Step flashing works like shingles for a corner. Each course of shingles along a wall gets its own L-shaped piece of metal — one leg lying flat on the roof, the other running up the wall — and each piece laps over the one below it. Water "steps" down from piece to piece and never finds a seam pointing uphill. The wall leg is then covered by siding or by counter-flashing so nothing is left exposed.
Why it matters on Umpqua Valley roofs
Roof-to-wall joints are where a huge share of the chronic leaks we chase in Roseburg, Winston, and Sutherlin actually start. Those intersections catch concentrated runoff for roughly 130 rain days a year, and wind-driven winter storms push water sideways into any gap. A wall joint that survives an Arizona climate on caulk alone doesn't stand a chance through an Oregon October.
When it fails, what it costs you
Step flashing rarely wears out on its own — the usual failure is human: a previous roofer reused bent, nail-holed flashing during a reroof, or skipped it entirely and smeared roofing cement along the wall. Cement cracks within a couple of seasons, and the leak often shows up far from the joint, running along framing before it stains a ceiling. Diagnosing that is classic repair detective work. The good news: because Douglas County requires full tear-offs, a proper roof replacement is the natural moment to get every wall joint re-flashed with new metal.
Can step flashing be reused when reroofing?
It shouldn't be. Old flashing is full of nail holes, fatigued bends, and sealant residue. New step flashing costs very little on a full reroof and removes the most common source of future wall-joint leaks.