---
title: "Good detailing and bar bending schedule"
subject: "Design of RCC Structure"
chapter: 7
key: "semester_7/design_of_rcc_structure:good-detailing-and-bar-bending-schedule"
source: https://www.bctengineer.com/q/semester_7/design_of_rcc_structure/good-detailing-and-bar-bending-schedule
site: BCT Engineering
---

# Good detailing and bar bending schedule

Design of RCC Structure · Chapter 7: Reinforcement detailing: Codal Provisions

- Asked in: 2079 Bhadra, 3+3 marks
- Video: [Bar Bending Schedule Basics | BBS OF STEEL REINFORCEMENT | Quantity surveying | Civil tutor](https://www.youtube.com/watch?v=nGoTdkCxsuk) — Civil Tutor
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/design_of_rcc_structure/good-detailing-and-bar-bending-schedule
- Whole chapter: https://www.bctengineer.com/md/semester_7/design_of_rcc_structure/chapter-7

## Question

Discuss about requirements for good detailing. Also describe bar bending schedule.

## Short answer

Good detailing follows codes (IS 456, SP 34, IS 13920), provides proper anchorage, uses simple standard shapes, avoids congestion, ensures specified cover, places steel correctly, gives clear drawings with bar marks, and allows construction sequence. Bar bending schedule (BBS) lists each bar's mark, diameter, shape, number, length, total length, and weight for ordering, cutting, bending, and cost estimation.

## Answer

#### Requirements for good detailing
Reinforcement detailing means the exact arrangement of bars shown on the drawings. Good detailing should:
1. **Follow the code** (IS 456, SP 34, and IS 13920 in seismic regions) for cover, spacing, anchorage, laps and curtailment.
2. **Provide proper anchorage and development length** for every bar, with hooks or bends where space is limited.
3. **Keep reinforcement simple**: use few bar diameters, standard shapes and regular spacing, so that it is easy to fabricate and place.
4. **Avoid congestion**, especially at beam-column joints, so that concrete can flow and be compacted; keep the minimum clear spacing between bars.
5. **Give the specified cover** (with spacers or cover blocks) for durability and fire resistance.
6. **Place bars where the stresses are**: tension steel on the tension face, curtailed at the correct points, with stirrups closely spaced near the supports.
7. **Provide clear drawings**: plan, elevation and sections with bar marks, diameters, spacing, lap positions and notes.
8. **Allow for construction**: bars must be capable of being placed in the sequence of erection, and lap positions and construction joints must be shown.

#### Bar bending schedule (BBS)
A **bar bending schedule** is a table prepared from the structural drawings that lists every bar of a member with its mark, diameter, shape, number, length of each bar, total length and weight. It is used for ordering, cutting, bending, fixing and checking the steel, and for estimating the quantity (and cost).

Steps:
1. Give each different bar a number (bar mark) on the drawing.
2. Find the cutting length of each bar = straight length + hook allowances - bend deductions. In usual site practice, a 45° bend deducts $1\phi$, a 90° bend $2\phi$ and a 135° bend $3\phi$, and a standard semicircular hook adds about $9\phi$ (IS 2502 practice).
3. Total length = number × length of each bar; weight = total length × unit weight, where unit weight $= \dfrac{\phi^2}{162}$ kg/m ($\phi$ in mm).

```text
Bar | Dia | Shape    | No. | Length | Total | Weight
mark| mm  |          |     | (m)    | L (m) | (kg)
----+-----+----------+-----+--------+-------+-------
 A  | 16  | straight |  3  | 4.20   | 12.60 | 19.9
 B  | 12  | cranked  |  2  | 4.40   |  8.80 |  7.8
 C  |  8  | stirrup  | 20  | 1.10   | 22.00 |  8.7
```

The schedule is checked against the drawings before the steel is cut.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which is a requirement of good detailing?
   A. Closely packed bars at joints
   B. Few bar sizes, standard shapes, regular spacing and avoidance of congestion
   C. Cover omitted for easy fixing
   D. Many different bar diameters
   Answer: B. Simple detailing eases fabrication and concrete placement. (Key point: Good detailing)

2. Why is the specified cover given?
   A. For durability and fire resistance
   B. To increase bar diameter
   C. To lower the weight
   D. To reduce stirrups
   Answer: A. Spacers/cover blocks keep specified cover. (Key point: Cover)

3. What is a bar bending schedule?
   A. A test report of steel
   B. A drawing of the formwork
   C. Table listing each bar's mark, diameter, shape, number, length and weight
   D. A list of concrete mixes
   Answer: C. It is used for ordering, cutting, bending and estimating steel. (Key point: BBS)

4. Unit weight of a bar of diameter φ mm in a BBS is
   A. φ / 162 kg/m
   B. 162 / φ² kg/m
   C. φ² / 16 kg/m
   D. φ² / 162 kg/m
   Answer: D. Weight = total length × φ²/162. (Key point: Weight)

## Related in Design of RCC Structure

- [Ductile detailing of beams and columns](https://www.bctengineer.com/question.md?key=semester_7%2Fdesign_of_rcc_structure%3Aductile-detailing-of-beams-and-columns) — Design of RCC Structure, chapter 12, asked 2×
- [Ductility requirements of RC beam with sketch](https://www.bctengineer.com/question.md?key=semester_7%2Fdesign_of_rcc_structure%3Aductility-requirements-of-rc-beam-with) — Design of RCC Structure, chapter 12, asked 4×
- [Ductile design per IS 13920, beam and column](https://www.bctengineer.com/question.md?key=semester_7%2Fdesign_of_rcc_structure%3Aductile-design-per-is-13920-beam) — Design of RCC Structure, chapter 12

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