Minimum time to keep formwork in place before removal. Early stripping can cause cracking, deflection, or collapse. Times assume OPC concrete at 15°C+ — extend for PPC/PSC or cold weather.
IS 456 Table 11 — Minimum Stripping Time (OPC at ≥15°C)
For PPC/PSC: add 50% more time. Below 15°C: consult engineer.
| Member / Step | Time | Condition | Note |
|---|
| Walls, Columns, Vertical Faces | 16–24 hours | Sides of beam (non-load bearing) | Can strip early — not load-bearing |
| Soffit of Slab (props left under) | 3 days | Props remain in place | Only remove side formwork |
| Soffit of Slab (props removed) | 7 days | Span ≤ 4.5m | |
| Soffit of Slab (props removed) | 14 days | Span > 4.5m | Longer spans need more time |
| Soffit of Beam (props left under) | 7 days | Props remain in place | |
| Soffit of Beam (props removed) | 14 days | Span ≤ 6.0m | |
| Soffit of Beam (props removed) | 21 days | Span > 6.0m | |
| Cantilever Slab / Beam | 14 days | All cantilevers | Critical — prop until 14 days |
| Arches (span ≤ 6m) | 14 days | | |
| Arches (span > 6m) | 21 days | | |
Notes
• NEVER strip formwork based on calendar alone — always verify concrete has gained sufficient strength
• Minimum strength for stripping: 2× the stress the member will carry at that stage
• After stripping soffit, immediately start curing the exposed surface
• Re-propping: when stripping soffit early (with props), ensure props carry load to ground, not to slab below
• In multi-storey construction, maintain props for at least 2 floors below the working floor
• For post-tensioned slabs: strip only after stressing is complete
• Keep written record of stripping dates for each pour/member