Cite this image:

Speckert, C. (2022). Jurisdictions: Maximum Permitted Height for Single Stair Buildings [Infographic]. McGill School of Architecture. Updated in April 2025. Retrieved from https://secondegress.ca/Jurisdictions

Maximum Building Height
Explanation of code interpretation and additional information regarding relevant restrictions to maximum floor area, occupancy load, travel distance, etc.

Note: Some jurisdictions have published a translation of their building code in English. Otherwise translations have been provided by a native speaker, Google Translation or have been interpreted via correspondence with a local architect. Please refer to the original source documents for clarification and updated information.

2 storeys
The National Building Code of Canada and provincial versions (except British Columbia, see below) does not permit multi-unit residential buildings exceeding 2 storeys to be served by a single exit. The requirements under 3.4.2.1.(2) allow floor areas in a building not more than 2 storeys in height to be served by a single exit. Group C is the occupancy category for residential uses.

The National Building Code of Canada does allow an individual dwelling unit to be served by a single exit under certain conditions captured in 3.3.4.4. and 9.9.9.1. that are commonly referred to as townhouse, rowhouse and stacked townhouse conditions.

3.4 Exits
3.4.2 Number and Location of Exits from Floor Areas
3.4.2.1. Minimum Number of Exits

2) A floor area in a building not more than 2 storeys in building height, is permitted
to be served by one exit provided the total occupant load served by the exit is not more than 60, and

a) in a floor area that is not sprinklered throughout, the floor area and the travel
distance are not more than the values in Table 3.4.2.1.-A, or

b) in a floor area that is sprinklered throughout
i) the travel distance is not more than 25m, and
ii) the floor area is not more than the value in Table 3.4.2.1.-B.

The exception under 3.3.1.3.(9) also confirms that a public corridor served by a single exit is permitted for conditions permitted by 3.4.2.1.(2).

3.3.1. All Floor Areas
3.3.1.3. Means of Egress

(9) Except as permitted by this Section and by Sentence 3.4.2.1.(2), at the point
where a doorway referred to in Sentence (8) opens onto a public corridor or exterior
passageway, it shall be possible to go in opposite directions to each of 2 separate exits.

6 storeys
The British Columbia Building Code has been amended to enable the design and construction of multi-unit residential buildings with a single exit stair, by ministerial order on August 27, 2024. The changes were developed based on the Single Egress Stair Building Designs: Policy and Technical Options Report prepared for the Building and Safety Standards Branch, Ministry of Housing, by Jensen Hughes. 

“Single exit stair residential buildings are far more than just a residential building with an exit stair removed. Single exit stair residential buildings are limited in height, area, travel distance and occupancy load, and include compensatory measures as well as rely on a high-level of operations and management oversight and a high-level of local fire department capability and capacity to achieve an acceptable level of risk comparable to other new buildings. “

The requirements apply to buildings of only residential occupancy that:

a) are not more than six storeys in building height

b) have a height not more than 18 m measured between the floor of the first storey and the uppermost floor level, excluding any floor level within a rooftop enclosure that is not considered as a storey in calculating building height in accordance with Sentence 3.2.1.1.(1),

c) contain not more than four dwelling units on each floor,

d) does not exceed an occupant load of 24 persons per floor, and

e) have a travel distance from

i) any part of the floor area to an exit not more than 25 m, and
ii) each dwelling unit to an exit of not more than 6 m.

Additional requirements include:

• automatic sprinkler systems throughout (NFPA 13), including balconies
• exits to be constructed with finishes of limited flame-spread rating and smoke development classification and increased fire separation of 2 hours
• increased exit facility width of 1500mm discharging directly to the exterior
• exit stair shafts to be designed to limit the movement of smoke
• increased fire-protection rating of not less than 45 minutes for all suite entry doors and  all suite entry doors and doors along public corridors to be equipped with hold-open devices
• requirements for a high-level local fire department and high-level building operations and management to ensure ongoing fire system inspections.

