Raising the High-Rise Threshold from 15m to 24m

Raising the High-Rise Threshold from 15m to 24m 

On Thursday (30-04-2026) the Bureau of Indian Standards (BIS), National Building Construction Standards (NBCS) 2026 replaces the National Building Code (NBC) 2016, transitioning from a prescriptive code to a voluntary guideline framework. Key changes include making fire safety provisions advisory rather than mandatory ("should" vs "shall"). This is not an amendment. It is a full replacement by the Bureau of Indian Standards. Part 4 Fire & Life safety (NBC 2016) is now changed in Part F — Fire and Life Safety. The new standards came into effect on April 30, 2026, simultaneously replacing the widely adopted National Building Code of India 2016 (SP 7: 2016).

Whether raising the high-rise threshold from 15 m to 24 m is correct depends on who you ask.

From a real estate and development perspective, it is considered correct. It reduces bureaucratic approvals, cuts construction costs, and allows for much-needed urban densification.

From a fire safety and civic infrastructure perspective, it is highly debated and often considered wrong.

Building Height. - means the vertical distance between grade and the highest point of a building; excluding an elevator housing, a mechanical housing, a roof stairway entrance, a ventilating fan, a skylight, a steeple, a chimney, a smoke stack, a fire wall, a parapet wall, a flagpole or similar device not structurally essential to the building.

Regulations precisely define where building height measurement begins and ends to ensure code compliance.

·        Starting Point: Typically measured from the average finished ground level, plinth level (max 1.2 meters), or the top of a stilt parking floor.

·        End Point: For flat roofs, it is measured to the top of the terrace or parapet wall. For sloping roofs, it is the midpoint between the eaves and the ridge.

·        Exclusions: Architectural features like decorative towers, lift heads, chimneys, and water tanks are often excluded from this height limit

Define building height:

To define building height accurately, you must first determine the specific regulatory framework you are using. Different authorities define it based on governing factors, safety factor, spatial volume (Zoning), life safety (Fire Codes), or architectural prestige (Structural). Below factors are most important to define building height. Its not possible for a country specified a uniform building height. Building height is vary location to location.

1.   Primary Governing Factors:

The maximum permissible height of a structure is dictated by several localized and environmental variables:

·        Road Width: Most municipalities tie building height directly to the width of the abutting road to ensure traffic flow and adequate light.

·        Setbacks: Dictates the minimum open distance required from property boundaries; taller buildings demand wider setbacks.

·        Floor Area Ratio (FAR) / Floor Space Index (FSI): Controls the overall volume of the building in relation to the plot size. If you max out your FAR, your height is automatically capped.

2.   Safety and Environmental Constraints:

Vertical expansion is heavily restricted by structural and safety agencies:

·        Airport Authorities: The Airports Authority of India (AAI) enforces strict height restrictions for properties falling within the approach and takeoff funnels of airports to ensure flight safety.

·        Fire Services: Taller structures—often classified as high-rises (typically above 15 meters)—require mandatory fire-fighting infrastructure, wider emergency access, and specialized No-Objection Certificates (NOCs).

·        Heritage & Defense Zones: Strict vertical limits apply near heritage sites, monuments, or restricted military zones to preserve aesthetics and security.

3.   The Zoning Definition (Urban Planning & Land Use):

Local municipal zoning laws define height to control density, shadows, and neighborhood aesthetics. Their definitions vary widely by city, but generally use one of three baselines:

·        To the Absolute Peak: The vertical distance from the curb level to the highest structural point of the building, including decorative parapets and pitched roof ridges.

·        To the Eave: The vertical distance measured only to the lowest point of the roof overhang, ignoring the slope of the roof.

·        By Total Stories: Defining height purely by the number of occupiable floors above ground level (e.g., "Maximum 3 stories"), regardless of the exact footage.

4.   The Fire Code Definition (High-Rise Classification):

For life safety and emergency rescue calculations, fire codes ignore the roof completely. Currently India don’t have any fire code, only Indian standard code is there basis on product. They define height based purely on human occupancy and rescue logistics:

·        The Occupiable Floor Baseline: The vertical distance measured from the lowest level of fire department vehicle access (the street or fire lane) to the floor surface of the highest occupiable story.

