IS 875:1987 Part 1 is the Indian Standard (BIS) for design loads (other than earthquake) for buildings and structures - dead loads. This code provides the unit weights of building materials, stored materials, and structural components. Structural engineers use it as the fundamental reference to calculate the permanent dead loads (self-weight) on buildings and structures during the initial design phase.
Specifies dead loads for structural design of buildings and structures, including weights of materials and components.
Unit weights of building materials for dead-load computation. Values are for design; site-measured weights govern when available.
| Reference | Value | Clause |
|---|---|---|
| Plain cement concrete (PCC) | 24 kN/m³ | Table 1 |
| Reinforced cement concrete (RCC) | 25 kN/m³ | Table 1 |
| Brick masonry (in cement mortar) | 19 kN/m³ | Table 1 |
| Stone masonry (granite/basalt) | 26.5 kN/m³ | Table 1 |
| Stone masonry (sandstone) | 21.5 kN/m³ | Table 1 |
| Cement plaster | 20.4 kN/m³ | Table 1 |
| Lime plaster | 17.3 kN/m³ | Table 1 |
| Structural steel | 78.5 kN/m³ | Table 1 |
| Cast iron | 70.7 kN/m³ | Table 1 |
| Aluminium | 27.0 kN/m³ | Table 1 |
| Water (fresh) | 9.81 kN/m³ | Table 1 |
| Glass — sheet | 25.5 kN/m³ | Table 1 |
| Timber — teak (seasoned) | 6.5 kN/m³ | Table 1 |
| Timber — sal (seasoned) | 8.7 kN/m³ | Table 1 |
| Marble flooring | 26.7 kN/m³ | Table 1 |
| Mosaic / terrazzo flooring | 22 kN/m³ | Table 1 |
| Asphalt roofing | 21 kN/m³ | Table 1 |
| Soil — dry sand | 16 kN/m³ | Table 1 |
| Soil — saturated sand | 20 kN/m³ | Table 1 |
| AAC / cellular concrete block (autoclaved)— manufacturer-specific; common range used in design | 5.5–8.0 kN/m³ | Table 1 |
| Hollow concrete block (typical) | 11–15 kN/m³ | Table 1 |
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
IS 875 (Part 1):1987 specifies dead loads (DL) — unit weights of building materials and stored materials — for structural design. Every Indian structural design starts with IS 875 Part 1 because self-weight is always the first load case.
You reference IS 875 Part 1 whenever: - Computing slab, beam, column self-weight in structural design - Estimating finish loads (plastering, flooring, waterproofing) as dead load - Specifying material densities in design basis reports - Verifying foundation design assumptions (total dead load magnitude) - Analysing existing structures for retrofit (re-computing dead load per as-built finishes)
Pair with: - IS 875 Part 2:1987 — imposed / live loads - IS 875 Part 3:2015 — wind loads - IS 875 Part 5:1987 — special loads (snow, temperature, erection) - IS 1893 Part 1:2016 — seismic weight calculation uses dead load + fraction of live load per Clause 7.3 - IS 456:2000 — load combinations use DL from IS 875 Part 1
From IS 875 Part 1:1987 Table 1 — structural material unit weights (kN/m³):
Concrete and related: - Plain concrete: 24 kN/m³ - Reinforced concrete: 25 kN/m³ - Lightweight concrete: 15-20 kN/m³ (depends on aggregate) - Prestressed concrete: 25 kN/m³ (same as RCC for design)
Masonry and walling: - Brick masonry (1st class, with 1:6 mortar): 20 kN/m³ - Brick masonry (hollow/2nd class): 19 kN/m³ - Stone masonry: 27 kN/m³ (granite, trap, basalt) - Laterite masonry: 22 kN/m³ - AAC block masonry: 8-10 kN/m³ (major weight saving over brick) - Mud / clay masonry: 19 kN/m³
Mortars and plasters: - Cement mortar: 21 kN/m³ - Lime mortar: 17 kN/m³ - Cement plaster (20 mm thick): 0.42 kN/m² - Lime plaster: 0.34 kN/m²
Flooring and finishes (kN/m² as surface loads, for standard thicknesses): - Marble flooring (20 mm): 0.53 kN/m² - Granite flooring (18 mm): 0.49 kN/m² - Kota stone (20 mm): 0.52 kN/m² - Ceramic tile (10 mm): 0.24 kN/m² - Mosaic tile (20 mm): 0.46 kN/m² - Vitrified tile (12 mm): 0.28 kN/m² - Carpet: 0.05 kN/m² - Wooden flooring (teak, 18 mm): 0.16 kN/m²
Waterproofing and roofing: - Bitumen waterproofing (3-layer): 0.20 kN/m² - APP membrane (4 mm): 0.04 kN/m² - Tile roofing (country tile): 0.50 kN/m² - GI sheet roofing (0.5 mm): 0.05 kN/m² - Stone slab roofing: 0.80 kN/m²
Structural steel: - Steel (IS 2062 grades): 78.5 kN/m³ (= 7850 kg/m³) - Cast iron: 72 kN/m³ - Aluminium: 27 kN/m³
The complete table has 100+ material entries. Any design-basis report should list the specific values used.
Slab: 150 mm thick RCC slab with standard finishes. Compute total dead load (kN/m²).