3 storeys (applicable only to the restoration and rehabilitation of heritage buildings)
Part 11 of the Vancouver Building By-Law sets out prescriptive alternative compliance measures for existing buildings.Section 11.5 sets out prescriptive alternative compliance measures for heritage buildings and is only applicable to the existing conditions and does not apply to new work which must conform to the requirements for new construction in other parts of the by-law

No. 22: Exits
Floor areas may be served by a single exit within the limits of Sentence 3.4.2.1.(2).(b) provided:

(a) the building does not exceed 3 storeys in building height,
(b) the building is sprinklered with fast-response sprinklers, and
(c) all floor areas are protected by a system of smoke detectors connected to a fire alarm system.

United States (IBC)

3 Storeys (up to 6 storeys in some jurisdictions)
The US model building code permits single exits in apartment buildings (R-2 occupancy) of not more than three storeys in building height, with a maximum of 4 dwelling units per storey. The building must be sprinklered throughout (NFPA 13-R).

Each state and some cities also have their own building code or amending regulations. New York City, the City of Seattle and State of Hawaii (Honolulu) allow for single exit conditions in apartment buildings of up to 6 storeys in building height, with additional restrictions on floor area, number of dwellings and travel distance. They also include additional automatic fire suppression, smoke control and compartmentation requirements.

(Revision December 2024: The City of Chicago does not adopt the 3 storey permissions of the IBC and limits single exits for R-2 occupancies to not more than 2 storeys.)

Seattle Building Code 2018 - Chapter 10: Means of Egress
Section 1006.3.3 Single exits

NYC Building Code 2014 - Chapter 10 Means of Egress (amended IBC 2009)
Section 1021.1 Single Exits

5. Buildings of Group R-2 occupancy of construction Type I or II not exceeding six stories and not exceeding 2,000 square feet (186 m2) per story. 

Hawaii State Building Code 2018 (amended IBC 2012)

Note: Additional information regarding other United States jurisdictions is available here: https://www.centerforbuilding.org/trackers

United States (NFPA)

4 Storeys
Chapter 30 of the NFPA 101 Life Safety Code permits a single exits in new apartment buildings of not more than four storeys in building height, with a maximum of 4 dwelling units per storey. 

5 storeys
Mexico City specifies that multi-family housing up to five storeys (including the ground floor) may have a single exit if they have not more than four dwelling units per storey.

4 storeys
Rules laid out by the Fire Department of Costa Rica's Engineering Unit defer to NFPA 101, which allows four storeys to be served by a single exit if there are no more than four units per storey and sprinklers are provided, among other limitations. In addition, there is an exception that allows single-exit buildings to be unsprinklered if the height is limited to three storeys.

Original text in Spanish:

7.20. Excepciones para medios de egreso
Puede aplicarse cualquier excepción para medios de egreso que esté establecida n la norma NFPA 101, siempre que se cumpla la totalidad de requerimientos stablecidos para su implementación, adicionalmente a efectos de este eglamento, se permite el uso de las siguientes excepciones para medios de egreso:

7.20.1) Apartamentos: (Ver resumen en tabla 6) Cualquier edificio de apartamentos, que enga tres pisos o menos y cuatro unidades de vivienda o menos en cada piso, puede contar con una única salida, siempre que se apliquen todas las siguientes condiciones:

a) Que la escalera esté separada del resto del edificio mediante barreras que
tengan una clasificación de resistencia al fuego no menor a 1 hora, con conjuntos de puertas cortafuego autocerrantes de 1 hora de resistencia que protejan todas las aberturas entre el cerramiento de la escalera y el edificio.

b) Que la escalera no sirva más de medio piso por debajo del nivel de descarga de la salida.

c) Que todos los corredores que sirven como acceso a las salidas tengan una
clasificación de resistencia al fuego mínimo de 1 hora.

d) Que no haya más de 11 m de distancia de recorrido desde la puerta de entrada de cualquier unidad de vivienda hasta la salida.

e) Que se provea una separación horizontal y vertical con clasificación de
resistencia al fuego de 1 hora entre las unidades de vivienda.

Brazil

80m (São Paulo) / 25 storeys (Rio de Janeiro)
São Paulo requires two exit staircases for buildings exceeding 36m in height, except that apartment buildings (Division A-2 occupancies) up to 80m in building height are permitted to be provided with a single exit staircase.

“5.5.3.5 Nas edificações com altura acima de 36 m, independente do item 5.5.3.1, é obrigatória a quantidade mínima de duas escadas, exceto para a Divisão A-2. Nas edificações da Divisão A-2, com altura acima de 80 m, independente do item 5.5.3.1, é obrigatória a quantidade mínima de duas escadas.“

Rio de Janeiro requires two exit staircases for apartment buildings (Division A-2 occupancies) of 25 or more storeys in building height.

