IS 1642

7/28/2019 IS 1642

1/18

Indian StandardIS 1642 : 1989( Rdkmd 1991)

FIRE SAFETY OF BUILDINGS(GENERAL):DETAILS OF CONSTRUCTION-CODE OF PRACTICE/ First Revision )

_~~ ~_First Reprint OCTOBER 1998

UDC 699.812 : 11

@ BIS 1990BUREAU OF INDIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002March 1990 Price Group 7

7/28/2019 IS 1642

2/18

Fire Safety Sectional Committee, BDC 36

FOREWORDThis Indian Standard ( First Revision j was adopted by the Bureau of Indian Standards on 20 June1989, after the draft linalized by the Fire Safety Sectional Committee had been approved by theCivil Engineering Division Council.The technical interpretation of fire safety of buildings is to convey the tire resistance of buildings interms of hours when subjected to a fire of known intensity. The fire grading of the building itselfenables the correct amount of storage and class of materials, or appropriate fire load to beapportioned for that particular application; the converse also holds good, thus, a building beingrequired to accommodate a particular fire load for a given period would require the shell or fabricmaterials and construction to be designed accordingly.Loss of life in tires is mainly due to smoke and hot gases being inhaled by occupants before acturalflames have devclopcd to a serious degree within the room concerned. Smoke and hot gasesspread through doorways and ventilators which are normally impossible to keep closed. Theessential requircmenls for lire safety in so far as materials and details of construction areconcerned, arc that the flamr smoke and hot gases should not spread so rapidly as to give theoccupants insufficient time to escape. Should a fire occur, the construction should not further tendto spread the fire.In order to reduce spread of fire, it is necessary that:

a) the fire should not spread rapidly from one room to another through the floors, partitionsbetween rooms, and particularly between rooms and passages and staircases, that is, thestructural elements should have adequate fire resistance; andb) the naterials which are exposed to possible ignition, that is, wall and ceiling linings shouldnot easily ignite, nor should the iire spread rapidly over the surface of the materials.

With a view to cover these aspects, this standard dealing with details of construction was firstformulated in 1960. This revision has been based on useful information collcctcd as a result ofresearch in the country and abroad over the past 23 years.The provisions given in this standard are those which are necessary at the time of construction ofbuilding new or addition or alterations for adopting fire safety measures. The provisions areapplicable for all types of buildings including high rise buildings ( above 15 m in height ). I&standard does not include othrr fire sarcty measures required to be adopted in the buildings ofvarious occupancica in respect ot provision of first-aid, fire fightingmeasurzs. alarm and extinguishingsystems, operation of tire lifts, ctc; demils of which arc covered in relevant lndian Standardsformulated/under formultitioo for each type of occupancy.For the purpose of deciding whether a particular requirement of this standard is complied with, thefinal value, observed or calculated, expressing the result of a test or analysis, shall be rounded ofiin accordance with 1S 2 : 1960 Rules for rounding 017 numerical values ( revj& j. The number ofsignificant places retained in the rounded off value should be the same as that of the specified valuein this standard.

7/28/2019 IS 1642

3/18

IS 1642 1989Indian Standard

FIRE SAFETY OF BUILDINGS(GENERAL):DETAILS OF CONSTRUCTION-CODE OF PRACTICE( First Revision )

1 SCOPE1.1 his standard lays down the essentialrequirements of fire safety of buildings with respectto details of construction.2 REFERENCESThe following Indian Standards are necessaryadjuncts to this standard:IS No.IS 655 : 1963IS 941 : 1985

IS 1644 : 1988

IS 1646: 1982

1s 3809 : 1979IS 435s : 1977IS 12459 : 1988IS 12777 : 1989

TitleSpecification for metal air ductsSpecification for blower andexhauster for fire fighting (secondrevision )Code of practice for fire safetyof buildings ( general ) : Exitrequirements and personalhazard (jet revision )Code of practice for fire safetyof buildings ( general ) : Electri-cal installation (first revision )Fire resistance test of structure( jirst revision )Specification for fire-resistantbrattice cloth ( jirst revision )Code of practice for fire protec-tion of cable runsFire safety - Flame spread ofproducts - Methods forclassification

3 TERMINOLOGY3.0 For the purpose of this standard, thedefinition of various terms will be as under.3.1 Fire ResistanceAbility of an element of building construction,component for structure to fulfil, for a statedperiod of time, the required stability, fireintegrity and/or thermal insulation and/or otherexpected duty in a standard fire resistance test( see 1s 3809 : 1979 ).3.2 Fire SeparationThe distance in metres measured from any otherbuilding on the site, or from other site or from

the opposite side of street or other public spaceto the building for the purpose of preventing thespread of fire.3.3 Fire Resisting WallThe wall, either load bearing or non-load bearing.capable of specifying the criteria of fire resistance( see 3.2 ) with respect to collapse, penetrationand excessive temperature rise.3.4 Separating WallThe wall provides complete separation of onebuilding from another or part of a building fromanother part of the same building to prevent anycommunication of fire or any access or heattransmission to wall itself which may cause orassist in the combustion of materials of the sideopposite to that portion which may be on fire.3.5 Venting FireThe process of iuducting heat and smoke toleave a building as quickly as possible by suchpaths that lateral spread of fire and heat ischecked, fire figh!ing operations are facilitatedand minimum fire damage is caused.4 TYPES OF CONSTRUCTION4.0 GeneralThe design of any building and the type ofmaterials used in its construction are importantfactors in making the building resistant to acomplete burn-out and in preventing the rapidspread of fire, smoke or fumes, which mayotherwise contribute to the loss of lives andproperty.4.1 The types of construction according to fireresistance are classified into four categories,namely, Type I, Type 2, Type 3 and Type 4construction. The fire resistance ratings forvarious types of construction for structural andnon-structural members should be as given inTable 1.4.2 For buildings above 15 m in height non-combustible materials should be used for cons-truction and the internal walls of staircasesshould be of brick work or reinforced concreteor any other material of construction with min-imum of 2 hours rating. The walls for the

1

7/28/2019 IS 1642

4/18

I!3 1642 : 1989chimney shall be of Type 1 or Type 2 construc-tion depending upon whether the gas tempera-ture is above 200 C or less.4.3 The fire resistance of an element of structureor combination of elements is determined fromone of the following three methods. The firetest is done according to IS 3809 : 1979.a>

W4

Information as established by researchdata ( see Note ).Direct application of the results of fireresistance test on an element of structures.On the basis for calculating the fireresistance of a structural element. ( Thismethod is not applicable to columns orwalls. )

5 WALLS

NOTE - In the absence of research data availablein this country, the data as arrived by BuildingResearch Establishment ( UK ) ( see Guidelines forthe Construction of Fire Resisting Structural Ele-ments ) has been adopted in this standard. Thercfcrc,while using this data it may be ensured that thespecification of material of construction are same asadopted in this Report. However, as and when datafrom indigenous source is available, the same.will beincorporated in the standard.

