UK Bar Bending Shape Codes Overview
BS8666 is the British Standard rebar shape code list required to be adhered to when using steel to reinforce concrete in construction in the United Kingdom and Northern Ireland. The latest update, BS8666:2020 (from BS8666:2005) updates the standard more closely inline with BS EN 1992-1-1 Eurocode 2 (which you can download for free here).
As BSI puts it:
This revised British Standard specifies requirements for the scheduling, dimensioning, cutting and bending of steel for the reinforcement of concrete conforming to BS 4449, BS 4483 and BS 6744; and designed to BS EN 1992-1-1, BS EN 1992-2, BS EN 1992-3 and BS 8110.
List of Rebar Shape Codes
Minimum Scheduling Radii
| d Nominal Bar Diameter (mm) | r Minimum Radius (mm) | M Minimum Diameter of Bending Former (mm) | Minimum End Projection | |
|---|---|---|---|---|
| General Min. 5d Straight | Links Where Bends <150° Min. 10d Straight | |||
| 8 | 16 | 32 | 115 | 115 |
| 10 | 20 | 40 | 120 | 130 |
| 12 | 24 | 48 | 125 | 160 |
| 16 | 32 | 64 | 130 | 210 |
| 20 | 70 | 140 | 190 | 290 |
| 25 | 87 | 175 | 240 | 365 |
| 32 | 112 | 224 | 305 | 465 |
| 40 | 140 | 280 | 380 | 580 |
| 50 | 175 | 350 | 475 | 725 |
* The minimum end projections for smaller bars is governed by the practicalities of bending bars.
Note 1 Due to ‘spring back’ the actual radius of bend will be slightly greater than half the diameter of former.
Note 2 BS 4449:2005 grade B500A in sizes below 8mm does not conform to BS EN 1992-1.1:2004.
Radius of Bending: Maximum Values Requiring Bending
| Bar Size | 8 | 10 | 12 | 16 | 20 | 25 | 32 | 40 |
|---|---|---|---|---|---|---|---|---|
| Radius (m) | 2.75 | 3.5 | 4.25 | 7.5 | 14.0 | 30.0 | 43.0 | 58.0 |
Note: Bars to be formed to a redius exceeding the above dimensions will be supplied straight.
What’s the difference between 2005 and 2020?
There are only a few noticeable differences between 8666:2005 and 8555:2020. In fact, most people will only recognize the two additional shape codes added to the standard. Actually there have been some small amendments to 20 other shape codes, some new reference data added, some changes to dimensioning of cranked bars and obtuse angles, and Table 1 has been updated to include dowel bars.
What is BS8666:2020 Used for?
The BS standard for scheduling, dimensioning, cutting and bending of steel reinforcement is used by designers, specifiers, contractors, cut and bent rebar suppliers, and fabricators. It’s vital these standards are not only kept up-to-date with regards to modern construction standards, but also that they are noted and adhered to by the aforementioned parties. Having standardised rebar shape codes ensures that all parties concerned with using steel reinforcement have a specified standard to follow when using or requesting shapes for steel reinforcement.
Within a bar bending schedule, BS8666:2020 shape codes are used to identify specific shapes rebar must be produced to, as well as the minimum and maximum tolerances in bending shapes.
Does that mean I have to re-learn the rebar shape codes?
It is advised that you know what the new revisions are, certainly. However, the changes aren’t significant, and 2005 is still in use, providing it’s noted in the schedule. Rather than a revision of the shape codes, a few shapes have been added which aren’t commonly used currently, though it’s more important to understand the updates to the current shapes and the data and revised tolerances provided within.
If needed, copies of BS 8666:2020 can be purchased on the BSI website here
