Commentary on Part 3 (Use and Occupancy) of the National Building Code of Canada: 1980

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COMMENTARY ON PART 3 (USE AND OCCUPANCY)

o f t h e

NATIONAL BUILDING CODE OF CANADA 1980

Issued by t h e

Associate Comi t t e e on t h e National Bui 1 ding Code National Research Council o f Canada

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F i r s t E d i t i o n 1982

@ National Research Council o f Canada 1982

Worl d Rights Reserved

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TABLE OF CONTENTS

PAGE

PREFACE

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v i i

CHAPTER 1 APPLICATION AND GENERAL PROVISIONS

A p p l i c a t i o n o f P a r t 3

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1 R e l a t i o n s h i p between P a r t 3 and t h e National F i r e Code

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2 General P r o v i s i o n s i n P a r t 3

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2 CHAPTER 2 SCOPE The Arrangement o f P a r t 3

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5 General Requirements (NBC S e c t i o n 3.1)

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5 S i z e and Occupancy Requirements

f o r F i r e Safety (NBC S e c t i o n 3.2)

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5 S a f e t y Requirements w i t h i n F l o o r Areas (NBC Section 3.3)

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6 Requirements f o r E x i t s (NBC S e c t i o n 3.4)

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7

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Service Spaces (NBC S e c t i o n 3.5) 8 H e a l t h Requirements (NBC S e c t i o n 3.6)

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8

CHAPTER 3 CONCEPTS AND TERMINOLOGY

General

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9 What i s a B u i l d i n g ?

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9 C l a s s i f i c a t i o n o f Bui 1 d i n g s by Major Occupancy

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10

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Separation o f Major Occupancies 12

C o n s t r u c t i o n Types

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13 Fire-Resistance Ratings

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14 F i r e Separations versus Fire-Resistance Ratings

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15 P r o t e c t i o n of Openings ...eeee..e.... 16

F i r e w a l l s

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20

F i r e Stopping

...e.e.e...

24 F l ame-Spread R a t i ngs

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28 Roof Coverings

...e.e.

30 Occupant Load

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Page

CHAPTER 4 REQUIREMENTS AFFECTING THE BUILDING AS A WHOLE

General

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33 B u i l d i n g Si ze Determination

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33 S t r u c t u r a l F i r e P r o t e c t i o n

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38 S p a t i a l Separations

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44

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E x t e r i o r Wall C o n s t r u c t i o n 57 E q u i v a l e n t Openings

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60 F i r e Exposure a t Corners

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60 V e r t i c a l F i r e Spread

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6 1 F i r e Alarm Systems

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63

F i r e and Smoke D e t e c t i o n Systems

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66

F i r e Department Access

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68

F i r e Suppression Systems

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73

High B u i l d i n g s

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74

A c c e s s i b i l i t y f o r P h y s i c a l l y Handicapped Persons

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77

Interconnected F l o o r Spaces

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78

CHAPTER 5 SAFETY WITHIN FLOOR AREAS General

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83 Access t o E x i t s

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83 S u i t e s

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85 C o r r i d o r s

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87 Capacity o f Access t o E x i t

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89 Assembly Occupancies

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9 1 I n s t i t u t i o n a l Occupancies

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94

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R e s i d e n t i a l Occupancies 95 Business and Personal Services Occupancies

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97

M e r c a n t i l e Occupancies

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97

I n d u s t r i a l Occupancies

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98

CHAPTER 6 EXITS General

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99

Width o f E x i t s

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100

Number o f E x i t s and Travel Di stance t o Them

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101

Distance Between E x i t s

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104 Doors

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105 Separation o f E x i t s

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107 Flame Spread i n E x i t s

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107 H o r i z o n t a l E x i t s

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108 F i r e Escapes

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108

CHAPTER 7 SERVICE SPACES General

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v i i

PREFACE

T h i s Comnentary c o n t a i n s m a t e r i a l t o a s s i s t t h e Code user i n a p p l y i n g t h e requirements o f P a r t 3 t o t h e N a t i o n a l B u i l d i n g Code o f Canada 1980. It

has been prepared under t h e d i r e c t i o n o f t h e Standing Committee on Use and Occupancy o f t h e Associate Conmittee on t h e N a t i o n a l B u i l d i n g Code, which i s a l s o r e s p o n s i b l e f o r p r e p a r a t i o n o f t h e requirements i n P a r t 3 o f t h e N a t i o n a l B u i l d i n g Code.

T h i s Comnentary describes t h e o v e r a l l arrangement o f P a r t 3 and i t s i n t e r r e l a t i o n s h i p w i t h t h e N a t i o n a l F i r e Code o f Canada 1980. It discusses t h e b a s i c concepts and t e r m i n o l o g y used i n P a r t 3 and p r o v i d e s examples t o i l l u s t r a t e and e x p l a i n a number o f t h e more complicated requirements.

Comments on t h i s document a r e welcomed and should be d i r e c t e d t o : The Secretary, The Associate Committee on t h e N a t i o n a l B u i l d i n g Code, N a t i o n a l Research Council o f Canada, Ottawa, O n t a r i o K I A OR6.

Ce document e s t d i s p o n i b l e en f r a n q a i s . On p e u t se l e p r o c u r e r en s ' addressant au SecrBtai re, Comit6 a s s o c i g du Code n a t i o n a l du b s t i m e n t

,

Conseil n a t i o n a l de recherches du Canada, Ottawa, O n t a r i o K I A OR6.

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CORMENTARY ON P A R T 3 ( U S E AND OCCUPANCY)

O F THE

N A T I O N A L B U I L D I W G CODE O F CANADA 1980

CHAPTER 1

APPLICATION AND GENERAL PROVISIONS

A

.1

This Comnentary has been prepared as a guide f o r users o f P a r t 3 o f t h e N a t i o n a l B u i l d i n g Code (NBC) because o f t h e d i v e r s i t y and c o m p l e x i t y o f t h e c o n d i t i o n s encompassed by t h a t P a r t . A .2 P a r t 3 o f t h e NBC i s concerned c h i e f l y w i t h t h e f i r e s a f e t y and h e a l t h o f t h e occupants o f b u i l d i n g s . However, t o i n t r o d u c e t h i s Comnentary i t i s a p p r o p r i a t e t h a t e x p l a n a t i o n s be p r o v i d e d r e g a r d i n g t h e Scope o f P a r t 3 i n r e l a t i o n t o o t h e r p a r t s o f t h e NBC and t h e r e l a t i o n s h i p o f P a r t 3 t o t h e N a t i o n a l F i r e Code o f Canada (NFC). The NFC i s a separate Code prepared under t h e auspices of t h e Associate Comnittee on t h e N a t i o n a l F i r e Code.

A p p l i c a t i o n o f P a r t 3

A . 3 P a r t 3 r e g u l a t e s a l l b u i l d i n g s c l a s s i f i e d by major occupancy as assembly occupancy, i n s t i t u t i o n a l occupancy o r h i g h hazard i n d u s t r i a l occupancy, regard1 ess o f s i z e . It a1 so r e g u l a t e s b u i l d i n g s o f a l l o t h e r occupancies when t h e y exceed 600 m2 i n b u i l d i n g area o r exceed 3 s t o r e y s i n b u i l d i n g h e i g h t . Other b u i l d i n g s a r e r e g u l a t e d by P a r t 9, Housing and Small B u i l d i n g s . Where such b u i l d i n g s c o n t a i n rooms o r spaces used f o r assembly, i n s t i tu t i o n a l o r h i g h hazard i n d u s t r i a l occupancies, such rooms o r spaces must a l s o conform t o P a r t 3.