5.1 The fire ratings of some types of constructionsfor walls ( see Note below 4.3 ) are given inTables 2 to 7. The specifications of materialsshould be so selected as to give these ratings.Table i Fire Resistance Ratings of Structural Elements ( in Hours )

( Clu~ses 4.1 atrd 5.10 )SINo. r--- Structural Element Type of Construction_*-.----____, ~~~-~~~~_~___

1

10 Structural members support wallsII Floor construction including walls12 Roof construction

Exterior walls:a) Fire separation less than 3.7 mb) Fire separation of 3.7 m ormore but less than 9 mc) Fire separation of 9m or more

Fire wallsFire separation assemblies ( likefire check doors )Fire enclosures of exitways, exit-way hallways, and stairwaysShaft other than exitways elevatorhoistwaysExitway access corridorsVertical separation of tenantspacesDwelling unit separationNon-load b-earing partitionsInterior bearing walls, bearingpartitions,columns, girders, trusses( other than roof trusses ) andframing

i) Bearingii) Non-bearingi) Bearingii) Non-bearingi) Bearing

ii) Non-beariug

i) Supporting morethan one floor_ii)-Supporting onefloor onlyiv) Supporting a roofonly

i) 5 m or less in heightto lowest memberii) More than 5 m butless than 6.7 m inheight to lowestmember

iii) 67 m or more inheight to lowestmember

Type 1 Type 2 Type 3 Type 4

2f*414422111t At4

33

8, 2I2 21 I2 21 12 22 22 22 21 11 11least half lan2 2

1) 1lb 11) 1li 1I9 11 1

0 0

2211

hour:211

2

7/28/2019 IS 1642

5/18

IS 1642 : 1989Table 2 Masonry Walls: Solid ( Required to Resist Fire from One Side at a Time )

( Clause 5.1)Nature of Constructioo and Materials Minimum Thickness (mm), Excluding any Finish, for a FireResistance (Hours ) of

--1

120(25)150

Load Bearing*---__-74

240(25)-

It140(25)175

10090

10090

10090

10090

10090

2(i$-

10090

10090

10090

10090

100IO0

36:-

170100

190100

loo

140100

140100

1 Reinforced* cement concrete2 Unreinforced cement concrete3 No-fines concrete with:a) I3 mm cementlsand or gypsum/sandb) ;fa;; hghtwelght aggregate gypsum4 Bricks of clay:a) Without finishb) With 13 mm lightweight aggregategypsum plaster5 Bricks of sand lime:a) Without finishb) With 13 mm lightweight aggregate

gypsum plaster6 Blocks of concrete:a) Without finishb) With 13 mm lightweight aggregategypsum plasterc) ya;it_ mm cement/sand or gypsum/7 Blocks of lightweight concrete:a) Without finishb) With 13 mm lightweight aggregategypsum plasterc) With 13 mm cementisand or gypsum/sand8 Blocks of aerated concrete:a) Without finishb) With 13 mm lightweight aggregategypsum plaster

9090

;x90SO

9090

*Walls containing at least 1 percent of vertical reinforcement.( ) Minimum thickness of actual cover to reinforcement.

170100

190100

lo0

I50100

180150

Non-Load Bearing _-I_-_--A--__1

150150

757.5

7575

757575

755075

50

150I50

2

150150

10090

90:0 10090

907590

10075SO

75 7563 7575 75

63 63

3

150150

17090

17090

14090100

1257590

75

4

150150

170IO0

170100

150100140

I4075100

100

Table 3 Masonry Walls: Hollows (Required to Resist Fire from One Side at a Time)(Clause 5.1 )

Nature of Construction and Materials Minimum Thickness ( mm ), Excluding any Finish, for a FireResistance ( Hours ) ofr------------ h---___________Load Bearing Non-Load Bearing__---- ____- ~ r ---___ -h_-______~1 l!, 2 3 4 : 1 1: 2 3 4

1 Bricks of clay:a), Without finishb) With 13 mm lightweight aggregategypsum plaster2 Bjocks of concrete:a) Without finishb) With 13mm cement/sand or gypsum!sandc) With 13 mm lightweight aggregategypsum plaster3 Blocks of lightweight concrete:a) Without finishb) Wi;i 13 mm cement/sand or gypsum/

c) With 13 mm lightweight aggregategypsum plaster

170 170 170 200 200 75 100 100100 100 170 170 170 75 75 90

90 125 12590 125 I25190 200 200 - - 75 90 90

100 100 100 - - ;: 905 7:63 63 75

170100

140140100

10010075

170 200100 170

125 125

140 150140 14090 100

3

7/28/2019 IS 1642

6/18

IS 1642 : 1989Table 4 Framed Construction, Load Bearing ( Required to Resist Fire from One Side at a Time )

( Clause 5.1 )Nature of Construction and Materials/Timber Studs at Centres not Exceeding Minimum Thickness ( mm ) of Protectionfor a Fire Resistance of 1 h600 mm, Faced on Each Side with

1 Plasterboard layers with joints staggered, joints in outer layertaped and filled - Total thickness for each face3 One layer of 127 mm plasterboard with a finish of lightweightaggregate gypsum plaster

2513

3 Metal lath and plaster, thickness of plaster:a) Sanded gypsum plaster ( metal lathing grade )b) Lightweight aggregate gypsum plaster

2213

Table 5 Framed Construction, Non-Load Beariug ( Required to Resist Fire from OneSide at a Time )( Clause 5.1 )

Nature of ronstrurtion and Materials/Steelor Timber Frame at Centres not Exceeding600 mm, Facings on Botb Sides of

