Code of Practice for Design Loads
(Other Than Earthquake)
The five-part Indian Standard series defining all structural loads — dead, imposed, wind, snow, and special loads with combinations — used in the design of buildings and structures across India.
📋 Note: Part 3 (Wind Loads) was comprehensively revised in 2015 with updated wind speed maps and new terrain categories. Parts 1, 2, 4, and 5 remain at the 1987 edition with subsequent amendments.
IS 875 is a five-part series, each part covering a distinct load type. Together they form the complete loading standard for Indian structural design, referenced by IS 456, IS 800, and IS 1893.
| Part | Title | Year | Scope |
|---|---|---|---|
| Part 1 | Dead Loads — Unit Weights of Building Materials | 1987 | Self-weight of all construction materials |
| Part 2 | Imposed Loads | 1987 | Floor, roof, and staircase live loads by occupancy |
| Part 3 | Wind Loads | 2015 | Design wind speed, pressure, and force coefficients |
| Part 4 | Snow Loads | 1987 | Ground and roof snow loads for hilly regions |
| Part 5 | Special Loads & Load Combinations | 1987 | Thermal, erection, accidental loads; LSM & WSM combinations |
Dead loads are the self-weight of all permanent components of a structure — structural members, finishes, fixed partitions, and services. Unit weights are used to calculate the load per unit area or volume.
| Material | Unit Weight (kN/m³) | Notes |
|---|---|---|
| Plain Concrete | 24 | Without reinforcement |
| Reinforced Concrete | 25 | With steel reinforcement |
| Structural Steel | 78.5 | All grades |
| Brick Masonry | 19 – 20 | Depends on brick density and mortar |
| Timber (hardwood) | 8 – 10 | Varies by species; teak ≈ 9.5 |
| Water | 10 | For tanks, swimming pools |
| Soil (dry) | 16 – 18 | Loose to medium compaction |
| Soil (saturated) | 18 – 20 | Below water table |
| Cement Mortar / Plaster | 20 | Cement:sand mortar |
| Fly Ash / Lightweight Concrete | 12 – 18 | Depends on mix |
| Aluminium | 27 | Structural aluminium alloys |
| Glass | 25 | Float glass, toughened glass |
Floor Finish Load A typical floor finish (tiles + screed) adds 1.0–1.5 kN/m² to the dead load. Brick partition walls are often treated as an equivalent uniform dead load of 1.0–2.0 kN/m² on slabs depending on wall height and spacing.
Imposed (live) loads represent the loads due to occupancy, furniture, movable equipment, and people. They are specified as uniformly distributed loads (UDL) and concentrated loads for different occupancy categories.
| Occupancy / Use | UDL (kN/m²) | Concentrated Load (kN) |
|---|---|---|
| Residential — bedrooms, living rooms | 2.0 | 1.8 |
| Residential — balconies | 3.0 | 1.5 |
| Office — general | 2.5 | 2.7 |
| Office — with filing / heavy equipment | 4.0 | 4.5 |
| Assembly halls, theatres | 4.0 | 3.6 |
| Corridors, lobbies, staircases | 3.0 – 5.0 | 4.5 |
| Retail shops | 4.0 | 3.6 |
| Warehouses / storage (light) | 7.5 | 4.5 |
| Warehouses / storage (heavy) | 15.0 | 9.0 |
| Flat roofs (accessible) | 1.5 | 1.8 |
| Flat roofs (inaccessible) | 0.75 | 0.9 |
| Sloping roofs (slope > 10°) | 0.75 – 1.5 | 0.9 |
Reduction for Large Floor Areas For floors supporting large areas, IS 875 Part 2 permits reduction of imposed loads. For areas exceeding 50 m², a reduction of up to 25% may be applied to beams and columns supporting multiple floors, subject to conditions in Cl. 3.2.
The 2015 revision introduced updated wind speed maps, new terrain categories, and revised pressure coefficients. The design wind speed at height z is calculated from the basic wind speed Vb using four multiplying factors.
| Wind Zone | Basic Wind Speed Vb (m/s) | Representative Cities |
|---|---|---|
| Zone I | 33 | Parts of central India, sheltered regions |
| Zone II | 39 | Delhi, Kolkata, Bhopal, Nagpur |
| Zone III | 44 | Mumbai, Pune, Hyderabad, Bengaluru |
| Zone IV | 47 | Chennai, Bhubaneswar, Raipur |
| Zone V | 50 | Coastal Andhra, Odisha, parts of Gujarat |
| Zone VI | 55 | Andaman & Nicobar Islands, extreme coastal zones |
Internal Pressure Coefficients For enclosed buildings, internal pressure coefficients Cpi = ±0.2 (for small openings). For buildings with large openings on one face, Cpi = +0.7 or −0.5. Net pressure = external − internal pressure coefficient (Cl. 7.3.2).
Snow loads are applicable to structures in hilly and mountainous regions of India — primarily Jammu & Kashmir, Himachal Pradesh, Uttarakhand, and parts of the Northeast. Ground snow load So is obtained from the snow load map.
| Roof Slope (α) | Shape Coefficient (μ) | Notes |
|---|---|---|
| α ≤ 30° | 0.8 | Flat and low-slope roofs |
| 30° < α ≤ 60° | 0.8 × (60 − α) / 30 | Linearly decreasing |
| α > 60° | 0.0 | Snow slides off; no design snow load |
Drift and Sliding Snow Additional provisions apply for snow drifting at parapets, valleys, and lower roofs adjacent to higher roofs. Sliding snow from upper roofs onto lower roofs must also be considered (Cl. 5 and 6).
Part 5 covers special loads (thermal, erection, accidental, impact) and provides the load combination tables for both Limit State Method and Working Stress Method design.
| Load Combination | DL (γf) | LL (γf) | WL / EL (γf) | Method |
|---|---|---|---|---|
| DL + LL | 1.5 | 1.5 | — | LSM |
| DL + WL (WL adverse) | 1.5 | — | 1.5 | LSM |
| DL + WL (DL stabilising) | 0.9 | — | 1.5 | LSM |
| DL + LL + WL | 1.2 | 1.2 | 1.2 | LSM |
| DL + EQ | 1.5 | — | 1.5 | LSM |
| DL + LL + EQ | 1.2 | 1.2 | 1.2 | LSM |
| DL + LL (WSM) | 1.0 | 1.0 | — | WSM |
| DL + LL + WL (WSM) | 1.0 | 1.0 | 1.0 | WSM (33% increase) |
Seismic vs. Wind Earthquake load (EL) and wind load (WL) are not combined simultaneously. The more critical of the two is used in combination with dead and live loads. IS 1893 governs earthquake load calculation.