Rebar detailing is the work of turning a structural engineer's concrete drawings into placing drawings and bar lists that define every reinforcing bar on a job: its mark, size, length, bent shape, quantity and exact location. The engineer decides how much reinforcement a footing, wall, slab or beam needs. The detailer works out the individual bars that deliver it, so the shop can cut and bend them and the crew can place them without guessing.
This is an introduction for contractors, builders and anyone new to the trade. If you are hiring a detailer, our guide to rebar detailing services covers deliverables and how to choose one.
Two meanings of "detailing"
You will see the word used in two related ways, which causes some confusion:
- Detailing as a design requirement. In concrete design, "detailing" means the rules the engineer follows for how bars are arranged: development lengths, hooks, splices, spacing and cover. In Canada those rules sit mainly in CSA A23.3 (including its clauses on details of reinforcement and on development and splices) and CSA A23.1. When an engineering textbook talks about "rebar detailing in civil engineering", it usually means this.
- Detailing as a trade service. The Reinforcing Steel Institute of Canada (RSIC) defines the detailer as the person or company who prepares the placing drawings and the list of materials from the plans and specifications. When a contractor says "send it to the detailer", this is what they mean, and it is the subject of the rest of this post.
The two meet in the middle. The engineer's structural drawings show the design and the typical details. The detailer applies them bar by bar, using the engineer's notes first and the standard practice defaults only where the drawings are silent.
What a rebar detailer actually decides
A structural drawing might say "15M @ 300 EW BOT" on a footing. That is a design requirement, not a set of bars. To turn it into something the shop can make, the detailer works out:
- Bar lengths. Element dimensions less the concrete cover at each end, plus hooks or bends where the drawings call for them, rounded to the precision the shop works to.
- Quantities. How many bars it takes to meet the specified spacing across the width, without exceeding it.
- Splices. Where a bar is longer than can be supplied or handled, where it laps or couples, following the engineer's lap lengths and splice locations.
- Shapes. Which bars are straight and which are bent, and the bend type and leg dimensions for each.
- Marks. A unique mark for each different bar, so every bundle can be tagged and every bar placed in the right spot.
- Fit. Whether bars fit where they cross, at corners, around openings and in congested beam-column joints, and whether cover and spacing still work.
- Releases. How the job is broken into drawings and shipments that follow the pour sequence.
What the detailer must not do is invent reinforcement. RSIC standard practice is explicit that where details are missing or parts of the structure are not designed, the detailer is not to assume reinforcing. The gap is flagged as a question to the engineer, usually through a request for information.
A worked example: detailing a simple footing
Here is how a detailer might handle one strip of footing, to show the kind of thinking involved. Assume the structural drawing shows:
- Footing 6,000 mm long by 1,500 mm wide
- Bottom reinforcement 15M @ 300 mm each way
- Concrete cast against earth, so 75 mm cover (from CSA A23.1)
Long bars (running the 6,000 mm length). Length is 6,000 less 75 mm cover at each end, which is 5,850 mm. RSIC practice gives bar lengths to the nearest 20 mm, and rounding down keeps the cover intact, so the bar is detailed at 5,840 mm. Across the 1,500 mm width, the bars sit within 1,350 mm (1,500 less two covers). At 300 mm maximum spacing that takes 5 spaces, so 6 bars at an actual spacing of 270 mm.
Short bars (running the 1,500 mm width). Length is 1,500 less two covers, 1,350 mm, rounded down to 1,340 mm. Along the 5,850 mm length they need 20 spaces to stay at or under 300 mm, so 21 bars.
The bar list for this footing would read something like this:
| Mark | Quantity | Size | Length | Shape | Weight (kg) |
|---|---|---|---|---|---|
| F1 | 6 | 15M | 5,840 mm | Straight | 55.0 |
| F2 | 21 | 15M | 1,340 mm | Straight | 44.2 |
Weights use the nominal 1.570 kg/m for 15M bar from CSA G30.18, giving about 99 kg for the footing.
