NBC 2016 for Factories: Occupancy, Exits, Travel Distance & Refuge — a Working Guide

Every fire officer, every fire consultant and every building-plan reviewer in India is reading from the same book: the National Building Code of India 2016, Part 4 — Fire and Life Safety. If you understand how that part thinks, every fire-side approval in your project becomes predictable. If you don’t, the code arrives as a series of expensive surprises delivered one inspection at a time.

This is a working guide to NBC 2016 for industrial buildings — how occupancy classification works, what drives exit and travel-distance requirements, when refuge areas and fire-resistance ratings bite, and the handful of design decisions that decide approval. It supports our guides on the Fire NOC process and the complete approvals roadmap.

How the code thinks: NBC does not ask “what is the building called?” It asks “what burns in it, how fast, and how do the people inside get out?” Every table in Part 4 is an answer to that question.

Occupancy classification — the master key

NBC 2016 classifies every building into occupancy groups. Three matter for industry:

Group	What it covers	Subdivision
G — Industrial	Buildings where products are fabricated, assembled, processed	G-1 low hazard · G-2 moderate hazard · G-3 high hazard
H — Storage	Warehouses, godowns, cold stores, truck terminals	By stored commodity & configuration
J — Hazardous	Processes/storage involving highly combustible, explosive or toxic materials	The strictest regime

The subdivision follows the contents and process, not the signage: a garment unit stitching fabric is a different fire problem from the same shed storing baled fabric five metres high; a paint-mixing room converts a corner of a G-2 building into a J-grade problem needing its own separation. Mixed-reality buildings are the norm — and NBC handles them by requiring each portion to meet the requirements of its own use, with fire separation between them.

Why classification is the whole game: the occupancy group + hazard class drive every downstream number — permissible height and area, fire resistance of the structure, exit widths, travel distance, and the fire-protection systems (hydrants, sprinklers, tank and pump sizing) whose selection tables key directly off occupancy. Classify wrong and every downstream number is wrong — which is why mis-classification is the leading cause of fire-scheme rejection.

Means of egress — the part that shapes your layout

Egress is the code’s heart, and it is layout, not equipment. The principles that bind an industrial building:

• At least two independent exits from any floor/area of consequence, placed remote from each other — so one fire cannot block both
• Travel distance limits — the walking distance from the farthest working point to the nearest exit is capped, with the cap tightening as hazard rises and relaxing where the building is sprinklered. For industrial occupancies the limits are on the order of a few tens of metres — which means a deep-plan shed simply cannot rely on doors at one end
• Exit width by occupant load — aggregate exit width is computed from persons per floor using the code’s unit-width flow rates; exits then may not be reduced, obstructed or locked
• Exit quality — outward-opening doors on escape routes, no collapsible gates on required exits, illuminated signage, protected stair enclosures where stairs serve as exits
• Dead-end limits — corridors and aisles that trap people past a short dead-end length are non-compliant regardless of total exit count

The practical translation: decide the exit strategy before freezing the machine layout. Machines, racking and mezzanines then live inside the egress skeleton. The reverse order — layout first, exits where space remains — is the single most common way factories fail plan scrutiny, at DISH and the fire office alike.

Height, refuge and the vertical thresholds

Height changes a building’s legal character:

• 15 m — the classic high-rise threshold: stricter provisions begin (protected stairs, standpipes/risers, lifts and services requirements)
• 24 m — refuge areas enter: protected areas at intervals where occupants can await rescue, with the first refuge at the code-specified level and further refuges at set vertical intervals above it
• Height also moves the fire-protection selection tables: wet risers, terrace tanks and pump capacities scale with it

Most factory sheds stay below these lines — but the utility block, the multi-storey annexe, the high-bay warehouse often do not. A 26-metre ASRS warehouse is a high-rise storage occupancy in the code’s eyes, with everything that implies.

Construction, separation and fire resistance

NBC types construction by fire-resistance rating (Type 1 highest, downward), and prescribes the minimum type by occupancy, height and area:

• Structural members need rated resistance — relevant to bare steel: unprotected steel loses strength rapidly in fire, so intumescent coating, encasement or a sprinkler trade-off enters the design conversation for larger/higher-hazard buildings
• Compartmentation — maximum compartment sizes by occupancy limit how far a fire can travel; big footprints get subdivided by fire walls/barriers or compensated with suppression
• Fire separation between uses — the paint store, the flammable-liquid room, the boiler house, the transformer/DG room each carry separation requirements from the general work area
• Openings protected — fire doors and dampers where services and passages cross rated barriers

What NBC makes you install

Part 4’s selection logic assigns fire-protection systems by occupancy, height and area — extinguishers and hose reels upward through hydrant rings, wet risers, sprinklers, fixed suppression for special risks, detection and alarm, and the static water storage and pump capacity that feed it all. The specifics for industrial buildings — including the tank-size and pump questions that dominate budgets — are covered in our Fire NOC guide; the code-side takeaway is that every system requirement traces back to the classification, which is why the classification is worth engineering attention, not clerical guesswork.