A .4 I n r e l a t i o n t o t h e i n s t a l l a t i o n o f b u i l d i n g s e r v i c e s and equipment, P a r t 3 r e g u l a t e s o n l y those aspects which a r e n o t covered by o t h e r p a r t s o f t h e Code. P a r t 6 c o n t a i n s t h e requirements f o r heating, v e n t i l a t i n g and a i r - c o n d i t i o n i n g i n s t a l l a t i o n s w h i l e P a r t 7, t h r o u g h r e f e r e n c e t o t h e Canadian P l unbing Code, s p e c i f i e s how t h e a p p r o p r i a t e p l umbing f a c i l i t i e s a r e t o be i n s t a l l e d . Copyright © NRC 1941 - 2019 World Rights Reserved © CNRC 1941-2019 Droits réservés pour tous pays

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Relationship between P a r t 3 and the Nati onal F i r e Code

A - 5 It i s i m p o r t a n t t o a p p r e c i a t e t h e s p e c i a l r e l a t i o n s h i p which e x i s t s between P a r t 3 o f t h e NBC and t h e NFC w i t h r e s p e c t t o f i r e s a f e t y and t h e need t o c o n s i d e r t h e c o n t e n t s o f b o t h codes i n b u i l d i n g design, c o n s t r u c t i o n and mai ntenance. The r o l e o f each code w i t h r e s p e c t t o f i r e s a f e t y can be s u m a r i z e d as f o l l o w s :

-

The N a t i o n a l B u i l d i n g Code e s t a b l i s h e s t h e standard o f f i r e s a f e t y f o r t h e c o n s t r u c t i o n o f new b u i l d i n g s , r e c o n s t r u c t i o n o f b u i l d i n g s , i n c l u d i n g extensions o r a1 t e r a t i o n s , and b u i l d i n g s i n v o l v i n g a change o f occupancy.

The N a t i o n a l F i r e Code e s t a b l i s h e s t h e standard f o r f i r e prevention, f i r e f i g h t i n g and f i r e s a f e t y i n b u i l d i n g s i n use, i n c l u d i n g standards f o r t h e conduct o f a c t i v i t i e s c a u s i n g f i r e hazards, maintenance o f f i r e s a f e t y equipment and egress f a c i l i t i e s , standards f o r p o r t a b l e e x t i ngui shers, 1 im i t a t i o n s on b u i l d i n g c o n t e n t s and t h e e s t a b l i s h m e n t o f f i r e s a f e t y plans, i n c l u d i n g t h e o r g a n i z a t i o n o f s u p e r v i s o r y s t a f f f o r emergency purposes. I n a d d i t i o n , t h e NFC e s t a b l i s h e s standards f o r t h e p r e v e n t i o n , containment and f i g h t i n g o f f i r e s o r i g i n a t i n g o u t s i d e b u i l d i n g s which may p r e s e n t a hazard t o a community.

A .6 The 2 codes have been developed as complementary and c o o r d i n a t e d documents i n o r d e r t o reduce t o a minimum t h e p o s s i b i l i t y o f c o n f l i c t i n t h e i r r e s p e c t i v e contents. I n o r d e r t o ensure t h e i r e f f e c t i v e a p p l i c a t i o n from a r e g u l a t o r y p o i n t o f view, i t i s i m p o r t a n t t h a t f i r e and b u i l d i n g o f f i c i a l s be f u l l y conversant w i t h t h e f i r e s a f e t y standards o f b o t h codes.

General Provisions i n P a r t 3

A.7 P a r t 3 has been prepared on t h e b a s i s t h a t i t r e g u l a t e s o n l y t h e b u i l d i n g which i s under c o n s i d e r a t i o n and does n o t i n any way a p p l y t o a d j a c e n t b u i 1 d i n g s o r p r o p e r t i e s . The s p a t i a l s e p a r a t i o n requirements i n t h e Code, f o r i n s t a n c e , use t h e p r o p e r t y l i n e as a base l i n e r a t h e r than t h e d i s t a n c e between 2 b u i l d i n g s where t h e b u i l d i n g s a r e l o c a t e d on d i f f e r e n t p r o p e r t i e s . I n t h i s way each b u i l d i n g i s r e g u l a t e d independently o f i t s n e i ghbouri ng p r o p e r t i e s , b u t each o f these n e i ghbouri ng p r o p e r t i e s must i n t u r n conform t o t h e same requirements when a p p l i c a t i o n i s made f o r a b u i l d i n g p e r m i t .

A -8 The requirements o f P a r t 3 a r e i n t e n d e d t o be i n t e r p r e t e d and e n f o r c e d by reasonable people u s i n g good judgment. T h i s f a c t i s e s p e c i a l l y i m p o r t a n t f o r users when faced w i t h s i t u a t i o n s which may n o t be covered s p e c i f i c a l l y i n t h e Code, o r i n which

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a l t e r n a t i v e design s o l u t i o n s a r e proposed which may n o t have been envisaged b y t h e Code committees r e s p o n s i b l e f o r t h e o r i g i n a l requirements. Many o f these judgments a r e d i f f i c u l t t o make because t h e r e i s o f t e n i n s u f f i c i e n t f a c t u a l knowledge t o equate t h e r e l a t i v e s a f e t y o f one s e t o f c o n d i t i o n s a g a i n s t another. I n any event, i n t h e design o f any major complex o r unusual b u i l d i n g , s i t u a t i o n s a r i s e i n which such judgments must be made, s i n c e t h e Code can never cover a l l p o s s i b l e s i t u a t i o n s . The Code i s c o n s t a n t l y under review, however, and i t i s r e v i s e d as experience i s gained froin i t s use and a d d i t i o n a l knowledge i s o b t a i n e d through research.

A.9 F i r e f i g h t i n g c a p a b i l i t i e s a r e assumed t o be a v a i l a b l e i n t h e e v e n t o f a f i r e emergency. Such f i r e f i g h t i n g c a p a b i l i t i e s may t a k e t h e form o f a p a i d o r v o l u n t e e r p u b l i c f i r e department o r i n some cases a p r i v a t e f i r e brigade. Where f i r e f i g h t i n g capabi 1 i t i e s a r e n o t a v a i 1 able, a d d i t i o n a l f i r e s a f e t y measures may be required, and here again judgment must be exercised.

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CHAPTER 2

SCOPE

The A r r a n g e n t o f Part 3

B .1 P a r t 3 c o n t a i n s 6 major Sections: 3.1 General

3.2 S i z e and Occupancy Requirements f o r F i r e S a f e t y 3.3 Safety Requi rements w i t h i n F l o o r Areas

3.4 Requirements f o r E x i t s 3.5 Service Spaces

3.6 H e a l t h Requirements

General Requirements (NBC Section 3.1)

B .2 S e c t i o n 3.1 i s made up l a r g e l y o f requirements t h a t d e f i n e concepts which a r e used throughout t h e remainder o f P a r t 3. To a l a r g e e x t e n t t h i s S e c t i o n may be considered as an e x t e n s i o n t o t h e d e f i n i t i o n s s e c t i o n o f t h e NBC, except t h a t some o f these concepts o r terms a r e complex. Indeed, many o f t h e s u b j e c t s f o r which requirements a r e described r e l a t e t o terms t h a t a r e d e f i n e d

i n an a b b r e v i a t e d form i n t h e d e f i n i t i o n s s e c t i o n ( P a r t 1 ) .

B -3 S e c t i o n 3.1 c o n t a i n s t h e scope o f P a r t 3. It a l s o c o n t a i n s t h e procedures f o r t h e c l a s s i f i c a t i o n o f a b u i l d i n g according t o i t s use by a major occupancy, which a r e fundamental t o t h e a p p l i c a t i o n o f o t h e r requirements i n P a r t 3. I n a d d i t i o n , S e c t i o n 3.1 c o n t a i n s r e q u i rements r e 1 a t i ng t o combustible c o n s t r u c t i o n , heavy t i m b e r c o n s t r u c t i o n , noncombustible c o n s t r u c t i o n , t e n t s and a i r - s u p p o r t e d s t r u c t u r e s , f i r e separations, p r o t e c t i o n o f openings, f i r e w a l l s, f i r e stopping, f lame-spread r a t i n g s , i n t e r i o r f i n i s h e s , f i r e - r e t a r d a n t t r e a t e d wood r o o f systems, r o o f c o v e r i n g s and occupant loads. Most o f these s u b j e c t s a r e a l s o d e f i n e d terms i n P a r t 1 and a r e used throughout P a r t 3 b u t i n a c o n t e x t which i n c l u d e s t h e a d d i t i o n a l requirements i n t h i s Section. It i s from t h e f o u n d a t i o n p r o v i d e d

by t h i s S e c t i o n t h a t t h e requirements i n P a r t 3 a r e developed.

