What is the minimum depth for a shallow foundation?

0.50 m below the natural ground level, but it must also reach adequate bearing soil (Clause 5.2).

Does this code cover the design of raft foundations?

No, raft foundations are explicitly excluded and are covered under IS 2950.

Where can I find the allowable bearing pressure values?

IS 1080 directs engineers to refer to IS 1904 for allowable bearing pressures and settlement criteria.

IS 1080

: 1985

Code of Practice For Design And Construction Of Shallow Foundations In Soils (Other Than Raft, Ring And Shell)

CurrentFrequently UsedCode of PracticeGeotechnical · Soil and Foundation Engineering

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This code sets out the guidelines for the design and construction of shallow foundations, such as pad footings, strip footings, and masonry foundations in soils. It establishes minimum depths, base dimensioning rules, and construction practices, though it explicitly excludes raft, ring, and shell foundations.

Code of Practice For Design And Construction Of Shallow Foundations In Soils (Other Than Raft, Ring And Shell)

Quick Reference Values

minimum depth of foundation0.5 m below natural ground level

minimum thickness at edge of reinforced footing150 mm

minimum thickness of plain concrete footing150 mm

minimum thickness of lean concrete base100 mm

Practical Notes

IS 1080 must be read in conjunction with IS 1904 (General requirements for design and construction of foundations).

The minimum depth of 500 mm is a baseline; engineers must still ensure that the foundation bypasses topsoil, roots, and loose matter to reach a competent stratum.

For plain concrete footings, ensure the base projection does not exceed the thickness of the footing to keep the stress dispersion within safe limits.