FIRE PROTECTION & SAFETY -1

FIRE PROTECTION AND SAFETY

23. General

23.1. This part of the section deals with safety from fire and explosion.  It specifies the demarcation of fire zones, restrictions on construction of building in each fire zone, classification of buildings based on occupancy, types of building construction according to fire resistance of the structural and non-structural components and other restrictions and requirements necessary to minimize danger to life from fire, smoke, fumes or panic before the buildings can be evacuated.  The section recognizes that safety of life is more than a matter of means of exits and accordingly deals with various matters, which are considered essential to the safety of life.

23.2. Fire protection techniques have to be based on the behavior characteristics of different materials and structural elements of buildings. The activities pursued by the occupants of buildings must also be taken into consideration for assessing the extent of hazards, and methods should then be devised by which the hazards could be minimized.  An indefinite combination of variables is involved in the phenomenon of fire, all of which cannot be quantified.  The requirements of this code should, therefore, be taken as guide and an engineering design approach should be adopted for ensuring a fire safe design for buildings.  It would also be necessary for this purpose to associate qualified and trained fire protection measures could be incorporated in the building design right from the beginning.

23.3. Absolute safety from fire is not attainable in practice.  The objective of this part is to specify measures, which will provide that degree of safety from fire, which can be reasonably achieved.  The code endeavors to avoid requirements, which might involve unreasonable hardships or unnecessary inconvenience or interference with normal use and occupancy of buildings, but insists upon compliance with minimum standards for fire safety necessary in public interest.

23.4. This part does not cover general fire prevention.  Nor does it cover the prevention of accidental personal injuries during the course of normal occupancy of buildings.

23.5. This part while recognizing that panic in a building on fire may be uncontrollable, deals with the potential panic hazard through measures designed to prevent the development of panic.  Experience indicates that panic seldom develops even in the presence of potential danger, so long as occupants of buildings are moving towards exits, which they can see within a reasonable distance, and with no obstruction or undue congestion in the path of travel.  However, any uncertainty as to the location or adequacy of means of egress, the presence of smoke or fumes and the stoppage of travel towards the exit, such as may occur when person stumbles and falls on stairs, may be conducive to panic.  Danger from panic is greater when a large number of people are trapped in a confined area.

23.6. Experience has shown that concealed spaces within a building such as space between ceiling and false ceiling, horizontal and vertical ducts, etc tend to act as flues/tunnels during a fire provision should, therefore, be made to provide fire stopping within such spaces.

23.7. Nothing in this section of the code shall be construed to prohibit better types of building construction, more exits or otherwise safer conditions than the minimum requirements specified in this part.

23.8. Compliance with this section shall not be construed as eliminating or reducing the necessity for other provisions for safety of persons using a building or structure under normal occupancy conditions.  Nor shall any provision of this code be construed as requiring or permitting any addition that may be hazardous under normal occupancy conditions.

23.9. One of the major points brought out in this section is limitation of heights and areas of buildings based on fire safety of the occupants.  Individual municipal corporations are free to alter Table 19 based on local conditions, but the ratios of areas as maintained in the table for different occupancies and types of constriction and types of construction shall be adhered to.

23.10. Advantage has been taken of the developments, particularly in fire resistance rating of materials, designating types of construction in a rational manner and relating the area limitations of different occupancies to different types of construction.

23.11. Halons (Halogenated hydrocarbons) which exhibit exceptional fire fighting and explosion prevention/suppression characteristics have been found to possess high ozone deleting potential.  They come under Group II of Appendix of the Montreal Protocol, the international environmental agreement for phasing out ozone depleting substances which came into force on 1 January 1989.  Due to increasing evidence that the ozone layer is getting depleted at a faster rate than thought earlier, the development countries accelerated their phase – out schedule with a view to achieving 100 percent phase – out of Halons by 1 January 1994, instead of the earlier target date of 1 January 2000 after which only essential use of Halon will be allowed.  For developing countries like India, the total phase-out of Halons is to be achieved by 1 January 2010, as per Montreal protocol unless a decision is taken in between to hasten up the phase-out of ozone depleting substances.  India having become a signatory to Protocol in June 1992 is committed to abide by the Montreal Protocol decisions.  Meanwhile, the practical implications of the phasing out of the Halons will cover, by and large, the following aspects:

1. Availability of Halons will be restricted:
2. Non-standard halon extinguishers, like aerosol type, shall not be permitted;
3. Discharge of Halons for training/testing, etc., shall not be permitted:
4. All efforts shall be made for avoiding/ minimizing halon emissions at various levels such such as production, fire equipment manufacture, user, service and maintenance;
5.  Since ‘ drop-In’ substitutes for Halons are likely to be available on a commercial scale in the near future wherever possible, instead of halon, use of suitable alternative extinguishing media/methods will be resorted to, even accepting some trade-offs, if necessary;
6. Halons shall be restricted for ‘ essential uses’ only for protection of critical fire explosion risk areas which would otherwise result in serious impairment of an essential service to society, or pose an unacceptable threat to life, the environment, or national security, and all other appropriate fire protection measures have been taken.

Note:  Detailed instruction which will be issued by the Government of India from time to time for implementation of the country programmed for the phasing out of ozone substance (ODS) shall have to be complied with.

23.12. The first version of this section was prepared in NBC 1970 and subsequently revised in 1983 and again in 2005.  As a result of implantation of this part, some useful suggestions have emerged.  These have been incorporated in this revision to the extent possible.  The major changes in this revision are:

1. Few tables for the fire resistance ratings of various building components such as walls, columns, beams and floors have been included.  These fire ratings are helpful for ensuring adherence during construction of the building to assess fire damage, for post fire structural safety assessment of various structural elements and adequacy of structural repairs.
2. The requirements for wet riser, downcomer, automatic sprinkler   installation, have velocity (10-15m/sec) water spray or foam generating system, etc for buildings have been modified.
3. Annexure giving guidelines for selection of fire detectors has been deleted and relevant Indian Standards on fire alarm system and smoke detectors have been referred.
4. Annexure for determination of fire loads and fire load density for arriving at the classification of occupancy hazard and calorific values of some common materials has been included.
5. Annexure for broad classification of industrial and non-industrial occupancies into low, moderate and high hazard has also been included.

23.13. The requirements given for industrial buildings (Group G) given for shall scale units in the urban areas.  For other industries the requirements will have to be worked out on the basis of relevant Indian Standards and also in consultation with local fire authority.

23.1. Scope

23.1.1. This section covers the requirements of fire protection of buildings through classification of buildings based on occupancy, type of construction, and their requirements.

23.1.2. This section also covers the exit requirements for all occupancies.

23.2. References - Indian Standards listed at Annexure 23-A.1 are necessary adjuncts to this section.

23.3. Classification of buildings based on occupancy

23.3.1. General classification – All buildings, whether existing or hereafter created shall be classified according to the use or the character of occupancy in one of the following groups;

Group A           Residential

Group B           Educational

Group C           Institutional

Group D           Assembly

Group E           Business

Group F            Mercantile

Group G           Industrial

Group H           Storage

Group J            Hazardous

Note:  The occupancies such as underground constructions like railway stations and house have   not been included in this section and shall be dealt separately.

23.3.1.1. Minor occupancy incidental to operations in another type of occupancy shall be considered as part of the main occupancy and shall be classified under the relevant group for the main occupancy.

Examples of buildings in each group are given in 23.3.1.1.1 to 23.3.1.1.9.

23.3.1.1.1. Group A residential buildings – These shall include any building in which sleeping accommodation is provided for normal residential purposes with or without cooking or dining or both facilities; except any building classified under Group C.

Buildings and structures under Group A shall be further subdivided as follows;

Subdivision A-1 Lodging or rooming houses

Subdivision A-2 One or two family private dwellings.

Subdivision A-3 Dormitories

Subdivision A- 4 Apartment houses (flats)

Subdivision A- 5 Hotels.

Subdivision A- 6 Hotels (starved)

a)  Subdivision A-1 Lodging or rooming houses - These shall include any building or group of buildings under the same management, in  which separate sleeping accommodation for a total of not more than 40 persons (beds), on transient or permanent  basis, with or without dining facilities but without cooking facilities for individuals is provided.  This includes inns, clubs, and hotels. A lodging or rooming house shall be classified as a dwelling in Subdivision A-2 if no room in any of its private dwelling units is rented to more than three persons.

b)  Subdivision A-2 One or two family private dwelling - These shall include any private dwelling which is occupied by members of one or two families and has a total sleeping accommodation for not more than 20 persons.  If rooms in a private dwelling are rented to outsiders, these shall be for accommodating not more than there persons per room. If sleeping accommodation for more than 20 persons is provided in any one residential building, it shall be classified as a building in Subdivision A-1. A-3 or A-4 as the case may be.

c)  Subdivision A-3 Dormitories – These shall include any building in which group sleeping accommodation is provided, with  or without dining facilities for persons who are not members of the same family, in one room or a series of closely associated rooms under joint occupancy and single

management, for example, school and college dormitories, students, and other hostels and military  barracks.

d) Sub divisional A–4 Apartment houses (flats) – These shall include any buildings or structure in which living quarts are provided are provided for three or more families, living independently of each other and with independent cooking facilities, for example, apartment houses, mansions and chawls.

e)  Sub divisional A–5 Hotels - These shall include any buildings or group of buildings under single management, in which sleeping accommodation, with or without dining facilities for hotels classified upto 4 star category  

e)  Sub divisional A–6 Hotels (Starred) - These shall include the hotels duly approved by the concerned authorities as Five Star and above Hotels.

23.3.1.1.2. Group B Educational buildings – These shall include any building used for school college or daycare purposes involving assembly for instruction, education or recreation for not less than 20 students. Buildings and structures under Group B shall be further subdivided as follows;

Sub division B-1 Schools upto higher secondary level.

Sub division B-2 All others/ training institutions.

a) Subdivision B–1 Schools up to higher secondary level – This subdivision shall include any building or a group of buildings under single management which is used for students not less than 20 in number.

b) Subdivision B-2 All others/ training Institutions – This subdivisions shall include any building or a group of buildings under single management which is used for students not less than 100 in number.

In the case of temporary buildings/ structures which utilized for educational purposes, the requirements shall be as per the provisions contained in Indian Standard given in Annexure 23-A.1 as well as the local regulations.

If residential accommodation is provided in the schools/institutions, it shall be classified as a building in Subdivision A-3.

