There is a piece of bent metal roughly the size of your hand that costs a few dollars, takes a competent roofer about ten minutes to fit, and is missing from a large proportion of Seattle homes. Its absence does not leak into your attic. It leaks into your walls, silently, for years.
Where a sloped roof runs alongside a vertical wall and then ends — the bottom of a dormer, the base of a two-storey wall meeting a lower roof, the end of a garage roof against the house — every drop of water that has been travelling down that junction arrives at one point.
A kickout flashing sits at that point, angled outward, and kicks the concentrated stream away from the wall and into the gutter. Without it, that stream simply carries on going: straight down, behind the siding, into the wall assembly.
The volume matters here. This is not incidental moisture. It is the collected runoff of an entire roof-to-wall run, delivered to a single spot, repeatedly, through eight months of Seattle wet season.
Three reasons, none of them good but all of them understandable.
It is a single small custom-bent piece at one location on a roof, easy to overlook when a crew is moving fast and the step flashing run is otherwise complete. It appears on no homeowner's checklist, so nobody asks for it. And on homes built before the detail became widely understood and enforced, it was frequently never installed at all — which covers a great deal of Seattle's housing stock.
It also does not announce itself. There is no ceiling stain, because the water never enters the attic. The failure produces no symptom in the place homeowners watch.
Inside the wall cavity, water wets the sheathing, the framing, and the insulation. In a climate that keeps materials above the moisture content decay fungi need for most of the year, that produces rot rather than a drip.
The sequence of discovery is nearly always the same. Nothing for years. Then paint failure or staining on the siding below the junction. Then swollen or soft siding, or trim that has gone spongy. Then, eventually, someone opens the wall — during a siding replacement, a window replacement, or a pre-sale inspection — and finds blackened sheathing and compromised framing behind it.
At that point the repair is not a flashing job. It is siding removal, sheathing replacement, potentially framing repair, insulation replacement, and refinishing. This is how a missing part costing a few dollars turns into a five-figure repair, and the reason is entirely that it took years to become visible.
Walk around the house and find every place a roof edge terminates against a wall that continues past it. Common locations: the lower end of a dormer, where a garage or porch roof meets the main house wall, where a lower roof section dies into an upper storey.
At the very bottom of each of those junctions, look for a small piece of metal angled outward toward the gutter. It should be obvious once you know to look — a deliberate diverter, not just the end of the flashing run.
If the step flashing simply stops and the shingles end against the wall with nothing kicking water outward, it is missing.
Then look at the wall directly below that point, at ground level if it is a lower junction. You are looking for a vertical band of paint failure, staining, moss or algae growth on the siding, swollen board edges, or trim that feels soft when pressed. That band is the water's path, and it tells you whether the omission has already been doing damage.
Honest answer: it is harder than installing it originally, and it is not a caulk-it-on job.
A proper retrofit requires removing the lowest courses of siding at the junction so the flashing can be integrated behind the water-resistive barrier and lapped correctly with the existing step flashing. Done that way it works permanently. Surface-mounted and sealed to the outside of the siding, it diverts some water and creates a new place for water to sit, which is why that version is not worth doing.
The cost is modest relative to what it prevents, and there is an obvious efficiency: if siding work is ever planned, that is the moment to address every kickout on the house at once. Similarly, if a re-roof is coming, kickouts at every roof-to-wall termination should be an explicit line in the scope rather than an assumption.
When you get roofing quotes, ask: does this include a kickout flashing at every roof-to-wall termination?
The answer is informative either way. A contractor who confirms it immediately and can point to the locations on your house has been paying attention. One who has to ask what you mean has told you something useful before you have spent anything.
This post is part of our in-depth coverage of roof repair & leak detection in Seattle.
A small piece of flashing at the base of a roof-to-wall junction that diverts concentrated runoff into the gutter instead of behind the siding. When missing, water enters the wall assembly rather than the attic, so there is no ceiling stain and damage accumulates invisibly for years.
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