“5.3.2.2 As edificações com 15 ou mais pavimentos, qualquer que seja a área do pavimento, devem possuir, no mínimo, duas escadas de emergência. Excetua-se as edificações das divisões (A-2, A-6, G-2).

"(D) As edificações das divisões (A-2, A-6, G-2) com 25 ou mais pavimentos, qualquer que seja a área construída, devem possuir no mínimo duas escadas de emergência."

25m
The Building Code of Australia permits one exit for apartment buildings (Class 2 building) of not more than 25m in building height. ‘Fire-isolated’ (corridor separated) exit stairs are required for buildings of more than 3 storeys or 4 storeys where sprinklering or increased fire separation is provided. A maximum dead end travel distance of 6m applies.

25m
The New Zealand Building Code permits one exit for apartment buildings (risk group SM) where the escape height is no greater than 25m if sprinklered, and 10m if unsprinklered. Dead-end limits on travel distance apply.

18m (effective September 30, 2026) / No Maximum Height Limit
Until recently, the United Kingdom did not have a maximum height limit for single stair in multi-unit residential buildings. Table 2.1 determines the maximum travel distance to the single exit stair. Office buildings can be single stair where the height of the uppermost occupied floor level does not exceed 11m above grade (Section 3.3) and the occupant load per storey does not exceed 60 persons.

Update (January 2023): In response to the Grenfell Tower inquiry, the Royal Institute of British Architects and London Fire Brigade submitted a request to further study the fire safety of single exit stair high-rise residential buildings. On December 23, 2022 the UK Government announced an open consultation to “introduce a threshold whereby residential buildings above 30 metres in height should be designed and built with 2 staircases.”

Update (July 2023): “The Housing Secretary, Michael Gove, announces that the UK government will require two staircases in all new residential high-rises taller than 18m.”

Update (September 2024): Amendment to Approved Documents, Building Regulation 2010, taking effect on 30 September 2026, including revised requirements applicable to horizontal escape for flats served by a single common stair. These include maximum travel distances for escape in one direction and requirement for flats to be separated from the common stair by a protected lobby or common protected corridor.
 

18m
Following the Grenfell disaster, Scotland reviewed the Building Standards on Fire Safety in Scotland and issued a recommendation for change to the guidance on escape (2.9).

“36. On the need for additional stairways there was no consensus amongst the Review Panel members. However the view of the chair, which was endorsed by all members of the international sub-group, was that there was a need to require at least two stairways in high rise domestic buildings with a storey at a height of 18m. This is firstly to provide an alternative in case of the failure of the first stairway and secondly to provide a route for escape if the other stairway is being used for fire-fighting operations. The height of 18m is currently used with in the Technical Handbooks and it was considered sensible to retain it as it is well known and relates to the ability of the fire service to intervene if absolutely necessary through the use of high reach appliances.”

“Recommendation 5 - Changes are needed to the simple guidance on escape. In particular, in domestic buildings over 18m there should be two stairways and fire service activated evacuation sounders in each flat.“

Building Standards Technical Handbook 2022: Domestic - Table 2.6 Escape routes from flats and maisonettes (including social housing dwellings) and any ancillary rooms
For buildings where the height of the topmost storey is more than 7.5m but not more than 18m above adjacent ground:

At least one escape route and
- protected lobbies (see clause 2.9.13), and
- smoke ventilation (see clause 2.9.14 – 2.9.16), and
- not more than 10m travel distance inside protected lobbies, or
At least two escape route [3] and
- not more than 30m travel distance in protected corridor

60m
Ireland’s technical guidance documents allow a single exit stairway for residential buildings (flats) with a building height of up to 60m.

(Note: a previous version of this jurisdictional scan incorrectly referenced a maximum building height of 10m / four storeys based on Section 1.6.6.1 Small Single-Stair Buildings, however larger buildings are permitted to be provided with a single vertical means of escape where other criteria is met).

