Maintenance · 5 min read
Roof Flashing Explained: Where Roofs Actually Leak
Published
Shingles shed water. Flashing handles every place shingles can't — and that's where nearly every leak originates.
Step flashing
Where a roof meets a vertical wall, individual L-shaped pieces are woven into each shingle course. A single continuous strip of aluminum instead — still common on cheap installs — will leak, because there's no way for water getting behind the siding to escape.
Kick-out flashing
At the bottom of a roof-to-wall transition, a kick-out diverts water away from the wall and into the gutter. Missing kick-outs are responsible for an enormous amount of hidden wall rot, because the damage happens inside the wall cavity where nobody sees it for years.
Chimney flashing
A proper chimney has base flashing, step flashing up the sides, a cricket on the upslope side if it's wide, and counterflashing let into the mortar joints. Tar smeared over the joint is a temporary patch, not a repair.
Valleys
Closed-cut valleys with ice barrier underneath work well for most homes. Open metal valleys shed debris better and are worth considering under heavy tree cover.
If any of this applies to your own home, our asphalt shingle roofing crews handle it every week, and you can see how we work in your area on our Troy, Ohio roofing page. Inspections and written estimates are free either way — call 937-749-7767.