Originally Posted by
Jeff Eastman
An inspector said:
"The underlayment has been installed beneath the metal drip edge. The manufacturer requires this on the rake edge of the roof. The underlayment should be installed on top of the drip edge at the downhill side of the roof. "
I always thought it was the other way around:
Underlayment UNDER the metal drip edge at eaves.
Underlayment Over the metal drip edge at rakes
Depends on where you are at.
In high wind prone regions (hurricane regions), and in South Florida for sure, the underlayment is under the metal drip edge 'all the way around the roof'. The metal drip edge is set in a bed of roof cement (the better way) or is simply nailed down with a 4" wide bed of roof cement applied over the drip edge / underlayment joint.
The metal drip edge *is on top* of the underlayment to hold the underlayment edges down during high wind events. This helps prevent the wind from getting in under the underlayment, once the wind gets under the underlayment, the entire roof system just peels right off, like peeling off a band-aid.
Other areas, however, insist that the only proper way to install drip edge is under the underlayment, other areas insist the only proper way is to install the drip edge over the underlayment along the rakes and under the underlayment along the eave over hang.