Shuttering not struck before the code minimum
Why — act while you have leverage
Formwork (the mould the concrete is poured into) removed early is the most common cause of a slab that sags permanently. The concrete has not yet carried its own weight, and the deflection you get is the deflection you keep.
What to look at
- A dated record of when each element was poured
- Props left in place, not removed and re-wedged
- Longer periods where the span is larger
How to check it yourself
Stripping times run from the pour, and the code separates vertical faces from soffit (the underside — the ceiling of the room below)s and from props. Props under slabs and beams stay far longer than the side shutters — reading "shuttering (the mould the concrete is poured into) removed" as one event is the mistake.
Where this comes from: IS 456:2000 cl. 11.3 — stripping time; Table 11 (indian standard or building code)