23.3.1.1.3. Group C Institutional buildings – These shall include any building or part thereof, which is used for purposes, such as medical or other treatment or care of persons suffering from physical or mental or illness, disease or infirmity; care of infants, convalescents or  aged persons and for penal   or correctional detention in which the liberty of the inmates is restricted.  Institutional buildings ordinarily provide sleeping accommodation for the occupants.

Buildings and structures under Group C shall be further subdivided as follows:

Subdivision C-1 Hospitals and sanatoria

Subdivision C-2 Custodial institutions

Subdivision C-3 Penal and mental institutions

a) Subdivision C-1 Hospitals and sanatoria  - This subdivision shall include under single management, which is used for physical limitations because of health or age, for example, hospitals, infirmaries, sanatoria and nursing homes.

b)  Subdivision C-2 Custodial institutions  - This Subdivision shall include any building or a group of buildings under single management, which is used for the custody and care of persons such as children, convalescents and the aged, for the aged and infirm, convalescent homes and orphanages.

c)  Subdivision C-3 Penal and mental institutions  - This subdivision shall include any building or a group of buildings under single management, which is used for housing persons under restraint, or who are detained for penal or corrective purposes, in which the liberty of the inmates is restricted, for example, jails, prisons, mental hospitals, mental sanatoria and reformatories.

23.3.1.1.4.  Group D assembly buildings - These shall include any building or part of a building, where number of persons not less   than 50 congregate or gather for amusement,  recreation, social, religious, patriotic, civil, travel and similar purposes, for example, theaters, motion picture houses, assembly hall, museums, skating rinks, gymnasiums, restaurants, places of worship, dance halls, club

Rooms, passenger stations and terminals of air, surface and marine public transportation services recreation piers and stadium, etc.,

Buildings under Group D shall be further subdivided as follows:

Subdivision D-1	Buildings having a theatrical or motion picture or any other stage and fixed seats upto 1000 persons.
Subdivision D-2	Buildings having a theatrical or motion picture or any other stage and fixed seats upto 1000 persons.
Subdivision D-3	Buildings without a permanent stage having accommodation for less than 300 persons with no permanent seating arrangement.
Subdivision D-4	Buildings without a permanent stage having accommodation for less than 300 persons with no permanent seating arrangement.
Subdivision D-5	All other structures including temporary structures designed for assembly of people not covered by subdivisions  D-1 to D-4
Subdivision D-6	This sub-division shall include any building for assembly of people provided with multiple service/facilities like shopping, cinema theatres and restaurants for example, multiplexes.
Subdivision D-7	This sub-division shall include any building or structure permanent or temporary meant for assembly of people not covered by D-1 to D-2, for example, underground or elevated railways.

a)  Subdivision D–1 -  This subdivision shall include any building primarily  meant for theatrical or operatic performances and exhibitions and which has a raised stage proscenium curtain, fixed or portable scenery or scenery loft, lights, motion picture houses, mechanical appliances or other theatrical accessories and equipment and which is provided with fixed seats for over 1000 persons.

b)  Subdivision D–2 - This subdivision shall include any building primarily meant for use as described for subdivision D-1 , but with fixed seats up to 1000 persons.

c)  Subdivision D–3  -  This subdivision shall include any building  its lobbies, rooms and other spaces connected thereto, primarily intended for assembly  of people but which has no theatrical stage or permanent theatrical stage or permanent theatrical and/or   cinematographic accessories and has accommodation for 300 persons or more, for example, dance halls, night clubs, halls for incidental picture shows, dramatic, theatrical or educational presentation, lectures or other similar purposes having no theatrical stage except a raised platform and used without permanent seating arrangement; art galleries exhibition halls, community halls, marriage halls, places of worship, museums,   lecture halls and passenger terminals.

d) Subdivision D–4 - This subdivision shall include any building primarily intended for use as described in subdivision D-3, but with accommodation for less than 300 persons with no permanent seating arrangements.

e) Subdivision D–5 -This subdivisions shall include any building or structure permanent or temporary mean for assembly of people not covered by subdivision D-1 to D-4 for example, grandstands, studio, amusement park structures reviewing stands and circus  tents.

f) Subdivision D–6 - This subdivisions shall include any building for assembly of people provided with multiple services/facilities like shopping, cinema theatres and restaurants for example, multiplexes.

g) Subdivision D–7 -These subdivisions shall include any building or structure permanent or temporary meant for assembly of people not covered by D-1 to d-6, for example, underground or elevated railways.

23.3.1.1.5. Group F Mercantile Buildings

These shall include any building or part of a building, which is used as shops, stores, market, for display and sale of merchandise, either wholesale or retail.

Mercantile buildings shall be further sub-divided as follows:

Sub-division F-1 Shops, stores, departmental stores markets with area up to 500 m².

Sub-division F-2 Shops, stores, departmental stores markets with area more than 500 m².

Sub-division F-3 Underground shopping centers.

Storage and service facilities incidental to the sale of merchandise and located in the same building shall be included under this group.

23.3.1.1 6. . Group G Industrial Buildings

These shall include any building or part of a building, which products or materials of all kinds and properties are fabricated, assembled, manufactured or processed, for example, assembly plants, industrial laboratories, dry cleaning plants power plants, generating units, pumping stations, fumigation chambers, laundries, buildings or structures in gas plants, refineries dairies and saw –mills, etc. Buildings under Group G shall be further sub-divided as follows:

Sub-division G-1 Buildings used for low hazard industries.

Sub-division G-2 Buildings used for moderate hazard industries.

Sub-division G-3 Buildings used for high hazard industries.

23.3.1.1.7. Group E, Business buildings -  These shall include any building  or part of a building which is used for transaction of business (other than that covered by Group F and part of buildings covered by 23.3.1.1); for keeping of accounts and records and similar purposes, professional establishments, service facilities, etc., city halls, town halls, court houses and libraries shall be classified in this group so far as the principal function of these is transaction of public business and keeping of books and records.

Business building shall be further sub-classified as follows:

Subdivision E-1 - Offices, banks, professional establishments, like offices of architects, engineers, doctors, lawyers and polices stations. 

Subdivision E-2 - Laboratories, research establishments, libraries and test houses.

Subdivision E-3 - Computer installations.

Subdivision E-4 - Telephone exchanges.

Subdivision E-5 - Broadcasting Stations.

23.3.1.1.8. Group F Mercantile buildings - These shall include any building or part of a building, which is used as shops, stores, market for display and sale of merchandise, either wholesale or retail.

Mercantile buildings shall be further sub classified as follows:

Subdivision F-1 - Shops, stores, departmental stores markets with area up to 500 m ².

Subdivision F-2 - Shops, stores, departmental stores, markets with area more than 500 m²

Subdivision F-3 - Underground shopping centers.

Storage and service facilities incidental to the sale of merchandise and located in the same building shall be included under this group.

23.3.1.1.9. Group G, Industrial buildings - These shall include any building or part of a building or part of a building or structure, in which products or materials of all kinds and properties are fabricated, assembled, manufactured or processed, for example assembly plants, industrial laboratories, dry cleaning plants, power plants, generating units, pumping stations, fumigation chambers, laundries, buildings or structures in gas plants, refineries, dairies and saw-mills, etc.,

Buildings under Group G shall be further subdivided as follows:

Subdivision G-1 - Buildings used for low hazard industries.

Subdivision G-2 - Buildings used for moderate hazard industries.

Subdivision G-3 - Buildings used for high hazard industries. 

The hazard of occupancy, for the purposes of the section, shall be the relative danger of the start and spread of fire, the danger of smoke or gases generated the danger of explosion or other occurrences potentially endangering the lives and safety of the occupants of the buildings.

Hazard of occupancy shall be determined by the Authority on the basis of the fire loads of the contents, and the processes or operations conducted in the building, provided, however, that where the combustibility of the building the flame spread rating of the interior finish or other features of the building or structure are such as to involve a hazard greater than the occupancy hazard, the greater degree of hazard shall govern the classification.

For determination of fire loads and fire load density for arriving at the classification of occupancy hazard, guidance material including the calorific values of some common materials are given at Annexure 23-A.2.

A broad classification of industrial and non-industrial occupancies into low, moderate and high hazard classes is given at Annexure 23-A.3 for guidance.  Any occupancy not covered in Annexure 23-A.3, shall be classified in the most appropriate class depending on the degree of hazard.

Where different degrees of hazard of occupancy exist in different parts of a building, the most hazardous of those shall govern the classification for the purpose of this section, except in cases where hazardous areas are segregated or protected as specified in the code.

a)  Subdivision G- 1 - This subdivision shall include any building in which the contents are of such comparative low combustibility and the industrial processes or operations conducted therein are of such a nature that there are hardly any possibilities for any self propagating fire to occur and the only consequent danger to life and property may arise from panic fumes or smoke, or fire from some external source.

b)  Subdivision G- 2 - This subdivision shall include any building in which the contents or industrial processes of operations conducted therein are liable to give rise to a fire which will burn with moderate rapidity or result in other hazardous situation and may give off a considerable volume of smoke, but from which neither toxic fumes nor explosions are to be feared in the event of fire.

c)  Subdivision G- 3  - This subdivision shall include any building  in which the contents or industrial processes of operations conducted therein  are liable to give rise to a fire which will burn with extreme rapidity or result in other Hazardous  situation or from which poisonous fumes or explosions are to be feared in the event of fire.

23.3.1.1.10. Group H-Storage buildings - These shall include any building or part of a building, used primarily for the storage or shuttering (including servicing, processing or repairs incidental to storage) of goods, wares or merchandise (except those that involve highly combustible or explosive products or materials) vehicles or animals for example, warehouses cold storage, freight depots, transit sheds, storehouses, freight depots, transit sheds, storehouses, truck and marine terminals, garages, hangers, grain elevators, barns and stables.

Storage properties are characterized by the presence of relatively small number of persons in proportion to the area.  Any new use which increases the number of occupants to a figure comparable with other classes of occupancy shall change the classification of the building to that of the new use, for example, hangars used for office purposes, garage buildings issued for manufacturing.

