I'm confused… I've seen two conflicting sources of information describing how a roof drip edge should be installed.
One source (Ask This Old House), states that a drip edge should be placed above roofing felt: https://youtu.be/dms-qDIUnUQ?t=11m31s
Another source (Handy Home), states that it depends on which side the drip edge it being placed… and the stuff on the sides should be BELOW the roofing felt: https://www.youtube.com/watch?v=YRciDPll_NY&feature=youtu.be&t=2m4s
Is this just a personal preference? Or is one method clearly superior?
Best Answer
It depends on where the drip edge is. At the side, or gabels, of a roof, the drip edge goes over the roofing felt. At the bottom of the roof, the drip edge goes under the roofing felt. I have no idea why Ask This Old House did the drip edge the way they did. The main purpose of underlayment is to keep water away from the decking if it gets under the shingles. Water will pass right under that drip edge.
But don't take my word for it. Your shingles will come with instructions that say how to place the drip edges.
Example Installation Instructions
Timberline® Shingles Installation Instructions (PDF)
Oakridge® Shingles Installation Instructions (PDF)
Example installation instructions located using a simple google search. Products listed are not recommended nor endorsed by the author of this post.