IS 875 — Design Loads

IS 875 — 'Code of Practice for Design Loads (Other than Earthquake) for Buildings and Structures' specifies the design loads for buildings in five parts: Part 1:1987 (Dead Load), Part 2:1987 (Imposed/Live Load), Part 3:2015 (Wind Load — major revision from 1987), Part 4:1987 (Snow Load), Part 5:1987 (Special Loads and Combinations). The five parts together cover all non-seismic loads required for routine building design. IS 875 is cross-referenced by IS 456:2000, IS 800:2007, and project-specific specifications.

IS 875 Part 1 (Dead Load): unit weights of materials in tabulated form. Concrete (RCC) 25 kN/m³; brick masonry 19 kN/m³; cement plaster 21 kN/m³; cement mortar 20 kN/m³; structural steel 78.5 kN/m³; gypsum 14 kN/m³; etc. Used to compute self-weight of structural elements and finishes. IS 875 Part 2 (Live Load): tabulated UDL values by occupancy. Residential 2.0 kN/m²; office working area 2.5 kN/m²; retail 4.0 kN/m²; school classroom 3.0 kN/m²; library 6.0 kN/m². Concentrated loads also tabulated for each occupancy. IS 875 Part 2 also provides live load reduction factors for vertical members (per Cl. 3.2) — important for tall building column design.

IS 875 Part 3:2015 (Wind Load) — the most-updated part: (a) Basic wind speed map of India in Annex A — Vb 33 m/s (Bangalore) to 55+ m/s (cyclone-prone coast). (b) Design wind speed Vz = Vb × k1 × k2 × k3 × k4. (c) Design wind pressure pz = 0.6 × Vz². (d) Pressure coefficients Cp from Tables 5-18 for various building shapes. (e) For tall buildings (>50 m) or unusual shapes, wind tunnel testing is recommended per Annex H. The 2015 revision introduced terrain Category 4 (city centre with closely-spaced tall buildings), updated pressure coefficients, and explicit cyclone-zone provisions in Annex D. IS 875 Part 4 (Snow Load): for J&K, HP, Uttarakhand, Sikkim, Arunachal Pradesh — Sg basic snow load 0.5-5+ kN/m² depending on elevation and location. Drift coefficients in Annex B are critical for buildings with parapets in snow zones.