23.3.1.1.11. Group J-Hazardous buildings - These shall include any building or part of building which is used for the storage, handling, manufacture or processing of highly combustible or explosive materials or products which are liable to burn with extreme rapidity and or which may produce poisonous fumes or explosions for storage, handling, manufacturing or processing which involve highly corrosive, toxic or noxious, alkalis acids or other liquids or chemicals producing flame, fumes and explosive, poisonous irritant or corrosive gases ; for the storage handling or processing of any material producing explosive mixtures of dust which result in the division of matter into fine particles subject  to spontaneous ignition.  Examples of buildings in this class are those buildings which are used for;

Storage under pressure of more than 0.1 N/mm² and in quantities exceeding  70 m³, of acetylene, hydrogen, illuminating and natural gases, ammonia, chlorine, phosgene, sulphur dioxide, carbon  dioxide, methyl oxide and  all gases subject to explosion, fume or toxic hazard, cryogenic gases, etc.,

Storage and handling of hazardous and highly flammable liquids, liquefiable gases like LPG rocket propellants, etc.,

Storage and  handling or explosive materials, other than liquids; and

Manufacture of artificial flowers, synthetic leather, ammunition, explosives and fireworks.

Note - A list of hazardous substances giving quantities, for which or exceeding which owners handling such substances are required to be covered under the public Liability Insurance Act has been notified under Govt. of India, Ministry of  Environment and Forests Notification  G.S.R 347 (E) dated  1^st August 1996.

23.3.2. Any building not covered by Annexure 23-A.3 or 23.3.1.1.11 shall be classified in the group, which most nearly resembles its existing or proposed use.

23.3.3. Where change in the occupancy of any building places it in a different group or in a different sub division of the same group, such building shall be made to comply with the requirements of code for the new group or its subdivision.

23.3.4. Where the new occupancy of building is less hazardous, based on life and fire risk, than its existing occupancy, it shall not be necessary to conform to the requirements of the code for the new group of its subdivision.

23.3.5. A certificate of occupancy shall be necessary, as required before any change is effected in the character or occupancy of any building.

23.4. Types of construction

23.4.0. General – The design of any building and the type of materials used in its construction are important factors in making the building resistant to a complete burn-out and in preventing the rapid spread of fire, smoke or fumes, which may otherwise contribute to the loss of lives and property.

The fire resistance of a building or its structural and non-structural; elements is expressed in hours against a specified test load which is expressed in k cal/m², and against a certain intensity of fire.  The fire-resistance test for structure shall be done in accordance with Indian Standard given in Annexure 23-A.1. For the purpose of this section, the types of construction according to fire resistance shall be classified into four categories, namely, Type 1 Construction; Type 2 Construction; Type 3 Construction; and Type 4 Construction.  The fire resistance ratings for various types of construction for structural and non – structural member shall be as given in Table 1.

 The internal walls of staircases should be of brick work or reinforced concrete or any other material of construction with minimum of 2 hours rating.  The walls for the chimney shall be of Type 1 and type 2 constructions depending on whether the gas temperature is above 200⁰ C or less.

23.4.1. The fire resistance ratings of various building components such as walls, columns, beams and floors are given in Table 2 to Table 18.  Fire damage assessment, post fire structural safety assessment of various structural Clemens of the building and adequacy of the structural repairs can be done by the fire resistance ratings mentioned in the tables.

Table 1 Fire resistance ratings of structural and non-structural elements (in hours)

Sl.No.	Structural element		Type of construction
			Type 1	Type 2	Type 3	Type 4
1	Exterior walls:
	Fire separation less than 3.7 m	bearing	4	2	2	1
		Non-bearing	2	1½	1	1
	Fire separation of 3.7 m or more but less than 9 m	bearing	4	2	2	1
		Non-bearing	1½	1	1	1

 

	Fire separation of 9 m or more	bearing	4	2	2	1
		Non-bearing	1	1	1	1
2	Fire resisting walls		4	2	2	2
3	Fire separation assemblies (like fire check doors)		4	2	2	2
4	Fire enclosures of exit ways, elevator and hoist ways		2	2	2	2
5	Shaft other than exit ways, elevator and stairways		2	2	2	2
6	Exit way access corridors		1	1	1	1
7	Vertical separation of tenant spaces		1	1	1	1
8	Dwelling unit separation. Non-load bearing partitions		1	1	1	1
			¬At least half an hour®
9	Interior bearing walls, bearing partitions, columns, girders, trusses (other than roof trusses) and framing	Supporting more than one floor	4	2	2	2
		Supporting one floor only	3	1½	1	1
		Supporting a roof only	3	1½	1	1
10	Structural members support walls		3	1½	1	1
11	Floor construction including walls		3	1½	1	1
12	Roof construction	5 m or less in height to lowest member	2	1½	1	1
		More than 5 m but less than 6.7 m in height to lowest member	1	1	1	1
		6.7 m or more in height to lowest member	0	0	0	0

Table 2 Masonry walls: Solid (Required to resist fire from one side at a time) (Clause 23.4.1)

Nature of construction and materials		Minimum thickness (mm), excluding any finish, for a fire resistance (hours) of
		Load bearing					Non-load bearing
		1	1½	2	3	4	1	1½	2	3	4
1	Reinforced cement concrete	120 (25)­	140 (25)­	160 (25)­	200 (25)­	240 (25)­	-	-	-	-	-
2	Un-reinforced cement concrete	150	175	-	-	-	-	-	-	-	-
3	No-fines concrete with:
a	13mm cement / sand or gypsum/sand	-	-	-	-	-	150	150	150	150	150
b	With 13 mm light weight aggregate gypsum plaster	-	-	-	-	-	150	150	150	150	150
4	Bricks of clay:
a	Without finish	90	100	100	170	170	75	90	100	170	170
b	With 13 mm lightweight aggregate gypsum plaster	90	90	90	100	100	75	90	90	90	100
5	Bricks of sand lime:
a	Without finish	90	100	100	190	190	75	90	100	170	170
b	With 13 mm lightweight aggregate gypsum plaster	90	90	90	100	100	75	90	90	90	100
6	Blocks of concrete:
a	Without finish	90	100	100	-	-	75	90	100	140	150
b	With 13 mm lightweight aggregate gypsum plaster	90	90	90	100	100	75	75	75	90	100
c	With 13 mm cement/sand or gypsum/sand						75	90	90	100	140
7	Blocks of lightweight concrete
a	Without finish	90	100	100	140	150	75	75	75	125	140
b	With 13 mm lightweight aggregate gypsum plaster	90	90	90	100	100	50	63	75	75	75
c	With 13 mm cement/sand or gypsum/sand						75	75	75	90	100
8	Blocks of aerated concrete:
a	Without finish	90	100	100	140	180	50	63	63	75	100
b	With 13 mm lightweight aggregate gypsum plaster	90	90	100	100	150
* walls containing at least 1 percent of vertical reinforcement. ­ Minimum thickness of actual cover to reinforcement.

Table 3 Masonry walls: Hollows (Required resisting fire from one side at a time) (Clause 23.4.1)

Nature of construction and materials		Minimum thickness (mm), excluding any finish, for a fire resistance (hours) of
		Load bearing						Non-load bearing
		1	1½	2	3	4	½	1	1½	2	3	4
1	Bricks of clay:
a	Without finish	170	170	170	200	200	75	75	90	100	170	170
b	With13mm lightweight aggregate gypsum plaster	100	100	170	170	170	75	75	90	90	90	100
2	Blocks of concrete:
a	Without finish						90	125	125	140	140	150
b	With 13mm cement/sand or gypsum/sand	190	200	200			90	125	125	140	140	140
c	With 13mm lightweight aggregate gypsum plaster	190	200	200	-	-	75	90	90	100	125	125
3	Blocks of lightweight concrete:
a	Without finish	100	100	100	-	-	75	90	90	100	140	150
b	With 13mm cement / sand or gypsum /sand	-	-	-	-	-	75	75	75	100	140	140
c	With 13mm lightweight aggregate gypsum plaster	-	-	-	-	-	63	63	63	75	90	100

Table 4 Framed construction, load bearing (Required to resist fire from one side at a time)

(Clause 23.4.1)

Sl.No.	Nature of construction and materials/timber studs at centres not exceeding 600 mm, faced on each side with	Minimum thickness (mm) of protection for a fire resistance of 1 h
1	Plasterboard layers with joints staggered joints in outer layer taped and filled – total thickness for each face	25
2	One layer of 12.7 mm plasterboard with a finish of lightweight aggregate gypsum plaster	13
3	Metal lath and plaster, thickness of plaster:
a	Sanded gypsum plaster (metal lathing grade)	22
b	Lightweight aggregate gypsum plaster	13

Table 5 Framed construction, non-load bearing (Required to resist fire from one side at a time) (Clause 23.4.1)

Sl. No.	Nature of construction and material/steel or timber frame at centers not exceeding 600 mm, facings on both sides of	Stud construction	Minimum thickness (mm) of protection for a fire resistance of
			½ h	1 h	1½ h	2h
A	Dry lining with materials fixed direct to studs (without plaster finish):
1	One layer of plasterboard with taped and filled joints	Timber or steel	12.7	-	-	-
2	Two layers of plasterboard with joints staggered, joints in outer layer taped and filled – total thickness for each face	Timber or steel	19	25	-	-
3	One layer of asbestos insulating board with transverse joints backed by fillers of asbestos insulating board not less than 9 mm, or by timber	Timber steel	9	12	-	-
-	One layer of wood wool slabs	Timber	25	-	-	-
5	One layer of chipboard or of plywood	Timber or steel	18	-	-	-
B	Lining with materials fixed direct to studs,  with plaster finish:
1	Plaster board of thickness:
a	With not less than 5 mm gypsum plaster finish	Timber or steel	9.5	-	-	-
b	With not less than 13 mm gypsum plaster finish		-	12.7	-	-
C	Wet finish:
1	Metal lath and plaster, thickness of plaster:
a	Sanded gypsum plaster	Timber or steel	13	-	-	-
b	Lightweight aggregate gypsum plaster	Timber steel	-	13 13	19	25

Table 6 Framed external walls load bearing (Required to resist fire from one side at a time)

(Clause 23.4.1)

Nature of construction and materials	Minimum thickness (mm) of protection for a fire resistance of 1h
Timber studs at centres not exceeding 600 mm with internal linings of :
1. Plasterboard layers with joint in outer layer taped and filled, total thickness of plasterboard	25

Table 7 Framed external walls non-load bearing required to resist fire only  from inside the building (A) (Clause 23.4.1)

