At the eave, the drip edge should be installed beneath which component?

At the eave, the drip edge should be installed beneath which component?

• A. the starter strip
• B. the underlayment
• C. the sheathing
• D. the siding

Answer: (B)

At the eave, water needs a clear path to the gutter, and the layering along the edge controls that path. The underlayment is the waterproof barrier that sits over the roof deck, and it must extend over the edge so water flows onto the drip edge rather than behind it. By placing the drip edge beneath the underlayment, the underlayment can lap over the edge, directing runoff onto the metal edge and into the gutter. The other components—starter strip, sheathing, and siding—don’t govern this edge-water flow in the same way: the starter strip is used to form the bottom shingle line, sheathing is farther behind underlayment, and siding is on the wall, not at the eave interface.

At the eave, water needs a clear path to the gutter, and the layering along the edge controls that path. The underlayment is the waterproof barrier that sits over the roof deck, and it must extend over the edge so water flows onto the drip edge rather than behind it. By placing the drip edge beneath the underlayment, the underlayment can lap over the edge, directing runoff onto the metal edge and into the gutter. The other components—starter strip, sheathing, and siding—don’t govern this edge-water flow in the same way: the starter strip is used to form the bottom shingle line, sheathing is farther behind underlayment, and siding is on the wall, not at the eave interface.