Fire-Performance Ratings: 1977: Supplement No. 2 to the National Building Code of Canada

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FIRE-PERFORMANCE

RATINGS

Supplement No. 2 to the

National Building Code of Canada

Issued by the

Associate Committee on the National Building Code

National Research Council of Canada

Ottawa

NRCC No.

15557

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First Edition 1961 Second Edition 1965

Third Edition 1975 Fourth Edition 1977

ONational Research Council of Canada 1977 World Rights Reserved

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TABLE O F CONTENTS

Page

...

PREFACE

vii

ABBREVIATIONS

...

ix

SECTION 1 GENERAL

Subsection 1.1

Subsection 1.2

Subsection 1.3

Subsection 1.4

Subsection 1.5

Subsection 1.6

Subsection 1.7

Subsection 1.8

Subsection 1.9

...

Introduction

1 Interpretation of Test Results

...

1 Aggregates Used in Concrete

...

2 ...

Types of Concrete

2 Equivalent Thickness

...

3 Contribution of Plaster Finish to Fire

Resistance of Masonry or Concrete Walls.

Floors and Roofs

...

3 ...

Tests on Floors and Roofs

5 Moisture Content

...

5 ...

Permanence and Durability

6 Subsection 1.10

Structural Steel

...

6 Subsection 1.1 1 Restraint Effects

...

6

SECTION 2 FIRE-RESISTANCE RATINGS

Subsection 2.1

S~~bsection

2.2 Subsection 2.3

Subsection 2.4

Subsection 2.5

Subsection 2.6

Subsection 2.7

Subsection 2.8

Subsection 2.9

Subsection 2.10

...

Masonry and Concrete Walls

7 Reinforced and Prestressed Concrete Floor

and Roof Slabs

...

9 Wood and Steel Framed Walls. Floors and Roofs

10 ...

Solid Wood Walls. Floors and Roofs

17 ...

Solid Plaster Partitions

18 ...

Protected Steel Columns

19 ...

Individually Protected Steel Beams

23 Reinforced Concrete Columns

...

24 ...

Reinforced Concrete Beams

26 ...

Prestressed Concrete Beams

26

SECTION 3 FLAME-SPREAD RATINGS AND SMOKE DEVELOPED

CLASSIFICATIONS

...

Subsection 3.1

Interior Finish Materials

27

SECTION 4 NONCOMBUSTIBILITY

Subsection 4.1

Test Method

...

30 ...

Subsection 4.2

Materials Classified as Combustible

30 ...

Subsection 4.3

Materials Classified as Noncombustible

30 APPENDIXA

FireTestReports

...

31

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vii

PREFACE

The contents of this document have been prepared on the recommendations of the Fire Test Board which was established by the Associate Committee on the National Building Code (ACNBC) for this purpose.

The fire-performance ratings contained herein are presented in a form closely linked to the performance requirements and the minimum materials specifications of the National Building Code and are intended for use with the 1977 edition.

These ratings have been assigned only after careful consideration of all available literature on assemblies of common building materials, where they are adequately identified by description. The assigned values based on this information will, in most instances, be conservative when com- pared to the ratings determined on the basis of actual tests on individual assemblies.

It is not practical at this time to assign metric values to the imperial units of measure in this docu- ment, as the test assemblies on which much of the information was based involved only imperial sized products.

Comments on this document are welcomed by the Associate Committee and should be for- warded to the Secretary, Associate Committee on the National Building Code, National Research Council of Canada, Ottawa, Ontario K1A OR6.

Le Code national d u biitiment, ses supplements et les documents qui s'y rattachent sont disponi- bles en fransais. On peut se les procurer en s'adressant au Secretaire, Comite associe du Code national du biitiment, Conseil national de recherches d u Canada, Ottawa, Ontario K1A OR6.

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LIST OF ABBREVIATIONS

Abbreviations of words and phrases in this Supplement have the following meanings: ACNBC

...

Associate Committee on the National Building Code ASTM

...

American Society for Testing and Materials

CGSB

...

Canadian Government Specifications Board

CSA

...

Canadian Standards Association

cu ft

...

cubic foot(fee t) cu in

...

cubic inch(es) deg.

...

.degree(s)

"

F

...

deree(s) Fahrenheit diam.

...

diameter FO

...

Fahrenheit degree(s) ft

...

foot(feet) hex.

...

hexagonal 11r

...

hour(s) in.

...

inch(es) lb

...

pound(s) . . min.

...

minimum min.

...

minute(s) mm

...

millimetre(s) No.

...

number(s) nom.

...

nominal

NRCC

...

National Research Council of Canada O.C.

...

on centre

oz.

...

ounce(s)

psi

...

p o n d ( s ) per square inch sq yd

...

square yard

T & G

...

tongue and groove

ULC

...

Underwriters' Laboratories of Canada

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SECTION 1 GENERAL

SUBSECTION 1.1

INTRODUCTION

1.1.1.(1) The fire-performance ratings set out in this document are recommended by the Fire

Test Board and approved by the ACNBC for use with the National Building Code of Canada 1977. The ratings apply to materials and assemblies of materials which comply in all essential details with the minimum structural design standards described in Sections 4.3 to 4.7 of Part 4 of the National Building Code of Canada 1977. Additional requirements, where appropriate, are described in other Sections of this Supplement.

(2) Section 2 of this Supplement contains fire-resistance ratings for walls, floors, roofs, col-

umns and beams related to the standard methods of test to which reference is made in Subsection 3.1.5. of the National Building Code of Canada 1977.

(3) Section 3 of this Supplement contains flame-spread ratings and smoke developed classifi-

cations for surface materials related to the standard methods of test referred to in Subsection 3.1.- 10. of the National Building Code of Canada 1977.

(4) Section 4 of this Supplement describes noncombustibility in building materials when tested in accordance with the specification ULC-S 1 14- 1975, "Standard Method of Test for Determina- tion of Non-Combustibility in Building Materials."

1.1.2. The standard fire tests to which reference is made in the National Building Code of Can-

ada 1977 are the basis for compliance with the National Building Code requirements.

The ratings shown in this document apply if more specific test values are not available. The con- struction of an assembly that is the subject of an individual test report must be followed in all essential details if the f re resistance reported is to be applied as a fire-resistance rating for use in the National Building Code.

1.1.3. The authority having jurisdiction may allow higher fire-resistance ratings than those cov-

ered in this Supplement where supporting evidence justifies a higher rating. Additional information is provided in summaries of ptlblished test information and the reports of fire tests carried out by the Division of Building Research, National Research Council of Canada, included in the bib- liography listed in Appendix A.

1.1.4. Assemblies containing materials for which there is no nationally recognized standard are

not included in this Supplement. Many such assemblies have been rated by Underwriters' Labora- tories of Canada. This information is published in their "List of Equipment and Materials," Vol- ume 11, Building Construction. Copies of this document may be obtained from Underwriters' Lab- oratories of Canada, 7 Crouse Road, Scarborough, Ontario M 1 R 3A9.

SUBSECTION 1.2 INTERPRETATION OF TEST RESULTS

1.2.1. The fire-performance ratings set out in this Supplement are based on those that would be obtained from the standard methods of test described in the National Building Code. The test methods are essentially a means of comparing the performance of one building component or assembly with another in relation to its performance in fire.

1.2.2. Since it is not practicable to measure the fire resistance of constructions in situ they must be evaluated under some agreed test conditions. A specified fire-resistance rating is not necessarily the actual time that the assembly would endure in situ in a building fire, but is that which the par- ticular construction must meet under the specified methods of test.

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1.2.3. Considerations arising from departures in use from the conditions established in the standard test methods may, in some circumstances, have to be taken into account by the designer and the authority having jurisdiction. Some of these conditions are covered at present by the provi- sions of the National Building Code.

