My Shed Stayed Dry in Normal Rain for Three Years. Then One Storm Told Me What I'd Missed.

The Hose Test

I kept the stream aimed at the same spot—low on the roof’s edge, where the rake trim meets the eave—and moved inside to watch.

The water wasn’t dripping from the ceiling or running down a rafter. It was appearing on the inside face of the wall, about six inches below the roofline, then trickling down to the floor.

That didn’t make sense. Shingles overlap. Underlayment sheds water down and out.

I went back up and kept spraying, this time watching the outside while my phone recorded video inside. When I angled the hose to mimic wind pushing rain upward and sideways, I could see water hitting the trim, then just… disappearing.

Not rolling off. Not beading up. Vanishing behind something.

I turned off the hose and climbed down to take a closer look at the joint where the metal drip edge tucked under the shingles. That’s when I finally saw it—or rather, saw what wasn’t there.