What is the primary purpose of Z-bar flashing in roofing?

The primary purpose of Z-bar flashing in roofing is to prevent water infiltration at roof edges. Z-bar flashing is designed to direct water away from vulnerable areas where roof surfaces meet vertical elements, such as walls or chimneys. This crucial aspect of roofing helps to ensure that water does not seep into the underlying structures, which can lead to water damage, mold growth, and significant structural issues over time.

Using Z-bar flashing creates a barrier that allows water to flow away rather than pooling or penetrating into seams or gaps. Its L-shaped design effectively channels water away from the roof edge, thereby protecting the building's integrity and extending the lifespan of the roofing system.

The other options, while related to roofing practices, do not capture the main function of Z-bar flashing. For instance, thermal insulation is more about the roofing material itself rather than the flashing; enhancing visual appeal is secondary to functionality; and structural support is not a role played by flashing. Each of these aspects contributes to roofing quality, but they do not pertain directly to the purpose of Z-bar flashing.