SUBSECTION

1.3 AGGREGATES USED IN CONCRETE

1.3.1. Early fire tests described a form of spalling which occurred in certain siliceous aggregate concretes. As a result, some restrictions were placed on ratings given to such concretes in the 1965 edition of this Supplement. More recent studies indicating that moisture content may contribute to spalling, coupled with standard tests on concretes having a high quartz content, have justified improved fire-resistance ratings for siliceous aggregate concretes in this edition.

1.3.2. Lightweight aggregate concretes generally exhibit better fire performance than natural stone aggregate concretes. A series of tests on concrete masonry walls, combined with mathemat- ical analysis of the test results, has allowed further distinctions between certain lightweight aggregates to be made.

SUBSECTION

1.4 TYPES OF CONCRETE

1.4.1.(1) For purposes of this document, concretes are described as Types S, N, L, L I , L2, L40S, L,20S or L220S as described in Sentences (2) to (8).

(2) Type S concrete is the type in which the coarse aggregate is granite, quartzite, siliceous gravel or other dense materials containing at least 30 per cent quartz, chert or flint.

(3) Type N concrete is the type in which the coarse aggregate is cinders, broken brick, blast furnace slag, limestone, calcareous gravel, trap rock, sandstone or similar dense material containing not more than 30 per cent of quartz, chert or flint.

(4) Type L concrete is the type in which all the aggregate is expanded slag, expanded clay, expanded shale or pumice.

(5) Type L, concrete is the type in which all the aggregate is expanded shale.

(6) Type L2 concrete is the type in which all the aggregate is expanded slag, expanded clay or pumice.

(7) Type L40S concrete is the type in which the fine portion of the aggregate is sand and lightweight aggregate in which the sand does not exceed 40 per cent of the total volume of all aggregates in the concrete.

(8) Type L,20S and Type L220S concretes are the types in which .the fine portion of the aggre-

gate is sand and lightweight aggregate in which the sand does not exceed 20 per cent of the total volume of all aggregates in the concrete.

1.4.2. Where concretes are described as being of Types S, N, L, L l or L2, the rating applies to the concrete containing the aggregate in the group that provides the least fire resistance. If the nature of an aggregate cannot be determined accurately enough to place it in one of the groups, the aggregates must be considered as being in the group that requires a greater thickness of concrete for the required fire resistance.

1.4.3.(1) The descriptions of the aggregates in Type S and Type N concretes apply to the coarse aggregates only. Coarse aggregate for this purpose means retained on a 4.76 mm (0.187 in.) sieve using the method of grading aggregates described in CSA A23.1-1973, "Concrete Materials and Methods of Concrete Construction."

(2) Increasing the proportions of sand as fine aggregate in lightweight concretes requires increased thicknesses of material to produce equivalent fire-resistance ratings. Lightweight aggregates for Type L and Types L-S concretes used in loadbearing components must conform to ASTM C330-75a, "Lightweight Aggregates for Structural Concrete."

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stand- :r and provi- iatural lemat- aggre- liceous :, blast ~ n t a i n - .ay, ex- clay or d light- aggre- : aggre- le total s to the nature the ag- rete for : coarse I.) sieve als and lires in- : aggre- 'orm to

1.4.4. Non-loadbearing lightweight components of vermiculite and perlite concrete, in the ab- sence of other test evidence, should be rated on the basis of the values shown for Type L concrete.

SUBSECTION 1.5 EQUIVALENT THICKNESS

1.5.1. The thickness of solid-unit masonry and concrete described in this Supplement is the thickness of solid material in the unit or component thickness. For units that contain cores or voids the Tables refer to the "equivalent thickness" determined in accordance with Articles 1.5.2. and 1.5.3.

1.5.2. Where a plaster finish is used, the equivalent thickness of a wall, floor, column or beam protection is equal to the sum of the equivalent thicknesses of the concrete or masonry units and the plaster finish measured at the point that will give the least value of equivalent thickness.

1.5.3.(1) Except as provided in Article 2.1.5., the equivalent thickness of a hollow masonry unit is calculated as equal to the actual overall thickness of a unit in inches multiplied by a factor equal to the net volume of the unit and divided by its gross volume. Net volume is determined as described in Sentences (2) to (4).

(2) For a concrete masonry unit, the unit is enclosed by plywood to form a rectangular box whose inside dimensions are equal to the maximum overall dimensions of the unit. All core spaces and voids created by setbacks and indentations in the outer surface of the unit are filled with No. 10 lead shot, 0.07 in. diam. and having a bulk density of 0.24 lb per cu in. The lead shot fill is then weighed.

The net volume of the unit V, = W

where v p

-KG

V, = the volume of the rectangular box in cubic inches. W = the weight of the lead shot filling material in pounds.

(3) The equivalent thickness of cored bricks is determined by direct measurement as described in CSA A82.2- 1967, "Methods for Sampling and Testing Standard Brick."

(4) The equivalent thickness of hollow clay tiles is determined by direct measurement as described in CSA A82.6-1954, "Standard Methods for Sampling and Testing Structural Clay Tile."

(5) Gross volume of a masonry unit is equal to the length of the unit multiplied by the height of the unit multiplied by the thickness of the unit.

SUBSECTION 1.6 CONTRIBUTION OF PLASTER FINISH TO FIRE

RESISTANCE OF MASONRY OR CONCRETE

WALLS, FLOORS AND ROOFS

1.6.1.(1) Except as described in Articles 1.6.4., 1.6.5., 1.6.6. and Sentence 1.6.7.(1), the actual thickness of the plaster finish or gypsum wallboard applied directly to concrete or masonry on one or both faces of a wall and on the fire-exposed faces of floors, beams and columns, is multiplied by the factor shown in Table 1.6.A., depending on the material to which the plaster is applied. The corrected thickness is then included in the "equivalent thickness" as described in Subsection 1.5. Plaster is required to conform to CSA A82.30-1965, "Interior Furring, Lathing and Gypsum Plastering." Plaster must be securely fastened to the wall or ceiling. Plaster applied directly to unit masonry or concrete without metal lath must not exceed %in. thickness on ceilings and %-in. thickness on walls.

(2) Portland cement-sand plaster must be applied in 2 coats; the first coat should contain 1

part portland cement to 2 parts sand by volume, and the second coat should contain 1 part portland cement to 3 parts sand by volume.

1.6.2.(1) Gypsum wallboard or gypsum lath shall be attached to masonry walls in accordance with Sentences (2) to (4). Copyright © NRC 1941 - 2019 World Rights Reserved © CNRC 1941-2019 Droits réservés pour tous pays

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(2) Gypsum wallboard or gypsum lath may be secured by self-tapping drywall screws 12 in.

O.C. penetrating Ya in. into horizontal steel furring channels spaced 24 in. O.C. and secured by concrete nails spaced not more than 16 in. O.C. which penetrate at least 7/16 in. into .the masonry.

Table 1.6.A.

Forming Part of Article 1.6.1

MULTIPLYING FACTORS(" F O R VARIOUS MASONRY O R CONCRETE C O N S T R U C I I O N S Type of Surface Protection Portland cement sand aggregate plaster

I

Type of Masonry or Concrete

1

Solid Clay Brick, Unit Masonry and Monolithic Concrete, Types N & S

Cored Clay Brick, Clay Tile, Mono- lithic Concrete, Type L40S and Unit Masonry, Type L ,20S Concrete Unit Masonry, Types L, and L220S Concrete Unit Masonry, Type L2 Gypsum sand plaster or gypsum wallboard Vermiculite or perlite aggregate plaster

Note to Table 1.6.A.:

( ' 1 Limiting conditions for this Table are found in Articles 1.6.4. to 1.6.7.

Column 1

(3) Gypsum wallboard or gypsum lath may be secured by self-tapping drywall screws 12 in. 0.c. penetrating ?is in. into steel studs spaced not more than 24 in. O.C. for single layer wallboard and not more than 16 in. O.C. for double layer wallboard with the studs secured by setting them into matching floor and ceiling runner channels adjacent to the masonry wall.