Size and Occupancy Requirements f o r F i r e Safety (NBC Section 3.2)

B -4 T h i s S e c t i o n i n c l u d e s requirements t h a t a f f e c t t h e b u i l d i n g as a whole s t r u c t u r e . Approximately 2/3 o f t h e e n t i r e Section, f o r example, c o n t a i n s requirements r e l a t i n g t o f l o o r by f l o o r f i r e compartmentation and f i r e - r e s i s t a n c e r a t i n g s f o r s t r u c t u r a l Copyright © NRC 1941 - 2019 World Rights Reserved © CNRC 1941-2019 Droits réservés pour tous pays

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members. These requirements v a r y i n r e l a t i o n t o t h e use o f t h e b u i l d i n g , t h e b u i l d i n g s i z e , t h e number o f s t r e e t s t h e b u i l d i n g f a c e s and whether o r n o t t h e b u i l d i n g i s s p r i n k l e r e d . Since many o f t h e requirements i n t h i s S e c t i o n depend on t h e s i z e o f t h e b u i l d i n g , d e t a i l s a r e p r o v i d e d t o d e s c r i b e how t h e b u i l d i n g s i z e i s determined.

B - 5 T h i s S e c t i o n a1 so c o n t a i n s requirements which s p e c i f y t h e minimum d i s t a n c e s between b u i l d i n g s t h a t may a f f e c t each o t h e r i n t h e e v e n t o f a f i r e and t h a t s e t 1 im i t s on a l l o w a b l e openings and t h e c o n s t r u c t i o n f o r t h e b u i 1 d i n g faces. These c o n s t r u c t i o n requirements f o r t h e f a c e o f a b u i l d i n g t h a t may be exposed t o f i r e o r t h a t may expose o t h e r b u i l d i n g s t o f i r e a r e expressed i n terms o f f i r e - r e s i s t a n c e r a t i n g s and c o m b u s t i b i l i ty, b u t a r e n o t t o be confused w i t h t h e s t r u c t u r a l f i r e p r o t e c t i o n requirements f o r t h e l o a d b e a r i n g members p r e v i o u s l y mentioned. The s t r u c t u r a l f i r e p r o t e c t i o n requirements ensure t h a t a b u i 1 d i n g w i l l remain s t r u c t u r a l l y i n t a c t f o r a reasonable p e r i o d o f t i m e a f t e r a f i r e has broken O I J ~ w i t h i n t h e b u i l d i n g , w h i l e t h e l a t t e r requirements

a r e t o ensure t h a t a f i r e i n one b u i l d i n g w i l l n o t i n v o l v e an a d j a c e n t b u i l d i n g f o r a c e r t a i n p e r i o d o f time.

B .6 Requirements a r e i n c l uded f o r covered ma1 1 s, covered v e h i c u l a r passageways and wal kways between b u i 1 dings. F i r e a1 arm and d e t e c t i o n systems a r e r e g u l a t e d i n r e l a t i o n t o b u i l d i n g s i z e , b u i l d i n g use and t h e number o f occupants i n t h e b u i l d i n g . Requirements re1 a t e d t o f i r e f i g h t i n g i n c l ude p r o v i s i o n s f o r access, water supply and standpipe and s p r i n k l e r systems. P r o v i s i o n s f o r t h e p h y s i c a l l y handicapped a r e a l s o i n c l u d e d as w e l l as requirements f o r emergency l i g h t i n g and power supply, and f o r t h e l i g h t i n g o f p u b l i c areas and e x i t s .

B

.7

A d d i t i o n a l requirements f o r h i g h b u i 1 dings a r e i n c l u d e d i n S e c t i o n 3.2. They cover such i t e n s as smoke c o n t r o l , e l e v a t o r c o n t r o l , e l e v a t o r s f o r f i r e f i g h t e r s , smoke venting, s p r i n k l e r i n g o f c e r t a i n spaces, a d d i t i o n a l r e s t r i c t i o n s on f l ame-spread r a t i n g s and smoke developed c l a s s i f i c a t i o n s o f f i n i s h e s , c e n t r a l alarni and c o n t r o l f a c i l i t i e s , v o i c e communication systems and emergency power supply f o r e s s e n t i a l equipment.

B -8 Where b u i l d i n g s a r e designed w i t h f l o o r openings t h a t a r e n o t p r o t e c t e d i n t h e t r a d i t i o n a l manner (e.g. a t r i a o r i n t e r c o n n e c t e d f l o o r spaces)

,

a d d i t i o n a l p r o t e c t i o n measures have been i n c o r p o r a t e d i n t o S e c t i o n 3.2.

Safety Requirements w i t h i n Floor Areas (NBC Section 3.3)

B - 9 Whereas S e c t i o n 3.2 was concerned w i t h requirements f o r t h e e n t i r e b u i l d i n g , S e c t i o n 3.3 i s concerned w i t h t h e s a f e t y Copyright © NRC 1941 - 2019 World Rights Reserved © CNRC 1941-2019 Droits réservés pour tous pays

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p r o v i s i o n s w i t h i n f l o o r areas, w i t h p a r t i c u l a r emphasis on t h e occupancy o r use o f t h a t f l o o r area.

B

. l o

S e c t i o n 3.3 r e g u l a t e s s a f e t y on i n d i v i d u a l f l o o r l e v e l s ( f l o o r areas)

,

i n c l uding a1 1 rooms and spaces o t h e r t h a n s e r v i c e rooms and s e r v i c e spaces t h a t a r e covered i n S e c t i o n 3.5. The r e g u l a t i o n s a r e grouped a c c o r d i n g t o t h e occupancy o f t h e f l o o r area, room o r space. T h i s occupancy i s n o t n e c e s s a r i l y t h e major occupancy f o r which t h e b u i l d i n g i s c l a s s i f i e d .

B -1 1 For example, a b u i l d i n g may be c l a s s i f i e d b y major occupancy as an o f f i c e b u i l d i n g and, as such, t h e p r o v i s i o n s f o r s t r u c t u r a l f i r e p r o t e c t i o n and f i r e p r o t e c t i o n equipment f o r o f f i c e b u i l d i n g s p r e s c r i b e d i n S e c t i o n 3.2 a p p l y t o t h e o v e r a l l s t r u c t u r e . W i t h i n t h a t b u i l d i n g , a room o r f l o o r area may be used as an assembly, i n s t i t u t i o n a l , business, r e s i d e n t i a l o r i n d u s t r i a l occupancy, i n which case t h e s p e c i a l p r o v i s i o n s o f S e c t i o n 3.3 a r e a p p l i e d t o t h e room o r area c o n t a i n i n g t h a t occupancy. An assembly room must t h e r e f o r e comply w i t h t h e requirements f o r assembly occupancy i n S e c t i o n 3.3 whether i t i s c o n t a i n e d i n an o f f i c e b u i l d i ng, h o s p i t a l

,

h o t e l , t h e a t r e , i n d u s t r i a1 o r o t h e r major occupancy.

B -12 I n t h e NBC, 1 i f e s a f e t y f o r t h e occupants o f any f l o o r area i s dependent i n t h e f i r s t i n s t a n c e on t h e use o r occupancy o f t h a t f l o o r area. The r i s k s t o these occupants occur i n t h e e a r l y stages o f a f i r e . These r i s k s a r e n o t t h e same f o r a l l occupancies, so each one must be r e g u l a t e d s e p a r a t e l y . S e c t i o n 3.3 c o n t a i n s requirements f o r access t o e x i t b o t h from open f l o o r areas as w e l l as from f l o o r areas t h a t a r e d i v i d e d up i n t o s u i t e s . Access t o e x i t i n c l u d e s a l l p o r t i o n s o f t h e f l o o r area, e x c l u s i v e o f t h e e x i t p o r t i o n . T h i s S e c t i o n a l s o p r o v i d e s f o r t h e s i z i n g o f access t o e x i t s and f o r l i m i t i n g t h e t r a v e l d i s t a n c e t o t h e e x i t s w i t h i n f l o o r areas. It c o n t a i n s r e s t r i c t i o n s on t h e design of guards around openings and i n s t a i r w a y s and on t h e use o f g l a s s i n doors o r windows t h a t may be mistaken f o r doors.

