When a homeowner in Roseburg or Winston calls about a ceiling stain, they usually assume "bad shingles." But shingles are simple — gravity pulls water down, each course sheds onto the one below, done. The hard part of a roof is everywhere that simple system gets interrupted: a chimney, a wall, a vent pipe, a valley where two planes meet.
Those interruptions are sealed with flashing — shaped pieces of metal (and one infamous piece of rubber) that redirect water back onto the shingles. Flashing is a small fraction of a roof's cost and the source of most of its leaks. If you understand these six spots, you understand where your roof will fail first.
Chimneys: step flashing plus counter-flashing
A chimney punches straight through the roof plane, so water hits it from above and runs around it on both sides. The proper defense is a two-layer system:
- Step flashing: L-shaped pieces of metal woven into each shingle course along the chimney's sides — one piece per course, stepping down the slope, each shedding onto the shingle below.
- Counter-flashing: a second layer embedded into the masonry mortar joints above, lapping down over the step flashing so water running down the brick can't sneak behind it.
The common failure isn't the metal — it's the shortcut. A smear of roofing tar where counter-flashing should be will look fine for a year or two, then crack in our summer heat and leak all winter. If your chimney's "flashing" is black goop, it's on borrowed time. Larger chimneys also need a cricket (a small peaked diverter) on the uphill side so water and debris don't pond behind them.
Sidewalls and the kick-out everyone skips
Where a roof runs alongside a vertical wall — a dormer, a second story, a garage wall — the same step-flashing logic applies, tucked behind the siding or wall weather barrier.
The critical piece is at the bottom of that run: kick-out flashing, a small angled diverter that throws the collected water away from the wall and into the gutter. Skip it, and every storm sends a sheet of roof runoff directly down the face of the wall — and eventually behind the siding.
⚠ Required here, missing everywhere
Kick-out flashing is required at sidewalls in Douglas County — and it's still one of the most common missing details we find on existing homes. The damage it prevents is the sneaky kind: sheathing and framing rot inside the wall, invisible until siding bulges or paint bubbles. If your roof dead-ends into a wall above a gutter, go look. No kick-out means water has been going somewhere it shouldn't for years.
Valleys: open vs. closed
A valley is where two roof planes drain into each other — which means it carries more water per square foot than anywhere else on the roof, and in our October-to-May wet season, that's a lot of water.
- Open metal valleys leave an exposed metal channel down the center. Water and debris move fast and wash out. In fir-needle country like the Umpqua Valley, this is usually our recommendation — needles rinse through instead of composting in place.
- Closed (woven or cut) valleys run shingles across the valley for a cleaner look. They can work well, but everything depends on what's underneath, because debris that lodges there holds moisture against the shingles.
Either way, a valley in western Oregon should have peel-and-stick membrane beneath it — we cover why in our ice and water shield guide.
Pipe boots: the 10-year failure everyone forgets
Every plumbing vent pipe through your roof wears a flashing with a metal base and a rubber gasket hugging the pipe. The metal lasts practically forever. The rubber doesn't. Our climate — soaking wet half the year, bone-dry and hot the other half — cracks that neoprene in roughly 10 to 15 years.
That timing is the trap: the boots fail at the midpoint of a 20–25 year shingle roof, when nobody is thinking about the roof at all. A cracked boot leaks a little with every storm, staining the ceiling near a bathroom or dripping down a vent pipe into a wall. The fix — a new boot — is one of the cheapest roof repairs there is when caught early. Caught late, you're replacing rotted decking too. Checking every boot by hand is a standard part of the annual inspection our Home Care Membership covers (from $49/month, with a photo report each visit) — mid-life flashing failures are exactly what it exists to catch.
Skylights and drip edge
Skylights are engineered penetrations with manufacturer flashing kits, and installed correctly they're reliable. The leaks we see come from three sources: aging seals in old units, improvised flashing instead of the proper kit, and debris dammed on the uphill side. If your skylight is as old as your roof, replace it during the reroof — pulling a working roof apart later to swap a failed skylight costs far more.
Drip edge is the humble metal along the eaves and rakes that kicks water off the roof edge into the gutter instead of letting it curl back under the shingles into the fascia. It's cheap, it's code on new work, and old homes around Douglas County often don't have it — which is a big part of why so many of them have soft fascia boards behind the gutters.
Reuse or replace? The honest answer during a reroof
Here's where bids quietly diverge. Flashing can sometimes be reused during a roof replacement — and "we'll reuse the existing flashing" is also where a suspiciously low bid hides its savings. Our honest rules of thumb:
- Always replace: pipe boots (the rubber is mid-life at best), drip edge (it's cheap and the old one is nail-riddled), and any flashing that's rusted, bent, or tarred over.
- Usually replace: valley metal and step flashing — new shingles deserve metal on the same clock, and step flashing is woven into the courses anyway.
- Sometimes keep: chimney counter-flashing that's well-embedded in sound mortar. Cutting good counter-flashing out can damage the masonry; lapping properly under it is the better craft call.
Whatever a contractor proposes, the flashing plan should be in writing, item by item. Since Douglas County requires full tear-offs (no shingle overlays), the reroof is the one moment every flashing detail is exposed and fixable — our permit guide covers what the county expects. And if a storm has bent or peeled flashing loose, document it before repairs; our insurance claims guide walks through that process.
Quick answers
What is kick-out flashing?
A small angled diverter at the bottom of a roof-to-wall joint that throws water into the gutter instead of down inside the wall. Required in Douglas County, and missing on a remarkable number of older homes.
Why do pipe boots fail so often?
The rubber gasket around the pipe cracks in roughly 10–15 years under our wet/dry cycle — long before the shingles die. It's a cheap swap when caught early.
Should flashing be replaced during a reroof?
Boots, drip edge, and valley metal: yes, as a rule. Sound, well-embedded chimney counter-flashing is the occasional honest exception. Get the plan in writing.
Open or closed valleys here?
Both can work, but open metal valleys shed our heavy runoff and fir needles better, so that's usually our recommendation — with membrane underneath either way.