Where should a drip edge be placed at the rake relative to the underlayment?

Where should a drip edge be placed at the rake relative to the underlayment?

• A. Between the two courses of shingles
• B. Directly to the roof sheathing
• C. Over the underlayment
• D. Beneath the roof sheathing

Answer: (C)

Water at the edge needs a clean, protective termination that directs it away from the roof. Placing the drip edge over the underlayment at the rake achieves that by letting the metal edge overhang the deck while the underlayment ends just beneath it. Water flows from the roof onto the drip edge and off, rather than seeping behind the edge or into the underlayment. If the drip edge were placed beneath the underlayment, behind the edge, water could get behind the flashing and the edge would be less effective at shedding water. A setup where the drip edge sits between shingles or directly on sheathing would also fail to provide a proper finished edge that protects the underlying materials and directs water away.

Water at the edge needs a clean, protective termination that directs it away from the roof. Placing the drip edge over the underlayment at the rake achieves that by letting the metal edge overhang the deck while the underlayment ends just beneath it. Water flows from the roof onto the drip edge and off, rather than seeping behind the edge or into the underlayment.

If the drip edge were placed beneath the underlayment, behind the edge, water could get behind the flashing and the edge would be less effective at shedding water. A setup where the drip edge sits between shingles or directly on sheathing would also fail to provide a proper finished edge that protects the underlying materials and directs water away.