Custom rebar stirrups are bent in the shop to the exact size, shape and hook your drawings call for, then tagged and bundled by mark so they drop straight into the beam or column. To order them, give the fabricator the bar size, shape, out-to-out dimensions, hook type, grade and quantity for each mark, or simply send the structural drawings and let the detailer work them out. Procut fabricates stirrups, ties, dowels and custom bent shapes to your bar lists.
Stirrups, ties and why they are bent to order
People use the words interchangeably, but they do different jobs:
- Stirrups wrap the main bars in beams and grade beams. They resist shear and hold the top and bottom bars at the right height.
- Ties wrap the vertical bars in columns and piers. They confine the concrete core and stop the vertical bars from buckling outward under load.
- Spirals do the job of ties in round columns, as one continuous coil.
All three must fit inside the concrete with the right cover all round, and around bars of known size. That is why they are almost always made to order. A stirrup that is 20 mm too big pushes the main bars into the cover zone; one that is 20 mm too small will not fit around them.
Common stirrup and tie shapes
The Reinforcing Steel Institute of Canada (RSIC) Manual of Standard Practice gives the standard shapes their own type codes: S-types for stirrups and T-types for ties. In plain terms, the shapes you will see most are:
| Shape | Where it is used |
|---|---|
| Open U stirrup | Beams where the top is closed by slab steel or a cap bar |
| Closed stirrup with 135° hooks | Beams that need closed stirrups, such as edge and spandrel beams |
| Two-piece closed stirrup (U plus cap tie) | Beams where the main bars have to be threaded in after the stirrups are set |
| Rectangular or square tie | Columns, piers and pilasters |
| Crosstie (straight bar with hooks) | Extra legs across wide beams or columns |
| Spiral | Round columns and piers |
RSIC notes that stirrups in edge and spandrel beams must be closed, with a longitudinal bar in each corner. It also explains why two-piece closed stirrups are often better than one-piece ones: where the main beam bars must be fed through tight column steel, crews end up "springing" one-piece closed stirrups open to get the bars in, which can crack or weaken the bar. A U stirrup with a separate cap avoids that. If your beam is congested, ask your engineer whether a two-piece detail is acceptable before ordering.
Sizing: out-to-out dimensions
Stirrups and ties are dimensioned out-to-out: from the outside of one leg to the outside of the other. To size them, start with the concrete dimension and take off the cover on each side.
When the drawings do not give a stirrup size, RSIC standard practice details it 80 mm smaller than the beam in both width and depth, and column ties 80 mm smaller than the column. For a 300 by 500 mm beam that gives a 220 by 420 mm stirrup. That default only works if the cover on your job matches it. If your cover is different, or the beam has bars in more than one layer, give the fabricator the actual dimension.
Fabricating tolerance for stirrups and ties under RSIC practice is plus or minus 13 mm, tighter than the tolerance on long bars because they have to fit inside the formwork.
Hooks: 90°, 135° and seismic
The hooks on the ends of a stirrup or tie anchor it into the concrete core. The three you will see are a 90° hook, a standard 135° hook, and a 135° seismic hook with a longer extension, used where the engineer has designed for seismic ductility. The RSIC stirrup and tie hook table gives these detailing dimensions:
| Bar size | Finished bend diameter | 90° hook | 135° standard hook | 135° seismic hook |
|---|---|---|---|---|
| 10M | 45 mm | 100 mm | 100 mm | 140 mm |
| 15M | 65 mm | 140 mm | 140 mm | 150 mm |
Hook dimensions are the detailing allowance added at each end. For 20M and larger stirrups and ties, RSIC uses the same dimensions as a standard 180° hook. The hook type is a design decision: if the drawings do not say, ask rather than assume, because seismic hooks cannot be added after the stirrups are bent.
What to put on your stirrup order
If you are ordering stirrups from your own schedule rather than having us detail the job, each line should give:
- Mark, so the bundle tag matches the drawing
- Bar size and grade, usually 10M or 15M in 400W unless noted
- Shape: open, closed, two-piece, tie or crosstie
- Out-to-out dimensions: width and height
- Hook type and direction: 90°, 135° or 135° seismic, and where the hooks sit
- Quantity: worked out from the member length and spacing
- Location: which beam, grid line or footing, so bundles reach the right spot
- Coating, if epoxy-coated or galvanized bar is specified
A simple line might read: "Mark S1, 10M 400W, closed stirrup with 135° hooks, 220 × 420 out-to-out, quantity 31, grade beam GB-2". If you are not sure how many you need, our rebar estimating guide shows how to count stirrups along a beam.
Premade, standard or custom stirrups
Some suppliers stock "standard" premade stirrups and ties in common sizes. They can be handy for a small repair or a single pier. For anything built from drawings, custom stirrups are the safer route:
- Premade sizes rarely match both your member size and your cover.
- Using a stirrup that is close enough usually means the main bars sit in the wrong place.
- A fabricator bends exactly the quantity you need of each size, tagged by mark.
On price, there is no single figure for a stirrup. Under RSIC estimating practice, all stirrups and ties count as light bending, which is listed separately from the bar itself. The cost of an order reflects the total weight of bar, how many different marks it contains, quantities per mark, hook types, any coating and the delivery. Many small marks cost more to make than a few large ones of the same total weight. Our article on rebar price in Canada explains what drives quotes.
On site: handling and placing
- Keep bundles tagged until the stirrups are placed. Stirrups for two beam sizes look almost identical in a pile.
- Check one from each bundle against the drawing before you start: width, height and hook type.
- Tie them firmly to the main bars at the spacing shown, so they do not slide during the pour.
- Do not reshape them on site. Re-bending a stirrup to make it fit can damage the bar. If they do not fit, stop and find out why.
Stirrups and ties are also the backbone of any rebar cage. If you are building footing or pier cages, see our guide to prefabricated rebar cages for footings and piers. For the full ordering process, from bar list to delivery, see how to order cut and bend rebar.
Order custom stirrups
Send us your structural drawings or your stirrup schedule. We prepare bar lists, bend stirrups, ties and dowels to suit, and tag and bundle every mark. Ask us about lead times and delivery for your job.
Request a stirrup quote or see our rebar products for fabricated rebar, straight bar and GFRP.
Frequently asked questions
What is a stirrup in rebar?
A stirrup is a bar bent into an open or closed loop that wraps around the main bars in a beam. Stirrups resist shear and hold the main bars in position while the concrete is placed.
What is the difference between stirrups and ties?
Stirrups are used in beams and mainly resist shear. Ties are used in columns and piers, where they confine the vertical bars and stop them from buckling. They are bent the same way and often from the same bar sizes, so people use the terms loosely.
Where can I buy rebar stirrups?
From a rebar fabricator, who will bend them to the sizes on your drawings, or as stock premade sizes from some supply yards. Premade sizes only work if they happen to match your member size and cover.
What size rebar is used for stirrups?
10M is the most common stirrup and tie size on residential and light commercial work, with 15M and larger used where the design calls for it. The size and spacing must come from the structural drawings.
What drives the price of fabricated stirrups?
The total weight of bar, how many different sizes (marks) are on the order, the quantity of each, the shape and hook type, any coating, and delivery. Send your schedule for an exact quote.