·        The Logic: This defines whether a building is classified as a "High-Rise" (75 feet / 23 meters under IBC/NFPA, or 24 meters under India's NBCS 2026). If firefighters cannot reach that highest floor using standard exterior ladders, the building falls into a stricter safety classification

5.   The Architectural Definition (Global Rankings):

The Council on Tall Buildings and Urban Habitat (CTBUH), which officially ranks the world's tallest skyscrapers, recognizes three separate definitions for height:

1.   Height to Architectural Top: Measured from the lowest open-air pedestrian entrance to the architectural top of the building. This includes spires but excludes antennas, signage, and flagpoles.

2.   Highest Occupied Floor: Measured to the floor level of the highest consistently occupied space inside the tower (excluding maintenance-only levels).

3.   Height to Tip: Measured to the absolute highest point of the building, including antennas, flagpoles, and technical equipment.

6.   Relevant Tools & Compliance

To determine exact, legally binding restrictions for your property, check:

·        Local Municipal Authorities: Review your city's specific Development Control Rules (DCR) or Master Plan.

·        State Zoning Bylaws: Search your state’s official urban development websites (e.g., the Ministry of Housing and Urban Affairs for overarching guidelines) to locate exact zoning classifications and height limits.

International code:

Per the 2021 IBC, a high-rise building is defined as:

 A building with an occupied floor located more than 75 feet above the lowest level of fire department vehicle access."

Starting in the 2024 IBC, the definition of high-rise building has been changed to be:

A building with an occupied floor or occupied roof located more than 75 feet above the lowest level of fire department vehicle access."

NFPA 1, NFPA 101, and NFPA 5000 explicitly define a High-Rise Building as "A building where the floor of an occupiable story is greater than 75 feet (23 metres) above the lowest level of fire department vehicle access."

Focus on the Occupant: Unlike standard zoning codes that measure to the peak of the roof, the NFPA only cares about the highest floor where a human can legally stand or work. If the roof peak is at 80 feet, but the highest occupiable floor is at 70 feet, the NFPA does not classify it as a high-rise.

The Fire Truck Baseline: The measurement begins strictly at the lowest point where a fire brigade vehicle can safely park and deploy its equipment.

According to NFPA-5000, the heights of buildings are based on their type of

Construction classification shall not exceed the allowable heights outlined in Table 7.4.1.

Let's walk through how to use Table 7.4.1 from NFPA 5000 (Building Construction and Safety Code) to determine the allowable building height and area based on occupancy classification and construction type.

First Step: Purpose of Table 7.4.1 (NFPA 5000) This table provides:
- Maximum allowable number of stories above grade
- Maximum allowable building height (in feet or meters)
- Maximum allowable floor area (in ft² or m² per story)

These values are based on:
1. Occupancy classification (e.g., Business, Assembly, Residential, etc.)
2. Construction type (Types I to V, where Type I is most fire-resistive)
3. Presence of sprinklers (can provide additional allowances)

Second Step: Key Steps to Use Table 7.4.1
1. Determine the occupancy classification (e.g., Business (B), Assembly (A), Residential (R), etc.)

2. Determine the construction type
- Type I: Fire-resistive (concrete/steel)
- Type II: Non-combustible
- Type III: Non-combustible exterior, combustible interior
- Type IV: Heavy timber
- Type V: Combustible (wood frame)

3. Check for an automatic sprinkler system
- If fully sprinklered, NFPA 5000 allows increases in both height and area.

4- Look up Table 7.4.1 to find the values for:
- Maximum stories
- Maximum height
- Maximum area per floor

5- Adjust for frontage and sprinkler increases if applicable (in accordance with Section 7.5 and other related sections).

6- If you need a larger area or height, you may:
- Upgrade to more fire-resistive construction (e.g., Type IIA or IA)
- Add frontage for area increase (Section 7.5.2)

Construction Type and Fire Resistance Ratings

In India, Construction Types and Fire Resistance Ratings (FRR) are regulated by IS 1642 and IS 3809.