A) Dry lining with materials fixed direct to studs( without plasrer finish ):I One layer of plasterboard with taped andfilled joints2 Two layers of plasterboard with jointsstaggered, joints in outer layer taped andfilled - Total thickness for each face3 One layer of asbestos insulating boardwith transverse joints backed by fillers of

asbestos insulating board not less than9 mm thick, or by timber4 One layer of wood wool slabs5 One layer of chipboard or of plywood

B) Lining with materials fixed direct to studs, withplaster finish:1 Plasterboard of thickness:

a) yniitinot less than 5 mm gypsum plaster]b) Tj;:hnot less than 13 mm gypsum plaster i1

C) Wet finish:1 Metal lath and plaster, thickness of plaster:

a) Sanded gypsum plasterb) Lightweight aggregate gypsum plaster

StudConstruction Minimum Thickness ( mm ) ofProtection for a FireResistance of

Timber or steel 127Timber or steel 19 25

TimberSteel

Timber 25Timber or steel 18

Timber or steel

1;

9.512.7

Timber or steelTimberSteel

13:: 19 25

Table 6 Framed External Walls Load Bearing ( Required to Resist Fire from One Side at a Time )( Clause 5.1 )

Nature of Construction and Materials Minimum Thickness ( ium ) of Protectionfor a Fire Resistance of 1 IITimber studs at centres not exceeding 600 mmwith internal linings of

1 Plasterbord layers with joints in outer layertaped and filled, total thickness of plasterboard 31

4

7/28/2019 IS 1642

7/18

IS 1642 : 1989Table 7A Framed External Walls Non-Load Bearing Required to Resist Fire Only fromInside the Building

( Clause 5.1 )

41

Nature of Construction and Materials Minimum Thirkness ( mm ) of Protectionfor a Modified Fire Resistance of_~_--_~ -- ----_th lh lth 2h 3hSteel frame with an external cladding of non-com-bustfble sheets ( excluding sheet steel ), with a steelsupporting framework and internal lining of:Metal lath and plaster, thickness of plaster:

a) Sanded gypsum plaster ( metal lathing grade )b) Lightweight aggregate gypsum plaster

13 1310 13 15 15 15

2 Two layer of plasterboard with joints staggeredjoints in outer layer taped and filled - Totalthickness3 Plasterboard of thickness:

a) With not less than 5 mm gypsum plaster finishb) With not less than 13 mm gypsum plaster finishC) With not less than 10 mm lightweight aggre-gate gypsum platser

4 One layer of asbestos insulating board with Jrans-verse joints backed by fillers of asbestos. msula-ting board not less than 9 mm thick, or by timber5 One layer of wood/wool slabs without finish6 One layer of compressed straw building slabs:

a) Without finishb) Wjth not less than 5 mm gypsum plaster finish

7 Aerated concrete blocks8 Bricks of clay:

a) Without finishb) With not less than 13 mm lightweightaggregate gypsum plaster

21 32

127959.5

9 950

5050

50 5075 15

12 12

63 639075

9075

12

1510090

4h

19

12

1001C3

90

Table 7B Framed External Walls Non-Load Bearing Required to Resist Fire Only fromInside the Building

( Cluwe 5.1 )Nature of Construction and Materials Minimum Thickness ( mm ) of Prot:rtionto Provide Sufficient lnsulation to L\

7/28/2019 IS 1642

8/18

1s 1642 : 1989Table 7C Framed Walls Non-Load Bearing Required to Resist Fiie Only fromInside the Building

( Clause 5.1 )Nature of Construction and Materials Minimum Thickness ( mm ) of Protectionfor a Fire Resistance of I$ II

1 ilasterboard not less than j.5 mm thick, finished with:a) Gypsum plasterb) Lightweight aggregate g> psum plaster

2 Plasterboard not less than 127 mm thick, finished with:a) Gypsum plasterbj Lightweight aggregate gypsum plaster

3 One layer of asbestcs insulating board with transverse jointsbacked by fi!lers of ashes!os insulating board not less than9 mm thick, or by timber

1310

1010

12

5.2 The separating walls should be carriedthrough the roof to a height of at least 60cmabove except in the case of reinforced brick/concrctc slab roof where it should be bondedflash ,with a top level of the slab. At the timecjf designing openings, particular attention shouldbe paid to all such factors as will limit firespread through these openings. Every openingin the wall should be protected by fire resistingdoors having the fire rating of not less than1 hour. Similar protection should also be donein other openings like rope races, motor alleyways, staircases. etc. of rating not less than2 hours. However, for Types 1, 2. 3 construction,a doorway or opening in a separating wall of anyfloor should be limited to 5.6 1112 in area with amaximum height of 2.75 m al:d maximum widthof 2 m.5.3 When building(s) and/or c;mpartment(s) areseparated by separating wall(s) and there is arerand~!/z 011one or more sides of such building(s)and/or compartment(s), it is necessary that theseparating wall should be built out across theverandulz and be carried through the roof ofthe same; otherwise the building(s) and/orcompartment(s) should be regarded as havinginternal communication and, therefore, subjectto danger of spread of fire.5.4 When opening in walls are provided to allowcable, etc, the space around cables and the wallshould be protected according to the provisiongiven in IS 12459 : 1988. However, such spacein case of openings provided to allow plumbing/gas,/stc~am pipes and similar services should besealed with iii!er material of fire rating not lessthan that of the walls in which these are situated.5.5 Where openings are permitted, they shouldnot exceed three-fourths of the area of the wallin case of an external wall.

6

5.6 A separating wall should be supported in avertical line by a similar separating wall throughall storeys below. The separating wall should becarried and bonded to the floor of appropriatefire-resisting construction.5.7 When a separating wall runs parallel to theaxis of the north light opening or gabled roof,the screen wall should be carried through, and60 cm above the top of the north light openingexcept in cases where the screen wall becomesof such a height that horizontal distance betweenthe north light opening and the roof of theadjoining building and/or compartment orbetween two sloping faces of the two consecutiveroofs at the level of the top of the screen wall,is at least 6 m.If, however, the separating wall is at right anglesto the axis of the north light opening or thegabled roof, the saw tooth? gaps should bebricked up and screen wall extended above theridge of the north light or the gabled roof.5.8 All separating walls should be built outto extend 15 cm beyond the eaves of the roofso as to effectively cut off the roofs of theparts so separated. The eaves should be cutaway on each side of this extension of the separat-ing wall. If there is an opening on both sides ofthe separating wall within 3 m of the wall, thoseon one side should be bricked up to full thicknessof wall, or an alternative should be provided withfire resisting doors of fire rating not less than of2 hours for walls of 4 hours rating and 1 hourfor other rating.5.9 Common wooden roof members (trusses,joists and purlins) should not pass through theseparating walls but they may be embedded there-in provided they do not extend more than 22.5cminto wall and are separated from the similarroof member in the adjoining building by at least11 cm or solid wall material.