Requirements f o r E x i t s (NBC Section 3.4)

The requirements f o r e x i t s a r e k e p t separate from t h e requirements t h a t a f f e c t t h e b u i l d i n g i n S e c t i o n 3.2 and from t h e requirements t h a t a f f e c t t h e f l o o r area use i n S e c t i o n 3.3. The e x i t i s t h e p a r t o f t h e escape r o u t e t h a t l e a d s from t h e f l o o r area i t serves t o a p u b l i c thoroughfare o r t o a s a f e open space o u t s i d e t h e b u i l d i n g . I n t h e case o f a t y p i c a l b u i l d i n g w i t h e x i t s t a i r s , i t i n c l u d e s t h e s t a i r w a y i t s e l f and t h e doors l e a d i n g i n t o and o u t o f t h e stairway. Once i n t h e e x i t system, t h e occupant i s c o n s i d e r e d t o be i n a l o c a t i o n o f r e l a t i v e Copyright © NRC 1941 - 2019 World Rights Reserved © CNRC 1941-2019 Droits réservés pour tous pays

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s a f e t y , thus t h e e x i t i n g i s general l y completed w i t h o u t r e - e n t e r i n g a f l o o r area.

8 -14 The S e c t i o n on e x i t s d e f i n e s what may be used as p a r t o f an e x i t system and t h e requirements f o r such f a c i l i t i e s , t h e number and l o c a t i o n of e x i t s , t h e w i d t h and h e i g h t o f e x i t s , flame-spread l i m i t s f o r exposed s u r f a c e s i n e x i t s , f i r e s e p a r a t i o n o f e x i t s from t h e remainder o f t h e b u i l d i n g , e x i t s i g n s and e x i t 1 i g h t i ng.

S e r v i c e Spaces (NBC S e c t i o n 3.5)

B .15 S e r v i c e spaces i n c l u d e any space p r o v i d e d i n a b u i l d i n g t o accommodate t h e i n s t a l 1 a t i o n o f b u i 1 d i n g s e r v i c e s such as chutes, ducts, pipes o r w i r i n g . They i n c l u d e a t t i c spaces, c r a w l spaces, d u c t spaces, s e r v i c e s h a f t s , s e r v i c e rooms and concealed spaces i n w a l l s and f l o o r s . Requirements f o r these spaces a r e i n c l u d e d i n a separate S e c t i o n o f t h e Code because, u n l i k e o t h e r p a r t s o f a f l o o r area o r e x i t system, such spaces a r e n o t u s u a l l y a c c e s s i b l e e i t h e r t o t h e b u i l d i n g occupant o r t o t h e general p u b l i c . They a r e n o t considered as h a v i n g any a p p r e c i a b l e occupant l o a d and, i n many cases, a r e unoccupied except f o r occasional i n s p e c t i o n o r s e r v i c i n g .

H e a l t h Requirements (NBC S e c t l o n 3.6)

B . I 6 T h i s S e c t i o n c o n t a i n s those r e q u i rements t h a t a f f e c t t h e heal t h o f t h e occupants. It c o n t a i n s p r o v i s i o n s f o r c o n t r o l l i n g t h e number o f p l umbing f a c i 1 i t i e s based on occupancy and occupant l o a d and, through r e f e r e n c e t o o t h e r p a r t s of t h e Code, r e g u l a t e s t h e h e i g h t s and areas o f rooms, n a t u r a l l i g h t i n g and v e n t i l a t i o n .

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CHAPTER

3

CONCEPTS AND TERMINOLOGY

General

C

-1

I n t h i s S e c t i o n o f t h e Comnentary, some o f t h e t e r n s and b a s i c concepts t h a t a r e d e f i n e d i n P a r t 1 and used i n P a r t 3 w i l l be discussed i n f u r t h e r d e t a i l . No a t t e m p t w i l l be made t o cover a l l of t h e terms t h a t a r e used, b u t r a t h e r t o c o n c e n t r a t e on t h o s e which seem t o g i v e r i s e t o t h e g r e a t e s t nunber o f misunderstandings.

What i s

a

Building?

Various attempts have been made i n t h e p a s t t o produce a more p r e c i s e d e f i n i t i o n o f t h e word b u i l d i n g . Such attempts have been r e 1 a t i v e l y unsuccessful, however, as t h e more p r e c i s e t h e d e f i n i t i o n becomes,. t h e more d i f f i c u l t i t i s t o apply. What s u i t s t h e needs o f one a u t h o r i t y may n o t s u i t t h e needs o f another. Some common sense, t h e r e f o r e , i s necessary i n a p p l y i ng t h e p r e s e n t d e f i n i t i o n , which merely s t a t e s t h a t a b u i l d i n g i s any s t r u c t u r e used o r i n t e n d e d f o r s u p p o r t i n g o r she1 t e r i n g any, use o r occupancy.

C - 3 An a u t h o r i t y when a d o p t i n g t h e Code may wish t o exclude c e r t a i n s p e c i f i c s t r u c t u r e s from t h e p r o v i s i o n s o f t h e Code and a l s o t o e x c l ude such s t r u c t u r e s t h a t a r e covered i n o t h e r l e g i s l a t i o n . I n t h e m a j o r i t y o f cases t h e r e i s no doubt o f t h e f a c t t h a t a s t r u c t u r e i s a b u i l d i n g , b u t t h e r e a r e a number o f i n s t a n c e s where a s t r u c t u r e may n o t be c l a s s e d as such ( a t r a n s m i s s i o n tower). There may be some advantage i n m a i n t a i n i n g t h e f l e x i b i l i t y o f t h e p r e s e n t d e f i n i t i o n i n those i n s t a n c e s where a s t r u c t u r e may p r e s e n t a p o t e n t i a l danger t o t h e pub1 i c b u t would n o t n o r m a l l y be considered as a b u i l d i n g .

C - 4 As discussed p r e v i o u s l y , t h e d e f i n i t i o n o f a b u i l d i n g i n c l udes s t r u c t u r e s which would n o t n o r m a l l y be considered as b u i l d i n g s i n a layman's sense. T h i s occurs more o f t e n i n i n d u s t r i a l uses, p a r t i c u l a r l y those i n v o l v i n g manufacturing f a c i l i t i e s and equipment t h a t r e q u i r e s s p e c i a l i z e d design. These s t r u c t u r e s may make i t i m p r a c t i c a l t o f o l l o w t h e s p e c i f i c requirements i n P a r t

3. S t e e l m i l l s , aluninum p l a n t s , r e f i n i n g , power g e n e r a t i o n and l i q u i d storage a r e examples o f such o p e r a t i o n s . A water t a n k o r an o i l r e f i n e r y , f o r example, has no f l o o r area, so i t i s obvious t h a t requirements f o r e x i t s from f l o o r areas would n o t apply. Requirements f o r s t r u c t u r a l f i r e p r o t e c t i o n i n 1 arge s t e e l m i l 1 s and p u l p and paper m i l 1 s, p a r t i c u l a r l y i n c e r t a i n sections, may

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n o t be p r a c t i c a l i n terms o f t h e c o n s t r u c t i o n n o r m a l l y used i n t h e o p e r a t i o n s f o r which t h e space i s intended. I n o t h e r p o r t i o n s o f t h e same b u i l d i n g , however, i t may be q u i t e reasonable t o r e q u i r e t h a t t h e p r o v i s i o n s o f P a r t 3 be a p p l i e d (e.g. t h e o f f i c e s e c t i o n s ) .

C

-5

Areas o f i n d u s t r i a l occupancy such as equipment penthouses, which may be occupied o n l y p e r i o d i c a l l y by s e r v i c e s t a f f , would n o r m a l l y n o t need t o have t h e same t y p e o f e x i t f a c i l i t y as f l o o r areas occupied on a c o n t i n u i n g b a s i s . Thus, good judgment must be e x e r c i s e d i n d e t e r m i n i n g whether o r n o t t o a p p l y a requirement when t h e r e a r e e x t e n u a t i n g circumstances, p r o v i d e d a1 ways t h a t t h e s a f e t y o f t h e occupant i s n o t threatened.