Step 1 — Self-weight of slab: RCC unit weight: 25 kN/m³ Slab thickness: 0.150 m Self-weight = 25 × 0.15 = 3.75 kN/m²
Step 2 — Floor finish (ceramic tile + bedding): Ceramic tile (10 mm): 0.24 kN/m² Cement mortar bedding (20 mm): 21 × 0.020 = 0.42 kN/m² Total floor finish: 0.66 kN/m²
Step 3 — Ceiling finish (plaster only): Cement plaster (12 mm): 21 × 0.012 = 0.25 kN/m² Or if POP / gypsum board: 0.15 kN/m² Typical: 0.25 kN/m²
Step 4 — Partition allowance (added even if not shown in plan, per NBC 2016 Part 4): Brick partitions on floor, uniformly distributed equivalent: 1.0 kN/m² (IS 875 Part 2 Clause 3.2 allows up to 1.5 kN/m² for residential; check against anticipated partitions)
Step 5 — False ceiling (if applicable): Gypsum board with frame: 0.15 kN/m²
Total dead load for typical residential slab: DL = 3.75 + 0.66 + 0.25 + 1.0 = 5.66 kN/m² (without false ceiling) DL = 5.66 + 0.15 = 5.81 kN/m² (with false ceiling)
In structural analysis, this is the 'superimposed' dead load per m² of slab. Multiply by slab area for total.
For bathrooms and kitchens (wet areas): Add: - Waterproofing membrane: 0.20 kN/m² - Additional tile + bedding: already counted - Sunken slab fill (for plumbing, 100-150 mm depth): 0.15 × 20 = 3.0 kN/m² (extra) Wet-area DL = ~8-9 kN/m² (including sunken fill)
For balconies: Usually floor finish only (no partition allowance, no false ceiling). DL ≈ 4.5 kN/m².
Roof slab: Add waterproofing (0.20), protective screed (50 mm × 25 = 1.25), and IPS bedding. Total roof DL ≈ 6.0-6.5 kN/m².
1. Underestimating ceiling / false ceiling loads. Modern buildings often have false ceilings (gypsum board, acoustic tiles, metal grid) with HVAC ducting above. Total load can be 0.3-0.5 kN/m² — significant compared to a 3.75 kN/m² slab self-weight. Include HVAC and services in your design basis.
2. Using wrong masonry unit weight. Brick walls (1st class, 1:6 mortar) are 20 kN/m³. Hollow block or AAC block walls are 8-10 kN/m³ — less than half. Many designers default to brick (20) for all wall weights; using AAC (10) in actual construction over-designs the beam supporting that wall by 50-100%. Match masonry type to design assumption.
3. Not adding partition allowance. Even if architectural plans show specific partition layouts, IS 875 Part 2 Clause 3.2 (referenced here because partition allowance is usually added alongside dead loads) requires 1.0-1.5 kN/m² for residential and office floors to account for future re-arrangements. Skipping this gives optimistic loads that fail when the owner adds partitions later.
4. Using exterior vs interior unit weights interchangeably. External brick walls (230 mm thick with plaster both sides) weigh ~6 kN/m of wall length per metre height. Internal partitions (115 mm or 100 mm blockwork) weigh 2-3 kN/m per metre height. Getting this wrong on beam design leads to misproportioned sections.
5. Forgetting stored material loads for special-use buildings. IS 875 Part 1 Table 2 covers stored materials — books, paper, metal, machinery. For libraries, warehouses, industrial buildings, these can be 10-25 kN/m² — far exceeding typical residential. Look at the building's intended use, not just 'residential' or 'commercial' generic values.
IS 875 Part 1:1987 is 39 years old and shows its age. Many modern materials (AAC blocks, EPS/XPS insulation, photovoltaic panels, green-roof soil, rainwater harvesting tanks, solar water heaters on roof) are not explicitly listed. Designers use manufacturer data sheets or extrapolate from similar materials — not ideal for traceability.
A revision has been pending since ~2012, intended to modernize material list, add new materials, and align with ISO 10722. Draft circulars have appeared periodically but no published update. Watch for CED 37 consultation.
For specialised loads: - Solar panels: 0.15-0.25 kN/m² (panel + frame + tilt structure) — not in IS 875, use manufacturer data - Green roof: 1.0-2.5 kN/m² (varies by soil depth and moisture) — IS 875 has generic 'soil' but not green-roof assembly - Rainwater tank on roof: check capacity × 10 kN/m³ (water) as live load - Rooftop HVAC equipment: 0.5-1.5 kN/m² uniform + point loads per manufacturer
Site reality check: Actual constructed dead loads often exceed design assumptions by 5-15% due to: thicker plaster than specified (site labour adds extra for finish), additional finishes (dado, panelling), unplanned modifications (balcony enclosures, additional rooftop equipment). Conservative DL estimation (add 5-10% margin on calculated values) helps absorb this variability without affecting safety.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Plain Cement Concrete (PCC) | 24.0 kN/m³ | 24.0 kN/m³ | EN 1991-1-1 |
| Reinforced Cement Concrete (RCC) | 25.0 kN/m³ | 25.0 kN/m³ | EN 1991-1-1 |
| Structural Steel | 78.5 kN/m³ | 78.5 kN/m³ | EN 1991-1-1 |
| Common Burnt Clay Brick Masonry | 18.85 kN/m³ | 16.0 - 20.0 kN/m³ (depending on brick density) | EN 1991-1-1 |
| Cement Plaster | 20.4 kN/m³ | 20.0 kN/m³ (for Cement mortar) | EN 1991-1-1 |
| Cast Iron | 72.08 kN/m³ | 72.5 kN/m³ | EN 1991-1-1 |
| Water (Fresh) | 9.81 kN/m³ | 10.0 kN/m³ | EN 1991-1-1 |
| Glass (Sheet/Plate) | 25.1 kN/m³ | 25.0 kN/m³ | EN 1991-1-1 |