Sl.No.	Nature of construction and materials	Minimum thickness (mm) of protection for a modified fire resistance of
		½ h	1 h	1½ h	2h	3h	4h
A	Steel frame with an external cladding of non-combustible sheets (excluding sheet steel), with a steel supporting framework and internal  lining of:
1	Metal lath and plaster, thickness of plaster:
a	Sanded gypsum plaster (metal lathing grade)	13	13	-	-	-	-
b	Lightweight aggregate gypsum plaster	10	13	15	15	15	19
2	Two layer of plasterboard with joints staggered joints in outer layer taped and filled – Total thickness	21	32	-	-	-	-
3	Plasterboard of thickness:
a	With not less than 5 mm gypsum plaster finish	12.7	-	-	-	-	-
b	With not less than 13 mm gypsum plaster finish	9.5	-	-	-	-	-
c	With not less than 10 mm lightweight aggregate gypsum plaster	9.5	-	-	-	-	-
4	One layer of asbestos insulating board with transverse joints backed by fillers of asbestos insulating board not less than 9 mm thick, or by timber	9	9	12	12	12	12
5	One layer of wood/wool slabs without finish	-	50	-	-	-	-
6	One layer of compressed straw building slabs:
a	Without finish	50	-	-	-	-	-
b	With not less than 5 mm gypsum plaster finish	-	50	-	-	-	-
7	Aerated concrete blocks	50	50	63	63	75	100
8	Bricks of clay:
a	Without finish	75	75	90	90	100	100
b	With not less than 13 mm lightweight aggregate gypsum plaster	-	-	75	75	90	90

Table 8 Framed external walls non-load bearing required to resist fire only from inside the building (B)

(Clause 23.4.1)

Sl. No.	Nature of construction and materials	Minimum thickness (mm) of protection to provide sufficient insulation to achieve a modified fire resistance of up to 4 h
B	Steel frame with an external cladding of sheet steel fully lapped, steel bolted and fixed to steel sheeting rails, with timber or steel supporting framework and internal lining of:
1	Metal lath and plaster, thickness of plaster:
a	Sanded gypsum plaster (metal lathing grade)	13
b	Lightweight aggregate gypsum plaster	10
2	One layer of plasterboard with joints taped and filled	12.7
3	Plasterboard of thickness, with not less than 5 mm gypsum plaster finish	9.5
4	One layer of asbestos insulating board with transverse joints backed by fillers of asbestos insulating board not less than 9 mm thick, or by timber	9
5	One layer of wood/wool slabs	25
6	One layer of compressed straw building slabs	50
7	One layer of chipboard or of plywood	18
8	Aerated concrete blocks	50
9	Bricks of clay	75
10	Any internal decorative lining with a cavity fill independently supported and retained in position of mineral fibre insulating material (excluding glass) at a density of 48 kg/m3	50

Table 9 Framed walls non-load bearing required to resist fire only From inside the building (C) (Clause 23.4.1)

Sl.No.	Nature of construction and materials	Minimum thickness (mm) of projection for a fire resistance of 1½ h
C	Timber frame with external cladding of weather boarding or external plywood’s 9.5 mm with an  internal lining of:
1	Plasterboard not less than 9.5 mm thick, finished with:
a	Gypsum plaster	13
b	Lightweight aggregate gypsum plaster	10
2	Plasterboard not less than 12.7 mm thick, finished with:
a	Gypsum plaster	10
b	Lightweight aggregate gypsum plaster	10
3	One layer of asbestos insulating board with transverse joints backed by fillers of asbestos insulating board not less than 9 mm thick, or by timber	9 12

Table 10 Reinforced concrete columns (Clause 23.4.1)

Nature of construction and materials			Minimum dimensions (mm), excluding any finish, for a fire resistance of
			½ h	1 h	1½ h	2h	3h	4h
1	Fully exposed	width	150	200	250	300	400	450
		cover	40	40	40	40	40	40
2	50% exposed	width	125	160	200	200	300	350
		cover	40	40	40	40	40	40
3	One face exposed	Thickness	100	120	140	160	200	240
		cover	40	40	40	40	40	40

Table 11 Concrete beams (Clause 23.4.1)

Nature of construction and materials			Minimum dimensions (mm), excluding any finish, for a fire resistance of
			½ h	1 h	1½ h	2h	3h	4h
1	Reinforced concrete (simply supported)	Width	200	200	200	200	240	280
		cover	20	20	20	40	60*	70*
2	Reinforced concrete (continuous)	Width	200	200	200	200	240	280
		Cover	20	20	20	30	40	50
3	Prestressed concrete (simply supported)	Width	100	120	150	200	240	280
		cover	25	40	55	70	80	90
4	Prestressed concrete (continuous)	Width	80	100	120	150	200	240
		cover	20	30	40	55	70	80

*Require attention to the additional measures necessary to reduce to risk of spalling

Table 12 Concrete floors (Clause 23.4.1)

Nature of construction and materials			Minimum dimensions (mm), excluding any finish, for a fire resistance of
			½ h	1 h	1½ h	2h	3h	4h
1	Reinforced concrete (simply supported)	Thickness	75	95	110	125	150	170
		cover	20	20	25	35	45 *	55*
2	Reinforced concrete (continuous)	Thickness	75	95	110	125	150	170
		cover	15	20	20	25	35	45*

*Require attention to the additional measures necessary to reduce to risk of spelling

Table 13 Concrete floors: Ribbed open soffit    (Clause 23.4.1)

Nature of construction and materials			Minimum dimensions (mm), excluding any finish, for a fire resistance of
			½ h	1 h	1½ h	2h	3h	4h
1	Reinforced concrete (simply supported)	Thickness	75	95	110	125	150	170
		width	125	125	125	125	150	175
		cover	20	20	35	45	55	65
2	Reinforced concrete (continuous)	Thickness	75	95	110	125	150	170
		width	125	125	125	125	150	175
		cover	20	20	20	35	45	55

Table 14 Encased steel columns, 203 mm x 203 mm (Protection applied on four sides)

(Clause 23.4.1)

Sl.No.	Nature of protection and materials	Minimum thickness (mm) of protection for a fire resistance of
		1 h	1½ h	2h	3h	4h
A	Hollow protection (without an air cavity over the flanges):	-	-	-	-	-
1	*Metal lathing with trowelled lightweight aggregate gypsum plaster	13	15	20	32	-
-	Plasterboard with 1.6 mm wire binding at 100 mm pitch, finished with lightweight aggregate gypsum plaster not less than the thickness specified:
a	9.5 mm plaster board	10	15	-	-	-
b	19 mm plaster board	10	13	10	-	20
3	Asbestos insulating boards, thickness of board
a	Single thickness of board, with 6 mm cover fillets at transverse joints	-	19	25	-	-
b	Two layers, of total thickness	-	-	-	38	50
4	Solid bricks of clay, composition or sand lime, reinforced in every horizontal joint, un plastered	50	50	50	75	100
5	Aerated concrete blocks	60	60	60	-	-
6	Solid blocks of lightweight concrete hollow protection (with an air cavity over the flanges)	50	50	50	60	75
B	Asbestos insulating board screwed to 25 mm asbestos battens	12	19	-	-	-
c	Solid protections
1	Concrete, nor leaner than 1:2:4 mix(un plastered)
a	Concrete not assumed to be load bearing, reinforced ­	25	25	25	50	75
b	Concrete assumed to be load bearing	50	50	50	75	75
2	Lightweight concrete, not leaner than 1:2:4 mix (un plastered) concrete not assumed to be load bearing, reinforced ­	25	25	25	40	60

* So fixed or designed, as to allow full penetration for mechanical bond.

• Reinforcement shall consist of steel binding wire not less than 2.3 mm in thickness, or a steel mesh weighing not less than 0.5 kg/m².  In concrete protection, the spacing of that reinforcement shall not exceed 200 mm in any direction.

Table 15 Encased steel beams, 406 mm x 176 mm (Protection applied on three sides)

(Clause 23.4.1)

Sl.No.	Nature of construction and materials	Minimum thickness (mm) of protection for a fire resistance of
		½ h	1 h	1½ h	2h	3h	4h
A	Hollow protection (without an air cavity beneath the lower flange):
1	* Metal lathing with trowelled lightweight aggregate gypsum plaster (metal lathing grade)	13	13	15	20	25
2	Plasterboard with 1.6 mm wire binding­ at 100 mm pitch, not less than the thickness specified:
a	9.5 mm plasterboard	10	10	15	-	-	-
b	19 mm plasterboard	10	10	13	20	-	-
3	Asbestos insulating board, thickness of board:
a	Single thickness of board, with 6 mm cover fillets at transverse joints	-	-	19	25	-	-
b	Two layers, of total thickness	-	-	-	-	38	50
B	Hollow protection (with an air cavity below the lower  flange):
1	Asbestos insulating board screwed to 25 mm asbestos battens	9	12	-	-	-	-
C	Solid protection:
1	Concrete, not leaner than 1:2:4 mix (un plastered):
a	Concrete not assumed to be load bearing, reinforcedí	25	25	25	25	50	75
b	Concrete assumed to be load bearing	50	50	50	50	75	75
2	Light weight concrete § not leaner than 1:2:4 (mix) un plastered	25	25	25	25	40	60

* so fixed, or designed, as to allow full penetration for mechanical bond.

Where wire binding cannot be used, expert advice should be sought regarding alternative methods of support to enable the lower edges of the plasterboard to be fixed together and to the lower flange, and for the top edge of the plasterboard to be held in position.

Reinforcement shall consist of steel binding wire not less than 2.3 mm in thickness or a steel mesh weighing not less than 0.5 kg/m2.  In concrete protection, the spacing of that reinforcement shall not exceed 200 mm in any direction.

Concrete not assumed to be load bearing, reinforced.