The regulatory framework classifies buildings into four structural categories (Type 1 to Type 4) based strictly on how long their components can withstand a fire without collapsing or transmitting critical heat.

1. Component-Specific Regulatory Examples

The code defines explicit material thickness and dimension requirements to fulfill these hourly ratings:

·        Solid Brick Walls: Requires a minimum thickness of 100 mm for a 1-hour rating, and 200 mm for a 4-hour rating.

·        RC Columns: Requires a minimum fully exposed dimension of 300 mm and a 40 mm concrete cover to achieve a 2-hour rating.

·        RC Floor Slabs: Requires a minimum solid thickness of 125 mm to fulfill a 2-hour rating.

2. The Four Types of Construction (As per IS 1642)

The classification depends on the combustibility of the materials used and the minimum fire resistance rating (expressed in hours) that the structural framework can guarantee:

·        Type 1 Construction (4-Hour FRR): Represents the highest standard of passive fire protection. Built entirely of non-combustible materials like heavily reinforced concrete (RCC) frames and thick masonry walls. All critical structural members (columns, load-bearing walls) must offer a baseline 4-hour fire resistance rating. Mandatory for high-rises and critical infrastructure.

·        Type 2 Construction (3-Hour FRR): Built with non-combustible materials similar to Type 1, but with slightly relaxed dimensional or material thresholds. Major load-bearing members must withstand fire exposure for at least 3 hours.

·        Type 3 Construction (2-Hour FRR): Commonly used for standard commercial structures and mid-rise residential apartments. The external structural envelope is non-combustible, but internal frames can have reduced protection. Key structural components require a minimum 2-hour fire resistance rating.

·        Type 4 Construction (1-Hour FRR): Applied to low-density, low-rise residential or light-hazard properties. Allows more vulnerable assemblies, requiring only a baseline 1-hour fire resistance rating for structural elements.

3. Core Fire Resistance Ratings (FRR) for Key Building Elements

Under Indian standards, different components within the same building are assigned targeted fire ratings based on their role in preventing collapse or securing evacuation routes:

·        Load-Bearing Infrastructure (2 to 4 Hours)

Columns, beams, main structural arches, and primary load-bearing walls must maintain full load capacity during a burnout. In Type 1 high-rises, these structural nodes require a rigid 120 to 240-minute rating.

·        Vertical Lifelines & Egress Enclosures (2 Hours / 120 Minutes)

The internal walls of emergency staircases, lift shafts, service ducts, and firefighting shafts must be built from solid brickwork or reinforced concrete. They require a mandatory minimum 120-minute fire rating to ensure smoke and intense heat cannot penetrate escape routes.

·        Fire Doors and Assembly Openings (1 to 2 Hours)

Fire doors placed at staircase enclosures, room compartments, and refuge areas must match the partition walls. They must feature a 60 to 120-minute rating tested under IS 3614 or BS 476 Part 22.

·        Service Shaft Access (30 to 120 Minutes)

Inspection panels and hatches for electrical cables, plumbing lines, or refuse chutes must be tightly sealed. Electrical shaft inspection doors require a 120-minute fire rating, while refuse chute hatches require at least a 60-minute fire rating.

Structural Integrity

In the Indian context, structural integrity is defined by a building's compliance with the Bureau of Indian Standards (BIS) codes, which legally dictate how structures must withstand intense environmental stresses unique to the subcontinent, such as severe earthquakes, cyclonic winds, and rapid concrete degradation.

Unlike Western countries that design primarily for heavy snow loads, Indian structural engineering prioritizes seismic ductility, monsoon moisture resistance, and localized construction quality control.

1. Seismic Design and Zoning (IS 1893)

India is divided into four distinct seismic zones (Zone II to Zone V). Structural integrity requires matching a building's flexibility to its geographic hazard level.

·        Zone V (Highest Risk): Encompasses the entire northeastern region, parts of Jammu & Kashmir, Himachal Pradesh, Uttarakhand, the Rann of Kutch, and North Bihar.

·        Ductile Detailing (IS 13920): For buildings in Zones III, IV, and V, structural integrity cannot rely on rigidity alone. Engineers must use ductile detailing, reinforcing concrete columns and beam-column joints with specific steel looping patterns so the building can sway and bend during an earthquake rather than snapping snap cleanly.