(4) Gypsum wallboard or gypsum lath may be secured by lath nails spaced 12 in. O.C. pene- trating 3/4 in. into nominal 1-in. by 2-in. wood strapping secured to the masonry by 2-in. concrete nails spaced not more than 16 in. O.C.

2

1.6.3. The following examples are included as a guide to the method of calculating the fire resistance of hollow concrete masonry walls with plaster o r gypsum wallboard protection.

Example (1)

3

A 1-hr fire-resistance rating is required of a hollow concrete masonry wall of Type N aggregate with %-in. gypsum wallboard on the fire-exposed face.

(a) %-in. gypsum wallboard on the fire-exposed side is assigned 10 min. in Table 2.3.A. provided the wallboard is attached as described in Article 1.6.2.

(b) The fire resistance required for the balance of the assembly = 60 min.-I 0 min. = 50 min.

(c) Interpolating between 45 min. and 1 hr in Table 2.1.A., for 50-min. fire resistance the

equivalent thickness of hollow concrete masonry wall required is 2.57 in.

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12 in. y con- 12 in. lboard ; them . pene- mcrete resist- 4. pro- min. Ice the Example (2)

A 2-hr fire-resistance rating is required for a hollow masonry wall of Type N aggregate with %-in gypsum wallboard on each face.

(a) %-in. gypsum wallboard on the fire-exposed side is assigned 15 min. in Table 2.3.A. (b) The fire resistance required of the balance of the assembly is 120 min.-15 min. = 105 min. (c) Interpolating between 1 % hr and 2 hr in Table 2.1.A., for 105-min. fire resistance the

equivalent thickness for hollow masonry units required is 3.7 in.+(0.7 in.^ 15/30)

= 4.05 in.

(d) The contribution of M-in. gypsum wallboard on the non-fire-exposed side using Table 1.6.A. = l/2 X 11/4=0.63 in. (See Article 1.6.7.)

(e) Equivalent thickness required of concrete masonry unit = 4.05-0.63 = 3.42 in.

(f) The fire-resistance rating of a concrete masonry wall having an equivalent thickness of 3.42 in. = 1 hr 20 min. As this is more than 1 hr the conditions of Article 1.6.5. are met and the rating of 2 hr is justified.

1.6.4. Where plaster or gypsum wallboard is applied to a floor or wall, the contribution of the plaster finish is limited by its ability to stay in place. Where the thickness of plaster on masonry or concrete exceeds 1% in., wire mesh with 0.062-in. diam. wire and openings not exceeding 2 in. by 2 in. must be embedded midway in the plaster.

1.6.5. Where plaster or gypsum wallboard is applied on both faces of a wall, the calculated fire resistance of the plastered assembly is not permitted to exceed twice the fire resistance of the un- plastered wall, because structural collapse may occur before the limiting temperature is reached on the surface of the non-fire-exposed plaster.

1.6.6. Where plaster or gypsum wallboard is applied only on the non-fire-exposed side of walls constructed of hollow clay tile, no increase in fire 'resistance over that of the same wall without plaster is permitted, because structural collapse may occur before the limiting temperature is reached on the plaster face.

1.6.7.(1) Where gypsum wallboard or plaster on gypsum lath is applied to masonry or monolithic concrete walls or concrete ceilings, and the gypsum wallboard or gypsum lath is securely fastened to the wall or ceiling, the contribution of the gypsum wallboard or plaster on gypsum lath on the fire-exposed face is shown in Tables 2.3.A. and 2.3.B.

(2) For the purpose of calculating the contribution to fire resistance, the assumed thickness of the gypsum wallboard or plaster on gypsum lath on the non-fire-exposed face is determined by multiplying the actual thickness of the gypsum wallboard or plaster on gypsum lath by the values shown in Table 1.6.A.

SUBSECTION 1.7

TESTS ON FLOORS

AND

ROOFS

1.7.1. All tests relate to the performance of a floor assembly or floor-ceiling or roof-ceiling assembly above a fire. It has been assumed on the basis of experience that fire on top will take a longer time to penetrate the floor than one below, and that the fire resistance in such a situation will be at least equal to that obtained from below in the standard test.

SUBSECTION 1.8 MOISTURE CONTENT

1.8.1. The moisture content of building materials at the time of fire test may have a significant influence on the measured fire resistance. In general, an increase in the moisture content should result in an increase in the fire resistance, though in some materials the presence of moisture may produce disruptive effects and early collapse of the assembly.

1.8.2. Moisture content is now controlled in standard fire test methods and is generally recorded in the test reports. In earlier tests moisture content was not always properly determined.

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SUBSECTION

1.9 PERMANENCE AND DURABILITY

1.9.1. The ratings in this Supplement relate to tested assemblies and do not take into account possible changes or deterioration in use of the materials. The standard fire test measures the fire resistance of a sample building assembly erected for the test. No judgment is made in the test as to the permanence or durability of the assembly.

SUBSECTION 1.10 STRUCTURAL STEEL

1.10.1. Structural steel fails at elevated temperatures because of excessive plastic deformation or creep and loss of strength, which causes the deflection of a member to reach unacceptable levels.

1.10.2. The tests on which the ratings for structural steel in this Supplement are based were for carbon steel members. Other steels may exhibit slightly better or worie performances than carbon steels. These differences in performance are, however, insignificant as far as the ratings in this document are concerned.

SUBSECTION

1.1 1

RESTRAINT EFFECTS

1.11.1. It is known that both edge restraint of a floor or roof and end restraint of a beam can sig- nificantly extend the time before collapse in a standard test. As a result, certain changes have been made in ULC-S 10 1 - 1975, "Standard Methods of Fire Endurance Tests of Building Construction and Materials."

1.11.2. In fire tests of floors, roofs and beams it is now necessary to state whether the rating applies to a restrained or to an unrestrained assembly. Whether or not a restrained rating can be applied depends on the type of construction and on the location in a building as described in Appen- dix A1 of ULC-S101-1975, "Standard Methods of Fire Endurance Tests of Building Construction and Materials." Acceptance criteria for unrestrained and restrained assemblies are described in Subsections 1.1 1.3. and 1.11.4.

1.11.3.(1) T o obtain an unrestrained assembly classification for an assembly tested restrained against thermal expansion, the conditions described in Sentences (2) to (6) are required by ULC- S101-1975, "Standard Methods of Fire Endurance Tests of Building Construction and Materials."

(2) The specimen shall have sustained the applied load during the classification period without developing unexposed surface conditions which will ignite cotton waste.

(3) The transmission of heat through the specimen during the classification period shall not have been such as to raise the average temperature on its unexposed surface more than 250°F above its initial temperature.

(4) For specimens employing steel structural members (excluding steel floor or roof units having spans equal to or less than those tested), the temperature of the steel shall not have exceeded 1,300°F at any location during the classification period, nor shall the average temperature recorded by 4 thermocouples at any section have exceeded l,lOO°F during this period.

( 5 ) For specimens employing conventionally designed concrete structural members, excluding

cast-in-place concrete roof or floor slabs having spans equal to or less than those tested, the average temperature of the tension steel at any section shall not have exceeded 800°F for cold-drawn prestressing steel or l,lOO°F for reinforcing steel during the classification period.

(6) For specimens employing 5 or more open-web steel joists, the average temperature recorded by all joist thermocouples shall not have exceeded l,lOO°F during the classification period.

(7) Assemblies tested in an unrestrained condition need only meet the criteria given in Sen-

tences (2) and (3).

1.11.4.(1) In a restrained assembly classification, the conditions described in Sentences (2) to (4) are required by ULC-S 10 1 - 1975, "Standard Methods of Fire Endurance Tests of Building Con- struction and Materials."

