NBC 2016 Refuge Area for High-Rise Buildings — Design Guide

In a 30-storey residential tower with a fire on floor 14, occupants on floors 25-30 cannot evacuate in time through a stair while heat and smoke are rising — the stair fills with smoke faster than people can descend. The NBC 2016 solution is the refuge area: a fire-rated floor or balcony where occupants assemble and wait for the fire department or for the smoke layer to clear. This article is the practical guide to refuge-area design for Indian high-rise buildings — when they're mandatory, what size they must be, what standards they must satisfy, and how architects integrate them without sacrificing rentable floor area.

What a refuge area is

Per NBC 2016 Part 4 Cl. 4.8 (Refuge Area), a refuge area is a fire-rated, ventilated, smoke-protected zone within the building where occupants can assemble during fire emergencies and wait for rescue. It is not a path of escape — it is a holding area separate from the evacuation route, designed to provide tenable conditions (breathable air, temperature below 35°C, no smoke ingress) for at least 2 hours while firefighters address the fire below.

Refuge areas serve two distinct populations: (a) mobility-impaired occupants — wheelchair users, elderly, injured persons who cannot self-evacuate via stairs. NBC requires refuge areas accessible from every floor for hospital occupancies and recommended for office above 24 m. (b) upper-floor occupants in burning towers — for buildings above 24 m where stair evacuation may take longer than the fire's progression. The refuge floor here serves as a tenable holding area until the fire department arrives.

When refuge area is mandatory

NBC 2016 Cl. 4.8.1 specifies refuge area requirements by occupancy and height:

Building height	Refuge frequency	Occupancy applicability
≤ 24 m (8 floors typical)	Not mandatory	—
24 m to 39 m	1 refuge area at mid-height	All except hospitals (which require every floor)
39 m to 60 m	1 refuge area at every 7 floors	All except hospitals
Above 60 m	Refuge at every 7 floors + 1 above 60 m	All; hospitals every floor
Hospitals (Group C-1)	Refuge area at every floor	Group C — irrespective of height

The "every 7 floors" rule is empirical — based on testing of evacuation time vs. smoke buildup in stairs. With pressurised stairs and active sprinkler systems, evacuation from above floor 7 of an unrelated zone takes ~10-15 minutes; refuge areas accommodate occupants who cannot make this descent in time. For hospitals where evacuation requires moving non-ambulatory patients, the every-floor refuge avoids any need for stair descent at all.

Required refuge area size

Per NBC 2016 Cl. 4.8.2, the size of each refuge area is calculated from the population it serves:

Refuge area size = (Occupants served × 0.3 m²/person) + minimum 15 m²

The 0.3 m² per person allowance assumes occupants stand or sit with minimal personal space — denser than normal occupancy but reasonable for the limited time they wait. The minimum 15 m² ensures even small buildings have a usable refuge regardless of population. Maximum population per refuge floor: NBC doesn't cap explicitly, but practical guidance suggests 200 occupants per refuge area.

Worked example — 30-storey residential tower

Building: 30 floors of residential apartments, 4 apartments per floor, 4 occupants per apartment = 16 occupants/floor. Total occupants 480.

Building height: 30 × 3 m = 90 m. Above 60 m threshold.
Refuge floors required: at every 7 floors above 24 m. So floors 7, 14, 21, 28 = 4 refuge floors. Plus one additional above floor 30 (or terrace refuge).
Per-refuge population: Each refuge serves 7 floors × 16 occupants = 112 occupants.
Refuge size required: 112 × 0.3 m² = 33.6 m². Above the 15 m² minimum, so refuge area = 35 m² typical.
Total refuge floor area: 4 × 35 m² = 140 m² of dedicated refuge area in the tower.

Refuge area design requirements

NBC 2016 Cl. 4.8.3 specifies what makes a refuge area function as such — not just any open space qualifies:

Fire-rated enclosure: 2-hour fire-rated walls separating refuge area from rest of building. 2-hour fire-rated door at the refuge entrance.
Smoke protection: The refuge area must have positive air pressure (slightly higher than outside corridor), or open balcony with operable but defaultedly-open louvers ensuring smoke cannot ingress. Pressurisation system: typically 25-50 Pa above outside corridor.
Independent ventilation: Mechanical ventilation supplying fresh outdoor air, NOT recirculated from elsewhere in the building. Ventilation rate: 8-12 air changes per hour.
Independent power supply: Connected to UPS or DG set, NOT just main grid. Ventilation must continue during electrical fire emergency.
Access: Accessible from at least two directions (separate fire stairs or one stair plus one corridor). Must be reachable without passing through the burning floor.
Communication: Refuge area must have intercom or voice-evacuation speaker connected to the fire-alarm panel. Wall-mounted emergency phone is typical.
Visibility: Adequately lit by emergency lighting (battery-backed for 2 hours).
Signage: Clear "REFUGE AREA" markings at the entrance from all approach directions.
Open balcony alternative: Some Indian high-rise designs use open external balconies (with 1.0 m railing) as refuge areas. Per NBC Cl. 4.8.4, this is acceptable if the balcony depth ≥ 1.2 m and the railing is non-combustible, with weather protection.
Connectivity to firefighters' lift: The refuge area must be reachable by the firefighter's lift — required in buildings ≥ 30 m height.