2. Wind and Cyclonic Loads (IS 875 Part 3)

India's massive coastline exposes structures to extreme cyclonic forces, while rising urban heights subject inland structures to high-velocity winds.

·        Design Wind Speed (V_b): Structural integrity calculations must factor in basic wind speeds ranging from 33 m/s (in sheltered inland areas) up to 55 m/s (in high-velocity cyclonic zones like coastal Odisha, Andhra Pradesh, and parts of Gujarat).

·        Terrain and Topography: The building frame must be engineered to resist overturning forces caused by these winds, which increase rapidly as the structure crosses the 15-metre and 24-metre height thresholds.

3. Environmental Durability and Concrete Cover (IS 456)

India's diverse climate—ranging from humid coastal zones to scorching, arid plains—directly impacts how long concrete maintains its structural strength.

·        Corrosion of Rebar: In coastal cities like Mumbai, Chennai, and Kolkata, airborne chlorides penetrate concrete and rust the internal steel rebar. As the steel rusts, it expands and causes the concrete to crack and flake off (spalling).

·        Nominal Cover Requirements: To preserve integrity, IS 456:2000 mandates strict concrete thicknesses (cover) protecting the steel based on exposure. This ranges from 20 mm for mild indoor conditions up to 50 mm or more for extreme coastal exposures.

4. Unique Structural Integrity Challenges in India

1.   The "Stilt Floor" (Soft-Story) Vulnerability: A very common practice in Indian cities is leaving the ground floor open for car parking (stilt floor) while building heavy masonry apartments above it. Without heavy structural shear walls or braced frames at the ground level, this creates a "soft story" that is highly prone to collapsing sideways during an earthquake.

2.   Construction Quality and Adulteration: Integrity is frequently compromised on-site due to excessive water being added to concrete mixes to make them easier to pour, incomplete compaction, or inadequate curing (keeping the concrete wet for 7 to 14 days to reach full strength).

3.   Unapproved Vertical Modifications: Property owners regularly add extra floors or unauthorized heavy brick partition walls years after construction without consulting a structural engineer, overloading the original foundation and column designs.

Why Raising the High-Rise Threshold from 15m to 24m Is Potentially Invidious

Raising the high-rise threshold from 15 metres to 24 metres is considered highly invidious (unjust, discriminatory, or harmful) because it compromises public safety, fire protection, and urban equity. While the shift—introduced via changes like the transition to the National Building Construction Standards (NBCS)—appeases real estate developers by cutting red tape, it strips critical safety protections away from millions of residents.

The specific regulatory and practical reasons why this change is deeply problematic include:

1. Creation of a "Regulatory Blind Spot" for Fire Safety

Under the original National Building Code (NBC) 2016 guidelines, any building above 15 metres (roughly 5 floors) was classified as a high-rise. This triggered mandatory, legally enforceable fire safety protocols.

·        The Loophole: Raising the bar to 24 metres means buildings up to 8 floors are no longer legally deemed high-rises.

·        The Consequence: These 5-to-8-story structures are completely exempt from mandatory "fire and life safety" provisions. They are no longer legally required to install automated sprinkler systems, external fire escapes, or central smoke alarms.

2. Transition from Mandates to Flawed "Advisories"

The shift strips away the legal teeth of fire enforcement.

·        The Language Shift: Provisions that previously used strict legal terms like "shall" have been replaced with "should" under the newer, loosened frameworks

·        No Enforcement: Fire safety for buildings between 15m and 24m has become purely advisory rather than mandatory. Municipal bodies and developers can simply choose to ignore them to save money, vastly increasing the likelihood of fatal blazes in dense urban pockets.

3. Exceeding the Reach of Standard Firefighting Equipment

The 15-metre threshold was not an arbitrary number; it was directly tied to the physical limits of municipal emergency services.

·        The Reach Limit: Most standard municipal fire department ladders and water tenders can easily reach up to 15 metres (4 to 5 floors) from the street level.

