What is the minimum time before removing column or wall formwork?

16 to 24 hours, provided the concrete is sufficiently hard to not be damaged. (Table 1)

When can props be removed from a 4m span slab?

After a minimum of 7 days. (Table 1)

What loads must formwork be designed for?

It must be designed for dead load (self-weight, concrete weight), live load (workers, equipment), lateral pressure from fresh concrete, and environmental loads like wind. (Clause 6)

What is the acceptable tolerance for the verticality of a column?

The deviation from vertical should not exceed 6 mm for every 3 meters of height. (Annex B)

IS 14687

: 1999

Formwork - Code of practice

CurrentFrequently UsedCode of PracticeBIMStructural Engineering · Construction Safety and Practices

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This code provides guidelines for the design, fabrication, erection, and dismantling of formwork for concrete structures. It covers the loads to be considered, material specifications for timber, steel, and plywood, recommended striking times, and safety requirements during formwork operations.

Lays down the requirements for the design, erection, use and dismantling of formwork for concrete construction.

Quick Reference Values

Minimum stripping time for vertical forms (columns, walls)16 to 24 hours

Minimum stripping time for slab soffits (props to be refixed immediately)3 days

Minimum stripping time for beam soffits (props to be refixed immediately)7 days

Minimum period before striking props to slabs spanning up to 4.5m7 days

Minimum period before striking props to slabs spanning over 4.5m14 days

Permissible deviation in cross-section dimensions for columns/beams+12 mm, -6 mm

Permissible deviation from vertical (for heights up to 3 m)6 mm

Key Formulas

Pressure on Formwork (P) = Unit weight of concrete × Height of pour (modified by factors like pour rate, temperature, vibration)

Practical Notes

Stripping times in Table 1 are minimums for OPC cement at temperatures above 15°C and must be increased for cold weather, special cements (like PPC/PSC), or complex structures.

Proper application of a suitable mould-release agent is critical to prevent concrete surface damage and ensure easy striking of forms.

Pay close attention to joints between formwork panels and tie-rod holes to prevent grout leakage, which can lead to honeycombing and aesthetic defects.