What is the primary function of a roof drain?

The primary function of a roof drain is to collect and manage water that accumulates on the surface of a roof. Roofs are designed to shed water, but during heavy rain or snowmelt, water can pool on the surface. The roof drain effectively directs this water away to prevent potential damage to the roof structure, such as leaks, mold growth, or structural deterioration due to standing water.

By facilitating proper drainage, roof drains help maintain the integrity of the roofing system and contribute to the overall safety of the building. This is particularly important in flat roof designs where water accumulation is more common. Options that refer to venting air or managing insulation do not serve the primary function needed for water management on roofs, while overflow management, though it may aid in preventing structural damage, is not the principal purpose of a roof drain.