Minimum and maximum reinforcement percentages, bar diameters, and spacing rules for all RCC structural members per IS 456. These are mandatory code provisions — violating them invalidates the design.
Related 📐 IS 456 ✏️ Rcc Column Reinforcement Pe… 📘 Concrete cover 📖 Min cover for RCC 🔧 RCC design
Slab (one-way & two-way)
Rule Value Clause Note Minimum steel (Fe 415) 0.12% of bD Cl 26.5.2.1 b = width, D = total depth Minimum steel (Fe 250) 0.15% of bD Cl 26.5.2.1 Maximum steel 4% of bD Cl 26.5.1.1 Practically ≤2% Minimum bar diameter — main 8 mm Practice 10mm preferred Minimum bar diameter — distribution 8 mm Practice Maximum spacing — main bars 3d or 300mm (whichever less) Cl 26.3.3(b) d = effective depth Maximum spacing — secondary/dist. 5d or 450mm (whichever less) Cl 26.3.3(b) Minimum spacing Bar dia or 25mm or max agg + 5mm Cl 26.3.2 Whichever is greatest
Beam
Rule Value Clause Note Minimum tension steel 0.85×bd/fy (≈0.2% for Fe415) Cl 26.5.1.1 b = width, d = eff depth Maximum tension steel 4% of bD Cl 26.5.1.1 At any section Side face reinforcement 0.1% of web area per face Cl 26.5.1.3 When depth > 750mm Minimum bar diameter — main 12 mm Practice Minimum bars — top & bottom 2 bars continuous Cl 26.5.1.2 Throughout length Stirrup — minimum diameter 8 mm (6mm for beams ≤ 150mm wide) Cl 26.5.1.6 Stirrup — maximum spacing 0.75d or 300mm Cl 26.5.1.5 Whichever is less Stirrup — minimum spacing 75 mm Practice For placing concrete
Column
Rule Value Clause Note Minimum longitudinal steel 0.8% of Ag Cl 26.5.3.1 Ag = gross cross-section Maximum longitudinal steel 6% of Ag Cl 26.5.3.1 4% at lap locations preferred Minimum number of bars 4 (rectangular), 6 (circular) Cl 26.5.3.1 Minimum bar diameter 12 mm Cl 26.5.3.1 Lateral tie diameter ≥ ¼ of largest bar or 6mm Cl 26.5.3.2(c) Whichever is greater Tie spacing — max Least of: 300mm, least dimension, 16 × smallest bar Cl 26.5.3.2(c) Maximum spacing between bars 300 mm Cl 26.5.3.1 Along periphery Minimum cover 40 mm (to ties) Cl 26.4.2.1 Effective cover ≥ 55mm
Footing
Rule Value Clause Note Minimum steel 0.12% of bD (Fe 415) Cl 34.5 Same as slab Maximum steel 4% of bD Practice Minimum bar diameter 10 mm Practice 12mm preferred Maximum spacing 3d or 300mm Cl 26.3.3 Minimum cover (bottom) 50 mm (PCC below), 75 mm (no PCC) Cl 26.4.2.2 Against ground Minimum depth at edge 150 mm Cl 34.1.2 For isolated footing
Retaining Wall (cantilever type)
Rule Value Clause Note Stem — vertical steel (earth face) 0.12% of bD (Fe 415) Cl 32.5 Main reinforcement Stem — horizontal steel (both faces) 0.12% of bD per face Practice Shrinkage/temperature Base slab — bottom steel (toe) As designed For upward soil pressure Base slab — top steel (heel) As designed For downward earth load Cover — earth face 50 mm Cl 26.4.2 Severe exposure
Staircase
Rule Value Clause Note Minimum steel 0.12% of bD (Fe 415) Same as slab Distribution steel 0.12% of bD Perpendicular to span Minimum bar diameter 10 mm (main), 8 mm (distribution) Practice Cover 25 mm Cl 26.4.2 Mild exposure
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