Removing formwork too early can cause cracks, deflection or collapse. IS 456 gives guidance on minimum stripping periods.
Typical minimum periods
- Vertical sides of columns, walls and beams: 16 to 24 hours.
- Slab soffit with props refixed immediately: about 3 days.
- Beam soffit with props refixed immediately: about 7 days.
- Props to slabs: 7 days for spans up to 4.5 m, 14 days for longer spans.
- Props to beams: 14 days for spans up to 6 m, 21 days for longer spans.
Important
These periods assume ordinary Portland cement and normal temperature. Cold weather, blended cement, long spans and heavy loads can need longer. Do not stack heavy material on a young slab, and confirm the schedule with your structural engineer.
General guidance only. Every project differs; consult your engineer for yours.