7/28/2019 IS 1642

9/18

X31642:1989

5.10 artition is used for separating sections orrooms of a building but is not expected to have afire resistance equa1 to any of the values. Infact, in practice it should not be considered other-wise than structure of light dimension and stren-gth consistent with the purpose for whichit is used. The minimum fire rating of the parti-tion is given in Table 1.6 COLUMNS AND BEAMS6.1 The fire ratings of some types of construction

are given in Tables 8, 9, 12 and 13 ( see Notebelow 4.3 ). The specifications of materialsshould be so selected as to give these ratings.

7 FLOORS AND ROOFS7.1 he fire ratings of some types of constructionis given in Tables 10, 11, 14, 15, and 16. Thespecifications of materials should be so selectedso as to give these ratings.

Table 8 Reinforced Concrete Columns( Cfuuse 6.1 )

Nature of Construction and Materials Minimum Dimensions ( mm ), Excluding any Finish,for a Fire Resistance ofr ______- -__-p__-th lh l$h 2h 3h -T 4h1 Fully exposed Width 150 200 250 300 400 450Cover 20 25 30 35 35 352 50 percent exposed Width 125 160 200 200 300 350Cover 20 25 25 25 30 353 One face exposed Thickness 100 120 140 160 200 240

Cover 20 25 25 25 25 25

Table 9 Concrete Beams( Clause 6.1 )

Nature of Construction and Materials

1 Reinforced concrete ( simply supported ) WidthCover

2 Reinforced concrete ( continuous ) WidthCover3 Prestressed concrete ( simply supported > WidthCover4 Prestressed concrete ( continuous ) Width

Cover

Minimum Dimensions ( mm ), Excluding any Finish,for a Fire Reshtance ofC-- --..--h-_----_----~+h lh l&h 2h 3h 4h

80 120 150 200 240 28020 30 40 60 70 8080 SO 120 150 200 24020 20 35 50 60 70

100 120 150 200 240 28025 40 55 70 80 9080 100 120 150 200 24020 30 40 55 70 80

Table 10 Concrete Floors( Clause 7.1 )

Minimum Dimensions (mm ), Excluding any Finish,Nature of Construction and Materirtls for a Fire Resistance ofP-- h-_---_____th lh lbh 2h 3h 4h1 Reinfoiced concrete ( simply supported ) Thickness 75 95 110 125 150 170

Cover I5 20 25 35 45 552 Reinforced concrete ( continuous ) Thickness 75 95 110 125 is0 170Cover 15 20 20 25 35 45

7

7/28/2019 IS 1642

10/18

1s 1642 : 1989Table 11 Concrete Floors: Ribbed Open Sofflt

( CIuuYe 7.1 )Nature of Construction and Materials

r

1 Reinforced concrete ( simply supported ) ThicknessWidthCover

2 Reinforced concrete ( continuous ) ThicknessWidthCover

Minimum Dimensions ( mm ), Excluding any Finish,for a Fire Resistance ofG lh

Alhh 2h 3h 4h

70 90 105 115 135 15075 90 110 125 150 17515 25 35 45 55 6570 90 105 115 135 150?5 80 90 110 125 15015 20 - 35 45 55

Table 12 Encased Steel Cohnns, 203 mm x 203 mm ( Protection Applied on Four Sides )( Clause 6.1 )


A) Hollow protection ( without an air cavity over thejlanges ):1 *Metal lathing with trowelled lightweight aggregate gypsum plaster2 Plasterboard with 1.6 mm wire binding at 100 mm pitch, finished withlightweight aggregate gypsum plaster not less than the thicknessspecified:

a)9-5 mm plasterboardb) 19 mm plasterboard

3 Asbestos insulating boards, thickness of board:a) Single thickness of board, with 6 mm cover fillets at transversejointsb) Two layers, of total thickness

4 Solid bricks of clay, composition or sand lime, reinforced in everyhorizontal joint, unplastered5 Aerated concrete blocks6 Solid blocks of lightweight concreteHollow protections ( with an air cavity over the flanges )

B) Asbestos insulating board screwed to 25 mm asbestos battensC) Solid protections

1, Concrete, not leaner than 1 : 2 : 4 mix ( unplastered ):a) Concrete not assumed to be load bearing, reinforced+b) Concrete assumed to be load bearing

2 Lightweight concrete, not leaner than 1 : 2 : 4 mix ( unplastered)concrete not assumed to be load bearing, reinforcedt*so fixed or designed, as to allow full penetration for mechanical bond.

Minimum Thickness (mm ) of Protec-tion for a Fire Resistance ofr~--__-h-___,lh 14 h 2h 3h 4h

13 15 20 32

1010

1513 20

19 25

50 50 503875

6050

6050

6050 60

12 19

25 25 25 5050 50 50 7525 25 25 40

50100

75

757560

*Reinforcement shall consist of steel binding wire not less than 2.3 mm in thickness, or a steel mesh weighingnot less than 05 kg/m*.direction.