TDG-B Volume 2 deals solely with dwelling houses, however “where very large or unusual dwelling houses (over 15m in height), are proposed, or where an alternative approach is required, some of the guidance in Volume 1 may be need to supplement that given by Volume 1.” TDG-B Volume 1 applies to all other types of buildings of up to 60m in height. These technical guidance documents require sprinklers in all ‘flatted’ dwellings over a building height of 15m and is based on a simultaneous evacuation strategy. British Standard BS5588-1:1990 is applicable for the performance-based design of buildings of more than 60m in height.

TDG-B Volume 1, Paragraph 1.6.6 identifies the applicable travel distance constraints and Paragraph 1.6.7.2 describes the design of escape stairways. A maximum travel distance of 45m from the farthest location in the floor area to the exit is permitted for unsprinklered buildings and is increased to 60m for sprinklered buildings.

16 Storeys
Sweden permits one exit for class 3 (residential) buildings up to 16 storeys with a maximum occupant load of 50 people per storey and a maximum travel distance of 30m. Different requirements for the fire-protection rating/smoke-tightness standard of closures apply for buildings of not more than 8 storeys and buildings of more than 8 but not more than 16 storeys.

45m
Denmark permits a single exit for multi-unit residential (category 4) buildings up to 45m in building height, with a maximum of 4 dwelling units per storey with direct access from the dwelling unit to the exit stair (no corridor separation). For building with floors more than 22m above ground, where the rescue openings cannot be reached by rescue ladder, a pressurized “security” stair with corridor separation is required and a maximum of 6 dwelling units per storey is allowed.

These are prescriptive, pre-approved conditions. According to a local architect, buildings over 45m in height require a performative code-compliance process and fire engineering consultations.

8 Storeys
Norway permits a single exit for multi-unit residential (risk class 4) buildings up to 8 storeys so long as each dwelling unit has an operable window or balcony for rescue and firefighting. A maximum travel distance of 15m from the dwelling unit entry door to the exit stair door applies.

Finland

52m
Finland allows for a single exit for multi-unit residential (’Yleensä‘) buildings up to 52 metres measured to the floor level of the uppermost occupied storey. The single exit staircase must be protected against fire (’Palolta suojattu’) in buildings exceeding 24 metres in height and 300m² in area. A fire sprinkler system is required for buildings exceeding 24 metres in height where a single staircase is provided.

The following graphic is from the unofficial translation. Legally binding versions only in Finnish and Swedish.

50m
France permits a single exit for residential buildings up to 50m in building height. Two means of egress and additional life safety measures are required for high-rise buildings (immeuble de grande hauteur) exceeding this height.

Belgium

25m
The Belgian code is subdivided by low-rise (under 10m), mid-rise (10m to 25m) and high-rise (over 25m) building heights. Belgium allows one exit for mid-rise buildings of not more than 25m in building height with a maximum occupant load of 50 people per fire compartment.

5 Storeys (12.5m Finish Floor Level)
The Netherlands permits one exit for multi-unit residential building where the floor level of the uppermost storey is no more than 12.5m above grade (5 storeys), where the floor area served by the single exit does not exceed 800m², with a maximum floor area per dwelling unit of 150m². The Netherlands also permits one exit for multi-unit residential buildings where the floor level of the uppermost storey is not more than 6m above grade (three storeys) with no more than 6 dwelling units served by the single exit.

Note: correspondence with a Dutch architect indicates that the 5 storey limit can be exceeded by providing a ‘safety escape route’ [Veiligheidsvluchtroute], such an escape route is separated by a non-enclosed exterior gallery to prevent the passage of smoke into a single staircase (see diagram below).

As a recent example, the multi-unit residential building BBSH20A in Amsterdam (completed in 2021), by Olaf Gisper Architects  is a 10 storey mass timber design with 29 dwelling units and a ‘safety escape route’ single exit stair.
https://olafgipser.com/projects/residential-building-bsh/#1 

Germany

60m
Germany permits a single exit for multi-unit residential buildings up to 60m in building height. Buildings over 22m with a single exit stair require additional fire safety measures including the fire separation and pressurization of the single exit stair as safety stair (Sicherheitstreppenraum) and assembly fire ratings of at least 120 minutes. An additional firefighting elevator is typically required for buildings over 30m in height.

The model high-rise building code applies to high-rise buildings over 22m in building height and is prepared by the federal “Bauministerkonferenz” (assembly of construction ministers) tasked with establishing the model code referenced by the 16 individual states within Germany.

