NBC 2016:2016 Part 6 is the Indian Standard (BIS) for national building code of india 2016 - structural design. Part 6 is the structural design Part — the largest and most cross-referenced Part of NBC 2016. It is organised in seven sections: Loads; Soils and Foundations; Timber and Bamboo; Masonry; Concrete; Steel; and Prefabricated and Composite Construction. Each section gives design procedures and anchors them to a parent IS code. For any actual design calculation, Part 6 directs the engineer to the parent IS — IS 456 for RCC, IS 800 for structural steel, IS 875 Parts 1-5 for loads, IS 1893 for earthquake, IS 13920 for ductile detailing. Part 6 is the integrator that tells you which code governs which part of a multi-material structure and how the interfaces are designed.
Covers structural design of buildings through seven sections: Loads, Forces and Effects; Soils and Foundations; Timber and Bamboo; Masonry; Concrete; Steel; and Prefabricated, Systems Building and Mixed/Composite Construction. Each section anchors the corresponding IS design code.
Live loads by occupancy, wind/seismic zones, safe bearing capacities, RCC cover and grade minimums — covering all 7 sub-sections.
| Reference | Value | Clause |
|---|---|---|
| Live load — Residential (rooms, kitchens) | 2.0 kN/m² | Sec 1 (ref IS 875 Part 2) |
| Live load — Office floors (general) | 2.5 kN/m² | Sec 1 (ref IS 875 Part 2) |
| Live load — Office floors (file/storage rooms) | 5.0 kN/m² | Sec 1 |
| Live load — Class rooms / Assembly with fixed seats | 3.0 / 4.0 kN/m² | Sec 1 |
| Live load — Assembly without fixed seats | 5.0 kN/m² | Sec 1 |
| Live load — Shop/retail floors | 4.0 kN/m² | Sec 1 |
| Live load — Warehousing / storage | ≥ 5.0 kN/m² (or as actual) | Sec 1 |
| Live load — Stairs (public buildings) | 5.0 kN/m² | Sec 1 |
| Roof live load — accessible flat roof | 1.5 kN/m² | Sec 1 |
| Roof live load — non-accessible (sloping) | 0.75 kN/m² (reduced for slope) | Sec 1 |
| Wind — basic wind speed range (India)— see wind-speed map | 33 – 55 m/s (50-yr return) | Sec 1 (ref IS 875 Part 3) |
| Wind — coastal high-wind zones (Vb) | 50 / 55 m/s | Sec 1 |
| Seismic zones — India classification | Zones II, III, IV, V | Sec 1 (ref IS 1893 Part 1) |
| Seismic zone factor Z | 0.10 / 0.16 / 0.24 / 0.36 | Sec 1 (Table 3 of IS 1893) |
| Safe bearing capacity — soft clay | 50 – 100 kN/m² | Sec 2 |
| Safe bearing capacity — medium dense sand | 150 – 250 kN/m² | Sec 2 |
| Safe bearing capacity — hard rock | ≥ 3,300 kN/m² (10–20% of UCS) | Sec 2 |
| Min depth of foundation (Rankine)— below seasonal moisture variation | 0.5 – 1.5 m | Sec 2 |
| Concrete — min grade for RCC | M20 (mild); M25 (mod. exposure) | Sec 5 (ref IS 456) |
| Concrete — min cover (slab/wall, mod. exposure) | 20 / 25 mm | Sec 5 (ref IS 456) |
| Concrete — min cover (column, mod. exposure) | 40 mm | Sec 5 (ref IS 456) |
| Masonry — min wall thickness (load-bearing, single-storey) | 230 mm (one brick) | Sec 4 |
| Steel — slenderness ratio (compression, main) | ≤ 180 | Sec 6 (ref IS 800) |
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
NBC 2016 Part 6 (Structural Design) is the National Building Code of India's umbrella structural-design framework — it ties together loads, soils/foundations, and the material design codes (timber/bamboo, masonry, concrete, steel, prefabrication) into one coordinated reference for building structural design. It is the map that points to the governing IS codes, adopted via building bye-laws by many authorities.
