Roof flashing is the thin, weather-resistant material that keeps water from slipping into small gaps where shingles meet walls, chimneys, vents, or edges. Without it, wind-driven rain finds openings and causes leaks, rot, and mold. Flashing works by directing water onto the surface of the roof so it can drain safely to gutters. It’s usually galvanized steel, aluminum, or copper, and it’s shaped to suit each joint or transition. Different areas need different profiles, and the right option to choose between different types of roof flashing depends on the detail you’re protecting.
Common Types of Roof Flashing
For each type, note location, purpose, and simple installation cues. Good flashing is only as strong as the overlap and sealant details that support it. Here are some of the most common types:
Step Flashing
- Where it goes: Along the sides of a dormer or wall where shingles run into vertical siding.
- What it does: Each small L-shaped piece “steps” up the slope, shingle by shingle, to move water back onto the roof surface.
- Notes: Pieces should overlap at least 2 inches, with the vertical leg tucked behind cladding. Shingles always cover the horizontal leg.
Counter Flashing
- Where it goes: Over step flashing at masonry or stucco, often on chimneys and walls.
- What it does: Shields the top edge of base or step flashing from wind and water.
- Notes: In brick, a reglet (a cut groove) holds the metal; the joint is sealed with a masonry-safe sealant. Counter flashing should not be mortared flush to the face without a reglet, or it may fail.
Apron Flashing
- Where it goes: At the front (downslope) side of a chimney, dormer, or wall-to-roof transition.
- What it does: Bridges the horizontal joint so water flows onto shingles.
- Notes: Often used with step and counter flashing around full chimney assemblies. Ensure the apron extends far enough onto the shingles to create a clean drip path.
Drip Edge Flashing
- Where it goes: Along eaves and rakes at roof edges.
- What it does: Keeps water from curling under shingles and protects the fascia edge.
- Notes: At eaves, underlayment goes over the drip edge; at rakes, the drip edge typically sits over the underlayment. Maintain a small kick at the bottom for clean runoff into gutters.
Valley Flashing
- Where it goes: In the valleys where two roof planes meet.
- What it does: Carries heavy water flow safely down the joint.
- Notes: An open metal valley with W-rib or center crimp helps split water. Overlaps should be generous, and nails must stay clear of the valley centerline.
Saddle Flashing
- Where it goes: Behind the upslope side of a wide chimney or at similar obstructions; often called a cricket.
- What it does: Splits and redirects water around the obstacle so it doesn’t pond.
- Notes: The mini-ridge should be centered and tied into step and counter flashing on both sides. On low slopes or large chimneys, building codes often require this detail.
Skylight Flashing
- Where it goes: Around factory skylight frames.
- What it does: Seals all four sides of the opening with head, sill, and step components.
- Notes: Use the manufacturer’s kit. Mix-and-match metal can void warranties. Proper curb height and shingle integration are critical.
Gable Flashing
- Where it goes: Along the sloped edges at gable ends; also called rake flashing.
- What it does: Protects the roof edge from wind-driven rain and shields the fascia or bargeboard.
- Notes: Similar to drip edge but sized for rakes. Keep a straight line and consistent reveal for clean water shedding and a tidy look.
Vent Pipe Flashing
- Where it goes: Around plumbing vents and exhaust stacks that penetrate the roof.
- What it does: A metal base and flexible “boot” seal the round opening.
- Notes: The upper shingles should overlap the top flange; the boot must fit snugly around the pipe. UV-safe boots last longer; replace cracked neoprene before leaks start.
Kickout Flashing
- Where it goes: At the bottom end of a wall-to-roof step-flashing run, where water needs to enter the gutter.
- What it does: “Kicks” water away from the wall cladding and into the gutter, preventing stains and hidden rot.
- Notes: Missing kickouts are a common failure point. The piece should be large enough to project water past the siding.
Conclusion
Flashing protects the small joints that cause big leaks. Match each location to the right profile: step flashing for sidewalls, counter flashing to guard masonry joints, apron at the downslope face, drip edge at eaves and rakes, valley metal where planes meet, and a saddle behind wide chimneys. Use manufacturer kits for skylights, a snug boot for vent pipes, and a proper kickout at the gutter. Overlap correctly, avoid nail lines in high-flow areas, and follow a clean water path from shingle to gutter. With those practices in place, roofs last longer, interiors stay dry, and repairs become rare for almost all types of roof flashing. Different types of roof flashing have unique advantages, so choose what works best for you.
For professional and renowned roof flashing services that are affordable too, you can contact Precision Roofing.