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NBC 2016 (SP 7:2016) Volume 1
2016 · PDF page 267
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The city or area under the jurisdiction of the Authority shall, for the purpose of the Code, be demarcated into distinct zones, based on fire hazard inherent in the buildings and structures according to occupancy (see 3.1), which shall be called as ‘Fire Zones’.
3.2.2.1 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 3.3), classification of existing buildings based on occupancy (see 3.1) and expected future development of the city or area. In large cities or areas, three fire zones may be necessary, while in smaller ones, one or two may be adequate.
3.2.2.2 The fire zones shall be made use of in land use development plan and shall be designated as follows:
a) Fire Zone No. 1 — This shall comprise areas having residential (Group A), educational (Group B), institutional (Group C), assembly (Group D), small business (Subdivision E-1) and mercantile (Group F) buildings, or areas which are under development for such occupancies.
b) Fire Zone No. 2 — This shall comprise business (Subdivisions E-2 to E-5) and industrial buildings (Subdivisions G-1 and G-2), except high hazard industrial buildings (Subdivision G-3) or areas which are under development for such occupancies.
c) Fire Zone No. 3 — This shall comprise areas having high hazard industrial buildings (Subdivision G-3), storage buildings (Group H) and buildings for hazardous uses (Group J) or areas which are under development for such occupancies.
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.
3.2.4.1 When any building is so situated that it extends to more than one fire zone, it shall be deemed to be in the fire zone in which the major portion of the building or structure is situated.
3.2.4.2 When any building is so situated that it extends equally to more than one fire zone, it shall be deemed
PART 4 FIRE AND LIFE SAFETY
to be in the fire zone having more hazardous occupancy buildings.
3.2.5.1 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, by special permit from the Authority for a limited period and subject to such conditions as may be imposed in the permit.
3.2.5.2 Such buildings and temporary structures shall be completely removed on the expiry of the period specified in the permit.
3.2.5.3 Adequate fire precautionary measures in the construction of temporary structures and Pandals shall be taken in accordance with good practice [4(4)].
3.2.6 Restrictions on the Type of Construction for New Buildings
These shall be as follows:
a) Buildings erected in Fire Zone No. 1 shall conform to construction of Type 1, 2, 3 or 4.
b) Buildings erected in Fire Zone No. 2 shall conform to construction of Type 1, 2 or 3.
c) Buildings erected in Fire Zone No. 3 shall conform to construction of Type 1 or 2.
The existing buildings in any fire zone shall not be required to comply with the requirements 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 to the occupants of the building itself or is an unsafe building. In the event of alteration, it shall be necessary to obtain permission of the Authority for such alteration consistent with fire hazard (see Part 2 ‘Administration’ of the Code).
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 or partitioning, for floor area exceeding for all high rise buildings shall be with the approval of local fire authority.
3.3.1 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 minutes against a specified fire load which is expressed in kcal/m , and against a certain intensity of fire. The fire-resistance test for structural element shall be done in accordance with accepted standards [4(2)]. For the purpose of the Code, 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 minimum fire resistance ratings of structural and non-structural members for various types of construction shall be as given in Table 1.
Non-combustible materials should be used for construction of buildings, and the internal walls of staircase enclosures should be of brick work or reinforced concrete or any other material of construction with minimum of 120 min rating. The walls for the chimney shall be of Type 1 or Type 2 Construction depending on whether the flue gas temperature is above C or less, respectively.
3.3.2 It is required that a structural and/or non-structural element/component shall have the requisite fire resistance rating as per Table 1. The fire resistance rating for the structural and non-structural elements shall be based on guidelines as per approved and accepted standards. The fire rating shall be validated and certified with a view to meeting the requirements of Table 1. In the absence of any validated/certified rating, guidance may be obtained from the information available in Annex C.
3.3.3 Load bearing steel beams and columns of buildings having total covered area of and above shall be protected against failure/collapse of structure in case of fire. This could be achieved by use of appropriate methodology using suitable fire resistance rated materials along with suppression system (see Annex C, Table 25 and Table 26).
3.3.4 The false ceiling, including all fixtures used for its suspension, shall be of non-combustible material and shall provide adequate fire resistance to the ceiling in order to prevent spread of fire across ceiling.
