Galvanized Steel Gutters (Galvanised Guttering): Pros, Cons and Upkeep
Updated · By the Roof to Footing editors
Galvanized steel gutters (galvanised steel guttering in British spelling) are steel gutters dipped in or coated with zinc. The zinc sacrifices itself to protect the steel, so the gutter stays rust-free until the zinc wears away. They're stiffer and stronger than aluminum gutters, handle snow and ladders well, and cost less than copper. The trade-off is weight and rust: once the zinc is gone, usually after 15 to 20 years in a wet climate, the steel starts to rust from the inside out.
Where they make sense
- Heavy snow and ice, where thin aluminum gutters sag or pull off.
- Outbuildings, barns and garages where looks matter less than toughness.
- Historic restorations that call for painted steel half round.
- Under a steel roof, painted to match.
Galvanized vs. aluminum vs. Galvalume
| Galvanized steel | Aluminum | Galvalume steel | |
|---|---|---|---|
| Strength | High | Low to medium | High |
| Rust resistance | Good until zinc wears off | Doesn't rust | Better than galvanized in most climates |
| Weight | Heavy; more hangers needed | Light | Heavy |
| DIY friendly | Harder to cut and handle | Easy | Harder |
| Paint | Needs a primer made for galvanized metal | Factory painted | Bare or factory painted |
If you like steel's strength but want longer rust resistance, look at Galvalume gutters, which use an aluminum-zinc coating.
Gauge and coating
Steel gutters are usually 26 or 28 gauge (lower number means thicker). Ask what coating weight the steel has; a heavier zinc coating, like G90, lasts longer than a light one. Pre-painted galvanized steel comes with a primer and finish coat applied at the mill and holds up better than painting it yourself.
Keeping them from rusting
- Keep them clean. Wet leaves and grit sitting in the trough hold moisture against the zinc. Clean twice a year.
- Watch the seams and inside bottom. Rust starts where water sits. A few rust spots can be wire-brushed, primed with a zinc-rich or galvanized-metal primer and painted.
- Don't mix metals. Copper downspouts, copper flashing above, or aluminum fasteners in contact with steel speed up corrosion. Use galvanized or stainless fasteners.
- Paint new galvanized correctly. Fresh zinc has an oily surface. Paint won't stick unless you clean it first and use a primer made for galvanized metal. Many painters let new galvanized weather for six months first.
Downsides worth knowing
- Weight. Plan for hangers every 24 inches or closer, screwed into rafter tails.
- Cut edges. Every cut exposes bare steel. Installers should seal cut ends and seams.
- Fewer seamless options. Steel is harder to roll-form on site than aluminum, so steel gutter often comes in sections with more joints.
If you're replacing old galvanized gutters that rusted through, ask whether the problem was the metal or poor slope that let water sit. Fixing the slope matters whichever metal goes up next.