·        The Trap: A 24-metre building requires specialized hydraulic platforms or internal wet-riser/sprinkler infrastructure to fight a fire on the upper floors. By exempting 24-metre structures from mandatory internal firefighting infrastructure, occupants on floors 6, 7, and 8 are left entirely defenseless if a fire breaks out, as external ladders cannot reach them.

4. Severe Over-Densification of Narrow Urban Roads

Tying building height to structural definitions allows developers to exploit congested areas.

·        Bypassing Frontage Rules: True high-rises typically require wider abutting roads (often 12 to 18 metres) to allow fire trucks to maneuver.

·        Congestion: By reclassifying an 8-story building as a "low/mid-rise," developers can legally build dense, tall structures on incredibly narrow alleys. In the event of an emergency, fire engines and ambulances will find it physically impossible to access the property due to choked, narrow street layouts.

5. Socio-Economic Disparity (Urban Equity)

This policy creates an invidious class divide in urban safety standards. Luxury residential mega-towers (well above 24 metres) will retain state-of-the-art fire detection, refuge areas, and suppression systems to meet compliance. Meanwhile, affordable, multi-storey housing units and redeveloped builder floors (falling in the 15m–24m sweet spot) will be built with minimal to no fire infrastructure to maximize developer profit margins. The burden of fire risk is effectively shifted entirely onto middle- and lower-income city dwellers.

National Building Construction Standards (NBCS) 2026 selectively mimics Western high-rise thresholds—like the US International Building Code (IBC) and NFPA 75-foot (~23 m) cutoff—while neglecting the infrastructure and enforcement ecosystems that make those heights safe. India has a population of approximately 1.48 billion people, making it the most populous country globally. In contrast, the United States has a population of about 349 million people, ranking third. This means India has roughly 4.2 times the population of the United States.

Fire Safety Pillar	Western Ecosystem (IBC / NFPA Basis)	Indian Scenario (NBCS 2026)
Infrastructure Disconnect	Hydraulic and Ladder Limitations: Western municipal fire departments are universally equipped with heavy-duty aerial apparatus, snorkel trucks, and high-reach hydraulic platforms designed to scale 75-foot structures from the exterior. Municipal Water Infrastructure: In the US, high-rise codes assume a baseline of highly reliable, high-pressure municipal water mains capable of feeding automatic fire sprinkler systems indefinitely. Third-Party Verification Ecosystems: In Western jurisdictions, third-party laboratory certifications (such as Underwriters Laboratories or Factory Mutual) and strict commissioning protocols ensure that components like fire-rated doors, smoke dampers, and sprinkler arrays perform as designed.	Funding: Conversely, a majority of tier-2 and tier-3 city fire brigades in India lack the funding, equipment, and narrow-lane access required to fight fires or execute rescues above 15 metres. Municipal Water Infrastructure: In India, most mid-rise buildings must rely on localized, maintenance-heavy underground tanks and private booster pumps. If a property's private pump fails during a power cut, there is no high-pressure municipal fallback. Third-Party Verification Ecosystems: In India, a lack of rigorous, accredited local testing laboratories often leads to the installation of unverified or substandard fire safety equipment.
Legal Framework	Mandatory & Enforceable: Strict statutory codes with swift legal penalties for non-compliance.	Advisory & Decentralized: Rebranded as "Standards"; vocabulary shifted to advisory language.
First Responder Assets	High Reach Standard: Widespread municipal availability of hydraulic trucks and snorkel ladders.	Severe Resource Gaps: Aerial assets are heavily concentrated in tier-1 metros; mostly absent in tier-2/3 cities.
Water Reliability	High-Pressure Mains: Constant, utility-provided water pressure feeding internal standpipes.	Localized Systems: Heavy reliance on building-specific tanks, booster pumps, and diesel generators.
Material Testing	Rigorous Certification: Independent, third-party listings required for all fire-rated assemblies.	Evolving Lab Footprint: Limited testing infrastructure leads to frequent installation of unverified fire components.

This comparison is often viewed as misleading because buildings in the US and Europe generally benefit from: 

• mandatory automatic sprinkler protection, 

• superior compartmentation, 

• stronger code enforcement, 

• wider access roads, 

• lower occupant densities, 

• better firefighter staffing and equipment, and

• far more robust emergency response infrastructure.