No Maximum Height Limit (75m / 100m deemed acceptable)
Switzerland permits a single exit for multi-unit residential buildings without a specified maximum building height with a 900m² maximum floor area per storey, a maximum total travel distance of 35m and a maximum occupant load of 100 per floor area. Sprinklering is typically not required.

The association of cantonal fire insurance companies establishes the fire safety regulations across Switzerland.

Update September 2024: According to several fire protection engineers practicing in Switzerland, high-rise buildings of more than 75 to 100m in building height are provided with two exits.

Austria

90m
Austria permits a single exit for multi-unit residential buildings up to 90m in building height provided that the single staircase includes additional compartmentation and smoke control measures. Maximum travel distances are also applicable. For buildings of more than 90m in height, a performance-based design (PBD) fire safety design would be required.

The Austrian Institute of Construction Engineering (OIB) publishes guidelines [available in German only] that harmonize the construction engineering regulations across the country. Implementation of building regulations in Austria are the responsibility of the territories.

The OIB fire protection regulations for buildings with an escape level more than 22m above ground further distinguish between three sub-categories of building height: (i) where the uppermost occupied storey is not more than 32m above ground, (ii) between 32m and 90m above ground, and (iii) buildings with the uppermost occupied storey more than 90m above ground.

Poland

25m
Poland permits a single exit for medium-high multi-unit residential (Division ZL IV) buildings up to 25m in building height or of a maximum of 9 storeys above grade. A single exit is also permitted in residential buildings exceeding 25m in building height with additional life safety measures and a maximum floor area per storey of 750m².

Romania

28m
Romania permits a single exit for multi-unit residential buildings of up to 28m in height.

Two exit staircases are required for buildings classified as ‘tall buildings’, defined as having a finished floor level of the entrance floor of the uppermost dwelling unit more than 28 meters above the level of firefighter access.

Belarus

75m
Belarus permits a single exit for multi-unit residential buildings of up to 75m in height.
Non-residential buildings with a single exit stair are permitted up to 15m in height, while residential buildings (Occupancy type F1.3) with a single exit stair are permitted where the floor area per storey served the single exit does not exceed 550m2. Several adjacent single exit stair conditions are permitted where a firewall separation having a fire-resistance rating of at least REI 45 is provided.

Refer to Chapter 7 and Annex G, Table G.1 of the Source Document.

Residential buildings of more than 75m in height and non-residential buildings of more than 50m in height are classified as high-rise buildings and follow a separate set of regulations which requires a minimum of two separate exit stairs.

Russia

75m
Russia permits a single exit for multi-unit residential buildings of up to 75m in height.

Multi-unit residential buildings with a single exit stair are permitted where the floor area per storey served the single exit does not exceed 500m2. The construction type and design of the exit staircase depends on the building height as well as the design of smoke control measures, fire alarm systems and fire suppression systems.

Refer to Chapter 6.1. of the Source Document.

Residential buildings of more than 75m in height and non-residential buildings of more than 50m in height are classified as high-rise buildings and follow a separate set of regulations which requires a minimum of two separate exit stairs. (Section 1.2)

Italy

80m
Italy permits a single exit for multi-unit residential buildings of up to 80m in building height with a maximum floor area per storey of 500m² to be served by the single exit.

The “Tabella A” [Table A] of the Italian prescriptive fire regulations for civil buildings provides several parameters in relation to:

- maximum floor area of each multi-storey fire compartment
- maximum floor area per storey
- specific fire protection requirements for the exit stair and elevator shafts
- required fire-resistance ratings (REI) of exit stairs, lifts, fire doors and walls
.

The requirements are sub-categorized depending on building height between type “a” (12m to 24m), type “b” (24m to 32m), type “c” (32m to 54m), type “d” (54m to 80m), and type “e” (above 80m). Buildings above 80m in height require two stairs and a helicopter rescue pad on the roof.


Buildings in Italy can also be designed by applying the performance-based Italian Fire Code. The ‘deemed-to-satisfy’ solution to achieve performance level II requires at least two exits where the uppermost occupied storey exceeds 32m in building height.

Codice di prevenzione incendi in inglese [Italian Fire Safety Code in English]

28m
Spain permits a single exit for multi-unit residential buildings up to 28m in building height measured as the floor level of the uppermost storey, where the total occupancy load of the building is not more than 500 people. The exit stair must be protected (fire separated) for residential buildings over 14m in building height.