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ccoun t the fire st as to .ere for carbon is doc-

(2) The specimen shall have sustained the applied load during the classification period without developing unexposed surface conditions which will ignite cotton waste.

(3) Transmission of heat through the specimen during the classification period shall not have been such as to raise the average temperature on its unexposed surface more than 250°F above its initial temperature.

(4) For specimens employing beams spaced more than 4 ft o.c., the beams shall achieve a fire- resistance rating on the basis of the temperature criteria specified in Sentences 1.1 1.3.(4) to (6) for assembly classifications up to and including 1 hr. For classifications greater than 1 hr, the above temperature criteria shall apply for a period of 'h the classification of the assembly or 1 hr, whichever is the greater.

1.11.5. The ratings for floors and beams in this Supplement, other than the specific test results in Tables 2.3.H. and 2.3.I., meet the conditions of ULC-S101-1975, "Standard Methods of Fire En- durance Tests of Building Construction and Materials" for unrestrained specimens. In a restrained condition the floor, roof or beams would probably have greater fire resistance, but the ex- tent of this increase can be determined only by reference to behaviour in a standard test.

:an sig- /e been ruction

SECTION 2 FIRE-RESISTANCE RATINGS

ing ap- be ap- 4ppen- ruc tion ibed in trained ULC- ?rials."

SUBSECTION

2.1 MASONRY AND CONCRETE WALLS

2.1.1. The minimum thicknesses of unit masonry and monolithic concrete walls for fire- resistance ratings from ?h hr to 4 hr are shown in Table 2.1.A. Types of concrete are described in Subsection 1.4. Hollow masonry units are rated on the basis of equivalent thickness as described in Subsection 1.5.

2.1.2.(1) Ratings obtained as described in Article 2.1.1. apply to either loadbearing or non-loadbearing walls, except for the walls described in Sentences (2) to (6).

without

(2) Gypsum tile walls are considered non-loadbearing. la11 not 250" F its hav- ~ceeded Ire rec- cluding le aver- I-drawn Lre rec- beriod. in Sen- 2) to (4) lg Con-

(3) Walls less than the minimum thickness prescribed for loadbearing walls in the National Building Code of Canada 1977 are considered non-loadbearing.

(4) Masonry cavity walls (consisting of 2 wythes of masonry with an air space between) that are loaded to a maximum allowable compressive stress of 55 psi have a fire resistance at least as great as that of a solid wall of a thickness equal to the sum of the equivalent thicknesses of the 2 wythes.

( 5 ) Masonry cavity walls that are loaded to a compressive stress exceeding 55 psi are not considered to be within the scope of this Supplement.

(6) A masonry wall consisting of 2 types of masonry units, either bonded together or in the form of a cavity wall, is considered to have a fire-resistance rating equal to that which would apply if the whole of the wall were of the material that gives the lesser rating.

2.1.3. If wood joists are built into a masonry wall, the thickness of masonry material between the end of the joist and the fire-exposed side of the wall must be not less than the equivalent thickness shown in the Tables for the fire resistance required.

2.1.4. On monolithic walls and walls of unit masonry, the full plaster finish on one or both faces multiplied by the factor shown in Table 1.6.A. is included in the wall thickness shown in Table

2 . I .A., under the conditions and using the methods described in Subsection 1.6.

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2.1.5. Where all the core spaces in a wall of hollow concrete masonry units are filled with loose

fill materials, such as expanded slag, burned clay or shale (rotary kiln process), vermiculite or perlite, the fire resistance of the wall is the same as that of a wall of solid units of the same concrete type and of the same overall thickness.

2.1.6. Short reinforced concrete walls or portions of walls that may be exposed to fire on both

sides simultaneously and that are required to carry a load during fire exposure shall have minimum dimensions and have minimum cover to steel reinforcement as described in Article 2.8.2.

Table 2.1.A.

Forming Part of Article 2.1.1.

Notes to Table 2.1.A.:

( 1 ) See definition of equivalent thickness in Subsection 1.5.

( 2 ) Hollow concrete masonry units made with Types S or N concrete must have a 28-day compressive strength

of at least 1,000 psi.

(3) Gypsum partition tile is wood fibred gypsum conforming to CSA A82.25-1950, "Gypsum Partition Tile or

Block."

MINIMUM EQUIVALENT THICKNESSES(') OF UNIT MASONRY

AND OF MONOLITHIC CONCRETE WALLS LOADBEARING

Type of Wall

Solid brick units (80 per cent solid and over), actual overall thickness Cored brick units and hollow tile units (less than 80 per cent solid), equivalent thickness Solid and hollow concrete masonry units, equivalent thickness Type S or N concrete(2) Type L120S concrete Type L, concrete Type L220S concrete Type L2 concrete Monolithic concrete and concrete panels

Type S concrete Type N concrete

Type L40S or Type L concrete Gypsum partition tile(3)

or block, non-loadbearing solid or hollow units, equivalent thickness

Column 1

AND NON-LOADBEARING, in.

l h r 3.5 2.8 2.9 2.6 2.5 2.5 2.5 3.5 3.4 2.8 2.0 4 Fire-Resistance 11/2hr 4.3 3.4 3.7 3.4 3.2 3.2 3.1 4.4 4.2 3.5 2.5 5 Y2hr 2.5 2.0 1.7 1.6 1.6 1.6 1.6 2.3 2.3 1.9 1.3 2 % h r 3.0 2.4 2.3 2.1 2.1 2.1 2.1 3 .O 2.9 2.4 1.7 3 Rating 2 h r 5.0 4.0 4.4 4.0 3.8 3.7 3.6 5.1 4.9 4.0 3.2 6 3 h r 6.0 4.8 5.6 5.1 4.8 4.6 4.4 6.2 5.9 4.9 4.1 7 4 h r 7.0 5.6 6.6 6.0 5.6 5.3 5.1 7.1 6.7 5.6 5 .O 8 Copyright © NRC 1941 - 2019 World Rights Reserved © CNRC 1941-2019 Droits réservés pour tous pays

(16)

th loose : or per- zoncrete on both de mini- -8.2. : strength )n Tile or

SUBSECTION 2.2

REINFORCED AND PRESTRESSED CONCRETE

FLOOR AND ROOF SLABS

2.2.141) Floors and roofs in a fire test are assigned a fire-resistance rating which relates to the

time that an average temperature rise of 250F0 or a maximum temperature rise of 325F0 at any location is recorded on the unexposed side, or the time required for collapse to occur, whichever is the lesser. The thickness of concrete shown in Table 2.2.A. is required to resist the transfer of heat during the fire-resistance period shown.

(2) The concrete cover over the reinforcement and steel tendons shown in Table 2.2.B. is re-

quired to maintain the integrity of the structure and prevent collapse during the same period.

Table 2.2.A.

Forming Part of Sentence 2.2.1 .(I)

I

MINIMUM THICKNESS OF REINFORCED CONCRETE FLOOR OR ROOF SLABS, in.

I

Table 2.2.B.

Forming Part of Sentence 2.2.1 .(2) Type of Concrete

Type S concrete Type N concrete Type L40S and Type L

concrete

Column 1

2.2.2. The fire resistance of floors containing hollow units may be determined on the basis of

"equivalent thickness" as described in Subsection 1.5.

Fire-Resistance Rating

MINIMUM CONCRETE COVER OVER REINFORCEMENT IN CONCRETE SLABS, in.

2.2.3. The contribution of plaster finish securely fastened to the underside of concrete is taken

into account in floor or roof slabs under the conditions and using the methods described in Sub- section 1.6.