Table 16 Timber floors – Tongued and grooved boarding, or sheets of tongued and grooved plywood or wood chipboard, of not less than 21 mm finished thickness (Clause 23.4.1)

Sl.No.	Nature of construction and materials	Minimum thickness (mm) of protection for a fire resistance of
		½ h	1 h	2 h
	37 mm (minimum) timber joists with a ceiling of:	-	-	-
1	Timber lathing and plaster, plaster of thickness	15	-	-
2	Metal lathing and plaster, thickness of plaster:
a	Sanded gypsum plaster (metal lathing grade)	15	-	-
b	Light weight aggregate gypsum plaster	13	13	25
3	One layer of plasterboard with taped and filled joints	12.7	-	-
4	Two layers of plasterboard with joints staggered, joints in outer layer taped and filled total thickness	19	31	-
5	One layer of plasterboard not less than 9.5 mm thick, finished with:
a	Gypsum plaster	5	-	-
b	Sanded gypsum plaster	13	-	-
c	Lightweight aggregate gypsum plaster	13	-	-
6	One layer of plasterboard not less than 12.7 mm thick, finished with:
a	Gypsum plaster	5	-	-
b	Lightweight aggregate gypsum plaster	10	-	-
7	One layer of asbestos insulating board with any transverse joints backed by fillets of asbestos insulating board not less than 9 mm thick, or by timber	9	12	-

Table 17 Timber floors – Tongued and grooved boarding, or sheets of tongued and grooved plywood or wood chipboard, of not less than 15 mm finished thickness (Clause 23.4.1)

Sl.No.	Nature of construction and materials	Minimum thickness (mm) of protection for a fire resistance of
		½ h	1 h	2 h
	37 mm (minimum) timber joists with a ceiling of:
1	Timber lathing and plaster, plaster of thickness	15	-	-
2	Metal lathing and plaster, thickness of plaster:
a	Sanded gypsum plaster (metal lathing grade)	15	-	-
b	Light weight aggregate gypsum plaster	13	13	25
3	One layer of plasterboard with taped and filled joints	12.7	-	-
4	Two layers of plasterboard with joints staggered, joints in outer layer taped and filled total thickness	22	31	-
5	One layer of plasterboard not less than 9.5 mm thick, finished with:
a	Gypsum plaster	5	-	-
b	Sanded gypsum plaster	15	-	-
c	Lightweight aggregate gypsum plaster	13	-	-
6	One layer of plasterboard not less than 12.7 mm thick, finished with:
a	Gypsum plaster	5	-	-
b	Lightweight aggregate gypsum plaster	10	-	-
7	One layer of asbestos insulating board with any transverse joints backed by fillets of asbestos insulating board not less than 9 mm thick, or by timber	9	12*	-
* Finished on top with 25 mm minimum thick glass fibre or mineral wool laid between joints

Table 18 Timber floors – Any structurally suitable flooring of timber or lignocelluloses boards

(Clause 23.4.1)

Sl.No.	Nature of construction and materials	Minimum thickness (mm) of protection for a fire resistance of
		½ h	1h
	37 mm (minimum) timber joists with a ceiling of:
1	Timber lathing and plaster, plaster of thickness	15	-
2	Metal lathing and plaster, thickness of plaster:
a	Sanded gypsum plaster (metal lathing grade)	15	-
b	Light weight aggregate gypsum plaster	13	19
3	One layer of plasterboard with joints taped and filled and backed by timber	12.7	-
4	Two layers of plasterboard with joints staggered, joints in outer layer taped and filled total thickness	25	-
5	Two layers of  plasterboard, each not less than 9.5 mm thick, joints between boards staggered and outer layer finished with gypsum plaster	5	-
6	One layer of plasterboard not less than 9.5 mm thick, finished with:
a	Gypsum plaster	13	-
b	Lightweight aggregate gypsum plaster	15	-
7	One layer of plasterboard not less than 12.7 mm thick, finished with:
a	Gypsum plaster	15	-
b	Lightweight aggregate gypsum plaster	13	-
8	One layer of asbestos insulating board with any transverse joints backed by fillets of asbestos insulating board not less than 9 mm thick, or by timber	12	-

23.5. Fire zones

23.5.1. Demarcation – The city or area under the jurisdiction of the authority shall for the purpose of the code, be demarcated into distinct zones, based on the fire hazard inherent in the buildings and structures according to occupancy, which shall be called as ‘Fire Zones.

23.5.2. Number and designation of fire zones.

The number of fire zones in a city or area under the jurisdiction of the Authority depends upon the existing layout, types of building construction (see 23.4) classification of existing buildings based on occupancy (see 23.3) and expected further development of the city for area.  In large cities or areas, three fire zones nay be necessary while in smaller ones, one or two may be adequate.

The fire zones shall be made use of in land use development plan and shall be designated as follows;

1. Fire Zone No.1,
2. Fire Zone No 2 , and
3. Fire Zone No 3.

Fire Zone no.1 - This shall comprise areas having residential (Group A), educational (Group B) institutional (Group C) and assembly (group D), Small business (subdivisions E-1) and retail mercantile (group F) buildings, or areas which are under development for such occupancies.  

Fire Zone no.2 - This shall comprise business (subdivisions E-2 to E-5) and industrial buildings (subdivision G-1 and G-2), except high hazard industrial buildings (Subdivision G-3) or areas which are under development for such occupancies.

Fire Zone no.3 - This shall comprise areas having high hazard industrial buildings (subdivisions G-3) storage buildings (Group H) and buildings for hazardous used (Group J) or areas which are under development for such occupancies

23.5.3. Change in the fire zone boundaries - When the boundaries of any fire zone are changed, or when it is intended to include other areas or types of occupancies in any fire zone, it shall be done by following the same procedure as for promulgating new rules or ordinances or both.

23.5.4. Overlapping fire zones - When any building is so situated that it extends equally to more than one fire zone it shall be deemed to be in the fire zone in which the major portion of the buildings or structure is situated.

When any building is so situated that it extends equally to more than one fire zone it shall be deemed to be in the fire zone having more hazardous occupancy buildings.

23.5.5. Temporary buildings or structures - Temporary buildings and structures shall be permitted only in Fire Zones No.1 and 2 as the case may be according to the purpose for which these are to be used, be special permit from the Authority for a limited period and subject to such conditions as may be imposed in the permit.

Such buildings and temporary structures shall be completely removed on the expiry of the period in the permit.

Adequate fire precautionary measures in the construction of temporary structures and pendals shall be taken in accordance with accepted standards.

23.5.6. Restrictions on the type of construction for new buildings

Buildings created in Fire Zone no.1 shall conform to construction of Type 1, 2, 3, or 4

Buildings created in Fire Zone no.2 shall conform to construction of Type 1, 2 or 3

Buildings created in Fire Zone no.3 shall conform to construction of Type 1 or 2.

23.5.7. Restrictions on existing buildings - The existing buildings in any fire zone shall not be required to comply with the requirement of the code unless these are altered, or in the opinion of the Authority, such building constitutes a hazard to the safety of the adjacent property or the occupants of the building itself or is an unsafe building.    In the even of alteration, it shall be necessary to obtain permission of the Authority for such alteration consistent with fire hazard.  Alterations, modifications renovations shall be accomplished so as to ensure conformity with all the safety requirements of the new buildings.  Such alterations shall not in any way bring down level of fire and life safety below that which existed earlier.  Any addition or alterations or construction of cubicles partitioning for floor area exceeding 500 m² shall be with approval of local fire authority for all high rise buildings with an exception of residential buildings.

23.6. General requirements of all individual occupancies

23.6.1. General – All buildings shall satisfy certain requirements which contribute, individually and collectively, to the safety of life from fire, smoke fumes and panic  arising from  these or similar causes.  There are, however certain General principles and common requirements which are applicable to all or most of the occupancies.   

23.6.1.1. Exceptions and deviations - Exceptions and deviations to the general provisions of requirements of individual occupancy in 23.8.6 to 23.16 in case of practical difficulty or to avoid unnecessary hardship, without sacrificing reasonable safety, the Authority may grant exemptions from the section. 

23.6.1.2. Occupation of building under construction - A building or portion of the building may be occupied during construction, repairs, and alterations during construction, repairs alterations or additions only if all means of exit and fire protection measures are in place and continuously maintained for the occupied part of the building.

A high rise building during construction shall be provided with the following fire protection measures, which shall be maintained in good working condition at all the times.

1. Dry riser of minimum 100 mm diameter pipe with hydrant outlast on the floors constructed with a fire service inlet to boost the water in the dry riser and maintenance should be as per the requirements laid down in Indian standard given in Annexure 23-A.1.
2. Drums filled with water of 2000 liters capacity with two fire buckets on each floor:
3. A water storage tank minimum 20000 liters capacity, which may be used for other construction purposes also.

Table 19 Comparative floor area ratios of occupancies on public street atleast 9m wide (Clause 23.6)

Occupancy classification	Type of construction
	Type 1	Type 2	Type 3	Type 4
Residential	UL	2.0	1.4	1.0
Educational	UL	2.0	1.4	1.0
Institutional	UL	1.5	1.0	0.8
Assembly	UL	1.0	0.7	0.5
Business	UL	2.9	2.3	1.6
Mercantile	8.0	1.8	1.4	1.0
Industrial	7.5	1.9	1.6	1.3
Storage (see Note 4)	6.0	1.5	1.3	1.0
Hazardous (see Note 4)	2.8	1.1	0.9	NP

UL – Unlimited   NP – Not permitted.

Note 1: The FAR values given in this table are subject to overall restrictions on the heights of buildings in the case of educational, institutional, assembly, storage and hazardous occupancies as specified in col. 2 of Table 20.

Note 2: This table has been prepared, taking into account the combustible content in the different occupancies as well as the fire resistance offered by the type of construction.

Note 3: This table should be modified by the Authority taking into account the other aspects as given below, subject to local byelaws.

(a)Density in terms of dwelling units per hectare; (b)Traffic considerations; (c)Parking spaces; (d)Local fire fighting facilities; and (e)Water supply, drainage and sanitation requirements;

Note 4: The FAR values specified in this table may be increased by 20 percent for the following services;

1. A basement or cellar space under a building constructed on stilts and used as a parking space and air conditioning plant room used as accessory to the principle use:

2. Watchman’s booth pump house, garbage shaft electric cabin or substation and other utility structures meant for the service of the building under consideration.
3. Projections and accessory building as specifically exempted under the code; and
4. Staircase room and lift rooms above the topmost store; architectural feature; and   chimneys and elevate tanks of dimensions as permissible under the code; the area of the lift shaft shall be taken only on one floor.

Note 5: In so far as single storey storage and hazardous occupancies are concerned, they would be further governed by Volume to Plot Area ratio (VPR) to be decided by the Authority.

23.6.2. Maximum height   - Every building shall be restricted in its height above the ground level and the number of storeys, depending upon its occupancy and the type of construction.  The height shall be measured as specified.  The maximum permissible height for any combination of occupancy and types of construction should necessarily be related to the width of street fronting the building or floor area rations and the local fire fighting facilities available.

23.6.3. Floor area ratio - The comparative floor area rations for different occupancies and types of constructions and types of construction are given in Table 19.