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.
| Sl No. | Structural Element | Fire Resistance Ratings (min) for Type of Construction | |||
| Type 1(3) | Type 2(4) | Type 3(5) | Type 4(6) | ||
| i) | Exterior walls: | ||||
| a) Fire separation less than 3.7 m: | |||||
| 1) Bearing | 240 | 120 | 120 | 60 | |
| 2) Non-bearing | 120 | 90 | 60 | 60 | |
| b) Fire separation of 3.7 m or more but less than 9 m: | |||||
| 1) Bearing | 240 | 120 | 120 | 60 | |
| 2) Non-bearing | 90 | 60 | 60 | 60 | |
| c) Fire separation of 9 m or more: | |||||
| 1) Bearing | 240 | 120 | 120 | 60 | |
| 2) Non-bearing | 60 | 60 | 60 | 60 | |
| ii) | Fire separation assemblies (like fire check doors) | 120 | 120 | 120 | 120 |
| iii) | Fire enclosures of exits | 120 | 120 | 120 | 120 |
| iv) | Shafts for services, lift hoistway and refuse chutes | 120 | 120 | 120 | 120 |
| v) | Vertical separation between adjacent tenant spaces | 60 | 60 | 60 | 60 |
| vi) | Dwelling unit separation: | ||||
| a) Load bearing | 120 | 120 | 60 | 60 | |
| b) Non-load bearing | 60 | 60 | 30 | 30 | |
| vii) | Interior bearing walls, bearing partitions, columns, beams, girders, trusses (other than roof trusses) and framing: | ||||
| a) Supporting more than one floor | 240 | 120 | 120 | 120 | |
| b) Supporting one floor only | 180 | 90 | 60 | 60 | |
| c) Supporting a roof only | 180 | 90 | 60 | 60 | |
| viii) | Walls supporting structural members | 180 | 90 | 60 | 60 |
| ix) | Floor construction | 120 | 90 | 60 | 60 |
| x) | Roof construction: | ||||
| a) 5 m or less in height to lowest member | 120 | 90 | 60 | 60 | |
| b) More than 5 m but less than 6.7 m in height to lowest member | 60 | 60 | 60 | 60 | |
| c) 6.7 m or more in height to lowest member | 0 | 0 | 0 | 0 | |
| NOTES | |||||
| 1 The above fire resistance rating shall be required to achieve the respective type of construction unless otherwise specified in the respective clauses for different applications/use. | |||||
| 2 In case of lift bank, the partition wall, if any, need not be of fire rating specified in this table. | |||||
Exceptions and deviations to the general provisions of requirements of individual occupancies are given as applicable to each type of occupancy in 6.1 to 6.9. In case of practical difficulty or to avoid unnecessary hardship, without sacrificing reasonable safety, local head, fire services may consider exemptions from the Code.
3.4.3.1 A building or portion of the building may be occupied 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.
3.4.3.2 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:
a) Dry riser of minimum 100 mm diameter pipe with hydrant outlets on the floors constructed with a fire service inlet to boost the water in the dry riser and maintenance should be in accordance with good practice [4(5)].
b) Drums of 2 000 litre capacity filled with water with two fire buckets on each floor;
c) A water storage tank of minimum 20 000 litre capacity, which may be used for other construction purposes also.
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3.4.4 Maximum Height, Floor Area Ratio and Open Spaces
3.4.4.1 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 in Part 3 ‘Development Control Rules and General Building Requirements’ of the Code. 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 ratios and the local firefighting facilities available.
NOTE — Set-back distances (according to the permissible height for each type of building as per the occupancy), width of streets providing approach to the building, permitted floor area ratio (FAR), permitted open space around or inside buildings, provision of adequate passageway and clearances required for firefighting vehicles, etc shall be strictly governed by the provisions of Part 3 ‘Development Control Rules and General Building Requirements’ of the Code.
The comparative floor area ratios for different occupancies and types of construction are given in Table 2 (see also Part 3 ‘Development Control Rules and General Building Requirements’ of the Code).
3.4.4.3 The requirements of open space around the building(s) shall be in accordance with Part 3 'Development Control Rules and General Building Requirements' of the Code.