What is a permanent benchmark as per this code?

A stable reference point whose Reduced Level (RL) is accurately known, typically a concrete pillar, from which levels for the construction can be transferred (Clause 4.3).

What is the acceptable tolerance for positioning a column?

The permissible deviation in setting out columns at any floor is generally ±5 mm, as specified in tolerance tables (e.g., Table 1).

How should right angles be checked during setting out?

By using precise instruments like a Theodolite, or for simpler checks, by using the 3-4-5 method or by ensuring diagonals of a rectangle are equal (Clause 6).

IS 11134

: 1984

Code of practice for setting out of buildings

CurrentEssentialCode of PracticeBIMStructural Engineering · Building Construction Practices incl. Painting, Varnishing

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This standard provides guidance on the procedures for accurately setting out a building from the design drawings onto the ground. It covers the establishment of a reference grid and benchmarks, methods for marking building lines, and the permissible tolerances for horizontal and vertical control to ensure the structure is built in its correct location and alignment.

Code of practice for setting out of buildings

Quick Reference Values

Permissible deviation in setting out columns at any floor±5 mm

Permissible deviation in setting out cross-section dimensions±5 mm

Permissible deviation in established benchmark level±3 mm

Permissible deviation from verticality (plumb) for total height of building > 30mNot more than 15 mm

Practical Notes

Always establish at least two permanent benchmarks on stable ground outside the building footprint and protect them from disturbance.

For rectangular layouts, always check the diagonal measurements after setting out the grid. They should be equal within the allowable tolerance to ensure squareness.

Ensure surveying instruments are properly calibrated before starting work to prevent systematic errors.