A reinforcement (rebar) detailing package turns the engineer's concrete design into drawings that show exactly where every bar goes, plus a bar bending schedule (BBS) that tells the fabricator how many bars of each mark to cut and bend, to what shape and dimensions. The engineer decides how much reinforcement is needed. The detailer shows it buildably, in the format the project's scheduling standard requires.
How do placing drawings differ from structural drawings?
The American Concrete Institute's detailing standard (ACI 315, part of the ACI Detailing Manual SP-66) separates the responsibilities of the engineer from those of the detailer. The engineer's structural drawings define the design requirements: concrete dimensions, bar sizes and spacing, cover, laps and special details. Placing drawings, in ACI's words, "are working drawings that show the number, size, length, and location of the reinforcing steel necessary for the placement and fabrication of the material". UK and Eurocode projects follow the same principle through the design drawings, the specification and BS 8666 scheduling.
| Engineer's structural drawings | Detailer's placing drawings and BBS | |
|---|---|---|
| Purpose | Define the design | Enable cutting, bending and fixing |
| Shows | Required reinforcement, cover, laps, details | Every bar mark, location, quantity, shape |
| Responsibility | Structural adequacy | Accurate representation of the design |
What does a bar bending schedule contain?
A bar bending schedule typically lists, for each bar mark:
| Column | Meaning |
|---|---|
| Member / location | Which element the bar belongs to |
| Bar mark | Unique identifier, matching the drawing |
| Type and size | Bar grade and nominal diameter |
| Number of members × bars per member | Total quantity |
| Length | Total cut length |
| Shape code | Standard shape reference |
| Bending dimensions (A, B, C, D, E/R) | Dimensions needed to bend the shape |
| Revision | Revision letter for changed bars |
Weight summaries by bar diameter are usually added for ordering and progress measurement. They also feed the project's material quantities.
Scheduling standards by region
- UK and many Eurocode-based projects: BS 8666:2020 specifies the scheduling, dimensioning, bending and cutting of steel reinforcement for concrete. It defines two-digit shape codes (for example 00 for a straight bar). Shapes that cannot be represented by a standard code are scheduled as shape code 99 with a dimensioned sketch, and BS 8666 states that no other shape code number or abbreviation shall be used in scheduling. It also tabulates minimum scheduling radii and end projections.
- US-based specifications: the ACI Detailing Manual (SP-66) and CRSI practice govern detailing and bar bending conventions.
- GCC projects: these frequently specify either British or American practice, or a client standard. Saudi and UAE owner specifications vary by client. Confirm which convention applies before scheduling starts, because shape codes and dimensioning methods differ.
None of these standards sets your reinforcement quantity. That comes from the design.
Industrial foundation specifics
Energy and process plant foundations add complexity beyond building slabs:
- Equipment foundations and pedestals with anchor bolt groups, sleeves and embedded plates that reinforcement must clear.
- Pipe rack foundations repeated many times with small variations. Bar marks must distinguish variants clearly.
- Large mats and compressor foundations with multiple layers, chairs and construction joints.
- Interfaces with vendor data that may arrive late and change anchor layouts.
Good rebar detailing on these structures relies on coordinated anchor and embed information as much as on scheduling skill.
Inputs checklist
- Approved concrete design drawings and reinforcement details
- Reinforcing instructions: laps, anchorages, cover and any couplers
- Vendor equipment anchor layouts and embed details
- Material grades and bar sizes available locally
- Scheduling standard (BS 8666, ACI, client standard) and the BBS template
- Pour breaks and construction joint locations
- Drawing standard and revision procedure
Frequently asked questions
Does the detailer decide lap lengths?
No. Laps and anchorages are design requirements set by the engineer or by the project's design standard. The detailer applies them as instructed.
Can a BBS be produced from a 3D model?
Yes. Tools such as Tekla Structures can model reinforcement and generate schedules, provided the output is configured to the required scheduling standard.
What is shape code 99?
In BS 8666, shape code 99 covers shapes that cannot be described by a standard code. They are scheduled with a fully dimensioned sketch.
Who sets the concrete cover shown on placing drawings?
The designer, through the governing code and the project specification. For example, ACI 318 requires at least 3 in (75 mm) of cover for concrete cast against and permanently in contact with the ground. The detailer shows the specified cover and positions bars to it, and raises a query where cover, bar size and spacing cannot all be achieved.
Next step
For equipment foundations, pedestals and industrial RCC packages, see reinforced concrete and rebar detailing and civil and structural drafting, or request a quote.
References
Technical sources consulted. Standards are paid documents; confirm clauses against the licensed edition named in your project specification.
- Details and Detailing of Concrete Reinforcement (ACI 315) · ACI (copy hosted by Regbar) (opens in a new tab)
- BS 8666:2020 shape codes · KB Rebar (summary of BSI standard) (opens in a new tab)
- BS8666 Shape Codes · Collins Reinforcements (opens in a new tab)
