Construction Dimensions - Rebar, Formwork, Steel Sections 2026
1 inch = 25.4 mm exact international standard essential rebar diameters, formwork tolerances, steel section verification with 12mm rebar = 0.472", 16mm = 0.630", 20mm = 0.787". Construction tolerances ±1mm coarse, ±0.5mm fine work ensuring fabrication compatibility across metric imperial drawings preventing cumulative dimensional discrepancies.
Structural steel UKB 356×127×33 section 356mm depth = 14.016" verifying US equipment compatibility. Formwork striking clearances 25mm = 1" standard, 40mm cover = 1.575" critical corrosion protection maintaining design life requirements throughout service period.
Rebar schedules specify 12-32mm diameters converting 0.472-1.260" matching US stock availability. Formwork tolerances ±3mm slabs, ±2mm beams ensuring concrete cover compliance. Steel fabrication ±1.5mm holes ensuring bolt group compatibility preventing connection failures load transfer.
Coarse ±1mm site tolerances, standard ±0.5mm fabrication, fine ±0.2mm steelwork, precision ±0.1mm machined components. BS EN 1090 execution classes EXC2-EXC4 dictate dimensional control ensuring structural reliability across manufacturing installation processes.
| mm | Inches | Fraction | Application |
|---|---|---|---|
| 6 | 0.236 | 15/64" | Mesh wire |
| 12 | 0.472 | 31/64" | Rebar T12 |
| 16 | 0.630 | 5/8" | Rebar T16 |
| 20 | 0.787 | 25/32" | Rebar T20 |
| 25 | 0.984 | 1" | Cover/sheet |
| 40 | 1.575 | 1-9/16" | XC4 cover |
| Size | mm | Inches | Tolerance |
|---|---|---|---|
| Rebar | ±0.4mm | ±0.016" | BS 4449 |
| Formwork | ±3mm | ±1/8" | Site |
| Steel fab | ±1.5mm | ±1/16" | EXC2 |
| Bolts | ±0.5mm | ±0.02" | EXC3 |
International standard no rounding engineering calculations.
Standard rebar diameter US imperial equivalence.
Coarse construction acceptable dimensional control.
Standard XC3 external concrete protection.
Foundation wet-dry soil contact durability.
T12 reinforcement matching US #4 bar.
25mm = 0.984" ≈ 1" standard construction cover external elements matching imperial formwork clearances ensuring compatibility across documentation systems.
16mm = 0.630" = 5/8" exact matching US #5 bar verifying reinforcement schedules stock availability preventing procurement delays.
±3mm slabs, ±2mm beams site tolerances ensuring concrete cover compliance durability requirements without excessive remedial works.
±1.5mm holes, ±2mm cuts EXC2 execution class ensuring bolt group compatibility connection efficiency load transfer.
20mm = 0.787" = 25/32" matching US #6 bar standard medium reinforcement structural elements.
40mm = 1.575" XC4 foundation specification wet-dry soil contact carbonation protection 50-year design life.
Site ±1mm coarse, fab ±0.5mm standard, steel ±0.2mm fine, machined ±0.1mm ensuring dimensional control execution classes.
BS 4449 ±0.4mm T12-T32 ensuring bond characteristics maintained structural performance verification.
For steel sections, visit Tata Steel | CARES | For rebar, check BCA