C -6 One problem w i t h many designs o f b u i l d i n g s i s t h a t o f d e c i d i n g what i s p a r t o f a b u i l d i n g and what i s n o t . A c o u r t y a r d t h a t i s surrounded by w a l l s , f o r example, i s r e g u l a t e d b y t h e egress requirements i n P a r t 3, b u t i s n o t n o r m a l l y considered t o be p a r t o f t h e b u i l d i n g . Where a f l o o r o r r o o f s e c t i o n i s c a n t i l e v e r e d o v e r ground space and t h e space below i s unenclosed, i t i s o f t e n a q u e s t i o n o f judgment as t o whether t h e space below should be considered as p a r t o f t h e b u i l d i n g o r as b e i n g o u t s i d e t h e b u i l d i n g . There a r e numerous o t h e r examples one can c i t e on t h i s s u b j e c t , and each s i t u a t i o n can p r e s e n t a d i f f e r e n t v a r i a t i o n o f t h i s problem. Since t h e degree t o which c e r t a i n aspects o f t h e b u i l d i n g a r e r e g u l a t e d i s dependent on t h e p r e s c r i b e d l i m i t s o f t h e b u i l d i n g , these boundaries can become q u i t e i m p o r t a n t i n a p p l y i n g t h e a p p r o p r i a t e r e g u l a t i o n s . There a r e o b v i o u s l y no simple answers t o t h i s complex problem, and here again common sense and good judgment must be e x e r c i s e d i n e s t a b l i s h i n g t h e b u i l d i n g l i m i t s .

C l a s s i f i c a t i o n o f B u i l d i n g s by Major Occupancy

The c l a s s i f i c a t i o n o f a b u i l d i n g by "major occupancy" i s n o r m a l l y t h e s t a r t i n g p o i n t i n e s t a b l i s h i n g which o f t h e Code requirements should be a p p l i e d t o t h a t b u i l d i n g . T h i s should n o t be confused w i t h t h e term "occupancy." Major occupancy i s d e f i n e d as " t h e p r i n c i p a l occupancy f o r which a b u i l d i n g o r p a r t t h e r e o f i s used o r i n t e n d e d t o be used and s h a l l be deemed t o i n c l u d e t h e s u b s i d i a r y occupancies which a r e an i n t e g r a l p a r t o f t h e p r i n c i p a l occupancy."

C - 8 F o r example, i f t h e p r i n c i p a l use o f a b u i l d i n g was e d u c a t i o n a l , t h e b u i l d i n g would be c l a s s i f i e d as a Group A, D i v i s i o n 2 major occupancy. W i t h i n t h e school, t h e r e may be s u b s i d i a r y occupancies such as o f f i c e s , 1 a b o r a t o r i e s and r e p a i r garages, as w e l l as classrooms. Nevertheless, t h e major occupancy o f t h e b u i l d i n g would be Group A, D i v i s i o n 2, and t h i s c l a s s i f i c a t i o n

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would be appl i e d wherever t h e requirements f o r major occupancy were s p e c i f i e d .

C

.9 S i m i l a r l y , one may have a b u i l d i n g whose p r i n c i p a l use i s manufacturing. The combustible c o n t e n t may be such t h a t t h e b u i l d i n g would be c l a s s i f i e d as b e i n g a Group F, D i v i s i o n 3 major occupancy, y e t w i t h i n t h e b u i l d i n g t h e r e may be s u b s i d i a r y occupancies which a r e an i n t e g r a l p a r t o f t h e o p e r a t i o n o f t h e p l a n t , such as o f f i c e s o r c a f e t e r i a s . These occupancies would n o t n o r m a l l y be considered as separate major occupancies as l o n g a s t h e y a r e s u b s i d i a r y t o t h e p r i n c i p a l o p e r a t i o n , which i s manufacturing.

C

. l o

Where a b u i l d i n g i s used f o r more t h a n 1 p r i n c i p a l purpose, i t must be c l a s s i f i e d f o r each major occupancy t h a t i t c o n t a i n s . F o r example, one may have a b u i l d i n g i n which t h e ground f l o o r c o n s i s t s o f a m e r c a n t i l e occupancy and above i t several s t o r e y s o f o f f i c e s n o t r e l a t e d t o t h e m e r c a n t i l e o p e r a t i o n . I n such a case t h e b u i l d i n g would be c l a s s i f i e d as c o n t a i n i n g 2 major occupancies (each o f which may a l s o c o n t a i n s u b s i d i a r y occupancies)

.

C . 1 1 These cases a r e r e l a t i v e l y c l e a r c u t , b u t t h e r e a r e o t h e r s where t h e d i v i d i n g 1 i ne between what i s a major occupancy and what i s a s u b s i d i a r y occupancy becomes obscure, and judgment must be used t o a r r i v e a t t h e proper c l a s s i f i c a t i o n o f t h e b u i l d i n g . A h o t e l , f o r example, may have a number o f shops on t h e ground f l o o r which may o r may n o t be l e a s e d t o tenants. While these shops serve t h e c l ie n t e l e o f t h e h o t e l ( a s we1 1 as o t h e r customers), they may o r may n o t be s u b s i d i a r i e s o f t h e p r i n c i p a l use o f t h e b u i l d i n g , which i s t o p r o v i d e accomnodations f o r t h e h o t e l guests.

C .12 Except i n t h e case o f Group F, D i v i s i o n 1 o r 2 occupancies, where t h e aggregate area o f t h e major occupancy i n a p a r t i c u l a r group o r d i v i s i o n does n o t exceed 10 p e r c e n t o f t h e area o f t h e s t o r e y on which i t i s l o c a t e d , t h e b u i l d i n g does n o t have t o be c l a s s i f i e d f o r t h a t major occupancy f o r t h e purposes o f d e t e r m i n i n g s t r u c t u r a l f i r e p r o t e c t i o n . T h i s does n o t exempt such major occupancies f r o m t h e requirements i n S e c t i o n 3.1 o f t h e NBC f o r t h e s e p a r a t i o n o f major occupancies from each o t h e r even though t h e y may occupy l e s s t h a n 10 p e r c e n t o f t h e f l o o r area. It must a l s o be s t r e s s e d t h a t t h i s requirement does n o t exempt these small major occupancies from t h e o t h e r requirements o f S e c t i o n 3.2 such as f o r f i r e a l a r m systems, t h e requirements f o r s p e c i f i c occupancies i n S e c t i o n 3.3 and t h e requirements f o r s e r v i c e rooms i n S e c t i o n 3.5 as a p p l i c a b l e . S u f f i c i e n t i n f o r m a t i o n must be p r o v i d e d on t h e p l a n s and i n t h e s p e c i f i c a t i o n s t o p e r m i t t h e b u i l d i n g t o be c l a s s i f i e d b y major occupancy and t h e f l o o r areas t o be c l a s s i f i e d according t o t h e i r i ntended use. Copyright © NRC 1941 - 2019 World Rights Reserved © CNRC 1941-2019 Droits réservés pour tous pays

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C.13 The c l a s s i f i c a t i o n o f a b u i l d i n g b y major occupancy i s based on t h e i n t e n d e d use o f t h a t b u i l d i n g . Subsequent a c t i v i t i e s o f an occasional n a t u r e which were n o t contemplated i n t h e o r i g i n a l design a r e n o t r e g u l a t e d under t h e s p e c i f i c requirements o f P a r t 3. Such a c t i v i t i e s may r e q u i r e a d d i t i o n a l s a f e t y measures t o ensure t h a t egress paths a r e c l e a r o f o b s t r u c t i o n s , combustible c o n t e n t s a r e c o n t r o l l e d and f i r e f i g h t i n g i s

i n i t i a t e d as q u i c k l y as p o s s i b l e .

S e p a r a t i o n o f M a j o r Occupancies

C .14 Under c e r t a i n c o n d i t i o n s i t i s necessary t o separate one major occupancy from another, t o p r o t e c t one major occupancy from t h e hazard c r e a t e d by another.

C.15 I n t h e case o f an assembly occupancy where t h e r e may be l a r g e numbers o f people i nvol ved, i n s t i t u t i o n a l occupancies where people may be under r e s t r a i n t o r r e c e i v i n g medical care, o r i n r e s i d e n t i a l occupancies where people may be asleep, i t i s considered necessary t o p r o t e c t t h e occupancy from a hazard t h a t may be c r e a t e d by another occupancy. The Code, t h e r e f o r e ,

r e q u i r e s t h a t each o f these major occupancies be p r o t e c t e d w i t h a r a t e d f i r e s e p a r a t i o n from o t h e r occupancies. The o b j e c t i v e o f t h i s requirement i s t o p e r m i t t h e evacuation of t h a t occupancy i n t h e event o f a f i r e i n an a d j a c e n t occupancy.

