A.Architect and roofing consultant Harrison McCampbell responds: Standard drip-edge profiles include a turned-out bottom lip that directs water away from the fascia. The distance from the end of this lip to the face of the fascia varies, depending on the manufacturer and the style of the drip-edge you are using, from as little as 1/4 inch to as much as 1 inch.
Most drip-edge profiles are successful at directing water away from the fascia during periods of heavy rain. During drizzly weather, though, rainwater is sometimes able to curl under a drip-edge and run down the fascia, especially if the drip-edge has a short lip. One manufacturer selling a drip-edge with an aggressive lip is Lamb & Ritchie...
to read the full article.