CSLB General Building (B)Finishes and Building EnvelopeEasy
A roofing crew is installing composition shingle roofing on a new residence and placing drip edge metal along both the eaves and the rake edges. Per standard California roofing practice, how should the drip edge be installed relative to the underlayment at each location?
- AOver the underlayment at both eaves and rakes
- BUnder the underlayment at both eaves and rakes
- CUnder the underlayment at the eaves and over the underlayment at the rakes
- DOver the underlayment at the eaves and under the underlayment at the rakes
Show answer & explanationAnswer & explanation
Correct answer: C. Under the underlayment at the eaves and over the underlayment at the rakes
Standard practice places drip edge underneath the underlayment at the eaves so water sheds off the metal into the gutter without getting behind it, and over the underlayment at the rakes so wind-driven rain is directed off the roof edge rather than up under the metal.
Why the other options are wrong
- A. Installing drip edge over the underlayment at the eave can let water run behind the metal into the fascia.
- B. Installing drip edge under the underlayment at rakes allows wind-driven rain to get behind it.
- D. This is the reverse of correct practice and invites water intrusion at both locations.
Drip Edge Sequencing
Drip edge metal is installed under the underlayment at eaves and over the underlayment at rake edges to properly shed water.
- Eave: drip edge under underlayment
- Rake: drip edge over underlayment
- Prevents water from getting behind fascia and rake trim
Memory trick: Under at the eave, over at the rake — remember 'UE-OR'.