What is the maximum out-of-plumb allowed for a steel column?

The deviation from vertical should not exceed H/500, where H is the height of the column (Clause 4.2.1).

What is the tolerance for the location of a column base plate in plan?

The deviation from the specified grid lines at the base should not exceed ± 5 mm (Clause 4.1).

How straight does a steel beam need to be after erection?

The deviation from straightness in the vertical or horizontal plane should not exceed L/750, where L is the span of the beam (Table 2).

Are these tolerances applicable before or after loading?

These tolerances apply to the structure as-erected, before the application of full dead and live loads, unless specified otherwise.

IS 12843

: 1989

Tolerances for the erection of steel structures

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This Indian Standard specifies the maximum permissible deviations in the erection of steel structures. It provides tolerances for member straightness, column positioning, verticality (plumb), and levels of beams to ensure structural integrity and proper fit-up of components.

Tolerances for the erection of steel structures

Quick Reference Values

Maximum deviation of column base from grid lines± 5 mm

Maximum deviation of column from plumb (individual)H / 500

Maximum deviation of column from plumb (adjacent)H / 1000

Maximum deviation of member straightness (compression)L / 1000 or 5 mm, whichever is less

Maximum deviation of member straightness (flexure)L / 750

Maximum deviation in level of beam at support± 5 mm

Key Formulas

Column Plumb Tolerance = H / 500 (where H is column height)

Member Straightness Tolerance = L / 1000 (for compression members, L is member length)

Practical Notes

This code deals with erection tolerances only; fabrication tolerances are covered by other standards like IS 7215.

Tolerances can be cumulative. Careful monitoring during each stage of erection is crucial to stay within the overall building limits.

Project-specific requirements or designer's specifications may impose stricter tolerances than those given in this standard.