The standard rebar tie wire is 16 gauge black annealed wire. The Reinforcing Steel Institute of Canada's Manual of Standard Practice uses it as the default unless the engineer specifies otherwise. When the bar itself is corrosion protected, the ties have to match: coated or non-metallic ties for epoxy-coated bar, zinc-coated or dielectric ties for galvanized bar, stainless wire for stainless bar, and non-corrosive ties for GFRP.
The standard: 16 gauge black annealed wire
Tie wire does one job: it holds bars in position while concrete is placed and vibrated. It is not counted as structural reinforcement, so it does not need to be strong, only soft enough to twist tight by hand or tool and stiff enough not to let bars shift.
That is why the industry settled on black annealed wire:
- Annealed means the wire has been heat treated to make it soft and pliable. It wraps around bars and twists tight without springing back or snapping.
- Black means it is uncoated, with the dark oxide finish left from annealing. It is the cheapest and most widely stocked option.
- 16 gauge is the default size. Wire gauge numbers run backwards, so a higher number is a thinner wire and a lower number is a heavier one.
Heavier or lighter gauges are sold, and some crews prefer them for particular jobs, but on specified work the gauge should match the specification. If the spec is silent, 16 gauge black annealed is the normal assumption in Canadian practice.
Matching tie wire to the bar type
Coated and corrosion-resistant bar changes what the ties are made of. The rules below follow the RSIC Manual of Standard Practice (2020):
| Bar type | Tie wire | Why |
|---|---|---|
| Black (uncoated) steel | 16 gauge black annealed, unless specified otherwise | Industry default |
| Epoxy-coated steel | Non-metallic ties or wire with a protective coating (plastic or epoxy coated) | Bare wire can damage the coating and create a corrosion point |
| Galvanized steel | Zinc-coated wire or dielectric (non-conductive) material | Avoids contact between zinc and dissimilar metal |
| Stainless steel | Stainless steel wire | Keeps carbon steel off the stainless bar |
| GFRP | Non-corrosive ties, such as plastic-coated wire or nylon ties | A corrosion-free system should not contain bare steel |
The same logic applies to chairs and bar supports. Epoxy-coated, galvanized and stainless bar should sit on non-corrosive or compatible supports; our guide to buying rebar chairs covers the support types.
A few details that come up on site:
- Stainless tied to black bar. RSIC practice accepts tying stainless reinforcing to regular reinforcing where the design mixes them, but the ties on the stainless bar itself are stainless.
- Epoxy-coated ties are a product, not a field treatment. Painting black wire after tying does not give the same protection as wire that arrives coated.
- GFRP and coated bar are softer to work around. Tying tools and pliers can nick coatings, so crews take more care with twist tension. Our post on installing and tying fiberglass rebar covers GFRP specifically.
Is tie wire galvanized, and does it rust?
Standard tie wire is not galvanized. It is plain black steel wire, and left in the rain it rusts like any other black steel.
Inside concrete, that does not matter much. Rebar and tie wire are both protected by the alkaline concrete around them and by the cover between the steel and the surface. A tie that is fully buried behaves like the bar it holds.
The problems come from wire that is not properly buried:
- Tails pointing at the form face. The twisted ends of a tie can stick out toward the formwork, eating into the cover. On exposed walls and slab soffits they can show up later as small rust spots. Bend tails inward, away from the face.
- Ties in thin cover zones. Where cover is already tight, such as slabs on chairs, a tie sitting on top of a bar adds to the steel thickness. Keep ties neat and tails flat.
- Wire left on the deck. Loose clippings on a slab or form surface can rust onto the finished concrete.
That is why some crews choose galvanized or coated wire for architectural concrete where any stain would be visible, even with black bar. It is a finish choice, not a code requirement, unless the specification says so. Cover itself is set by CSA A23.1; see our concrete cover guide for the values.
Types of ties and tying methods
How the wire goes around the bars matters as much as the wire itself. The common tie types are:
- Single (snap) tie. One diagonal wrap and twist. The fastest tie and the normal one for slabs and mats where the bars just need to stay put.