In concrete protectlon, the spacmg of that reinforcement shall not exeed 200 mm in any

8

7/28/2019 IS 1642

11/18

IS 1642 : 1989Table 13 Encased Steel Beams, 406 mm x 176 mm ( Protection Applied on Three Sides )

( Clause 6.1 )

A)

B)

C)


HoIlow protection ( without an air cuvity beneath the lowerflange ):1 *Metal lathing with trowelled lightweight aggregategypsum plaster ( metal lathing grade )2 Plasterboard with 1.6 mm wire bindingt at 100 mm pitch,finished with lightweight aggregate gypsum plasternot less than the thickness specified:

a) 9.5 mm plasterboardbJ 19 mm plasierboard3 Asbestos insulating board, thickness of board:

a) Single thickness of board, with 6 mm cover fillets attransverse jointsh) Two layers, of total thicknessHollow protection ( with an air cuvity below the lowerJ kige ):1 Asbestos insulating board screwed to 25 mm asbestosbattensSolid protection:1 Concrete, not leaner than 1 : 2 : 4 mix ( unplastered ):

a) Concrete not assumed to be load bearing, reinforcedtb) Concrete assumed to be load bearing2 Lightweight concrete not leaner than 1 : 2 : 4 ( mix )unplastered

Minimum Thickness ( mm ) of Protectionfor a Fire Resistance ofr----- A__._---_---\th lh l;h 2h 3h 4h

13

1010

9

:;25

13 15 20 25

10 1510 13 20

19 25 38 50

12

*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 .methodsof support to enable ihe lower edges of the plasterboard to be fixed together and to the lower flange, and forthe top edge of the plasterboard to be held in position.meinforcement shall consist of steel binding wire not less than 2.3 mm in thickness or a steel mesh weighingnot less than 0.5 kg/m*. In concrete protection, the spacing of that reinforcement shall not exceed 200 mm in anydirection.gconcrete not assumed to be load bearing, reinforced.

Table 14 Timber Floors - Tongued and Grooved Boarding, or Sheets of Tongued and GroovedPlywood or Wood Chipboard, of not Less than 21 mm Fished Thickness

( Clause 7.1 )Nature of Construction and Materials Minimum Thickness (mm) of Protec-tion for a Fire Resistance of

37 mm ( minimlrm ) timber joists with a ceiling of: _---A__.-_ih lh 2hTimber lathing and plaster, plaster of thicknessMetal lathing and plaster, thickness of plaster:

a) Sanded gypsum plaster ( metal lathing grade)b) Lightweight aggregate gypsum plasterOne layer of plasterboard with taped and filled jointsTwo layers of plasterboard with joints staggered, joints in outer layer tapedand filled total thicknessOne layer of plasterboard not less than 9.5 mm thick, finished with:

a) Gypsum plasterb Sanded gypsum plasterc) Lightweight aggregate gypsum plasterOne layer of plasterboard not less than 127 mm thick, finished with:

a) Gypsum plasterb) Lightweight aggregate gypsum plasterOne layer of asbestos insulating board with any transverse joints backed byfillets of asbestos insulating board pot less than 9 mm thick, or by timber

15

::12-7195

::

109

13 25

31

12

9

7/28/2019 IS 1642

12/18

IS1642:1989Table 15 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 7.1 j


37 mm ( minimrrm ) timber joists wirh a ceiling of:1 Timber lathing and plaster, plaster of thickness2 Metal lathing and plaster, thickness of plaster for:


3 One layer of plasterboard with taped and filled joints4 Two layers of plasterboard with joints staggered, joints in outer layer tapedand filled total thickness

Minimum Thickness (mm j ofProtection for a FireResistance of_--- --c---Tl;h Ih 2h

15

1513 13 2512.722 31

5 One layer of plasterboard not less than 9.5 mm thick, finish with:a) Gypsum plaster 5b) Sanded gypsum plaster 15c) Lightweight aggregate gypsum plaster 13

6 One layer of plasterboard not less than 12.7 mm thick, finished with:a) Gypsum plaster 5b) Lightweight aggregate gypsum plaster 10

7 One layer of asbestos insulating board. with any transverse joints backed byfillets 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 beetween joints.

Table 16 Timber Floors - Any Structurally Suitable Flooring of Timber or Particle Boards( Clause 7.1 )Nature of Construction and Materials Minimum Thickness (mm ) ofProtection for a FireResistance ofr-__h____~37 mm ( minimum ) timber joists with a ceiling of:

1 Timber lathing and plaster, plaster of thickness2 Metal lathing and plaster, thickness of plaster for:


3 One layer of plasterboard with joints taped and filled and backed by timber4 TWO layers of plasterboard with joints staggered, joints in outer layer tapedand filled total thickness

th15

151312725

Ih

19

Two layers of plasterboard, each not less than 9.5 mm thick, joints betweenboards staggered and outer layer finished with gypsum plasterOne layer of plasterboard not less than 9.5 mm thick, finished with:

a) Sanded gypsum plasterb) Lightweight aggregate gypsum plaster

One layer of plasterboard not less than 12.7 mm thick, finished with:a) Sanded gypsum plasterb) Lightweight aggregate gypsum plaster

One layer of asbestos insulating board with any transverse joints backed byfillets of asbestos insulating board not less than 9 mm thick, or by timber

5

1315

I51312

10

7/28/2019 IS 1642

13/18

7.2 In case of a building more than 15 m inheight, all iloors should be compartmented witharea not cxcceding 751) m2 by a separation wallwith 2 hours fire rating, for floors havingprovision of sprinklers. The area may beincreased bv 50 percent. In long buildings, thefire separation walls should be at distance notexceeding 40 m. For departmental stores,shopping centres and similar occupancies, thearea may be reduced to 500 m2. Where thisis not possible provision of the sprinklers shouldbe kept with appropriate spacing.7.3 A surface covering of non-combustible andnon-toxic material should be laid directly on theincombustible floor. Wood flooring may be laiddirectly on such surface covering, or directly onsuch floor provided that in either case there is nointervening space and that any wood fillets foraffixing such flooring is bedded not more than2.5 cm in the non-combustible floor.7.4 In the case of building used for storage pur-poses, the floor surface should conform to theabove, in addition, it should be at least 15 cm abovethe ground level or the level of the door sillswhichever is higher, and should slant towardsthe doors.7.5 An opening through a floor should complywith the following:

At the time of designing openings parti-cular attention should be paid to all suchfactors which will limit fire spreadthrough these openings.Whm opening in floors are provided toallow cabie, etc, the space around cableand the floor should be protected accord-ing to th eprovision given in IS 12459 : 1988.However, such space in case of openingsprovided to allow plumbing/gas/steampipes and similar services should be sealedwith filler material of fire rating not lessthan 1 hour.Openings for steam, gas and/or waterpipes and electrical conduits, whether ofiron or earthenware, should have a radialclearance, to allow for any heat expansion,not greater than 3 mm.The enclosure for staircases and hoistsshould be cons;ructcd entirely of brick,concrete or of reinforced concrete orsimilar material of construction having2 hours rating. Every opening from theenclosure on to a roof used as floor or toany other part of the building should befitted with a fire resistant door of ratingnot less than 1 hour.If any staircase or hoist extends to the topstorey of a building the roof of which is nota roof used as a floor, the enclosing wallsshould be carried through and at least45 cm abcvc the reef of the building and

11

IS 1642: : 989a skylight or window glazed should beprovided above the roof of the building.Alternatively, if the roof of the building isused as a floor. it should comply with (d),and this should also apply for any furnaceor motor chamber communicating with thestaircase or hoist enclosure.