A real footing adds more: dowels into the wall above, corner and intersection bars where footings meet, steps in elevation, and any hooks the engineer shows. Each becomes another mark. Detailers also differ in small conventions, such as how they set the first and last bar, so treat this as an illustration of the method rather than a rule. For a full example including laps and corners, see footing rebar laps and corner bars.
The standards behind the decisions
Canadian detailers work from a short stack of documents:
| Document | What it gives the detailer |
|---|---|
| Structural drawings and specification | The design: sizes, spacing, cover, laps, grades, special requirements |
| CSA A23.1 | Cover, bend diameters, placing tolerances and construction requirements |
| CSA A23.3 | Design rules for development, hooks, splices and spacing |
| CSA G30.18 | Bar sizes, grades and nominal dimensions and masses |
| RSIC Manual of Standard Practice | Drawing conventions, bend types, fabrication tolerances and defaults when drawings are silent |
Our post on Canadian rebar detailing standards explains each one and lists the RSIC defaults, such as footing bars extending to within 75 mm of each face unless the drawings say otherwise.
What the detailer produces
The output is two linked documents:
- Placing drawings, which show each element with its bars called out by quantity, size, mark and spacing, plus the dimensions the crew needs to place them.
- Bar lists, which give every mark's quantity, size, grade, length and bend dimensions, and drive the shop's cutting and bending.
RSIC practice is that placing drawings are for placing reinforcing steel only, not for coordinating other trades, and that the fabricator or detailer does not stamp them. The engineer reviews them and approves, approves with corrections, or rejects them. If you have a set in front of you, our step-by-step guide on how to read rebar shop drawings explains the callouts and bar list columns.
Who does rebar detailing
Most rebar detailing in Ontario is done by or for the rebar fabricator supplying the job, either by in-house detailers or by an independent detailing firm working for the fabricator. Detailers work in specialized software, but the judgment is the same as on paper: reading the structural set carefully, spotting conflicts and asking the right questions.
The trade is largely learned on the job. RSIC runs a detailer certification program to standardize the practice, with a minimum two-year apprenticeship before a candidate's placing drawings go to an RSIC committee for review.
Where detailing goes wrong, and how to help
Most detailing problems start with the information going in:
- Old or partial drawings. Detailing from a superseded structural revision produces perfect drawings of the wrong thing.
- Missing architectural dimensions. Slab edges, steps, openings and wall heights are often only on the architectural set.
- Unanswered questions. A drawing on hold waiting for an answer is a delivery that can't ship.
- Site changes. A footing poured lower than drawn, or a sleeve moved, changes the bars.
Give your detailer the full current set, answer questions quickly, and tell them about site conditions. Our post on rebar placement drawings covers the contractor's side of that process.
Detailing and fabrication under one roof
We provide reinforcing steel estimates and detailing for reinforced concrete structures, prepare bar lists and placing drawings from your structural drawings, then cut, bend, tag and bundle the bar in our shop, in sizes from 10M to 55M. Take-offs and quotes are free.
Send us your drawings for a take-off and quote, or see our rebar products and detailing.
Frequently asked questions
What is rebar detailing?
Rebar detailing is turning a structural engineer's concrete design into placing drawings and bar lists: every bar is given a mark, size, length, shape, quantity and location so it can be cut and bent in the shop and placed correctly on site.
Is rebar detailing the same as structural design?
No. The engineer designs the reinforcement and decides how much steel goes where. The detailer interprets that design into individual bars. Under Canadian standard practice, detailing never replaces the engineer, and the engineer reviews the detailer's drawings.
What is the difference between rebar detailing and estimating?
An estimate (take-off) adds up the weight of each bar size to price the job. Detailing defines every individual bar and where it goes, producing the documents the shop fabricates from and the crew places from.
How do you become a rebar detailer in Canada?
Most detailers learn on the job at a rebar fabricator or detailing firm. The Reinforcing Steel Institute of Canada runs a detailer certification program that requires at least a two-year apprenticeship and a review of the candidate's placing drawings.