Type of Concrete

Types S, N, L40S or L concrete

Prestressed concrete slabs Types S, N, L40S or L concrete

Column 1

2.2.4. In prestressed concrete slab construction, the concrete cover over a n individual tendon is

the minimum thickness of concrete between the surface of the tendon and the fire-exposed surface of the slab, except that for ungrouted ducts the assumed cover thickness is the minimum thickness of concrete between the surface of the duct and the bottom of the slab. For slabs in which several tendons are used, the cover is assumed to be the average of those of individual tendons, except that the cover for any individual tendon must be not less than % of the value given in Table 2.2.B. nor less than YI in.

% h r 2.3 2.3 1.9 2 3/4hr 3 .O 2.9 2.4 3 l h r 3.5 3.4 2.8 4 Fire-Resistance Rating % h r % 3/4 2 1 % h r 4.4 4.2 3.5 5 % h r 5/s 1 3 2 h r 5.1 4.9 4.0 6 l h r % 1 4 3 h r 6.2 5.9 4.9 7 4 h r 7.1 6.7 5.6 8 1 % h r % 1

YI

(17)

2.2.5. Minimum dimensions and cover to steel tendons of prestressed concrete beams are shown in Subsection 2.10.

SUBSECTION

2.3 WOOD AND STEEL FRAMED WALLS, FLOORS

AND ROOFS

2.3.1. The fire-resistance rating of walls, floors and roofs, incorporating wood, steel, light-gauge steel members and open-web steel joists for ratings up to and including 1% hr is determined by this Subsection, except as described in Tables 2.3.H. and 2.3.1.

2.3.2. The ratings apply to both loadbearing and non-loadbearing walls and to loadbearing floors and roofs.

2.3.3. The fire-resistance rating of a framed assembly is equal to the time assigned for the contribution to fire resistance of the membrane on the fire-exposed side plus the time assigned for the contribution to fire resistance of the framing members plus the time assigned for additional contribution to fire resistance by other protective measures, such as inclusion of insulation or reinforcement in a membrane.

2.3.4. The fire-resistance rating of a framed assembly depends on the time during which the wall face or membrane on the fire-exposed side remains in place. Tables 2.3.A. and 2.3.B. list the time during which the membrane on the fire-exposed side will remain in place during the standard test.

Table 2.3.A.

I

TIME ASSIGNED T O WALLBOARD MEMBRANES

I

Description of Finish Time, min. %-in. fibreboard

%-in. Douglas Fir plywood phenolic bonded %-in. Douglas Fir plywood phenolic bonded %-in. Douglas Fir plywood phenolic bonded %-in. gypsum wallboard

M-in. gypsum wallboard %-in. gypsum wallboard

Double %-in. gypsum wallboard

Y2

+

%-in. gypsum wallboard

Double M-in. gypsum wallboard Double M-in. gypsum wallboard

3/ 16-in. asbestos cement

+

%in. gypsum wallboard 3/ 16-in. asbestos cement

+

%-in. gypsum wallboard Composite %-in. asbestos cement on 7/ 16-in. fibreboard

I

Column 1

I

2

I

(1) Wire mesh with 0.062-in.-diam. wire and 1-in. by 1-in. openings must be fastened between the 2 sheets of wallboard.

(2) Values shown apply to walls only.

2.3.5.(1) When the membrane falls off there is a brief period during which the studs or joists are exposed directly to the furnace before structural failure occurs. Table 2.3.C. lists the time involved from failure of the membrane to collapse of the assembly.

(18)

hown Table 2.3.B.

:ontri- or the :ontri- force- ce wall e time 1 test. heets of ists are ,valved

I

T I M E ASSIGNED T o LATH AND PLASTER(1, PROTECTION, min.

I

Type of Plaster

I

Type of Lath

- -

Wood lath Y2-in. fibreboard %-in. gypsum lath %-in. gypsum lath %-in. gypsum lath Metal lath Metal lath Metal lath in. Portland

1 I I

Gypsum Cement, and ter Thickness, Sand(2) or Lime and Sand

Sand and Gypsum Gypsum Perlite

Asbestos

/

and Sand

I

z:z:

/

Or

1

Fibre G v ~ s u m Portland Cement and J 1 (3 lb/bag

1

and of cement) Vermiculite Notes to Table 2.3.B.:

( 1 ) The values shown for these membranes have been limited to 80 min. because the fire-resistance rating de-

rived from these Tables must not exceed 1 % hr.

(2) For mixture for portland cement-sand plaster see Sentence 1.6.1 .(2).

(2) The fire resistance of a framed assembly is primarily the sum of the time to failure of the membrane exposed to fire and the time to structural failure of the framing members. The membrane on the non-fire-exposed side, whatever its nature, may be expected to fail when the structural members fail. It is, however, required to remain in place and to be a barrier to smoke and flame until collapse of the framing members.

2.3.6. Where fire exposure can be expected to occur only on one side of a wall, such as on the interior side of a n exterior wall, the wall is assigned a rating dependent on the interior membrane and the framing as described in Tables.2.3.A., 2.3.B. and 2.3.C. The membrane on the outside or non-fire-exposed side may consist of sheathing, sheathing paper and siding as described in Table 2.3.D. or may be any membrane that is assigned a time for contribution to fire resistance of at least 15 min. in Tables 2.3.A. or 2.3.B.

Table 2.3.C.

TIME ASSIGNED FOR CONTRIBUTION O F WOOD OR LIGHT STEEL FRAME

Description of Frame

Wood studs 16 in. O.C. Steel studs 16 in. O.C.

Wood floor and roof joists 16 in. O.C.

Open web steel joist floors and roofs with ceiling supports 16 in. O.C.

(19)

Table 2.3.D.

Note to Table 2.3.D.:

( 1 ) Exterior membrane may be any combination of sheathing, paper and exterior finish.

MEMBRANE(') ON EXTERIOR FACE OF WOOD OR LIGHT-STEEL STUD WALLS

2.3.7. In the case of a floor or roof the standard test provides only for testing for fire exposure from below. Floor or roof assemblies of wood, light-gauge steel members or open-web steel joist framing must have an upper membrane consisting of a subfloor and finish floor conforming to Ta- ble 2.3.E. or any other membrane that has a contribution to fire resistance of at least 15 min. in Table 2.3.A.

Sheathing %-in. T & G lumber

5/ 16-in. exterior grade plywood %-in. gypsum wallboard

None

Column 1

2.3.8. Mineral wool insulation provides additional protection to wood studs by shielding the studs from exposure to the furnace, and thus delaying the time of collapse. The use of reinforcement in the membrane exposed to fire also adds to the fire resistance by extending the time to failure. Table 2.3.F. shows the time increments that can be added to the fire resistance if these fea- tures are incorporated in the assembly.

2.3.9. The fire-resistance rating is the sum of the time attributed to the contribution to fire resistance of the membrane on the fire-exposed side in Tables 2.3.A. and 2.3.B., the time attributed to the contribution to fire resistance of the structural frame in Table 2.3.C. and the additional times listed in Table 2.3.F.

Paper

Sheathing paper

-

2

2.3.10.(1) The values shown in Tables 2.3.A. and 2.3.B. apply only if the supports for the fire-exposed membrane are not more than 16 in. O.C.

Exterior Finish .

Lumber siding

Wood shingles and shakes %-in. plywood exterior

grade

'/4-in. hardboard Metal siding Stucco on metal lath Masonry veneer %in. exterior grade

plywood 3

(2) Wood studs are assumed to be not less than 2 in. by 4 in. nom. size wood joists and not less than 2 in. nom. thickness. Actual dimensions for dressed lumber are given in CSA 0141-1970, "Softwood Lumber."

(3) The allowable spans for wood joists listed in the ACNBC Span Tables for Wood Joists, Rafters, Trusses and Beams 1977 are provided for floors supporting specific occupancies.

(4) Plaster thickness is measured from the face of gypsum or metal lath.