Each portion of a building, which is separated by one more continuous fire resting walls, having a fire resistance of not less than 2 h, extending from the foundation to 1 m above the roof at all points, may be considered to be a separate building for the calculation of maximum permissible height and floor area, provided opening, if any in the separating wall are also protected by fire assemblies not less than 2h

23.6.4. Open spaces - The open spaces around or inside a building shall conform to the requirements.

For high rise building, the following additional provisions of means of access to the building shall be ensured.

1. The width of the main street on which the building abuts shall not be less than 12 m and one end of this street shall join another street not less than 12 m in width;
2. The road shall not terminate in a dead end; except in the case of residential building, up to a height of 30 m.
3. The compulsory open spaces around the building shall not be used for parking; and
4. Adequate passageway and clearances required for fire fighting vehicles to enter the premises shall be provided at the main entrance; the width of such entrance shall be not less than 4.5m. If an arch or covered gate is constructed, it shall have a clear head – room of not less than 5m.

23.6.5. Mixed occupancy – When any building is used for more than one type of occupancy, it shall conform to the requirements for the occupancies of higher hazard.  Unless the high hazard area is separated by separating walls of 4 h rating, the occupancies shall not be treated individually.

23.6.6. Openings in separating walls and floors - At the time of designing openings in separating walls and floors, particular attention shall be paid to all such factors as will limit fire spread through these openings and maintain fire rotting of the structural member.

For types 1 to 3 constructions a doorway or opening in a separating wall on any floor shall be limited to 5.6.m² in area with a maximum height of 2.75m.  Every wall opening shall be protected with fire – resisting doors or steel rolling shutters having the fire rating of not less than 2h, conforming to India Standards in Annexure 23-A.1.  All openings in the floors shall be protected by vertical enclosures extending above and below such openings, the walls of such enclosure having a fire resistance of not less than 2 h and all openings therein being protected with a fire resisting assembly having a fire-resistance rating as specified in 23.6.8.

For Type 4 Construction, opening in the separating walls or floors walls or floors shall be fitted with 2h fire resisting assemblies.

Openings in walls or floors which are necessary to be provided to allow passages of all buildings services like cables, electrical wiring, telephone cables, plumbing and fixtures etc., shall be protected by enclosure in the form of ducts/shafts having a fire resistance not less than 2h.  the inspection door of all service shafts shall have fire resistance not less than 1 h.  medium and low voltage wiring running in shafts/ducts, shall either be armored type or run through metal conduits and the walls shall be filled in by a filler material,  compressed asbestos, fibre glass wool, rock wool , ceramic wool, etc, mixed with cement or any other material having fire resistance rating of not less than one hour.

Note: In the case of building where it is necessary to lower or lift heavy machinery or goods from one floor to the other it may be necessary to provided larger opening in the floor.  Such opening shall be provided with removable covers which shall have the same strength and fire resistance as the floor.

Vertical opening - Every vertical opening between the floors of a building shall be suitably enclosed or protected, as necessary, to provide the following:

1. Reasonable safety to the occupants while using the means of egress by preventing spread of fire, smoke, or fumes through vertical openings from floor to floor to allow occupants to complete their use of the means of egress. Further it shall be insured to provide a clear heitht of 2 100 mm in the passage/escape path of the occupants.
2. Limitation of damage to the building and its contents.

Fire Stop or Enclosure of Openings - Where openings are permitted, they shall not exceed three-fourths the area of the wall in the case of an external wall and they shall be protected with fire resisting assemblies or enclosures having a fire resistance equal to that of the wall or floor in which these are situated. Such assemblies and enclosures shall also be capable of preventing the spread of smoke or fumes through the openings so as to facilitate the safe evacuation of building in case of a fire.

23.6.7. Electrical installations – For requirements regarding electrical installations from the point of view of  fire safety, reference may be made to Indian Standards at Annexure 23-A.1

23.6.8.  Fire stop or enclosure of all openings - Where openings are permitted, they shall  not exceed three – fourths the area of the wall in the case of an external wall and they shall be protected with fire resisting assemblage equal to that of the wall or floor in which these are situated.  Such assemblies and enclosures shall also be capable of preventing the spread of smoke or smoke or fumes through the openings so as to facilitate the safe evacuation of building in case of a fire. [see also Annexure 23-A.1.]

23.6.9.  Fire detection extinguishing system – In buildings of such size, arrangement or occupancy that a fire may not itself provide adequate warning to occupants, automatic fire detection and alarm facilities shall be provided, where necessary, to that they may escape, or to facilitate the orderly conduct of fire exit drills.

The fire detection and extinguishing system shall conform to accepted standards as given in Annexure 23-A.1.  Guidelines for selection of various types of fire detectors for different occupancies shall conform to IS standards in Annexure 23-A.1.

Note : Fire detectors for use in an automatic fire alarm system  shall conform to Indian Standards given and the automatic fire alarm system using such detectors shall be installed in accordance with Indian Standards given at Annexure 23-A.1.

The requirement of fire detection and alarm systems are covered for each occupancy under 23.8.6 to 23.16.17; attention is also drawn to such requirements in case of high rise buildings (15m or more in height) as given in Annexure 23-A.4).

23.6.10. Fixed fire-fighting installations.

23.6.10.1. All buildings depending upon the occupancy use and height shall be protected by wet riser, downcomer, automatic sprinkler installation, high/medium velocity water spray, from gaseous or dry powder system..

These fixed installations shall on from to accepted standards.  The typical requirements of wet riser/down comer installation and capacity of water storage tanks and fire pumps shall be as specified in Table 27.  The typical arrangements if downcomer and wet riser installations are shown in Fig.1 and Fig.2. The wet riser shall be designed for zonal distribution ensuring that unduly high pressures are not developed in risers and hose pipes.

In situations where one occupancy is provided with all the required fire protection arrangements but due to proximity of unprotected buildings around, causing exposure hazard to the protected building, the protected building walls facing the unprotected building shall be provided with water curtain/ drencher system which can be actuated, when necessary.

First –aid fire fighting appliances shall be provided and installed in accordance with Indian Standards given in Annexure 23-A.1.  The fire fighting equipment and accessories to be installed in buildings for use in fire fighting shall conform to appropriate Indian Standards given in Annexure 23-A.1 and shall be maintained periodically so as to ensure their prefer serviceability at all times.

Fig 1 Typical arrangement of down-corner for building above 15 m but not exceeding 30 m in height

In addition to wet riser or downcomer, first-aid hose reels shall be installed on all the floors of

buildings of 15m in height or more.  The first aid hose reel shall be connected directly to the riser/downcomer main and diameter of the hose reel shall not be less than 19mm.

23.6.10.2. Static water storage tanks- A Satisfactory supply of water for the purpose of fire fighting shall always be available in the form of underground/ terrace level static storage tank with capacity specified for each building with arrangements of replenishment by main or alternative source of supply at the rate of 1,000 liters per minute.  When this is not practicable, the capacity of static storage tanks(s) shall be increased proportionately in consultation with the local fire brigade.

The Static storage water supply required for the above mentioned purpose shall entirely be accessible to the fire engines of the local fire service.  Provision of suitable number of manholes shall be made available for inspection, repairs, insertion of suction hose, etc.  The covering slab shall be able to withstand the vehicular load of 22.5 tonnes at any given point when the slab forms a part of pathway/driveway.

Fig 2 Typical arrangement of wet riser and total sprinkler system of building other than apartment exceeding 30 m height

The domestic suction tank connected to the static water tank shall have an overflow capable of discharging 2250 liters per minute to a visible drain point from which by a separate conduit the overflow shall be conveyed to storm water drain.

1. To prevent stagnation of water in the static water storage tank, the suction tank of the domestic water supply shall be fed only through an overflow arrangement to maintain the level therein at the minimum specified capacity (see Fig.3.)
2. The static water storage tank shall be provided with a fire storage collecting head with 4 number 63 mm diameter (2number 63 mm diameter for pump with capacity 1 400 1/min)  instantaneous male inlets arranged in a valve box at a suitable point at street level and connected to the static tank by a suitable fixed pipe not less than 150 mm in diameter to discharged at the rate of 2 250 water into the tank when required at the rate of 2250 liters per minute, if tank is in the basement or not approachable for the fire engines.

Fig 3 Typical arrangement for providing combined fire fighting and domestic water storage tank

23.6.10.3. Automatic sprinklers - Automatic sprinklers shall be installed in:

a)  Basements used as car parks or storage occupancy, if the area exceeds 200 m^2;

b) Multi-level basements, covered, upper floors used as car parks, and for housing essential services ancillary to a particular occupancy or for storage occupancy, excluding any area to be used for sub- station, A.C.  Plant and DG set;

c)   Any room or other compartment of a building exceeding 1125 m² in area except as in (g) (see Note), if so advised by local authority;

d)   Departmental stores or shops, if the aggregate covered area exceed 750 m^{2 ;}

e)  All non – domestic floors of mixed occupancy which constitute a hazard and are not provided with staircases independent of the remainder of the buildings;

f)  God owns and warehouses, as considered necessary.

g) On all floors of the buildings other than residential buildings, if the height of the buildings, if the height of the buildings exceeds 30m (45 m in case of group housing and apartments) (see Note);

h)  Dressing room, scenery docks, stages   basements of theatres;

j)  In hotels, hospitals, industries low and moderate hazard mercantile buildings of height 15 m or above;

k)   In hotels below 15m, if covered area at each floor is more than 1 000 m²

m)  false ceiling voids which are used for storage or as return air plenums exceeding 800 mm in height in sprinklered buildings; and

n)   Canteen provided in upper floors of D-1 and D-2 occupancies shall be sprinkler.

Note:  It is desirable that all high rise buildings should be fully sprinkler irrespective of their height and occupancy.  If selective sprinkling is adopted, there is a real danger of a fire starting on one of the lower unsprinkled floors gathering momentum, spreading upwards from floors to floors through the unspinklered floor and reaching the first sprinkler floor as a fully developed fire.  In such an event, the sprinklers can be rendered useless or ineffective. 

23.6.10.4. Automatic high velocity water spray or emulsifying system - Automatic high velocity water spray or emulsifying system shall be provided for protection of indoor transformers as applicable in accordance with D-1.16 and of accepted standards given in Annexure 23-A.1.

23.6.10.5. Fixed foam installation - Fixed foam generating system shall be provided for protection of oil storage area for boilers with its ancillary storage of furnace oils in basement.  Fixed foam installations can be low, medium or high expansion types, which can cover fire risks in oil storage areas generally.   High expansion foams are used for cable tunnels and other confined areas.