C . I 6 I n t h e case o f a h i g h hazard i n d u s t r i a l occupancy, .there i s a known hazard t h a t should be contained. Therefore, t h i s major occupancy i s r e q u i r e d t o be i s o l a t e d from a l l o t h e r s by f i r e separations. I n t h i s case, t h e p r i n c i p a l purpose i s t o c o n t a i n t h e f i r e and n o t t o p r o t e c t t h e i n d u s t r i a l use from t h e e f f e c t s o f a f i r e i n another space. Because o f t h e extreme hazard involved, a h i g h hazard i n d u s t r i a l o p e r a t i o n i s n o t p e r m i t t e d t o be l o c a t e d i n any b u i l d i n g t h a t c o n t a i n s a Group A, B o r C

occupancy.

C.17 Mercanti 1 e occupancies, business and personal s e r v i c e s occupancies and 1 ow and medi um hazard i ndus t r i a l occupancies do n o t p r e s e n t as s e r i o u s a f i r e r i s k as a h i g h hazard i n d u s t r i a l occupancy. It i s n o t necessary, t h e r e f o r e , t o c o n t a i n t h e occupancy i n t h e same way. L i f e s a f e t y i s n o t as c r i t i c a l a f a c t o r i n these occupancies as i t i s i n t h e case o f assembly, i n s t i tu t i o n a l and r e s i d e n t i a l occupancies. The occupants a r e awake and aware and t h e r e a r e no unusual evacuation problems. I n these occupancies, t h e r e f o r e , s e p a r a t i o n on t h e b a s i s o f major occupancy c o n s i d e r a t i o n s i s n o t deemed necessary. There a r e o f course requirements f o r s e p a r a t i o n o t h e r t h a n those based s o l e l y on major occupancy c o n s i d e r a t i o n s . These requirements f o r s e p a r a t i o n depend upon t h e p a r t i c u l a r a c t i v i t i e s w i t h i n a f l o o r Copyright © NRC 1941 - 2019 World Rights Reserved © CNRC 1941-2019 Droits réservés pour tous pays

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area and a r e n o t n e c e s s a r i l y c o n f i n e d t o a p a r t i c u l a r major occupancy.

Construction Types

C

.I8

Many o f t h e requirements throughout P a r t 3 depend on whether t h e b u i l d i n g i s o f cornbusti b l e o r noncombustible c o n s t r u c t i o n . B u i l d i n g s over a c e r t a i n h e i g h t o r area a r e r e q u i r e d t o be o f noncombustible c o n s t r u c t i o n . The b u i l d i n g area and b u i l d i n g h e i g h t l i m i t s f o r which t h e b u i l d i n g i s p e r m i t t e d t o be o f combusti b l e c o n s t r u c t i o n depend on t h e major occupancy c l a s s i f i c a t i o n , t h e number o f s t r e e t s t h a t t h e b u i l d i n g faces and whether o r n o t t h e b u i l d i n g i s s p r i n k l e r e d . Since combustible c o n s t r u c t i o n i s d e f i n e d as c o n s t r u c t i o n t h a t does n o t conform t o t h e requirements f o r noncombustible c o n s t r u c t i o n , i t i s perhaps more i m p o r t a n t a t t h i s stage t o a p p r e c i a t e what i s meant by "noncombustible c o n s t r u c t i o n , " and t o d i f f e r e n t i a t e between i t s meaning and t h a t o f t h e t e r m "noncombustible" as a p p l i e d t o a p a r t i c u l a r b u l l d i n g m a t e r i a l .

C -19 When t h e term noncombustible i s a p p l i e d t o a m a t e r i a l , i t means t h a t t h e m a t e r i a l w i l l pass t h e t e s t f o r n o n c o m b u s t i b i l i t y as d e f i ned i n CAN4-S114, "Standard Method o f T e s t f o r Determination o f Noncombusti b i l i ty i n Bui 1 d i n g M a t e r i a l s

."

T h i s standard c o n s t i t u t e s a severe t e s t i n which a m a t e r i a l e i t h e r passes o r f a i l s b u t i s n o t i n i t s e l f t h e s o l e c r i t e r i a f o r j u d g i n g t h e acceptabi 1 i t y o f a b u i 1 d i n g m a t e r i a l .

C -20 F o r t h i s reason, t h e term noncombusti b l e c o n s t r u c t i o n has been i ntroduced. I n t h i s t y p e o f c o n s t r u c t i o n b u i 1 d i n g assembl i e s a r e r e q u i r e d t o be c o n s t r u c t e d o f noncombusti b l e m a t e r i a l s, b u t w i t h c e r t a i n s p e c i f i e d combustible elements permitted. The o n l y combustible elements t h a t may be used a r e those 1 is t e d i n t h e p a r t o f t h e Code d e s c r i b i ng noncombusti b l e c o n s t r u c t i o n . I n a d d i t i o n , where combustible m a t e r i a l s a r e p e r m i t t e d , t h e r e a r e i n many cases r e s t r i c t i o n s p l a c e d on t h e flame spread p r o p e r t i e s .

I n some cases, such as i n t e r i o r f i n i s h e s , r e s t r i c t i o n s a r e a l s o p l a c e d on t h e t h i c k n e s s o f t h e m a t e r i a l . I f an assembly c o n s t r u c t e d e s s e n t i a1 l y o f noncombusti b l e m a t e r i a1 c o n t a i ns combustible elements n o t s p e c i f i c a l l y p e r m i t t e d by t h e Code f o r noncombustible c o n s t r u c t i o n (such as combustible s i d i n g ) , t h e assembly i s considered t o f a l l w i t h i n t h e c a t e g o r y o f combustible c o n s t r u c t i o n .

C.21 Combustible c o n s t r u c t i o n i s u s u a l l y considered t o be conventional wood frame o r heavy t i m b e r c o n s t r u c t i o n . Conventional wood frame c o n s t r u c t i o n i s described i n c o n s i d e r a b l e d e t a i l i n S e c t i o n 9.23 o f t h e NBC. Heavy t i m b e r c o n s t r u c t i o n i s a s p e c i a l c a t e g o r y o f combustible c o n s t r u c t i o n and i s considered t o be acceptable where

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combustible c o n s t r u c t i o n h a v i n g a % h f i r e - r e s i s t a n c e r a t i n g would n o r m a l l y be r e q u i r e d . T h i s i s achieved through p l a c i n g minimum s i z e l i m i t s on columns and beams as w e l l as t h e t h i c k n e s s o f f l o o r and r o o f planking. These s i z e l i m i t s p l u s t h e f a c t t h a t such c o n s t r u c t i o n does n o t normal l y c o n t a i n concealed spaces g i v e s t h e c o n s t r u c t i o n a s u b s t a n t i a l degree o f f i r e s a f e t y . Heavy t i m b e r c o n s t r u c t i o n i s r e l a t i v e l y d i f f i c u l t t o i g n i t e and once i g n i t e d o r s u b j e c t e d t o an exposing f i r e has reasonable d u r a b i l i t y t o r e s i s t c o l l a p s e . It should be noted t h a t under t h e standard f i r e t e s t c o n d i t i o n s wood w i l l c h a r a t an average r a t e o f about 0.64 mn p e r minute, so t h a t a f t e r 40 min approximately 25 mn depth o f wood w i l l be burned. It f o l l o w s , t h e r e f o r e , t h a t t h e l a r g e r t h e c r o s s - s e c t i o n a l area o f a member, t h e l o n g e r t h e member w i l l m a i n t a i n i t s s t r u c t u r a l s t a b i l i t y i n a f i r e .

C .22 One o t h e r category o f b u i l d i n g c o n s t r u c t i o n i s r e g u l a t e d i n P a r t 3, namely, t e n t s and a i r-supported s t r u c t u r e s . A i r - s u p p o r t e d s t r u c t u r e s a r e those which have t h e i r shapes maintained through t h e use o f a c o n s t a n t a i r pressure s u p p l i e d by means o f a blower. Such s t r u c t u r e s must conform t o t h e space s e p a r a t i o n s r e q u i r e d f o r any o t h e r s t r u c t u r e ( e x c e p t when 1 ocated on t h e same p r o p e r t y ) and must conform t o t h e requirements i n S e c t i o n 3.3 f o r f i r e s a f e t y w i t h i n f l o o r areas and S e c t i o n 3.4 f o r e x i t s . While such s t r u c t u r e s do n o t have t o conform t o t h e c o m b u s t i b i l i t y and s t r u c t u r a l f i r e p r o t e c t i o n requirements i n S e c t i o n 3.2, s i n c e t h i s would o b v i o u s l y be i m p r a c t i c a l , t h e y do have t o be c o n s t r u c t e d o f a m a t e r i a l t h a t w i l l meet ULC-S109, "Standard f o r F l ame Tests o f F l ame-Resistant F a b r i c s and Films." T h i s concession i s p e r m i t t e d on t h e b a s i s t h a t such s t r u c t u r e s do n o t c o n t a i n i n t e r i o r wa,ll s, f l o o r s , mezzani nes o r s i m i l a r c o n s t r u c t i o n .