(20)

cposure :el joist ; to Ta- min. in ing the .nforce- to fail- ese fea- to fire .ributed di tional

2.3.11. The fastening of the membrane to the supporting construction is important if the as-

signed fire-resistance rating is to be attained. Fastening to wood and metal supports is specified in CSA A82.30-1965, "Interior Furring, Lathing and Gypsum Plastering" and CSA A82.31-1963, "Gypsum Wallboard Application," but must be not less than the minimum requirements in Table 2.3.G.

Table 2.3.E.

1

FLOORING OR ROOFING OVER WOOD, LIGHT-GAUGE STEEL MEMBERS

OR OPEN-WEB STEEL JOISTS

Type of

Assembly Structural Members Subfloor or Roof Deck Finish Flooring or Roofing

Floor

Hardwood or softwood flooring on building paper Resilient flooring, parquet

Steel joists

Wood or steel joists

2-in. reinforced concrete or 2-in. concrete on metal lath or formed steel sheet, or

1 %-in. reinforced

gypsum-fibre concrete on %-in. gypsum wallboard

thick panel-type underlay Ceramic tile on 1 %-in.

mortar bed %-in. plywood or 1 1 / 16-in.

Finish flooring

floor felted-synthetic-fibre floor coverings, carpeting, or ceramic tile on %-in.-

Roof

Wood or steel joists

Steel joists

%-in. plywood or 1 1 / 16-in. T & G softwood

2-in. reinforced concrete or 2-in. concrete on metal lath or formed steel sheet, or

1 '/'-in. reinforced

gypsum-fibre concrete on %-in. gypsum wallboard

Finish roofing material with or without insulation

I

Column I

I

2

I

3

I

4

I

(21)

Table 2.3.F.

TIME ASSIGNED FOR ADDITIONAL PROTECTION

Fire .

Description of Additional Protection Resistance, min. Add to the fire-resistance rating of wood stud walls if the spaces between

the studs are filled with mineral wool batts conforming to CSA A101-

1968, "Specification for Mineral Wool Thermal Building Insulation" and 15 weighing not less than '/4 lb/sq ft of wall surface

Add to fire-resistance rating of plaster on gypsum lath ceilings if 0.030-

in.-diam. wire mesh with 1-in. by 1-in. openings or 0.062-in.-diam. diago- 3 0 nal wire reinforcing at 10 in. O.C. is placed between lath and plaster

Add to fire-resistance rating of plaster on gypsum lath ceilings if 3-

in.-wide metal lath strips are placed over joints between lath and plaster 10 Add to fire-resistance rating of plaster on %-in.-thick gypsum lath ceilings

(Table 2.3.B.) if supports for lath are 12 in. O.C. 10

Column 1 2

Table 2.3.G.

Forming Part of Article 2.3.1 1

MINIMUM FASTENING OF WALLBOARD OR LATH T O WOOD FRAME

Minimum Nail Sizescl) Maximum Surface

Spacing Gypsum lath Ceiling, 1 %-in., 0.092-in.-diam. nails with %-in. head 4 in. O.C.

Wall, 1%-in., 0.092-in.-diam. nails with 19/64-in. head 5 in. O.C. Metal lath Ceiling, 1 %-in., 0.132-in.-diam. nails with 7/ 16-in. head 6 in. O.C. Wall, 1-in. large head asphalt roofing nails 7 in. O.C. Gypsum Ceiling, 1 %-in., 0.092-in.-diam. nails with 7/32-in. head 6 in. O.C. wallboard Wall, 1%-in., 0.092-in.-diam. nails with 7/32-in. head 8 in. O.C. Fibreboard lath Ceiling, 1 %-in., 0.092-in.-diam. nails with 19/64-in. head 4% in. O.C. Wall, 1%-in., 0.092-in.-diam. nails with 19/64-in. head 4l/2 in. O.C.

Column 1 2 3

Note to Table 2.3.G.:

( 1 ' Wood screws shall be the same length as required for nails.

(22)

O.C.

I

O.C.

I

2.3.12. Supplementary ratings based on tests are included in Tables 2.3.H. and 2.3.1. The values

shown in these Tables are higher than the fire-resistance ratings obtained by calculation and apply only to constructions which conform in all details to the descriptions given.

Table 2.3.H.

FIRE-RESISTANCE RATING O F RESTRAINED OPEN-WEB S T E E L J O I S T F L O O R S AND R O O F S ( ' )

Type of Construction

Ceiling: Perlite or Vermiculite Plaster o n Ye-in. Perforated Gypsum Lathc2) T o p Slab

o r Floor

Steel joist floors(5)

Column 1

Spacing of Plaster Fire-

)/s-in. Furring Plaster _Thickness' _{Reinforcement}'laster Resistance

1

Channels(3

I

Mix

1

i n 4

1

Rating

1

2-in. portland cement concrete slab reinforced by 6-in. x 6-in., 0.162-in.-diam. wire mesh over ribbed metal lath supported by bar joists spaced 24 in. O.C. 2 16 in. ( 6 ) ( 6 ) Extra clips passed through lath along each channel a t 5 % in. o.c.(lO) 12 in. Notes to Table 2.3.H.:

( 1 ) The ratings in Table 2.3.H. and the following notes are from "Fire Endurance of Open-Web Steel Joist Floors with Concrete

Slabs and Gypsum Ceilings," James V. Ryan and E.W. Bender. Building Materials and Structures Report BMS 141., Na-

tional Bureau of Standards, Washington, 1954.

( 2 ) Three-eighths of an inch perforated gypsum lath secured to furring channels by 0.078-in.-diam. galvanized wire clips tied to

the furring channels at 12 in. or 16 in. o.c., depending on the spacing of the channels, and under the lath so as to provide continuous support for the lath.

( 3 ) Three-quarter-inch steel furring channels fastened to joists by double-strand wire ties.

( 4 ) Thickness includes finish coat.

( 5 ) The design tensile stress in the open-web steel joists of the tested assemblies did not exceed 18,000 psi.

( 6 ) One hundred pounds of gypsum plaster to 2% cu ft of aggregate.

( 7 ) Diagonal wire, 0.078-in.-diarn., galvanized, placed between lath and plaster running at 45 deg. to the furring channels and

tied back to the wire clips at the point of junction with the furring channels.

( 8 ) Galvanized wire mesh, 0.034-in.-diam. with 1 in. hexagonal openings, fastened under the lath and tied back to the furring

channels at 12 or 16 in. O.C. depending on the spacing of the channels.

(9) Scratch coat, 100 Ib of gypsum plaster to 2 cu ft of aggregate. Brown coat, 100 Ib of gypsum plaster to 3 cu ft of aggregate.

(10) Additional looped wire clips 0.078-in.-diam.. galvanized wire passed through the lath and tied to the furring channels to pro-

vide extra support.

0.078-in.-diam. diagonal wire '/z ( 9 ) ( 9 ) I-in., 0.034-in. -diam. hex. wire mesh(8) with I-in. openings S/e 1 0.078-in.-diam. diagonal wire 10 in. o.c.(7) I-in., 0.034-in. -diam. hex. wire mesh(8) 3 hr 4 hr Copyright © NRC 1941 - 2019 World Rights Reserved © CNRC 1941-2019 Droits réservés pour tous pays

(23)

Table 2.3.1.

Notes to Table 2.3.1.:

( I ) The design tensile stress in the open-web steel joists did not exceed 18,000 psi.

(2) The ratio of weight of portland cement to combined fine and coarse aggregates for the floor slab must be not less than 1 :6%.

The slab thicknesses are measured from the top flange of the joists and, unless otherwise indicated, are for monolithic construction. To obtain the listed fire-resistance ratings, the average thickness of the slabs cast in place should be Yi in. greater than at the joists. This greater average thickness usually results from the sag of metal lath forming or the placing of the more rigid forms under the top flange of the joists.