23.6.10.6. Carbon dioxide fire extinguishing system  -  Fixed  carbon dioxide fire extinguishing installation shall be provided in accordance with Indian Standard given at (13) of Annexure 23-A.1 on premises where eater of form can not be used for fire extinguishing because of the special nature of the contents of the building /areas to be protected.  For some special fire risk, carbon dioxide may not be suitable and it may be necessary to provided BCF (Bromochloro-difluromethane) - Halon 1211 or BTM (Bromochloro – trifluromethane) – Halon 1301.

However, the use of halos shall be discouraged, as Halons are ozone depleting substances (ODS) and their use is being phased out throughout the world.

Fire fighting equipment shall be suitably located and clearly marked by luminous signs.

Note: This provision shall not apply to occupancies A-2 and A-4 less than 15m in height.

23.6.11. Air–conditioning and ventilation – Air Conditioning and ventilation required of different rooms or areas in any occupancy shall be as given in Section 18 Air–Conditioning.

Air-Conditioning and ventilating systems shall be so installed and maintained as to minimize the danger of spread of fire, smoke or fumes thereby from one floor or fire area to another, or from outside into any occupied building or strutting. (See Annexure 23-A.4.)

 Air-Conditioning and ventilating systems circulating air to more than one floor or fire area shall be provided with dampers designed to close automatically in case of fire and thereby preventing

spread of fire or smoke.  Such a system shall also be provided with automatic controls to stop fans in case of fire unless arranged to remove smoke from a fire, in which case these shall be designed to remain in operation.

Air-Conditioning system serving large places of assembly (over 1000 persons), large departmental stores or hotels with over 100 rooms in a single block shall be provided with effective means for preventing circulation of smoke through the system in the case of a fire in air filters or from other sources drawn into the system and shall have of approved smoke sensitive devices for actuation.

From fire safety point of view, it will be preferable to provide separate air handling units for the various floors so as to avoid the hazards arising from spread of fire and smoke through the A.C. ducts. The A.C ducts should conform to Indian Standards given in Annexure 23-A.1.

For normal operation, air changes schedule should be as follows:

Table 20

Space to be ventilated	Air changes per hour
* Assembly hall auditoria	3 - 6
* Bed rooms/living rooms	3 - 6
Bath rooms/toilets	6- 12
* Cafes/restaurants	12 - 15
Cinemas/theatres (Non-smoking)	6 - 9
Class rooms	3 - 6
* Factories (Medium metal work)	3 - 6
* Garages	12 - 15
* Hospital wards	3 - 6
* Kitchens (common)	6 - 9
* Kitchens/domestic	3 - 6
Laboratories	3 - 6
* Offices	3 - 6

* Contaminates for normal operation of ventilating system such heat, smoke and fumes shall be collected separately by local exhaust ventilation.

23.6.12. Smoke venting - Smoke venting facilities where required for safe use of exits in windowless buildings, underground structures. Large area factories shall be automatic in action with manual controls in addition.

Natural draft smoke venting shall utilize roof vents or vents in walls at or near the ceiling level; such vents shall be normally open, or if closed shall be designed for automatic opening in case of fire, by release  of smoke sensitive devices.

Where smoke venting facilities are installed for purpose  of exit safety, these shall be adequate to prevent dangerous accumulation of smoke during the period of time  necessary to evacuate the area served, using available exit facilities with a margin of safety to allow for unforeseen contingencies.  It is recommended that smoke exhaust equipment should have a minimum capacity of approximately a 5 min air change.  Where mechanical venting is employed, it shall be fire safe.

The discharge apertures of all natural draft smoke vents shall be so arranged as to be readily susceptible to opening by fire service personal.  

Power operated smoke exhausting systems may be substituted for natural draft vents only by specific permission of the Authority.

23.6.13. Heating - Installation of chimney and heating apparatus shall conform to Indian Standards given in Annexure 23-A.1.

23.6.14. Additional precautions - In addition to the factors covered by 23.6.2 to 23.6.13 there are certain aspects, applicable to particular occupancies only which may affect the spread of fire smoke or fumes and thus the safe evacuation of the building in case of fire, Some such aspects are:

1. Interior finish and decoration;
2. Seating, arise, railings and turnstiles in place of assembly.
3. Service equipment and storage facilities in buildings other than storage buildings; and
4. Hazards in stage, in waiting spaces projection booths, etc, in theaters and cinemas.

23.6.15. Surface interior finishes - The use of flammable surface finishes on walls (including external façade of the building) and ceilings affects the safety of the occupants of a building.  Such finishes tend to spread the fire and even though the structural elements may be adequately fire resistant, serious danger to life may result.  It is therefore, essential to have adequate precautions to minimize spread of flame on wall, façade of building and ceiling surfaces.

The finishing materials used for various surfaces and décor shall be such that it shall not generate toxic smoke/fumes.

The susceptibility to fire of various, types of wall surfaces is determined in terms of the rate of spread of fire.  Based on the rate of spread of fire surfacing material shall be considered as divided into four classes as follows [See Indian Standards given in Annexure 23-A.1].

Class 1 Surface of very low flame spread

Class 2 Surface of low flame spread

Class 3 Surface of medium flame spread

Class 4 Surface of rapid flame spread

The uses for which surface materials falling into various classes shall be adopted in building construction are given below:

Table 21

Class 1	Class 2	Class 3
May be used in any situation	May be used in any situation except on walls, facade of the building staircase and corridors.	May be used only in living rooms and bed rooms (but not in rooms on the roof) and only as a lining to solid walls and partitions; not on staircases or corridors or façade of the building.

Note:  Paneling (lining) shall be permitted in a limited area.  It shall not be permitted in a vestibule.

Materials of class 4 which include untreated wood fiberboard’s may be  used as ceiling lining, provided the ceiling is at least 2.4m from the top surface of the floor below, and the wall surfaces conform to requirements of class (see Note under 23.6.15.3).  Class 4 materials shall not be used in kitchens, corridors and staircases.  Some types contain bitumen and, in addition to risk from spread of fire, emit dense smoke on burning; such materials shall be excluded from use under these conditions and shall also not be used for construction of ceiling where the plenum is used for return air in air – conditioned buildings.

When frames, walls partitions or floors are lined with combustible materials, the surfaces on both sides of the materials shall conform to the appropriate class, because there is considerable danger from fire starting and rapidly spreading within the concealed cavity unknown to the occupants whose escape may be hampered there by.  For detailed information on materials and details of construction with their fire-resistance rating, reference may be made to Indian Standards given in Annexure 23-A.1

23.6.16. Glazing

23.6.16.1. Building of Types 1 to 4 construction shall employ one of two types of glazing described in 23.6.16.2 and 23.6.16.3. Except that type 4 construction may have the alternative of hardwood sashes or frames or both. 

23.6.16.2. Wired glass shall comply with the following requirements:

a)   Thickness of glass – The thickness of glass shall be not less than 6.0 mm and minimum ½ hr. fire resisting rating

b)   Embedded wire netting – Embedded wire netting shall be not larger than 10 mm mesh.

c)   Size of squares of glass -- The area shall not exceed 0.25m ².

d)  Sashes and frames –The sashes or frames or both shall be entirely of iron or other suitable metal securely bolted or keyed into the wall except in the case of panels in internal doors.

e)   Setting of glass – The panels of glass shall be set in rebates or grooves not less than 6.0 mm in width or depth, with due allowance for expansion, and shall be secured by hard metal fastenings to the sashes or frames independently of any lead cement or putty used for weather-proofing purposes.

23.6.16.3. Electro – copper glazing shall comply with the following requirements:

1. Thickness of glass shall be not less than 6.5mm and minimum ½ hr. fire resisting rating
2. Size of squares of glass shall not exceed 100 cm²

c)   Sectional lights – The square glasses to be formed by Electro-copper glazing into sectional lights shall not exceed 0.37 m2 in area.

d)   Sashes and frames - The sashes or frames or both shall be entirely of iron or other hard metal, securely bolted or keyed into the wall, except when in panels in internal doors.

e)   Fixing of sectional lights-  The sectional lights shall be set in rebate or grooves not less than 6.5.mm in width or depth with due allowance for expansion and shall be secured by hard metal fastenings to the sashes or frames independently of any lead, cement or putty used for weather – proofing purposes.

23.6.16.4. Maximum permissible area shall be 5m²  for protection by wired glass or electro-copper glazing.

23.6.16.5. Casement -- Hard metal casements, not exceeding 0.8.m² fitted with wired glass or electro – copper glazing in accordance with 23.6.16.2 to 23.6.16.3, secured to the frames by hard metal hinges not more than 60 cm apart and by fastening at top, center and bottom shall be permissible.

23.6.17. Skylights - Wired glass for skylights or monitor lights shall comply with the following requirements:

a) Thickness of glass shall be not less than 6.0mm and shall be of minimum ½ hr. fire resisting ruing.

b) Embedded wire netting shall be not larger than 10mm mesh;

c) Frames and glazing – The frame shall be continuous and divided by bars spaced at not more than 70 cm centers.  The frame and bars shall be of iron or other hard metal, and supported on a curb either of metal; or of wood covered with sheet metal.  The glass shall be secured by hard metal fastenings to the frame and bars independently of any lead, cement or putty used for weather proofing purpose Maximum permissible area shall be 5m² for protection by wired glass.

23.6.18. Fire lifts - Where applicable fire lifts shall be provided with a minimum capacity for 8 passengers and fully automated with emergency switch on ground level.  In general, buildings 15 m in height or above shall be provided with fire lifts.

In case of fire, only fireman shall operate fire lifts.  In normal course, it may be used by other persons.

Each fire lift shall be equipped with suitable inter-communication equipment for communicating with the control room on the ground floor of the building. 

The number and location of fire lift in a building shall be decided after taking into considerations various factors like building population, Floor area, section of building (compartmentation), etc

23.7. Exit requirements

23.7.1. An exit may be a doorway corridor; passageway (s) to an internal staircase or external staircase, or to a verandah or terraces(s) which have access to the street, or to the roof of a building or a refuge area.  An exit may also include a horizontal exit leading to an adjoining building at the same level.

Lifts and escalators shall not be considered as exits.

23.7.2. General

Every building meant for human occupancy shall be provided with exits sufficient to permit safe escape of occupants, in case of fire or other emergency.

In every building exit shall comply with the minimum requirements of this part, except those not accessible for general public use.

All exits shall be free of obstructions.

