Galvanized Steel Flashing
Galvanized steel flashing is zinc-coated sheet metal used to direct water away from critical roof intersections, penetrations, and transitions, offering corrosion resistance at a moderate cost.
Standard Metal Flashing Material
Galvanized steel flashing is sheet metal coated with a protective layer of zinc, used at critical roof junctions, penetrations, and transitions to redirect water and prevent leaks. Galvanized steel is the most commonly used flashing material on residential roofs because it offers a balance of corrosion resistance, workability, and cost. It is used for step flashing, counter flashing, drip edge, valley metal, and custom-fabricated pieces at unique intersections.
On insurance estimates, flashing should always appear as separate line items, not bundled into the shingle installation price.
Where Galvanized Flashing Is Used
Every point where the roof changes direction, meets a wall, or has a penetration requires flashing. Step flashing at wall intersections, counter flashing at masonry transitions, drip edge at rakes and eaves, valley flashing in roof valleys, and boot flashing around pipes are all typically galvanized steel. The zinc coating protects the steel from rust in most environments, though in coastal or industrial areas with salt air or chemical exposure, the coating degrades faster.
When existing galvanized flashing shows white rust (zinc oxide), the protective coating is depleted and the underlying steel will corrode. This condition justifies replacement in the estimate.
Estimating Galvanized Flashing
Xactimate prices flashing by linear foot for straight runs and by each for fabricated pieces. Each flashing type has its own selector code. A common estimating error is using a generic "flashing" line item instead of specifying the exact type and material at each location. Step flashing, counter flashing, valley metal, and drip edge are all different products with different prices. Specify each one correctly, and include the material type (galvanized steel vs. aluminum vs. copper) to ensure accurate pricing.
Frequently asked questions
Galvanized steel flashing typically lasts 20 to 30 years before the zinc coating wears through and corrosion begins. Lifespan depends on climate, air quality, and whether the flashing contacts dissimilar metals, which accelerates galvanic corrosion.
Flashing should be included as separate line items in the estimate, not lumped in with shingle installation. Step flashing, counter flashing, drip edge, valley metal, and pipe boot flashing are all individual line items with their own pricing.
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