For a quick indicative read on what your building triggers, use the free Fire NOC Requirement Checker.

The design decisions that decide approval

1. Classify honestly, block by block — the storage bay is H, the paint room is J-grade risk, even inside a G-2 factory. Draw the boundaries and separate them properly.
2. Fix the egress skeleton first — exits, travel distances, aisle widths — then lay out machines and racking inside it.
3. Check the vertical thresholds early — 15 m and 24 m are step-changes; crossing one casually (a mezzanine here, a silo there) imports a regime.
4. Design tender access with the site plan — approach width, gates and turning geometry are Part 4 requirements, and un-fixable after boundary walls are cast.
5. Use the sprinkler trade-offs deliberately — sprinklering a building buys relaxations (travel distance, compartment size) that often pay for the system in a big-footprint shed. That is an engineering trade, best made early.
6. Keep one drawing set — the NBC logic must read identically on the architectural, factory (DISH) and fire drawings. Reviewers cross-check; contradictions bounce files.

Common mistakes

1. Classifying the whole building by its mildest area — the office front does not launder the high-bay store behind it.
2. Deep-plan sheds with end-wall exits only — travel distance fails in the middle bays; the fix after construction is new openings through finished walls.
3. Mezzanines added “temporarily” — they add occupant load, travel distance and sometimes a storey to the count; undeclared, they fail the next inspection.
4. Collapsible gates and outward-blocked doors on required exits — cheap hardware, guaranteed objection.
5. Ignoring the sprinkler relaxations — paying for both oversized compartmentation and no suppression is the worst of both worlds.
6. Treating NBC as the fire officer’s problem — the code binds the architect’s plan, the structure and the layout; the fire scheme just inherits it.

Frequently asked questions

Is NBC 2016 legally binding?

NBC is a code, given force by the state building bye-laws, fire Acts and development-authority regulations that adopt it — which across Punjab, Haryana and UP they do. Practically: every reviewing authority reads your building against NBC 2016.

What occupancy group is a factory?

Group G (Industrial), subdivided G-1 (low), G-2 (moderate) or G-3 (high hazard) by the process and contents. Warehouses are Group H (Storage); genuinely hazardous processes/storage fall under Group J.

What is the travel distance limit in a factory?

It depends on hazard class and whether the building is sprinklered — the caps are on the order of a few tens of metres and tighten as hazard rises. The operative point: it is a layout constraint; deep-plan buildings need exits distributed, not concentrated.

How many exits does a factory need?

At least two independent, remote exits from any significant floor/area, with aggregate width computed from occupant load — and more as area, load and travel distance demand.

When is a refuge area required?

Refuge provisions enter above the code’s height threshold (24 m), with refuges at prescribed vertical intervals. Most single-storey plants never meet this; high-bay and multi-storey buildings must check early.

What is a high-rise in NBC terms?

Buildings above 15 m attract the high-rise regime — protected stairs, riser/standpipe and services requirements. Height is measured per the code’s rules; parapets and stair bulkheads have their own treatment.

Do sprinklers relax other requirements?

Yes — sprinklered buildings earn defined relaxations (notably travel distance and compartment limits). In large-footprint industrial buildings this trade-off is often the economically correct design.

What fire resistance does a steel shed need?

By construction type required for the occupancy/height/area. Where rated members are required, bare steel needs protection (coatings/encasement) or a design route that compensates — settle this at structural design, not at inspection.

How does NBC treat mixed occupancies?

Each portion meets its own occupancy’s requirements, with fire separation between them — the storage block, the flammable store and the factory floor are assessed as what they are.

Does NBC apply to warehouse racking?

Storage height, commodity and configuration drive Group H requirements — high-piled and high-bay storage move suppression and detection scope sharply upward. Racking layout is fire design, not just logistics.

Who enforces NBC on my project?

The building-sanction authority, the factory inspectorate and the state fire service, each reading their slice of the same code — which is why one coordinated drawing set matters more than any single approval.

Where do the fire-system requirements come from?

Part 4’s occupancy-based selection logic — covered in working detail in our Fire NOC guide, with an instant indicative read from the Fire NOC checker.

Design to the code, not around it

• Fire NOC Requirement Checker — what your building likely triggers, in two minutes
• Fire-NOC Assistance — NBC-compliant scheme design, submission and inspection support
• Request a Budgetary Proposal — a real number for the compliant fire and MEP scope
• The complete factory approvals roadmap — where NBC sits in the whole sequence

Secured Engineers Pvt. Ltd. is an MEPF and fire-protection EPC contractor — 535+ projects across 18+ states, ISO 9001:2015. This guide summarises NBC 2016 concepts for orientation; the code and your state’s adoption of it prevail — design against the current text and your authority’s requirements.