IS 1904:1986 is the Indian Standard (BIS) for design and construction of foundations in soils (general requirements). This code outlines the general requirements for the design and construction of shallow foundations in various soil types. It provides guidelines on required site investigation, determination of safe bearing capacity, and permissible settlement limits for different types of structures.
Lays down general requirements for the design and construction of foundations for buildings and structures in different soil types.
Min depth, factor of safety, permissible total/differential settlement, presumptive SBC ranges and bore-hole depth requirements for shallow foundations.
| Reference | Value | Clause |
|---|---|---|
| Min depth of foundation (Df) — general | ≥ 1.0 m below ground | Cl. 4.1 |
| Min depth — black cotton soil | ≥ 1.5 m below NGL (below shrinkage zone) | Cl. 4.1.1 |
| Factor of safety — bearing capacity (shear) | 3.0 (gross / net) | Cl. 4.2 |
| Factor of safety — settlement | Design for permissible value, no FoS on settlement | Cl. 4.3 |
| Permissible total settlement — isolated footing on sand | 50 mm | Cl. 4.3 (Table 1) |
| Permissible total settlement — isolated footing on clay | 75 mm | Cl. 4.3 (Table 1) |
| Permissible total settlement — raft on sand | 75 mm | Cl. 4.3 (Table 1) |
| Permissible total settlement — raft on clay | 100 mm | Cl. 4.3 (Table 1) |
| Permissible differential settlement — RC frame | 1/500 (isolated); 1/750 (raft) | Cl. 4.3 (Table 1) |
| Permissible angular distortion — masonry buildings | 1/1000 | Cl. 4.3 (Table 1) |
| Permissible angular distortion — steel frame | 1/300 (general); 1/500 (cracking risk) | Cl. 4.3 (Table 1) |
| SBC — soft clay (typical) | 50 – 100 kN/m² | Cl. 5 / Annex (presumptive) |
| SBC — medium clay | 100 – 200 kN/m² | Cl. 5 / Annex (presumptive) |
| SBC — loose sand | 100 – 200 kN/m² | Cl. 5 / Annex (presumptive) |
| SBC — dense sand | 300 – 450 kN/m² | Cl. 5 / Annex (presumptive) |
| SBC — gravel/dense gravel | 300 – 450 kN/m² (compact); >450 (very dense) | Cl. 5 / Annex |
| SBC — hard rock | ≥ 3300 kN/m² | Cl. 5 / Annex (presumptive) |
| Min bore-hole depth (footings) | 1.5 × B below founding level (B = footing width) | Cl. 4.4 / refer IS 1892 |
| Loading combinations — DL + LL + EQ | 33 % increase in SBC (with EQ) | Cl. 4.2 / IS 1893 |
| Plate load test — plate sizes | 300, 450, 600 mm (square) | Cl. 5.2 / refer IS 1888 |
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Design Philosophy | Working Stress Method (WSM) / Allowable Stress Design (ASD) | Limit State Design (LSD) | EN 1997-1:2004 |
| Factor of Safety (Static Bearing Capacity) | Global factor of 2.5 to 3.0 | Uses partial factors on actions, materials, and/or resistance (e.g., γM for material properties, γR for resistance) | EN 1997-1:2004 |
| Minimum Foundation Depth (Nominal) | 500 mm below natural ground level | 450 mm to be clear of topsoil; must be below frost penetration depth and zone of seasonal moisture variation | BS 8004:2015 |
| Permissible Total Settlement (Isolated Footing on Sand) | 50 mm | Not prescribed; value to be agreed upon based on structural tolerance. Annexes may give indicative values. | EN 1997-1:2004 |
| Permissible Total Settlement (Raft on Sand) | 75 mm | Not prescribed; depends on structure's sensitivity to total and differential settlement. | EN 1997-1:2004 |
| Permissible Differential Settlement (Clay) | 1/400 (ratio of settlement difference to distance) | Values depend on structure type (e.g., 1/500 for frames, 1/1000 for sensitive finishes); not a single codified value. | BS 8004:2015 (Annex A) |