India Soil Bearing Capacity Map — IS 1904

Indicative safe bearing capacity (SBC) for any Indian city based on regional soil type per IS 1904 + IS 6403. Six soil classes from Rocky (330-660+ kN/m²) to Soft Clay (< 50 kN/m²). Drives foundation type, depth, and dewatering needs.
44
rocky
16
lateritic
76
alluvial
19
sandy
33
black-cotton
9
soft-clay
Rocky · Hard rock / weathered rock · 330–660+ kN/m²
Lateritic · Iron-rich tropical soils · 200–330 kN/m²
Alluvial · River-deposit fertile soils · 150–250 kN/m²
Sandy / Desert · Loose to dense sand · 100–200 kN/m²
Black Cotton · Expansive montmorillonite clay · 50–150 kN/m²
Soft Clay / Marshy · Low strength deltaic soils · < 50 kN/m²
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Click any spot on the map to drop a pin and get the estimated zone. Map data © OpenStreetMap contributors.

About SBC classification

Safe Bearing Capacity is the maximum pressure soil can support without shear failure or excessive settlement, including a factor of safety (typically 3). Regional soil maps give a starting estimate — final design always requires SPT / CPT / plate-load testing per IS 1888 / IS 4453.

Foundation type by zone

  • Rocky: open footings 0.6-1.2 m. Rock-anchor for tall structures.
  • Lateritic: open footings 1.0-1.5 m. Watch for iron-pan layers.
  • Alluvial: isolated / raft for > G+3. SPT-based bearing.
  • Sandy: liquefaction risk in seismic zones III+. Densify or pile.
  • Black Cotton: under-reamed piles or anchor below active zone (1.5-3 m).
  • Soft Clay: pile foundation mandatory. Sand drains or PVD ground improvement.

Cross-references

Source IS / IRC / NBC standards

IS 1904:1986Foundation Loads — SBC referenceIS 2720Methods of Test for Soils — sieve analysis, plasticity, etc.IS 456:2000Cl. 8.2 exposure — affects concrete in foundations

Related maps

Groundwater DepthDrives foundation dewatering needsSoil SulphateDrives cement choice for foundationsSeismic ZonesLiquefaction risk for sandy soils in Zone III+

Calculators & tools

RCC Footing DesignIsolated footing per IS 456 — uses SBCCost CalculatorSoil type modifies foundation cost band

Articles & guides

Foundation Selection GuideWhich foundation for which soil + loadIS 2720 Soil TestingAll parts quick reference

Frequently asked questions

What is safe bearing capacity?

SBC = ultimate bearing capacity (qu) ÷ factor of safety (typically 3). It's the maximum pressure soil can sustain without shear failure or excessive settlement. SBC for shallow foundations per IS 6403 considers cohesion, friction, depth, width, water table, and load eccentricity.

How accurate is regional SBC estimate?

Regional maps give ±50% accuracy. Always confirm via site-specific testing — SPT (IS 2131), CPT (IS 4968), plate-load (IS 1888). Soil profile can vary dramatically within 100m, especially in alluvial / coastal regions.

Which Indian regions have the worst soil for foundations?

Two zones are challenging: (1) Black-cotton soil belt — Maharashtra (Vidarbha), MP, Telangana, north Karnataka — high swell-shrink kills shallow foundations. (2) Soft marine clay — Bengal delta, Mumbai reclamation, parts of Brahmaputra valley — SBC < 50 kN/m², requires piles.

Is open well foundation still used?

Mostly historical except for bridges. Modern bridges over rivers in alluvium use well foundations (driven steel + concrete shell, sunk by dredging) per IRC 78. For buildings, open well replaced by isolated / raft / pile foundations per IS 1904.

Regional SBC values are indicative starting estimates only. IS 1904 mandates site-specific geotechnical investigation for any structure beyond temporary single-storey. For loose sandy fill, recently reclaimed land, organic soils, or in seismic zones III+, plate-load test + SPT analysis required by code.

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