7.6 Linings or false ceilings should not be permis-sible in buildings and in situations, where permit-ted, such additions should not detract in anywayfrom minimum fire rating of half an hour.In some cases, requiring provision of skylights,monitor lights or north lights in the roofs andwhere thrse are necessary. the glazings should beof glass in metal frames fcr lire rating of halfan hour minimum.7.7 Composite roofs may be used over 3s ad-dition to the roofs of bui!dings as a weathcr-proofing, but should not be considered as a roofin itself. that is, without the sunport of a non-combustible construction beneath, unless it is ofnot less than half an hour fire resistance.8 AIR-CONDlTIONENG8.1 Air-conditioning systems should be so instal-led and maintained as to minimize the danger ofspread of fire, smoke or fumes thereby from onefloor or lire area to another, or from outside intoany occupied building or structure.8.2 Air-conditioning systems circulating air tomore than one floor area should be provid-.ed with dampers designed to close automaticallyin case of fire and thereby prevent spread of tireor smoke. Such a system should also be providedwith automatic controls to stop fans in case offire, unless arranged to remove smoke from a fire,in which case these should be designed to remainin operation.8.3 Air-conditioning system serving large placesof assembly ( over 1000 persons ), large depart-mental stores or hotels with over 100 rooms in asingle block should be provided with elTectivemeans for preventing circulation of smokethrough the system in the case of a lire in airfilters or from other sources drawn into thesystem even though there is insufficient heat toactuate heat sensitive devices controllingfans or dampers. Such means should consist ofapproved effective smoke sensitive controls.8.4 Air-conditioning should conform to thefollowing:

a)

3Cl

Escape routes like staircases, commoncorridors, lift lobbies, etc, should not beused as return air passage.The ducting should be constructed ofmetal in accordance with IS 655 : 1963.Wherever the ducts pass through fire wallsor floor, the opening around the ducts

7/28/2019 IS 1642

14/18

IS 1642 1989

4e)

f 1

g>

should be sealed with fire resistingmaterials of same rating as of walls/floors.As far as possible, metallic ducts should beused even for the return air instead ofspace above the false ceiling.The material used for insulating the ductsystem ( inside or outside ) should be offlame resistant ( see IS 4355 : 1977 ) andnon-conductor of heat.Area more than 750 m* on individual floorshould be seggregated by a fire wall andautomatic tire dampers for isolation shouldbe provided.In case of more than one floor, arrange-ment by way of automatic fire dampers forisolating by ducting at every floor fromthe main should be made. Where plenu-mus used for return air passage, ceilingand its fixtures and air filters of the airhandling units should be flame resistant[ see 8.4 (e)]. Inspection panels should beprovided in the main trunking. Nocom-bustible material should be fixed nearerthan 15 cm to any duct unless such ductingis properly enclosed and protected withflame resistant material. The fire dampersshould be located in conditioned air ductsand return air ducts passages at thefollowing points which will operate auto-matically and are simultaneously switch offair handling fans:

i) at the fire separation wall,ii) where ducts/passages enter the centralvertical shaft,

iii) where the ducts pass through floor,andiv) at the inlet of supply air duct and thereturn air duct of each compartmenton every floor.

In case of buildings more than 24 m in height innon-ventilated lobbies corridors. smoke extractionshaft should be provided. The automatic tiredamper should bc so arranged so as to close bygravity in a direction of movement and to remaintightly closed upon operation.9 SMOKE AND FIRE VENTING9.1 Provision has to be made for venting whichallows escape of hot gases and smoke release byaccidental burning of combustible material storedOT are being processed inside a building, and willgive ample time for all the inmates to escapebefore the roof collapses either in part or whoiiyin the event of fire. Provisions in this regard areessential for industrial buildings; details of whichare covered in a separate Indian Standard. Theprovision in regard to the domestic buildings aregiven in 9.2. The form of vent should be a venti-

lator-cum-exhaust which in addition to therequisite grading of fire rating be easily openable.9.2 Smoke venting facilities, where required forsafe use of exits in windowless buidings, under-ground structures, large area factories, depart-mental store, domestic dwelling, theatres, cinemas,lecture halls, etc, or *here required should beautomatic in action.9.3 Natural draft smoke venting should utilizeroof vents or vents in walls at or near the ceilinglevel; such vents should be normally open, or ifclosed, should be designed for automatic openingin case of fire, by release of heat smoke sensitiveelements, breakage of glass, or melting of plasticunder the influence of heat; or by other approvedmeans.9.4 Where smoke venting facilities are installedfor purposes of exit safety, these should be ade-quate to prevent dangerous accumulation ofsmoke during the period of time necessary toevaluate the area served, using available exitfacilities with a margin of safety to allow forunforeseen contingencies.9.5 The discharge apertures of all natural draftsmoke vents should be so arranged as to bereadily susceptible to. opening by fire servicepersonnel.9.6 Power operated smoke exhausting systemsmay be substituted for natural draft vents( see IS 941 : 1985 ).9.7 In case of buildings more than 15 m in heightthe staircase should be ventilated to the atmos-phere at each landing and a vent at the top, thevent openings should be 0.5 m in the externalwail and top. If the staircase cannot be ventilatedbecause of location or other reasons, the provisionshoul~i be made for pressurization ( 50 Pa ) to beseparated automatically with the fire alarm. Theroof of the shaft in the latter case should bc 1 mabove the surrounding roofs. Glazing or glassbricks should not be used in the staircase.10 SERFJCE DUCTS10.1 Service ducts should be enk,losed by wailsand doors ( if any ) of 2 hours fire rating; ifducts are larger than 1 m3 the floor should sea]them, but provide suitable openings for the pipesto pass through, with the gaps sealed.10.2 A vent opening at the top of the serviceshaft should be provided between one-fourth andone-half of the area of the shaft.11 BASEMENTS11.1 Each basement should be separately venti-1,ated. Vents with cross-sectional area ( aggre-gate. ) not less than 2.5 percent of the floor areaspread evenly round the perimeter of the base-ment should be provided in the form of grills orbreakable stallboard lights or pavement lights or