Therefore, comparing only the “height number” in isolation, without considering the baseline fire and life safety ecosystem, can create a dangerously distorted equivalence._ 

The concern becomes even more serious in the Indian context because:

• fire services already suffer from severe manpower and infrastructure deficiencies, 

• urban densities are extremely high, 

• access constraints are common, 

• response times are often delayed, and

• a substantial number of residential fires occur in the 15–24 m height range itself.

For this reason, many fire professionals believe that the earlier 15 m threshold should not have been diluted unless accompanied by strong compensatory safeguards such as: 

• mandatory sprinklers,

• protected staircases,

• enhanced compartmentation, 

• smoke management systems, 

• improved firefighting infrastructure, and

• stronger enforcement mechanisms.

The real issue is whether India’s present fire safety ecosystem is sufficiently mature and resilient to safely absorb such deregulation.

Real Estate and Development Pressures

Though rarely articulated openly, the upward revision of the threshold also substantially reduces compliance burdens — read “Ease of Doing Business” (EoDB) advantages — for a very large stock of residential and mixed-use buildings falling between 15 m and 24 m.

By moving these buildings out of the “high-rise” category, developers may avoid or dilute several mandatory fire and life safety provisions, resulting in: 

• reduced construction costs, 

• simplified approvals, 

• increased saleable area, and

• faster project execution.

This is one of the principal reasons why the change continues to generate intense debate within the fire safety fraternity.

On date 08 Jun 2026, The Karnataka government had recently proposed to increase the height of high-rise buildings from the existing 15 metres to 21 metres.
The government had issued a draft notification in this regard on June 4. Convener of Citizens’ Agenda for Bengaluru, Sandeep Anirudhan said the government has been repeatedly betraying Bengaluru.
“It appears the Karnataka government has learned little from the recent Delhi fire tragedy, which has exposed the consequences of regulatory dilution and weak enforcement. Instead of strengthening compliance and ensuring accountability, the government is once again proposing amendments that benefit real estate interests and effectively regularise violations.'

“Rather than enforcing planning norms in the larger public interest, the government seems to be weakening them. This creates a dangerous cycle: developers proceed on the expectation that any violations or deviations will eventually be legitimised through subsequent amendments. Such a regulatory culture encourages disregard for the law and undermines respect for planning institutions,” he said.

Anirudhan said there is already widespread lawlessness in urban development in Bengaluru, with inadequate infrastructure, recurring flooding, traffic congestion, pressure on water resources and safety concerns.

“At a time when stricter norms are required, the proposed amendment moves in the opposite direction by promoting greater density and reduced safeguards without corresponding investment in public infrastructure,” he said.

He said policies that prioritise short-term commercial interests over public safety, environment and the city’s carrying capacity will lead to deterioration in quality of life and expose Bengalureans to hazards.

“This proposed notification seeks to clarify key planning approval issues, particularly those involving A-Khata sites, family subdivision, amalgamation, setbacks, basement parking, FAR and high-rise buildings,” said advocate Prashanth Mirle.

“The notification affects density, infrastructure load, road width, drain buffers, fire safety, redevelopment potential and neighbourhood planning. Proposals relating to high-rise buildings on roads of 12 metres and above, along with revised setback, basement parking and FAR norms, require careful scrutiny given Bengaluru’s strained civic infrastructure,” Mirle said.

Reference:

1.        http://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926.1053

2.        https://ukfireservices.com/uttarakhand_fire/wp-content/uploads/2016/06/nbc_part4_fls.pdf

3.        https://bhadrafiresafety.blogspot.com/2026/05/nbcs-2026-implementation.html

4.        https://www.lawinsider.com/dictionary/building-height

5.        https://www.sciencedirect.com/science/article/pii/S2950601825000429

6.        https://udo.raleighnc.gov/book/export/html/56

7.        https://www.buildingcode.blog/blog/high-rise-building-requirements-an-overview-for-architects-and-engineers

8.        https://newsaspire.com/new-building-standard-makes-fire-safety-advisory-raises-height-threshold-to-24m/

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