these components plays a critical role in preventing water intrusion, managing airflow, and maintaining durability and energy efficiency.

In contrast, the other options are more limited in scope. Shingles and nails alone do not represent the full picture of what constitutes a roof system, nor do the three layers of insulation, which, while important, are just one aspect of the overall assembly. Additionally, limiting the definition to just the roof deck and rafters ignores other critical parts like waterproofing materials and ventilation systems that are necessary for a fully functioning roof system.