How should a drip edge be applied at the rake?

Applying a drip edge at the rake over the underlayment is essential for effective water management on a roof. When the drip edge is positioned over the underlayment, it ensures that any water that runs down the roof is directed off the edge and away from the roofing materials below. This is particularly important because it prevents water from infiltrating underlying layers, which could lead to damage, mold, or rot.

Placing the drip edge over the underlayment also allows for proper layering, which enhances the integrity of the roofing system. It functions as a barrier, effectively shedding water and protecting the areas where the roof materials meet, thus extending the lifespan of the roofing components. This approach aligns with industry best practices and building codes that require effective water drainage solutions.

In contrast, the alternative placements such as under the underlayment would not protect the materials effectively, and installing it at the ridge or gable does not appropriately utilize the drip edge's function to control water runoff from the roof.