The plaster for the ceiling must be applied on expanded metal, woven wire or paper-backed wire lath of appropriate weight for the spacing of the supports. The lath must be tied to the supports to give the equivalent strength of single 0.047-in.-diam. steel- wire ties spaced 5 in. o.c. The thickness of plaster is measured from the back side of flat lath and to the back of the flat portion of ribbed lath.

(4) The ratings in Table 2.3.1. are from "Fire Resistance Classifications of Building Constructions," Building Materials and Struc-

tures Report BMS 92. National Bureau of Standards. Washington. 1942.

FIRE-RESISTANCE RATING O F RESTRAINED OPEN-WEB S T E E L J O I S T

Type of Con- struction Steel joist floors Column 1 ASSEMBLIES FOR

Top Slab or Floorc2)

2'h-in. reinforced concrete or 2- in. reinforced gypsum tile with %-in. mortar finish

1-in. by 2-in. Pine flooring on I- in. by 2-in. nailing strips set % in. into 2-in. concrete on rib lath 1-in. portland cement mortar finish on 2-in. concrete on rib lath

2-in. reinforced concrete or 2-in. reinforced gypsum tile with %-in. mortar finish

2%-in. reinforced concrete or 2- in. reinforced gypsum tile with %-in. mortar finish

2Y2-in. reinforced concrete or 2- in. reinforced gypsum tile with %-in. mortar finish

2-in. reinforced concrete or 2-in. precast reinforced portland cement concrete or gypsum slabs, the precast slabs to be finished with top coating of mortar % in. thick

2

R O O F S AND FLOORS(')

Ceiling or Soffit Protection on Metal Lath(3)

%-in. gypsum-sand plaster 1 :2, 1:3

%-in. gypsum-vermiculite or gypsum- perlite plaster scratch coat 1 bag (100 Ib) gypsum to 2 cu ft vermiculite o r perlite, brown coat 1 bag (100 lb) gypsum to 3 cu ft vermiculite o r perlite

3h-in. gypsum-vermiculite or gypsum- perlite plaster scratch coat 1 bag (100 lb) gypsum to 2 cu ft vermiculite or perlite, brown coat 1 bag (100 lb) gypsum to 3 cu ft vermiculite o r perlite

1-in. gypsum-vermiculite or gypsum- perlite plaster scratch coat 1 bag (100 Ib) gypsum to 2 cu ft vermiculite or perlite, brown coat 1 bag (100 lb) gypsum to 3 cu ft vermiculite o r perlite

2-in. precast reinforced gypsum tile, well anchored into beams with metal ties o r clips and covered with %-in. 1 :3 gypsum-sand plaster 3 Fire- Resistance Ratings,( hr 2 2 3 4 4 4 Copyright © NRC 1941 - 2019 World Rights Reserved © CNRC 1941-2019 Droits réservés pour tous pays

(24)

I:6%. ,true- an at rigid ~t for steel- d o n itruc-

2.3.13.(1) Where a beam is included with a n open-web steel joist or similar construction and is

protected by the same continuous ceiling, the beam is assumed to have a fire-resistance rating equal to that assigned to the rest of the assembly.

(2) The ratings in this Supplement assume that the construction to which the beam is related is

a normal one and does not carry unusual loads from the floor or slab above.

SUBSECTION 2.4

SOLID WOOD WALLS, FLOORS AND ROOFS

2.4.1. The minimum thickness of solid wood walls, floors and roofs for fire-resistance ratings

from lh hr to 1 '/z hr is shown in Table 2.4.A.

Table 2.4.A.

MINIMUM NOMINAL THICKNESS(') OF SOLID WOOD WALLS, ROOFS AND FLOORS, in.

Solid wood(2) floor with building paper and

finish flooring on to^ I 4 I 4 I 6 I 8 I Type of Construction

(

Solid wood, splined or tongued-and- grooved floor with building paper and finish flooring on topc3)

Solid wood(2) walls of loadbearing vertical d a n k

r

-

-Column 1 1 2 1 3 1 4 l ~ 1

1

Solid wood(2) walls of non-loadbearing horizontal plank

( 1 ) See CSA 0141-1970, "Softwood Lumber" for actual sizes to correspond with the nominal dimensions.

( 2 ) The assembly consists of nominal 2-in.-thick members on edge fastened together with 4-in. common wire

nails spaced not more than 16 in. O.C. and staggered in the direction of the grain.

(3) The floor consists of nominal 3-in. by 8-in. planks either tongued and grooved or with %-in. by 1%-in. splines set in grooves and fastened together with 3%-in. common nails spaced not more than 16 in. O.C.

1 '/2 hr

3

4

2.4.2.(1) The fire-resistance ratings of the assemblies described in Table 2.4.A. are increased by

15 min. if one of the finishes described in Clauses (a) to (c) is applied on the fire-exposed side: 1 hr

lh hr

4

(a) %-in.-thick gypsum wallboard,

3/i hr

3

4

(b) %-in.-thick gypsum-sand plaster on metal lath, or

4

(c) Y2-in.-thick gypsum-sand plaster on %-in. gypsum lath.

-

6

(2) Fastening of the plaster to the wood structure must conform to Subsection 2.3.

-

8

4

2.4.3. Supplementary ratings based on tests are included in Table 2.4.B. The ratings given apply

to constructions that conform in all details with the descriptions given.

(25)

Table 2.4.B.

Notes to Table 2.4.B.:

( I ) The ratings and notes are taken from "Fire Resistance Classifications of Building Constructions," Building Materials and Structures Report BMS 92, National Bureau of Standards, Washington, 1942.

(2) Ratings for plywood faced panel are based on phenolic resin glue being used for gluing facings to wood frames. If other types of glue are used for this purpose, the ratings can be taken to apply if the facings are nailed to the frames in addition to being glued.

FIRE-RESISTANCE RATINGS O N NON-LOADBEARING BUILT-UP SOLID WOOD PARTITIONS")

SUBSECTION 2.5

SOLID PLASTER PARTITIONS

Construction Details

Solid panels of Y~-in. wood boards 2% to 6 in. wide grooved and joined with wood splines, nailed together, boards placed vertically with staggered joints, 3 boards thick Solid panels with 3/ 16-in. plywood facings(2) glued to 1 %-in. solid wood core of glued T & G construction for both sides and ends of core pieces with T & G rails in the core about 2% ft apart

Column 1

2.5.1. The minimum thickness of solid plaster partitions for fire-resistance ratings from 95 hr to 4 hr is shown in Table 2.5.A.

Table 2.5.A.

Overall Thickness, in. 2 l/4 2% 2 Fire-Resistance Rating, h r % 1 3

Notes to Table 2.5.A.:

( 1 ) Metal lath is expanded metal lath or welded woven wire fabric supported on %-in. vertical light steel studs

spaced not more than 24 in. O.C. Plaster is applied to both sides of the metal lath.

(2) For mixture for portland cement-sand plaster see Sentence 1.6.1.(2).

(3) CSA A82.30-1965, "Interior Furring, Lathing and Gypsum Plastering" does not permit solid plaster partitions to be less than 2 in. thick.

MINIMUM THICKNESS O F NON-LOADBEARING SOLID PLASTER PARTITIONS, in.

Type of Plaster on Metal Lath(')

Portland cemen t-sandc2) or Portland cement-lime-sand G ypsum-sand Gypsum-vermiculite, Gypsum-perlite, Portland cement-vermiculite 0 r Portland cement-perlite Column 1 Fire-Resistance Ratings 'hhr 2(3) 20) 20) 2 % h r - 2(3) 2(3) 3 l h r - 2% 20) 4 1Y2hr - - 2% 5 2 h r - 2% 6 3 h r - - 3% 7 4 h r - - 4 8 Copyright © NRC 1941 - 2019 World Rights Reserved © CNRC 1941-2019 Droits réservés pour tous pays

(26)

SCTBSECTION 2.6 PROTECTED STEEL COLUMNS

wood gs are

:I studs

r parti-

2.6.1. The minimum thickness of protective covering to steel columns is shown in Tables 2.6.A.

to 2.6.E. for fire-resistance ratings from '/z hr to 4 hr.

