General Standards for UK Detailing

1. All reinforcement details (such as minimum diameter and minimum or maximum spacing) are only for comparison purpose to raise RFI if the design intent does not meet the requirement. Any changes or addition or omission to design intent based on standard practice or for flexibility or for consistency or for simplified/rationalized method of detailing must be confirmed with client prior to detailing. 

2. Detailing standards to be checked with client whether the design is based on BS or EC2 prior to detailing. 

3. Cover to reinforcement to be cross checked against nominal cover specified for each case (i.e Internal, External, Earth face etc.) 

a. If given cover < nominal cover, adequate tolerance (refer Table) to be adapted and the same to be confirmed with client. 

b. If given cover ≥ nominal cover, additional tolerance to be ignored and the same to be confirmed with client. 

c. Minimum cover to be 25mm (or main bar Ø) and Maximum cover to be 40mm (or 70mm to axis of main bars) to avoid concrete spalling. Surface mesh / sacrificial bars may be required if cover exceeds 40mm. 

4. Reinforcement spacing to be cross checked against minimum and maximum spacing specified for each case.

a. Minimum clear spacing to be 25mm vertically and maximum spacing varies for each case.

b. Spacing may be increased or decreased to suit minimum or maximum spacing requirement and the same to be confirmed with client. 

5. Reinforcement diameter to be cross checked against minimum diameter specified for each case.

a. No reinforcement to be less than 8mm. 

b. Minimum Link reinforcement to be ≥ (main bar Ø / 4) or 8mm 

6. Reinforcement congestion to be checked to adapt alternate detail and the same to be confirmed with client.

a. Maximum area of reinforcement (refer Table) to be cross checked. 

b. Minimum clear spacing to be checked at laps, for bundled bars, for bar dia over 32mm and at junctions (such as beam and column junctions). 

c. Preferably all laps to be staggered for bar Ø ≥ 16mm 

d. Mechanical splices using couplers for bar Ø > 32mm and spacing < 100mm may be proposed to client to avoid congestion.

Note : 

1. Minimum and maximum area of steel shown here are in percentage of steel required for cross-sectional concrete area (Ac). 

2. Percentage of steel shown only for fy = 500Mpa. 

3. Percentage of steel shown only for main reinforcement . 

4. Percentage of steel for all other case should be referred in the corresponding codes. 

7. Minimum bending value for links with 90ᴼ hook to be 10Ø+r+Ø (refer Table)

8. Use of Special shape to be confirmed with Seniors / Client prior to detailing.

a. Shape with 5 bend or more may be impractical and the same to be confirmed with client. 

b. Alternative arrangement using standard shapes may be proposed to client to avoid special shape. 

c. Clear picture with all necessary bending dimensions to be shown in the BBS for special shapes.

9. Reinforcement site bending to be checked whether it will work practically.

a. Curved bars can be supplied as straight if radius of bending exceeds the limit shown in the Table 

b. Bar Ø ≤ 12mm can be bent at site and placer note to be kept in the drg. 

c. Wall vertical bars at corner to be cranked if Ø ≥ 20mm. d. Circular column vertical bars do not required to crank at laps.

10. Total area for mesh to be shown on RC drgs including 22% for 300mm lapping allowance.

11. All pull-out bars (Ex: Kwikastrip) to be shown indicatively UNO. Separate BBS may be produced based on product standards for pull-out bars only if there is any client request. 

12. All coupler bars to be detailed considering length measured from pour line to end of bars to avoid errors in end preparations. Coupler bars may be detailed considering end preparation only if there is any client request. 

a. Standard Coupler bar length measured from pour line,

b. Positional Coupler bar length measured from pour line,

c. Standard Coupler bar length considering end preparation,

d. Positional Coupler bar length considering end preparation,

13. Construction sequence is to be confirmed with client prior to detailing.

a. Top down construction is required coupler or pull-out starters from slab to column or wall below and from capping beam to liner wall. 

b. Underpinning construction sequence and dowel bar arrangement to be confirmed with client if not given. 

c. Coupler or pull-out starters from capping beam to ground floor slab or beam or lining wall to be detailed based on method of construction.

d. All column and wall starters to be detailed along with foundations or to be clearly cross referenced.

e. Temporary opening or crane opening or infill slab and future opening starter bars (Coupler or pull-out starters) arrangements to be confirmed with client if not given.  

f. Core wall construction method (Traditional or slip form or jump form) to be confirmed with client prior to detaining.

14. Chair bars to be detailed to support top mat in slab or raft, if height of chair h > 300mm as per BS 7973-1; chair bar Ø can be one bar Ø less than top mat bar Ø spaced at 50xØ of supporting top bar and the same to be confirmed with client prior to detailing. 

15. The position of all starters to be specified clearly to avoid possible clashes with continuation pour. Special care to be taken for the position of couplers starters and bar Ø ≥ 20mm.

16. Overall restricted length of bars for each diameter to be confirmed with client prior to detailing 

a. Available stock length is 12m for Ø ≥ 12mm and 8, 9 or 10m for Ø < 12mm. 

b. For transportable bent bars, shortest side of imaginary rectangle to be < 2.75m.

17. At least two slab bottom bars should pass through the column as per EC2 requirement and hence placer note to be kept in the drg to ensure the same at site. 

18. Slab bars at first layer (i.e. T1 & B1) to be placed parallel to shorter span UNO.

19. No kicker require for upstands.