Architectural integration

The challenge for architects is providing 35 m² of dedicated refuge area on multiple floors without losing rentable space. Three common Indian patterns:

Sky-bridge or terrace refuge: Designate the building's sky-bridge connecting two cores or a partial-floor terrace as the refuge. Dedicated; doesn't impact rental floor.
Dedicated refuge floor (no rental): One floor at every 7-storey interval contains lift machine room, water tank, and refuge area. Architecturally efficient because services already concentrated here.
Balcony refuge — fire balcony per apartment: Each apartment has a small enclosed balcony (1.5 m × 2 m typical) as the refuge. Sums to building-wide refuge area, no dedicated floor needed. Common in newer Indian apartment design but requires careful detailing.

The lift machine room and water tank floor (typically every 6-7 floors) is the natural candidate for refuge area integration. The architectural cost is small (~1-2% of rentable area) and the safety benefit is enormous.

Common Indian project mistakes

Confusing refuge with assembly area: Lobbies, common corridors, and waiting areas are NOT refuge areas — they don't have fire-rated enclosure or pressurisation. NBC explicitly defines refuge as a designated, fire-protected zone.
Refuge area without independent ventilation: Just a fire-rated room without ventilation will fill with carbon dioxide from occupants in 30-60 minutes. Ventilation system on UPS is mandatory.
Using refuge as storage or service: The refuge must remain unobstructed at all times. Indian buildings often use them as storage for housekeeping equipment — fire NOC inspectors penalise this severely at periodic audit.
Treating refuge as a decorative balcony: Open balconies must satisfy specific NBC depth (≥1.2 m) and railing height (≥1.0 m) requirements. Glass-railed decorative balconies typically don't qualify.
Refuge area exit only via the fire stair: NBC requires multi-direction access. A refuge area reachable only via the same stair that's smoke-filled is non-compliant.

Site reality: A 28-floor Mumbai residential tower had refuge areas on every 7th floor as required, but they shared HVAC ductwork with the apartment levels — meaning smoke from a fire could enter the refuge through the ducts. Discovered during fire NOC commissioning. Retrofit required separate ducting and additional pressurisation fan: ₹1.4 crore. Always specify refuge ventilation as completely independent of rest of building.

Hospital refuge requirements

Hospitals (Group C-1) follow stricter rules per NBC Cl. 4.8.5:

Refuge area on EVERY floor — not every 7 floors. Reflects the inability to move non-ambulatory patients downstairs.
Refuge size per floor: 0.5 m² per patient bed + 0.3 m² per staff/visitor.
Direct access from patient rooms: Maximum 22.5 m travel distance from any patient room to refuge.
Bed-accessible: Refuge must accommodate hospital beds being wheeled in. Door width ≥ 1.5 m.
Independent oxygen supply: If patients require oxygen, refuge area must have piped O₂ supply.
Examination and triage capability: Refuge must be sized to allow medical staff to examine and triage patients during fire emergency.

Frequently asked

What is a refuge area in a high-rise building?

A refuge area is a fire-rated, ventilated, smoke-protected zone designated as a holding area where occupants assemble during fire emergencies. Per NBC 2016 Part 4 Cl. 4.8: 2-hour fire-rated enclosure, independent ventilation, positive air pressure or open balcony, accessible from multiple directions, sized at 0.3 m² per occupant served (minimum 15 m²).

When is refuge area mandatory in Indian buildings?

Per NBC 2016 Cl. 4.8.1: mandatory for all buildings above 24 m height (typically 8 floors). Refuge frequency: 1 at mid-height for 24-39 m buildings; 1 at every 7 floors for 39-60 m; 1 at every 7 floors plus 1 above 60 m for buildings ≥ 60 m. Hospitals (Group C-1) require refuge on EVERY floor regardless of height.

How much refuge area is needed per occupant?

Per NBC 2016 Cl. 4.8.2: 0.3 m² per occupant served, with minimum 15 m² per refuge area. For a typical 7-floor zone with 100 occupants: 100 × 0.3 = 30 m² required. Hospital beds require 0.5 m² per bed. Refuge floors are typically integrated with lift machine rooms and water tanks to minimise rentable-floor impact.

Is an open balcony acceptable as refuge area?

Yes, per NBC 2016 Cl. 4.8.4 — provided: (a) balcony depth ≥ 1.2 m, (b) railing ≥ 1.0 m height, non-combustible, (c) weather protection (overhang or canopy), (d) access from multiple directions, (e) emergency lighting, (f) signage. Open balconies are increasingly common in modern Indian apartment design as integrated refuge areas, simplifying compliance.

What is the difference between refuge area and assembly point?

Refuge area is INSIDE the building — fire-rated, smoke-protected, independent ventilation, designated for occupants who cannot safely evacuate. Assembly point is OUTSIDE the building — typically a designated patch of paving or open ground where evacuated occupants gather for headcount and emergency response. Both required by NBC; they serve different functions.

Related references on InfraLens

The one-page summary

If you remember nothing else: Refuge area mandatory above 24 m height. Every 7 floors above 39 m. Every floor for hospitals. 0.3 m² per occupant served, minimum 15 m². 2-hour fire rating, independent ventilation on UPS, multi-direction access, open balcony alternative if depth ≥ 1.2 m. Architects typically integrate refuge with lift machine rooms (every 7 floors) — small architectural cost, large life-safety benefit.