Fire-Resistance R a t i n g s

C .23 A f i r e - r e s i s t a n c e r a t i n g i s determined i n t h e f i r s t i n s t a n c e on t h e b a s i s o f a standard t e s t i n a w a l l o r f l o o r furnace i n which assembl i e s a r e s u b j e c t e d t o standard f i r e t e s t c o n d i t i o n s on one s i d e t h a t a r e i n t e n d e d t o s i m u l a t e a r a p i d l y developing f i r e . Tested w a l l assemblies must be a t l e a s t 9.3 m2 i n area and t e s t e d f l o o r assemblies must be a t l e a s t 16.7 m2 i n area. The standard temperature reaches 538'C a f t e r 5 min d u r a t i o n , i n c r e a s i n g t o 704'C a f t e r 10 min, 927'C a f t e r 1 h, 1 010°C a f t e r 2 h and 1 093°C a t t h e end o f 4 h.

C -24 The standard Canadian t e s t i s ULC-S101, "Standard Methods o f F i r e Endurance Tests o f B u i l d i n g C o n s t r u c t i o n and M a t e r i a l s." I n t h i s t e s t , a specimen i s n o r m a l l y r a t e d on t h e b a s i s o f i t s a b i l i t y t o pass several c r i t e r i a . The temperature r i s e on t h e unexposed s i d e o f a w a l l o r f l o o r c e i l i n g assenbly must n o t exceed 139'C

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average w i t h no s i n g l e p o i n t temperature exceeding 163'C.

No

flame o r h o t gases t h a t would i g n i t e c o t t o n b a t t i n g a r e t o be a d m i t t e d through t h e w a l l o r f l o o r , and t h e w a l l o r f l o o r must n o t c o l l a p s e under a s p e c i f i e d load. The s h o r t e s t d u r a t i o n o f t i m e a t which any one o f these events occur determines t h e f i r e - r e s i s t a n c e r a t i n g o f t h e assembly. For w a l l s and p a r t i t i o n s which a r e i n t e n d e d f o r a r a t i n g o f 1 h o r more, a separate hose stream t e s t i s n o r m a l l y undertaken as w e l l , t o demonstrate t h e a b i l i t y o f t h e w a l l t o w i t h s t a n d t h e e f f e c t s o f a hose stream. I n t h e case o f columns, a l l s i d e s o f t h e column a r e exposed t o t h e t e s t temperature i n a standard t e s t .

C .25 There a r e a number o f s i m i l a r t e s t methods f o r f i r e r e s i s t a n c e i n N o r t h America, and t h e a u t h o r i t y h a v i n g j u r i s d i c t i o n must r e v i e w t h e r e s u l t s from these t e s t methods i n comparison w i t h ULC-S101 t o determine t h e i r acceptabi 1 i t y

.

C .26 Chapter 2, " F i re-Performance R a t i n g s

,"

o f t h e Supplement t o t h e NBC 1980 p r o v i d e s methods f o r d e t e r m i n i n g t h e f i r e - r e s i s t a n c e r a t i n g o f many common assemblies c o n s t r u c t e d w i t h g e n e r i c b u i l d i n g m a t e r i a l s. The r a t i n g s o b t a i n e d a r e l a r g e l y based on p a s t t e s t r e s u l t s , a l t h o u g h t h e o r e t i c a l c o n s i d e r a t i o n s have a l s o been used t o extend e x i s t i n g experimental data.

C .27 I n Canada, U n d e r w r i t e r s ' L a b o r a t o r i e s o f Canada and Warnock Hersey P r o f e s s i o n a l Services L i m i t e d pub1 i s h 1 is t i n g s o f p r o p r i e t a r y products and assemblies which have been t e s t e d and r a t e d . These l i s t i n g s a r e v a l u a b l e sources o f i n f o r m a t i o n on t h e s u b j e c t .

C .28 I n determining r a t i n g s , i t should be noted t h a t f l o o r - c e i l i n g and r o o f - c e i l i n g assemblies a r e r a t e d f o r f i r e exposure from t h e underside o f t h e assembly o n l y . I n t e r i o r w a l l s and p a r t i t i o n s a r e r a t e d f o r f i r e exposure from each s i d e (one s i d e exposed a t a t i m e ) . E x t e r i o r w a l l s on t h e o t h e r hand a r e r a t e d f o r f i r e exposure from w i t h i n t h e b u i l d i n g o n l y . F i r e - r e s i s t a n c e r a t i n g s a r e assigned t o combustible as w e l l as noncombustible c o n s t r u c t i o n assemblies, and such r a t i n g s depend s o l e l y on t h e a b i l i t y o f t h e c o n s t r u c t i o n t o meet t h e t e s t c r i t e r i a .

F i r e Separations Versus F i re-Resi stance Rati ngs

C .29 It i s i m p o r t a n t t o keep i n mind t h e d i f f e r e n c e between t h e terms " f i r e s e p a r a t i o n " and " f i r e - r e s i s t a n c e r a t i n g . " A f i r e s e p a r a t i o n i s d e f i n e d as a c o n s t r u c t i o n assembly t h a t a c t s as a b a r r i e r a g a i n s t t h e spread of f i r e . Where an assembly i s r e q u i r e d t o a c t as a f i r e separation, t h e r e f o r e , a l l openings through i t must be protected. A f i r e s e p a r a t i o n may o r may n o t be r e q u i r e d t o have a f i r e - r e s i s t a n c e r a t i n g . A f i r e - r e s i s t a n c e Copyright © NRC 1941 - 2019 World Rights Reserved © CNRC 1941-2019 Droits réservés pour tous pays

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r a t i n g i s a measure o f t h e l e n g t h o f t i m e a r e p r e s e n t a t i v e p o r t i o n o f t h e assembly i s a b l e t o w i t h s t a n d t h e c o n d i t i o n s o f t h e standard f i r e t e s t .

C .30 I f a f i r e s e p a r a t i o n i s r e q u i r e d t o have a f i r e - r e s i s t a n c e r a t i n g o f 1 h, t h e requirements a r e u s u a l l y expressed i n terms o f " a f i r e s e p a r a t i o n having a f i r e - r e s i s t a n c e r a t i n g o f a t l e a s t 1 h." I n a number o f cases i t may a l s o be expressed as a "1 h f i r e s e p a r a t i o n " b u t t h i s has t h e same meaning. Roofs and e x t e r i o r w a l l s a r e n o t n o r m a l l y r e q u i r e d t o be f i r e s e p a r a t i o n s b u t i n many cases a r e r e q u i r e d t o have a f i r e - r e s i s t a n c e r a t i n g . No 1 im i t s a r e s p e c i f i e d as t o how many u n p r o t e c t e d openings may p e n e t r a t e an assembly t h a t i s o n l y r e q u i r e d t o have a f i r e - r e s i s t a n c e r a t i n g . I n t h e case o f e x t e r i o r w a l l s, however, openings w i l l a f f e c t t h e r e q u i r e d space s e p a r a t i o n between b u i l d i n g s o r t h e d i s t a n c e t o a p r o p e r t y l i n e .

C .31 I n general, f l o o r s a r e r e q u i r e d t o a c t as f i r e separations, b u t t h e r e a r e a number o f exceptions t o t h i s requirement. F l o o r assemblies over crawl spaces, f o r example, need n o t be c o n s t r u c t e d as f i r e s e p a r a t i o n s b u t may be r e q u i r e d t o have a f i r e - r e s i s t a n c e r a t i n g . I n these cases, no f i r e p r o t e c t i o n i s r e q u i r e d f o r any openings t h r o u g h t h e f l o o r assembly, s i n c e no f i r e s e p a r a t i o n i s required. There a r e o t h e r c i rcumstances where openings a r e p e r m i t t e d through f 1 o o r s t o c r e a t e i nterconnected f l o o r spaces. T h i s s u b j e c t w i l l be considered l a t e r under t h e heading

"

I n t e r c o n n e c t e d F l oor Spaces

."