No building shall be so altered as to reduce the number, width or protection of exits to less the required.

Exits shall be clearly visible and the routes to reach the exit shall be clearly marked and sign posted to guide the population of the floor concerned.  Signs shall be illuminated and wired an independent electrical circuit on an alternative source of supply.  The sizes and colors of the exit signs shall be in accordance with Indian Standards given in Annexure 23-A.1.

Note: This provision shall not apply to A-2 and A-4 occupancies less than 15 m in height.

The floors of areas covered for the means of exit shall be illuminated to values not less than 1 ft candle (10 lux) at floor level.  In auditorium, theatres, concert halls and such others places of assembly, the illumination of floor exit/access may be reduced during periods of performances to values not less than 1/5 ft candle (2 lux).

Fire–Check doors for fire resistance of 2 h shall be provided at appropriate places along the escape routes to prevent spread of fire and smoke, and particularly at the entrance to lifts and stairs where a ‘ funnel or flue effect’ may be created, inducing an upward spread of fire and smoke

All exits shall provide continuous means of egress to the exterior of a building or to an exterior open space leading to a street.

Exits shall be so arranged that they may be reached without passing through another occupied unit.

23.7.3. Occupant load – For determining the exits required the number of persons within any floor area or the occupant load shall be based on the actual number of occupants, but in no case less than that specified in Table 22.

23.7.3.1. Mezzanine – The occupant load of a mezzanine floor discharging to a floor below shall be added to that floor occupancy and the capacity of the exits shall be designed for the total occupancy load thus established.

23.7.4. Capacity of exits

23.7.4.1. The unit of exit width, used to measure the capacity of any exit shall be 50 cm.  A clear width of 25 cm shall be counted as an additional half unit.  Clear widths less than 25 cm shall not be counted for exit width.

Note: The total occupants from a particular floor must evacuate within 2 5 minutes for type 1 construction, 1.5 minutes for Type II construction and 1 minute for Type III construction.  Size of the exit door/exit way shall be calculated accordingly keeping in view the travel distance as per Table 24.

Table 22 Occupant load (Clause 23.7.3)
Sl. No.	Group of occupancy	Occupant load, floor area in m2/person
01	Residential (A)	12.5
02	Educational (B)	4
03	Institution (C)	15*
04	Assembly(D) With fixed or loose seats and dance floors Without seating facilities including dining rooms	0.6* 1.5+
05	Mercantile (F) Street floor and sales basement Upper sale floors	3 6
06	Business and industrial (E&G)	10
07	Storage (H)	30
08	Hazardous (J)	10

*Occupant load in dormitory portions of homes for the aged, orphanages   insane asylums etc, where sleeping accommodation is provided shall be calculated at less than 7.5.m² gross floor area/ persons.

+ The gross floor area shall include, in addition to the assembly room or space, any occupied connecting room or space in the same storey or in the storeys above or below where entrance is common to such rooms and spaces and they are available for use by the occupants of the assembly place.  No deductions shall be made in the gross area for corridors, closets or other subdivisions; the area shall include all space serving the particular assembly occupancy.

Occupants per unit's exit width shall be in accordance with Table 23.

23.7.4.2. Horizontal exit allowance - When horizontal exit is provided in buildings of mercantile, industrial business and assembly occupancies the capacity per storey per unit width of exit of stairways in Table 23 may be increased by 50 percent; and in buildings of institutional occupancy it may be in creased by 100 percent.

Table 23 occupants per unit exit width (clause 23.7.4.2)

Sl. No.	Group of occupancy	Number of occupants
		Stairways	Ramps	Doors
01	Residential (A)	25	50	75
02	Educational (B)	25	50	75
03	Institutions (C)	25	50	75
04	Assembly (D)	40	50	60
05	Business (E)	50	60	75
06	Mercantile (F)	50	60	75
07	Industrial (G)	50	60	75
08	Storage (H)	50	60	75
09	Hazardous(J)	25	30	40

23.7.5. Arrangement of exits

Exits shall be so located that the travel distance on the floor shall not exceed the distance given Table 24.

Table 24 Travel distance for occupancy and type of construction

Sl.No	Group of occupancy	Maximum travel distance construction
		Types 1&2 (m)	Types 3 &4 (m)
01.	Residential   (A)	30.0	22.5
02	Educational  (B)	30.0	22.5
03	Institutions   (C)	30.0	22.5
04	Assembly     (D)	30.0	30.0
05	Business       (E)	30.0	30.0
06	Mercantile    (F)	30.0	30.0
07	Industrial     (G)	45.0	*
08	Storage        (H)	30.0	*
09	Hazardous    (J)	22.5	*

Note 1: For the sprinklers system, the travel distance may be increased by 50 percent of the values specified.

Note 2: In so far as basements are concerned, the travel distance will reckon half the value as prescribed in Table 24.  Ramps shall also be counted as one of the means of escape.

* Construction of type 3 or 4 is not permitted.

The travel distance to an exit from the dead end of a corridors shall not exceed half the distance specified in table 24, except in as assembly and institutional occupancies in which case it shall not exceed 6 m.

Whenever more than one exit is required for any room space or floor of a building, exits shall be placed as remote from each other as possible and shall be arranged to provide direct access in separate directions from any point in the area served.

23.7.6. Number of exits

General – The general requirements of number of exits shall supplement the requirement of different occupancies in 23.8 to 23.16.

All buildings which are 15 m in height or above and all buildings used as educational, assembly, institutions industrial, storage and hazardous occupancies, and mixed occupancies with any of the aforesaid occupancies having area more the 500 m² on each floor shall have a minimum of two staircases.  They shall be of enclosed type; at least one of them shall be on external walls of buildings and shall open directly to the exterior space or to an open place of safety.  Further the provision or otherwise of alternative air case shall be subject to the requirements of travel distance being complied with.

23.7.7. Doorways

Every exit doorway shall open into an enclosed stairway or a horizontal exit of a corridor or passageway providing continuous and protected means of egress.

No exit doorway shall be less than 100 cm in width except assembly buildings where door width shall be not less than 200 cm.  Doorways shall be not less than 200 cm in height.

Exit doorway shall open outwards that is, away from the room, but shall not obstruct the travel along any exit.  No door when opened shall reduce the required width of stairway or landing to less than 90 cm; overhead sliding shall not be installed.

Note:  In the case of buildings where there is a central corridor, the doors of rooms shall open inwards to permit smooth flow of traffic in the corridor:

Exit door shall not open immediately upon a flight of stairs; a landing equal to at least the width of the door shall be provided in the stairway at each doorway the level of landing shall be the same as that of the floor which it serves.

Exit doorways shall be openable from the side which they serve without the use of a key.

Mirrors shall not be placed in exit ways or exit doors to avoid confusion regarding the direction of exit.

23.7.8. Corridors and passageways

Exit corridors and passageways shall be of width not less than the aggregate required width of exit doorways leading from them in the direction of travel to the exterior.

 Where stairways discharge through corridors and passageways, the height of corridors and passageways shall be not less than 2.4m.

All means of exit including staircases lift lobbies and corridors shall be adequately ventilated.

23.7.9. Internal staircases - Internal stairs shall be constructed of non combustible materials throughout.

Interior stairs shall be constructed as self-contained unit with an external wall constituting at leas one of its sides and shall be completely enclosed.

A staircase shall not be arranged round a lift shaft.

Hollow combustible construction shall not be permitted.

No gas piping shall be laid in the stairway.  No electrical panels shall be all mixed in the stairway. Ducting in stairway may be permitted if it is of 1hr. fire resistance rating.

Not withstanding the detailed provision for exists in accordance with 23.7.3, 23.7.4 and 23.7.5, the following minimum width shall be provided for staircases:

Table 25

a	Residential buildings (dwellings)	1.0 m
b	Residential hotel buildings	1.5 m
c	Assembly buildings like auditorium, theatres and cinemas	2.0 m
d	Educational buildings upto 30 m in height	1.5 m
e	Institutional buildings like hospitals	2.0 m
f	All other buildings	1.5 m

The minimum width of tread without nosing shall be 250 mm for internal staircase of residential buildings.  This shall be 30 cm for assembly, hotels, educational, institutional, business and other buildings.  The treads shall be constructed and maintained in a manner to prevent slipping

The maximum height of riser shall be 19 cm for residential buildings and 15 cm for other buildings and the number shall be limited to 15 per flight.

Hand rails shall be provided at a height of 100 cm to be measured from the base of the middle of the treads to the top of the hand rails. Further, the gap between the two verticals shall not exceed 30 cm.  This gap shall be reduced to 15 cm, where children are likely to use the staircase. Balusters / railing shall be provided such that the wish of staircase does not reduce.

The number of people in between floor landings in staircase shall not be less than the population on each floor for the purpose of design of staircase.

1. The minimum headroom in a passage under the landing of a staircase and under the staircase shall be 2.2 m.
2. For building 15 m in height or more, access to main staircase shall be through a fire / smoke check door of 2 hour fire resistance rating.  Fire resistance rating may be reduced to one an hour for residential buildings. (except hotels and starved hotels)
3. No living space, store or other fire risk shall open directly into the staircase or staircases.
4. External exit door of staircase enclosure at ground level shall open directly to the open spaces or through a large lobby, if necessary.
5. The main staircase and external staircase shall be continuous from ground floor to the terrace level.
6. No electrical shafts/AC ducts or gas pipe, etc. shall pass through the staircases.  Lift shall not open in staircase.
7. No combustible material shall be used for decoration/wall paneling in the staircase.
8. Beams/columns and other building features shall not reduce the head room/width of the staircase.
9. The exit sign with arrow indicating the way to the escape route shall be provided at a suitable height from the floor level on the wall and shall be illuminated by electric light connected to corridor circuits. All exit way marking signs should be flush with the wall and so designed that no mechanical damage shall occur to them due to moving of furniture or other heavy equipments.  Further, all landings of floor shall have floor indicating boards prominently indicating the number of floor as per bye-laws.
10. The floor indication board shall be placed on the wall immediately facing the flight of stairs and nearest to the landing.  It shall be of size not less than 0.5 x 0.5 m.
11. k)   Individual floors shall be prominently indicated on the wall facing the staircases.
12. In case of single staircase it shall terminate at the ground floor level and the access to the basement shall be by a separate staircase.  However, the second staircase may lead to basement levels provided the same is separated at ground level by ventilated lobby with discharge points to two different ends through enclosures.

23.7.10. .Pressurization of staircases (protected escape routes)