Gutters · Steel gutters (galvanized)
How long do steel gutters last?
A galvanized steel gutter's clock is the zinc on it. The zinc industry's own note on coating thickness puts a G90 coating — the standard weight for outdoor galvanized sheet — at about 20 years before red rust shows in average suburban air, and 16 to 17 years where the air works on it faster. There is no warranty bar here: the rainware paper in this trade is written for aluminum.
Updated
Typical service life: 16–20 years
Both figures are the GalvInfo Center's own: "G90 will last 20 years before 5% red rust in an average suburban locale," and at a corrosion rate of 0.05 mil a year "the life of a G90 coating would be approximately 16 to 17 years." That is the zinc's life rather than the gutter's — first rust, not a hole through the trough. A prepainted steel gutter carries paint on top of the zinc and runs longer than the bare figure; InterNACHI's baseline chart puts galvanized steel gutters and downspouts at a flat 20.
Tier 2 · trade / standards literature Range from GalvInfo Center (International Zinc Association) — GalvInfoNote 1.6 — Selecting Coating Thickness (Weight or Mass) for Galvanized Steel Sheet Products, checked 2026-08-27.
Climate here means the zinc corrosion rate, and GalvInfo's note is candid that it spans an order of magnitude — under 0.01 mil a year at the benign end, and high enough at the very acidic end that the note says galvanized steel is not the preferred product there. It also records that industrial-area service life is now longer than it was thirty to fifty years ago as sulfur dioxide fell, while marine rates barely changed, because deposited sea salt rather than airborne pollution governs them. In dry interior air a galvanized gutter can run past the suburban figure; within sight of surf it will not reach it.
Why there is no warranty bar here
The gutter warranties in this trade are written for aluminum. Englert's seamless-gutter term covers gutter "shaped and rollformed from Englert's aluminum gutter coils" and nothing else; Alside publishes a single rainware gutter warranty and it is the aluminum one; and Amerimax, whose galvanized sectional gutter is the home-center default, warrants its materials only "to be free from defects in material and workmanship at time of purchase." Steel gutter moves as coil and stock with no service term attached to it, which leaves the zinc coating's own documented life as the honest number on this page.
What shortens it
- Cut ends, screw holes and deep scratches, where the steel is bare and the zinc has to protect it sideways instead of by covering it
- Wet leaf mat in the trough, which keeps the bottom from ever drying and spends zinc where nobody looks
- Salt in the air — sea salt and road-salt spray both raise the zinc corrosion rate sharply, and GalvInfo's note singles marine air out as the one exposure that has not improved with cleaner industrial air
- Runoff from a copper roof or copper flashing above, which is aggressive to galvanized steel
- Paint failure on prepainted steel, because the coating over the zinc is the first line and the zinc underneath is only the reserve
- Moisture trapped between the back of the trough and the fascia, which rusts the gutter from the side nobody sees
Signs of wear to look for
- Rust blooming first at cut ends, miters, screw heads and any scratch through the coating
- Orange staining running down siding or masonry below the gutter line
- The trough bottom turning brown where wet debris has been sitting through the season
- Pinholes and rust-through in the trough bottom, usually at the low end of a run
- Blistered or flaking paint on prepainted steel with rust showing at the edges of the blisters
- Sagging, which on a section this stiff and heavy usually means the fastening rather than the steel
Other gutters materials
- Aluminum gutters 20+ yrs
- Vinyl gutters 25+ yrs
- Copper gutters 50+ yrs