Portugal

28m
Portugal allows a single exit for apartment buildings of not more than 28m in height with a maximum travel distance of 15m. Buildings greater than 28m in height require at least two exits regardless of occupancy types.

The minimum clear width of the exit staircase serving residential occupancies also varies depending on building height.

- for buildings of not more than 9m in height, min. 900mm wide

- for buildings of 9m to 28m in height, min. 1200mm wide

- for buildings of more than 28m in height, min. 1400mm wide

Regulamento Técnico de Segurança Contra Incêndio em Edifícios [Technical Regulation on Fire Safety in Buildings]

16m
Egypt permits a single exit for any building up to 16m in building height where the occupant load is not more than 60 persons per floor and the travel distance to the exit is not more than 9 metres.

6 Storeys
Kenya permits a single exit for any building up to 6 storeys in building height or where the floor level of the uppermost storey is not more than 17m above grade.

3 Storeys
Rwanda permits a single exit for buildings of up to 3 storeys in building height and no individual escape route shall be designed for a population of more than 200 persons.

The required width of the escape route is specified in Table 3.10.2-3. 

Any Basement or Above Ground Storey

3.4.6.12
A building with a storey above or below the ground level shall be served by not less than two separate stairways; and the entrance to the emergency stairway shall not be less than 5.0 meters from the entrance to any other stairway.

3 Storeys
South Africa permits a single exit for buildings up to 3 storeys in building height.

21.5m
Turkey permits a single exit for buildings with a height of not more than 21.50m.

15m
The UAE permits a single exit for buildings up to 15m in building height where an automatic sprinkler system is provided, with a maximum floor area per storey of 500m² and where there are not more than 4 dwelling units per storey.

29m
The Israeli code permits a single exit for buildings not more than 29m in building height. Buildings up to 13m in height can have a single unprotected stair. The Israeli code also sets a maximum travel distance of 30m to the exit stair. Buildings exceeding 13m in height may have a single protected stair if residential use, or any use not exceeding a maximum occupancy load of 30 people per floor.  All buildings regardless of occupancy exceeding 29m in building height require two stairs, one of which may be an exterior stair.

30m / 6 Storeys
3.1.10.2.4. - In the following cases, each residential unit can exceptionally access only one exit. A single exit is allowed for buildings up to 23m in height with maximum 2 dwelling units per floor, in which the stair must be fire rated.

According to a local architect, the fire regulations were amended in 2019 to permit a maximum height of 30m, or 6 storeys above ground, in which the stair must be ventilated, the building sprinklered, and a maximum of 3 dwelling units per floor.

3 Storeys
8.18.2 (c) - Buildings classified as Group R-2 equipped throughout with an automatic sprinkler system in accordance with Section 7.3 of SBC 801 and provided with emergency escape and rescue openings in accordance with Section 8.25 shall have a maximum height of three stories above grade, or as agreed by the local municipality.”

15m
India permits a single exit for multi-unit residential buildings up to 15m in building height with a maximum floor area of 500m² per storey.

33m
Bangladesh permits a single exit for multi-unit residential buildings of up to 10 storeys or 33m in height. A single exit is not permitted for high-rise buildings, defined as buildings of more than 10 storeys or 33m in height, measured from the level of fire department vehicle acess.

Article 3.14.2 specifies that a single exit is permitted from floor areas where the occupant load does not exceed 50 occupants. For residential uses (Classification A), occupancy load is calculated as 1 occupant per 18m2 in gross floor area (Table 4.3.1.) corresponding to a maximum floor area of approximately 900m².

The 2020 edition of the Bangladesh National Building Code (BNBC) specifies the minimum requirements for the design and construction of all buildings within Bangladesh. In addition, Rajdhani Unnayan Kartripakkha (RAJUK) [Capital City Development Authority] is the public agency responsible for co-ordinating urban development in Dhaka and is resposible for approving and enforcing building safety requirements in Dhaka city. Although their rules apply only to Dhaka, they are generally followed in other parts of the country as well. RAJUK rules in effect since 2008 specify that flats in apartment buildings (A2 occupancy) can be served by a single exit in buildings of up to 10 storeys and 33m in height with a maximum of 4 dwelling units per storey and a maximum travel distance of 23m to the exit.

