G.I. wire — short for galvanized iron wire — is a fundamental material on every Philippine construction site. It serves as the primary tie wire for binding rebar, fastening scaffolding, and dozens of other tasks. This guide covers the different gauges available, their uses, and how to choose the right one.
What is G.I. Wire?
G.I. wire is low-carbon steel wire that has been coated with a layer of zinc through a galvanizing process. The zinc coating protects the underlying steel from rust and corrosion, giving G.I. wire a longer service life than uncoated black iron wire — especially in outdoor and humid environments.
It is sold in large coils, typically 35 kg per roll, and is available in a range of gauges from the heavy #6 to the fine #16.
Available Gauges and Approximate Diameters
| Gauge | Approx. Diameter | Common Use |
|---|---|---|
| #6 | ~5.0mm | Heavy structural binding, utility poles |
| #8 | ~4.1mm | Heavy tie wire, agricultural fencing stays |
| #10 | ~3.4mm | General construction binding, bundling |
| #12 | ~2.8mm | Rebar tying, general construction |
| #14 | ~2.0mm | Light rebar tying, garden wire |
| #16 | ~1.6mm | Fine binding, plant ties, crafts |
All gauges are sold in 35 kg rolls at Una Wire Products.
G.I. Wire vs. Black Iron Wire
Both G.I. wire and black iron (B.I.) wire are used for tying and binding on construction sites, but they have key differences:
| G.I. Wire | Black Iron (B.I.) Wire | |
|---|---|---|
| Coating | Zinc (galvanized) | None (dark oxide) |
| Rust resistance | Good | Poor |
| Flexibility | Moderate | Very flexible (annealed) |
| Cost | Higher | Lower |
| Best for | Outdoor use, long-term exposure | Rebar tying inside concrete |
For rebar tying that will be encased in concrete, B.I. wire is the standard choice because its flexibility makes it easier to twist and its lower cost makes it economical for high-volume use. G.I. wire is preferred when the wire will remain exposed — agricultural fencing, outdoor bundling, and coastal environments.
Common Construction Uses of G.I. Wire
Rebar Tying
The most common use on construction sites. G.I. wire in #12 or #14 gauge is used to tie rebar at intersections, holding the steel grid in position before a concrete pour. Workers typically use a wire-twisting tool (wire twister or pliers) to quickly loop and twist the wire.
Scaffolding Lashing
Heavier gauges (#8, #10) are used to lash bamboo or steel scaffolding members together. The galvanized coating makes it appropriate for outdoor scaffolding exposed to rain.
Agricultural and Farm Fencing
G.I. wire is used as horizontal strands in agricultural fencing, stretched between posts to create simple field boundaries or support for mesh or barbed wire.
Need G.I. wire for your project?
Una Wire Products carries G.I. wire from #6 to #16 gauge in 35 kg rolls. Contact us for pricing.
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