It sits at the top of the structural stack:
Part 6 is organised into sections (loads/forces/effects; soils & foundations; timber & bamboo; masonry; concrete; steel; prefabrication) and its role is coordination:
The engineering point: NBC Part 6 is the structural-design index and coordination layer, not a substitute for the detailed material codes. Two errors bracket its misuse — treating it as optional 'guidance' when local bye-laws have made it mandatory, and trying to design *from* it instead of from the specific IS codes it points to. Used correctly, it ensures the loads, foundation, and material designs are mutually consistent and code-compliant.
Scenario: structural design of a building (RCC frame, masonry infill, foundations).
Step 1 — regulatory check: confirm whether the local building bye-laws adopt NBC 2016 — if so Part 6 is mandatory, not advisory.
Step 2 — load basis (Part 6 → load codes): establish dead/imposed/wind (IS 875) and seismic (IS 1893 Part 1) loads/combinations per the framework.
Step 3 — foundation: soils & foundations per Part 6 / IS 1904 and the geotechnical report.
Step 4 — material design via the governing codes: RCC to IS 456, steel to IS 800, masonry to IS 1905, prestressed to IS 1343 — Part 6 coordinates; the IS codes do the design.
Step 5 — consistency: ensure loads, foundation and material designs all reference the same framework.
Part 6 keeps the whole design coherent and bye-law-compliant; the detailed member design still lives in the individual IS codes.
1. Designing 'from the NBC' instead of from the IS codes. Part 6 coordinates and points to IS 456/IS 800/IS 1905/etc. — the detailed design lives there.
2. Treating it as optional. Where local bye-laws adopt NBC, Part 6 is mandatory, not advisory.
3. Inconsistent load/material basis. The point of the framework is a *coherent* set of loads + material codes — mixing editions/bases defeats it.
4. Ignoring non-glamorous sections. Soils/foundations and prefabrication sections matter as much as concrete/steel.
5. Assuming NBC overrides IS codes. It aligns with and references them — it does not supersede the governing material codes.
NBC 2016 Part 6 is the structural-design coordination layer of the National Building Code — the framework that binds loads, soils/foundations and the material design codes into one consistent, bye-law-adoptable reference. The two practitioner essentials: it is frequently made mandatory by local building bye-laws (so it is regulatory, not optional, where adopted), and it is an index/coordination document, not a replacement for the detailed material codes — the actual member design still lives in IS 456, IS 800, IS 1905, IS 1343 with loads from IS 875/IS 1893. Use it to ensure the loads, foundation and material designs are mutually consistent and compliant; never try to design 'from the NBC' in place of the governing IS codes, and never treat it as advisory where the local authority has adopted it.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| High-Rise Building Definition Threshold | Building height ≥ 15 m | Building with an occupied floor > 75 ft (≈ 23 m) above lowest level of fire dept. vehicle access | IBC 2024 |
| Mandatory Refuge Area Requirement | Yes, for buildings > 24m, at 24m and then every 15m. Area is 0.3 m²/person or 15 m² min. | No specific prescriptive requirement; addressed by other means like evacuation elevators or additional stairwells. | IBC 2024 |
| Min. Corridor Width (Institutional/Hospitals) | 2.0 m for non-ambulatory patients; 2.4 m if for stretcher movement | 96 inches (≈ 2.44 m) in new healthcare occupancies | NFPA 101:2024 |
| Max. Travel Distance (Business Occupancy, Sprinklered) | 45 m | 300 ft (≈ 91 m) | NFPA 101:2024 |
| Fire Resistance of Exit Stair Enclosure (High-Rise) | 2 hours | 2 hours | IBC 2024 |
| Automatic Sprinkler Trigger (New Hotels) | Mandatory if height > 15 m | Required in all new hotels, regardless of height (with few exceptions for small buildings) | NFPA 101:2024 |
| Ramp Slope (Means of Egress) | Maximum 1 in 10 (10%) | Maximum 1 in 12 (≈ 8.3%) | IBC 2024 |