According to Mr. Maidul Islam, the previous edition of the BNBC defined high-rise buildings as buildings of more than 6 storeys or 20m in height and it is still common practice of local government agencies to require two exit stairs for buildings of more than 6 storeys in height.

One Storey
Pakistan requires that “in new and existing occupancies, the number of means of egress from any balcony, mezzanine, story, or portion thereof shall be not less than two” and that “exit access corridors shall provide access to not less than two exits.”

As a result, any building of more than one storey requires two exits. 

18 Storeys
China permits a single exit for multi-unit residential buildings up to 18 storeys in building height with a maximum floor area of 650m² per storey. A maximum travel distance of 15m from the dwelling unit door to the exit applies for buildings less than 10 storeys in height, which is shortened to a maximum travel distance of 10m for buildings between 10 and 18 storeys in height.

No Maximum Height Limit
South Korea does not set a maximum building height for multi-unit residential buildings with a single exit stair.

The code only limits single exit stair conditions for residential occupancies based on horizontal restrictions, including a maximum of 4 dwelling units per storey or a maximum inhabited floor area of 300m²per storey as well as maximum travel distance limits.

Article 35 requires the exit stair to be a ‘firefighting’ stair (safe evacuation stair) for apartment buildings of 16 or more storeys if the floor area per storey exceeds 400m².

5 Storeys, 14 storeys, Any Height
Japan’s building code includes several trigger levels to define permitted conditions for single staircase buildings in both residential or office buildings:

• For buildings of up to two storeys in height, a single open staircase (without corridor separation) is permitted to serve a maximum floor area per storey of 200m² for combustible construction and 400m² for non-combustible construction. A fire sprinkler system is not required.
• For buildings of three to five storeys in height, a single ‘fire-compartmented’ staircase (i.e. corridor separation) is permitted to serve a maximum floor area per storey of 100m² for combustible construction and 200m² for non-combustible construction. A fire sprinkler system is not required.
• For buildings of six to fourteen storeys, a single exterior staircase is permitted and for buildings of fifteen or more storeys and a single ‘fire-compartmented’ staircase with a vestibule is permitted to serve a maximum floor area per storey of 100m² for combustible construction and 200m² for non-combustible construction. A fire sprinkler system is required for buildings of 11 or more storeys in height. An evacuation balcony and hatch is also required for buildings of six or more storeys in height served by a single staircase.

Singapore

60m
Singapore permits a single exit in apartment buildings up to 24m so long as the one-way travel distance is complied with, and exceeding 24m in height under the following conditions:

(a) The building’s habitable height does not exceed 60m, unless otherwise permitted by the SCDF.

(b) The single exit staircase shall serve not more than four apartments or maisonettes at each storey.

(c) Provision of exits for each residential apartment or maisonette shall comply with the requirements under Cl.9.2.1a.(5).

(d) Travel distance from the most remote exit door to the exit staircase from each apartment or maisonette shall not exceed 15m.

(e) The approach to the exit staircase shall be through cross-ventilated corridor/lobby in accordance with Cl.1.4.28, except that the ventilation openings shall have a minimum width of 2m and a minimum height of 1.2m, as well as the following requirements:

(i) the openings shall be unobstructed from the parapet wall or balustrade level upwards and be positioned on opposite sides of the corridor/lobby such that they provide cross ventilation throughout the entire space of the corridor/lobby; and

(ii) the entire cross-ventilated corridor/lobby shall be unobstructed and maintained at minimum 2m width throughout.

(f) Where multiple ventilation openings are provided on opposite sides of the corridor/lobby, the minimum width and height of each opening shall not be less than 1m and 1.2m respectively, provided the aggregate width of the openings at each opposite side is not less than 2m. (See Diagram 9.2.1a.(4)(f))

6 storeys or 17m (uppermost finish floor height)

(1)    Every building shall be provided with such means of escape in case of emergency as may be required by the intended use of the building.

(2)    Without prejudice to paragraph (1), every building which exceeds 6 storeys in height or in which the level of the floor of the uppermost storey is more than 17 m above the level of the ground at the point of discharge of the main staircase shall, in addition to the main staircase, be provided with a second staircase as means of escape in case of emergency. (L.N. 294 of 1976)

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