Table 2.6.A.

Forming Part of Article 2.6. I.

MINIMUM THICKNESS OF CONCRETE OR MASONRY PROTECTION TO STEEL COLUMNS, in.

Monolithic concrete Type S concrete(') (column spaces filled)c2) Type N or L concrete(') (column spaces filled)c2)

I

- -

Concrete masonry unitsc3) or precast reinforced concrete units Type S concrete

(column spaces not filled) Types N and L concrete (column spaces not filled) Clay or shale brickc4)

(column spaces filled)c2) Clay or shale brickc4)

(column spaces not filled) Description of Cover

Gypsum partition tile or blockc5)

(column spaces not filled) Hollow clay tilec6)

(column spaces filled)c2) Hollow clay tilec6)

(column spaces not filled)

Column 1

95 hr

-

( I ) Applies to cast-in-place concrete reinforced with 0.205-in.-diam. wire wrapped around column spirally 8 in.

o.c., or 0.062-in.-diam. wire mesh with 4-in. by 4.-in. openings.

( 2 ) The space between the protective covering and the web or flange of the column is filled with concrete, ce-

ment mortar or a mixture of cement mortar and broken bricks.

(3) Concrete masonry reinforced with 0.205-in.-diam. wire or wire mesh with 0.047-in.-diam. wire and %-in. by

W-in. openings, laid in every second course.

(4) Brick cover 3 in. thick or less must be reinforced with 0.092-in.-diam. wire or 0.047-in.-diam. wire mesh with

%-in. by H-in. openings, laid in every second course.

( 5 ) Gypsum partition tile or block with gypsum-sand mortar and reinforced with 0.047-in.-diam. wire mesh with

%-in. by %-in. openings, laid in every horizontal joint and lapped at corners. Gypsum partition tile is wood- fibred gypsum conforming to CSA A82.25-1950, "Gypsum Partition Tile or Block."

(6) Hollow clay tiles and masonry mortar reinforced with 0.047-in.-diam. wire mesh with %-in. by Ys-in. open-

ings, laid in every horizontal joint and lapped at corners.

(') Two inch nominal is 2 i n k 3 per cent with cores conforming to CSA A82.5-1954, "Structural Clay

Non-Loadbearing Tile."

(8) Two inch nominal hollow clay tile, reinforced with 0.047-in.-diam. wire mesh with %-in. by %-in. openings

laid in every horizontal joint and covered with %-in. gypsum-sand plaster and with limestone concrete fill in column spaces, has 4-hr fire-resistance rating.

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Table 2.6.B.

I

MINIMUM THICKNESS OF PLASTER PROTECTION TO STEEL COLUMNS, in.

1

Column 1

Fire-Resistance Rating(')J2) Description

Gypsum-sand plaster on %-in. gypsum lathc-7) Gypsum-perlite or vermiculite plaster on %-in. gypsum lath(3)

Notes to Table 2.6.B.:

( 1 ) Fire-resistance ratings of lh hr and % hr apply to columns whose W I D ratio is 0.5 or greater. Fire-resistance ratings greater than % hr apply to columns whose W I D ratio is greater than 1.0. Where the W / D ratio is between 0.5 and 1.0 and the required fire-resistance rating is greater than hr. the total thickness of protection specified in the Table must be increased by 50 per cent. (To determine W / D , refer to Article 2.6.5.)

( 2 ) Where the thickness of plaster over gypsum lath is 1 in. or more, wire mesh with 0.062-in.-diam. wire and openings not exceeding 2 in. by 2 in. must be placed midway in the plaster.

( 3 ) Lath held in place by 0.047-in.-diam. wire wrapped around lath 18 in. O.C.

( 4 ) Expanded metal lath 2.5 lb/sq yd fastened to H-in. by %-in. steel channels held in vertical position around

column by 0.047-in.-diam. wire ties.

(!) For mixture for portland cement-sand plaster see Sentence 1.6.1 .(2). Gypsum perlite or ver-

miculite plaster on '/2-in. gypsum lathc3) Gypsum perlite or vermicu-

lite plaster on double %-in. gypsum lathc3) Portland cement-sand

plaster o n metal

Table 2.6.C.

9 ' 2 '/z 1 Note to Table 2.6.C.:

( 1 ) T o determine W / D refer to Article 2.6.5.

MINIMUM THICKNESS OF GYPSUM-SAND PLASTER O N

METAL LATH PROTECTION T O STEEL COLUMNS, in.

Fire-Resistance Ratings W / D ( ' ) 0.5 to 1.0 over 1 .O to 1.5 over 1.5 to 2.0 over 2.0 to 3.0 over 3.0 l/2 95 1 Column 1 9 ' 2 95 1 2 %I % - 3 1 1 - 4 1 '/z 1 - 5 2 1 '/z - 6 7 Copyright © NRC 1941 - 2019 World Rights Reserved © CNRC 1941-2019 Droits réservés pour tous pays

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Table 2.6.D.

stance atio is ~rotec- .) .e and round Table 2.6.E.

MINIMUM THICKNESS OF GYPSUM-PERLITE OR GYPSUM-VERMICULITE PLASTER ON METAL LATH PROTECTION TO STEEL COLUMNS, in.

1

STEEL COLUMNS WITH SHEET-STEEL MEMBRANE AND INSULATION AS SHOWN

IN FIGURES 2.6.(a) AND 2.6.(b)

1

W/D(I) , 0.5 to 1.0 over 1.0 to 1.5 over 1.5 to 2.0 over 2.0 to 3.0 over 3.0 Fire-Resistance Ratings Type of Protection See Figure 2.6.(a) See Figure 2.6.(b) S tee1 Thicknessl1) in. See Figure 2.6.(a) Note to Table 2.6.D.:

( 1 ) T o determine W / D refer to Article 2.6.5.

2 h r 1% 1 1 )/4 7 8 6 '/Z hr 78 70 70 7 8 7 8 0.020 0.025 See Figure 2.6.(b)

Notes to Table 2.6.E.:

( ' 1 Minimum thickness, galvanized or wiped-zinc-coated sheet steel.

( 2 ) Sheet steel is to be securely fastened to the floor and superstructure, or where sheet-steel cover does not ex-

tend floor to floor, fire stopping must be provided a t the level where sheet-steel protection ends. In the latter case an alternate type of fire protection shall be applied between the fire stopping and the superstructure.

( 3 ) Conforming to CSA A101-1975, "Mineral Fibre Thermal Building Insulation," Type lA, minimum density 1.9 lb/cu ft; column section and batts wrapped with 1-in. mesh chicken wire.

1 hr 70 70 7 8 78 4 7 % hr 78 70 70 7 8 I 78 3 Column 1 Fastening(*) 0.025 I Column 1 11/2hr 1 '/4 )/4 70 7 8 5/s ---- -5 3 hr - 1% 1% 1 l/4 1 1 2 No. sheet-meta1 screws, )/a in. long, 8

in. O.C.

Self-threading screws or No. 8 sheet-metal screws, 24 in. O.C.

0.030 4 hr - 1% 1 % 1% 1% Insulation No. 8 sheet-metal screws, )/s in. long, 8 in. O.C.

2

Fire-Resis tance Rating,

h r

2-in. mineral wool

batts(31

2 layers %-in. gyp-

sum wallboard

3-in. mineral wool battsc3) %-in. gypsum wallboard CrimPedJoint Or No.

8 sheet-metal screws,

)A

1 '/z

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FIGURE 2.6.(a) Column protected by sheet-steel membrane and mineral-wool insulation.

SCREW OR CRIMP J O I N T

FIGURE 2.6.(b) Column protected by sheet-steel membrane and gypsun 1 wallboard.