12

7/28/2019 IS 1642

15/18

by way of shafts. Alternatively, a system of airinlets should be provided at basement floor leveland, smoke outlets at basement ceiling level.Inlets and extractors may be terminated atground level with stallboard or pavement lightsas before, but ducts to convey fresh air to thebasement floor level have to be laid. Stallboardand pavement lights should be in positions easilyaccessible to the fire brigade and clearly marked&SMOKE OUTLET, or AIR INLET with anindication of area served at or near the opening.11.2 The staircase of basements should be ofenclosed type having fire resistance of not lessthan 2 hours and should be situated at theperiphery of the basement to be entered atground level only from the open air and in suchpositions that smoke from any fire in the base-ment should not obstruct and exit serving theground and upper storeys of the building andshould communicate with basement through alobby provided with fire resisting self-closingdoors of I hour fire resistance. If the traveldistance exceeds 18.50 n, additional staircasesshould be provided at proper placer.11.3 In multi-level basements, intake ducts mayserve aI1 basement levels, but each basement andbasement compdrtment should have separatesmoke outlet duct or ducts. Mechanical extrac-tors for smoke venting ( see IS 941 : 1985 )from low basement levels should also be provilded, with provision of automatic operation ofsystem actuation of heat/smoke sensitive detec-tors or sprinklers and also manully. Mechani-cal extractors should have an inter-lockingarrangement, so that extractors should continueto operate and supply fans should stop auto-matically with the actuation of fire detectors.Mechanical extractors should be designed topermit 30 air changes per hour in case of tireor distress call. However, for normal operation,only 28 air changes should be maintained.Mechanical extractors should have an alternativesource of supply. Ventilating ducts should beintegrated with the structure and made out ofbrick masonry or RCC as far as possible andwhen this duct crosses the transformer area orelectrical switch board, fire dampers should beprovided. Basement/sub-basement should notbe used for storage, cooking purposes, garrageand shops unless provision is made for sprinklersystem. If cut-outs are provided from basementsto the upper floors or to the atmosphere all sidesof the cut-out openings in the basements shouldbe protected by automatic spray in the event ofa fire.12 CHIMNEYS12.1 Over and above the provisions given in 4.2,the following previsions should be followed:

a) A clearance of at least 4 cm between theouter surface of the chimney and anyadjacent combustible material forming

b)

C)

d)

4

f

g>

IS 1642 : 1989part of a wall lining enclosing thechimney.The tire resistance of any structuresurrounding a flew or flew pipe should benot less than that for external walls. Inthe case of flew pipe there should be anair space between it and the surroundingstructure of sufficient width to permitaccess to the pipe for inspection andrepair.When a flew pipe passes though any otherroom or an enclosed roof space it shouldbe protected by structure having a fireresistance equal to the external walls.The chimney excluding the pot should becarried to a minimum height of 1 mabove the highest point of its junctionwith the roof.The outlet of a flew from domesticappliance having a roof covering shouldbe at least 2.5 m in a horizontal plainfrom the roof of any structure built uponthe roof or at least 0.6 m higher than anyridge within 2.5 m.If the roof covering is not fire resistant,no flew outlet should be lower than theridge for the highest point of the roof orless than 1 m above any ridge within25 m.Where a metal chimney passes through aroof covering which is not fire resistant,it shall be guarded by a suitable iron ormetal thimble extending not less than22.5 cm above and below roof tionstruc-tion and of a size to provide not less than15 cm clearance on all sides of chimneys.

13 STAIRCASES AND LIFTS13.1 StaircasesThe details with regard to the provisions of stair-cases have been given in IS 1644 : 1988.13.2 Lifts13.2.1 The general requirements for the provi-sion of lifts should be as follows:

a)

-9cl

Walls of lifts and enclosures should havea fire rating of 2 hours; lift shaft shouldhave a vent at the top of area not lessthan O-2m2.Lift motor room should be located pre-ferably on top of the shaft and separatedfrom the shaft by the floor of the room.Landing doors in lifts and enclosuresshould have a fire resistance of not lessthan 1 hour.

13

7/28/2019 IS 1642

16/18

IS 1642 : 19894

e)

f >g)

h)

j)k)

The number of lifts in one lift tank shouldnot exceed 4. Individual shafts in a bankshould be separated by a wall of 2 hoursfire rating.Lift care door should have a fire resis-tance rating of not less than 1 hour.Collapsible gates should not be used forlifts and should have doors with fire resis-tance of at least 1 hour.In opening other than the lift lobby doorin the lobby enclosure wall should alsohave the minimum fire resistance of onehour.Exit from the lift lobby, if located in thecore of the building should be to a self-closing stop door of minimum 1 hourfire rating.Lifts should not normally communicateto the basement.Suitable arrangements, such as providingslope in the floor of lift lobby should bemade to prevent water used during firefighting, etc, on any landing from enteringthe lift shaft.

m) The sign should be oosted and maintained at every floor at or near the lift indicatingthat in case of fire occupants should usethe stairs unless instructed otherwise.The sign should also contain a plan foreach floor showing the location ofstaircase.13.2.2 Fire Lifts13.2.2.1 Where applicable, fire lifts should beprovided with a minimum capacity for 8 passen-gers with floor area of not less than I.4 m2 andfully automated with emergency switch on theground level. In general, building over 15 min height should be provided with fire lifts. Eachfire lift should be equipped with suitable inter-communication equipment communicating withthe control room on the ground floor of thebuilding. The number and location of fire liftsin a building should be decided after taking intoconsideration various factors like building,population, floor. areas, section of building( comparmentation ), etc. The words fire liftshould be conspicously displayed in illuminouspaint on the lift landing door at each floorlevel.14 kEFUSE AREA14.1 In case of buildings more than 24 m inheight, refuse area of 15 ms or an area equal to0.25 ms per person to accommodate the occupantsof two consecutive floors, whichever is higher,should be provided as under. Refuse areashould be provided on the peripheri of the floorand open to air at least on one side protected

17.1 The electrical services should conform tothe following ( see also IS 1646 : 1982 ):a) The electric distribution cables/wiringshould be laid in a separate duct. Theduct should be sealed at every alternativefloor with non-combustible materialshaving the same fire resistance as that ofthe duct. Low and medium voltage wiringrunning in shaft and above false ceilingshould run in separate conduits.