- Wrap and single tie. An extra wrap around one bar before the twist. Used on walls so horizontal bars do not slide down the verticals during the pour.
- Saddle tie. The wire goes under one bar and around the other. Used in footings and mats to hold bent bar ends in position.
- Wrap and saddle tie. A heavier version for cages and mats that will be lifted by crane, where the ties take real strain.
- Figure-eight tie. Sometimes used in walls in place of the wrap and single tie.
The wire comes in a few forms:
- Reel or coil wire cut and twisted with tying pliers. Cheapest per tie and the most flexible.
- Pre-cut loop ties with a loop at each end, twisted with a hand twister. Faster for repetitive work and very consistent.
- Spools for battery tying tools. Tying tools use wire made for that tool, in the gauge and coating the maker specifies. Check that the tool's wire meets the job specification, especially on coated or stainless bar.
How much tie wire does a job need?
There is no fixed ratio of wire to rebar, but you can estimate it from the layout.
Step 1: Count intersections. For a grid, multiply the number of bars in one direction by the number in the other. A 6 m by 9 m slab with 15M at 400 mm each way has 16 bars one way and 24 the other (length ÷ spacing, plus one, rounded up), so 16 × 24 = 384 intersections.
Step 2: Apply the tying frequency. RSIC practice is that it is not necessary to tie every intersection, and a tie at every fourth or fifth intersection is sufficient to hold bars in place. Additional tying must be called for by the engineer. At every fourth intersection, the slab above needs about 96 grid ties.
Step 3: Add the ties that always get made. Laps, corners, dowels, bar ends and bars tied down to chairs add to the grid count. On walls, columns and cages, almost every intersection near laps and corners gets tied. Our guide to laying and tying footing rebar shows where these extra ties go.
Step 4: Convert ties to wire. The length of wire per tie depends on bar size and tie type, so measure your own: cut wire for ten typical ties, measure the total and divide. Multiply by the tie count, divide by the length on the coil label, and add an allowance for waste and offcuts.
This is also how to think about tie wire cost. What you pay depends on the wire type (black, galvanized, coated or stainless), the form (reel, loop ties or tool spools), the quantity and how many ties the job's layout and spec demand. Coated, galvanized and stainless wire cost more than black wire, and a job that requires tying every intersection uses far more of it.
Keep tying tight enough that bars stay within placing tolerances during the pour. Our post on rebar placement tolerances covers what is allowed.
Ordering rebar and accessories together
Tie wire is a small line on any concrete job, but the wrong type on coated or stainless bar can undo the point of paying for corrosion protection. Put the wire type on your order alongside the chairs and bar supports.
We detail, cut, bend and tag rebar from 10M to 55M, supply GFRP bar and deliver across the GTA and Ontario. We don't supply tie wire or accessories, so source those from a building supply yard. Send us your drawings for a quote or see our rebar products.
Frequently asked questions
What size tie wire is used for rebar?
16 gauge black annealed wire is the industry standard in Canada unless the engineer specifies something else. The Reinforcing Steel Institute of Canada's Manual of Standard Practice uses it as the default.
Is rebar tie wire galvanized?
Standard tie wire is not. It is black annealed steel. Galvanized or other zinc-coated wire is used with galvanized rebar, and some crews use it where wire ends could show on an exposed concrete face.
Does rebar tie wire rust?
Black annealed wire rusts if it sits in the weather, the same as black rebar. Once it is cast inside concrete with proper cover it is protected the same way the bar is. Rust stains usually come from wire tails left pointing toward the form face.
What tie wire do you use for epoxy-coated rebar?
Coated or non-metallic ties. Industry practice is that all tie wire, chairs and bar supports used with epoxy-coated bar are non-metallic or have a suitable protective coating, so nothing bare touches the coated bar.
How many rebar ties do I need?
Count the bar intersections and apply the tying frequency on your job. Industry practice treats a tie at every fourth or fifth intersection as normal, with laps, corners and dowels always tied, unless the engineer asks for more.