Water mains, telephones lines, inter-cornlines. gas pipes or any other service lineshould not be laid in the duct for electriccables.The inspection pane1 doors and any otheropening in the shaft should be providedwith fire doors having fire resistance ofnot less than 1 hour.Medium and low voltage wiring running inshafts, and within false ceiling should runin metal conduit. Any 230 V wiring forlighting or other services above falseceiling should have 660 V grade insula-tions. The false ceiling including allfixtures used for its suspension should beof non-combustible material.-An independent and well-ventilatedservice room should be provided on the

with suitable railings: . .a) For floors above 24 m and up to 39 m -one refuse area on the floor immediatelyabove 24 m.b) For Eoor above 39 m - one refuse area onthe floor immediately above 39 m and soon after every 15 m.

15 REFUSE CHUTES15.1 Refuse chutes should have an enclosure wallof non-combustible material with fire resistanceof not less than 2 hours. They shall not belocated within the staircase enclosure or serviceshafts, or air-conditioning shafts. Inspectionpanel and doors should be tight fitting with1 hour fire resistance; the chutes should be asfar away as possible from exits.16 DRAINAGE16.1 It is essential to make provision fordrainage of any such water on all floors to pre-vent or minimize water damage of the contents.The drain pipe should be provided on the exter-nal wall for drainage of water from all floors.On large area floors several such pipes may benecessary which should be spaced 30 m apart.The pipe should conform to relevant IndianStandards.17 ELECTRICAL SERVICES

14

7/28/2019 IS 1642

17/18

IS 1642 : 1989ground Boor with direct access from out- decor should be such that the flame spread ratingside or from the corridor for the purpose should not be more than the values given in 18.3of termination of electric supply from the to 18.6 and in addition should not generate toxicliccnsecs service and alternative supply smoke/fumes.cables. The doors provided for the serviceroom shou!d have fire resistance of not 18.3 Susceptibility to fire of various types ofless than 2 hours. wall surfaces is determined in terms of -flamespread ( see IS 12777 : 1989 ).

18 FINISHES18.1 There are certain aspects. 18.3.1 In case of buildings more than 15 m inaPPlicableo height, the interior finish material should notparticular occupancies Only. which may affb ha& rating xceeding Class 1.the spread of fire. smoke or fumes and thus thesafe evacuation of the building in case of fire.Some such aspects are as follows: 18.3.2 The situation under wh;ch materials fallinginto various classes should be used in buildingconstruction is given below:a) Interior finish and decoration;

b) Seating. aisles, railings and turnstiles inplace of assembly; Class 1 Class 2 Class 3c) Service equipment and storage facilities inbuildings other than storage buildings; andd) Hazards on stage, in waiting spaces, pro-jection booths, etc, in theatres andcinemas.

18.2 The use of flammable surface finishes onwall< ( including external facade of the building )and ceilings affects the safety of the occupantsof a building. Such finishes tend to spread thefire and even though the structural elementsmai be adequately fire resistant, seriousdanger to life may result. It is, therefore,essential to have adequate precautions to mini-mize spread of flame on wall, facade of buildingand ceiling surfaces.

May be used May be usedin any situa- in any situa-tion tion, excepton walls, fa-cade of thebuilding andceilings ofstaircases andcorridors

Should be used onlyin living rooms andbedrooms ( but notin rooms on theroof) and only asa lining to solidwalls and partitions.Not on staircasesor corridors orfacade of the buil-ding

NOTE - Panelling ( lining ) should be permitted in alimited area. It should not be permitted in a vestibule.18.3.3 When frames, walls, partitions or floors arelined with combustible materials the surfaces onboth sides of the material should conform to

Any materials used for various surfaces and the appropriate class.

15

7/28/2019 IS 1642

18/18

Bureau of Indian Standards131s is a statutory institution established under the Bureau offndian Sfandards Act, 1986 to promoteharmonious development of the activities of standardization, marking and quality certification of goodsand attending to connected matters in the country.CopyrightBlS has the copyright of all its publications. No part of these publications may be reproduced in any formwithout the prior permission in writing of BIS. This does not preclude the free use, in the course ofimplementing the standard, of necessary details, such as symbols and sites, type or grade designations;Enquiries relating to copyright be addressed to the Director (Publications), BIS.Review of Indian StandardsAmendments are issued to standards as the need arises on the basis of comments. Standards are alsoreviewed periodically; a standard along with amendments is reaffirmed when such review indicates thatno changes are needed; if the review indicates that changes arc needed, it is taken up for revision. Usersof Indian Standards should ascertain that they are in possession of the latest amendments or edition byreferring to the latest issue of BIS Handbook and Standards: Monthly Additions.This Indian Standard has been developed from Dot : No. BDC 36 (4208)

Amendments Issued Since PublicationAmend No. Date of Issue Text Affected

BUREAU OF TNDIAN STANDARDSHeadquarters:Mnnak Bhavan. 9 Bahndur Shah Zafar Marg, New Delhi 1 IO 002Telephones : 323 01 3 1.323 33 75. 323 94 02Regional Offices :Central : Manak Bhnvan. 9 Bahadur Shah Zafar Mar8

NEW DELHI I IO 002Eastern : 1114 C. 1.T. Scheme VII M, V. 1. P. Road, Maniktola

CALCLJTTA 700 054Northern : SC0 335-336, Sector 34-A. CHANDIGARH 160 022

Southern : C. 1. T. Campus. IV Cross Road, CHENNAI 600 113

Western : Manakalaya, E9 MIDC, Marol, Andheri (East)MUMBAI 400 093

Telegrams : Manaksanstha(Common to all offices)

Telephone1 32323 386 417

1 33737 864 99,3376,337 911610

1 600 380 435

{ 23535 025 19,2356,235 043 425832 92 95,832 78 58832 78 9-l. 832 78 92

Branches : AHMADABAD. BANGALORE. BHOPAL. BHUBANESHWAR. COIMBATORE.FARIDABAD. GHAZIABAD. GUWAHATI. HYDERABAD. JAIPUR. KANPUR.LUCKNOW. NAGPUR. PATNA. PUNE. THIRUVANANTllAPURAM.

Printed at Kay Kay Printers, Delhi

Documents

IS 1642