However, i n general

,

openings through f l o o r s t h a t c o u l d p e r m i t f i r e t o spread from one f l o o r t o another a r e r e q u i r e d t o be p r o t e c t e d b y s h a f t s o r f i r e dampers, depending on t h e t y p e o f opening. A s h a f t w a l l t h a t p r o t e c t s openings i n f l o o r s i s r e q u i r e d t o have t h e same f i r e r e s i s t a n c e as t h e f l o o r s i t connects.

Protection o f Openi ngs

C .32 A c l o s u r e i s d e f i n e d as " a d e v i c e o r assembly f o r c l o s i n g an opening through a f i r e separation, such as a door, a s h u t t e r , w i r e d g l a s s o r g l a s s b l o c k , and i n c l u d e s a l l components such as hardware, c l o s i n g devices, frames and anchors .I1 A c l o s u r e may o r

may n o t be r e q u i r e d t o have a f i r e - p r o t e c t i o n r a t i n g . The term " f i r e - p r o t e c t i o n r a t i n g " i s used i n s t e a d o f " f i r e - r e s i s t a n c e r a t i n g " because d i f f e r e n t c r i t e r i a a r e used i n d e t e r m i n i n g t h e r a t i n g o f a c l o s u r e . A1 though t h e c l o s u r e i s s u b j e c t e d t o t h e same exposure t o h e a t as r e q u i r e d i n t h e standard w a l l and f l o o r t e s t s , t h e c r i t e r i a f o r e s t a b l i s h i n g t h e r a t i n g f o r c l o s u r e s i s 1 ess severe. F o r example, c l o s u r e s g e n e r a l l y do n o t have t o meet t h e temperature r i s e on t h e unexposed f a c e c r i t e r i o n . E x i t doors i n b u i l d i n g s o v e r 3 s t o r e y s h i g h , such as f i r e doors i n e x i t s t a i r s h a f t s , a r e an e x c e p t i o n t o t h i s general r u l e . F i r e doors Copyright © NRC 1941 - 2019 World Rights Reserved © CNRC 1941-2019 Droits réservés pour tous pays

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opening o n t o a separated, dead-end c o r r i d o r t h a t p r o v i d e s t h e o n l y access t o e x i t a r e a l s o an exception. Temperature r i s e l i m i t s a r e imposed on such doors t o ensure t h a t t h e occupants o f a b u i l d i n g w i l l be a b l e t o pass t h e f i r e door w i t h o u t b e i n g a f f e c t e d by t h e h e a t from a f i r e . When an e x i t door i s p r o t e c t e d b y an unoccupied v e s t i b u l e o r c o r r i d o r , these l i m i t s a r e waived on t h e assumption t h a t t h e p o t e n t i a l f o r d i r e c t f i r e exposure i s reduced. Doors i n f i r e w a l l s a r e a1 so r e q u i r e d t o have temperature r i s e 1 im i t s because o f t h e c r i t i c a l n a t u r e o f t h i s t y p e o f f i r e separation.

C -33 C l osures a r e p e r m i t t e d t o have a r a t i n g somewhat l e s s than t h a t r e q u i r e d f o r t h e w a l l o r f l o o r assembly i n which t h e y a r e l o c a t e d . T h i s i s because t h e y n o r m a l l y occupy o n l y a p o r t i o n o f t h e f i r e s e p a r a t i o n and a r e n o n - s t r u c t u r a l , so t h a t a l o w e r r a t i n g may be t o l e r a t e d w i t h o u t undue o v e r a l l r e d u c t i o n i n f i r e s a f e t y . I n a d d i t i o n , i t i s assumed t h a t combustaibles a r e n o t s t o r e d a d j a c e n t t o c l o s u r e s

.

C -34 An e x i t s t a i r enclosure p e n e t r a t i n g a f l o o r r e q u i r e d t o be a f i r e s e p a r a t i o n w i t h a 2 h f i r e - r e s i s t a n c e r a t i n g would be r e q u i r e d t o have w a l l s having a 2 h f i r e - r e s i s t a n c e r a t i n g , and t h e e x i t door i n t o t h e e x i t s t a i r w a y c o u l d be a 1.4 h door w i t h a p p r o p r i a t e hardware and l a t c h e s . E x i t doors t o t h e e x t e r i o r do n o t have t o have a f i r e - p r o t e c t i o n r a t i n g unless r e q u i r e d f o r exposure p r o t e c t i o n .

C -35 There a r e a l s o s p e c i a l cases where exceptions a r e made t o p e r m i t 20 min door assemblies i n f i r e s e p a r a t i o n s r e q u i r e d t o p r o v i d e up t o a 1 h f i r e - r e s i s t a n c e r a t i n g . A 20 min r a t i n g i s what one would achieve w i t h a w e l l c o n s t r u c t e d 45 m t h i c k s o l i d c o r e wood door w i t h hardware and frame designed t o w i t h s t a n d a 20 min f i r e t e s t . I n general such doors a r e p e r m i t t e d o n l y i n f i r e s e p a r a t i o n s t h a t a r e n o t r e q u i r e d t o have a r a t i n g o f more than

;L, h i n b u i l d i n g s up t o 3 s t o r e y s i n h e i g h t , and f o r s u i t e entrance doors o r doors s e r v i n g classrooms o r p a t i e n t s ' bedrooms where t h e c o r r i d o r s e p a r a t i o n i s n o t r e q u i r e d t o exceed 1 h.

C

-36 Where t h e f i r e - r e s i s t a n c e r a t i n g o f a f l o o r o r r o o f assembly has been c a l c u l a t e d on t h e b a s i s o f Chapter 2, " F i r e Performance ~ a t i n g s " o f t h e Supplement t o t h e NBC 1980, and where p a r t o r a l l o f t h e r e q u i r e d f i r e r e s i s t a n c e i s achieved b y means o f a membrane, such as gypsum w a l l b o a r d o r l a t h and p l a s t e r , openings t o d u c t s through t h e c e i l i n g membrane may be p r o t e c t e d w i t h f i r e s t o p f l a p s which a r e i n t e n d e d t o m a i n t a i n t h e i n t e g r i t y o f t h e membrane. It should be noted t h a t a f i r e s t o p f l a p i s a d e v i c e f o r m a i n t a i n i n g t h e i n t e g r i t y o f membrane f i r e p r o t e c t i o n , whereas a f i r e damper i s a d e v i c e t h a t i s s e p a r a t e l y t e s t e d and

r a t e d t o ensure i t w i l l p r o v i d e a r e q u i r e d f i r e - p r o t e c t i o n r a t i n g . F i r e s t o p f l a p s a r e p e r m i t t e d o n l y when openings a r e Copyright © NRC 1941 - 2019 World Rights Reserved © CNRC 1941-2019 Droits réservés pour tous pays

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1 ess than 930 cm2 and l e a d d i r e c t l y i n t o a noncombustible duct. There a r e a l s o r e s t r i c t i o n s on t h e spacing and percentage o f openings t h a t can be p e r m i t t e d i n such c e i l i n g membranes i n any f i r e compartment. Where t h e opening i s l e s s than 130 cm2, t h e f i r e stop f l a p may be o m i t t e d where t h e opening i s d i r e c t l y i n t o a noncombustible duct. Where actual t e s t s show t h a t o t h e r sizes and q u a n t i t i e s o f openings w i l l n o t cause t h e f i r e - r e s i s t a n c e r a t i n g t o drop below t h e r e q u i r e d r a t i n g , such openings can o f course be permitted.

C .37 Figures C-1, C-2 and C-3 show t y p i c a l examples o f where f i r e stop f l a p s and f i r e dampers a r e required.

REQUIRED FlRE SEPARATIONS

HAN

FlRE DAMPERS HELD - OPEN BY FUSIBLE LINKS

OPENINGS I N CEILING NOT RESTRICTED A N D NEED NOT

/

VERTICAL FIRE SEPARA'TI O N HAVE FIRE STOP FLAPS

Figure C-1 An assembly where t h e membrane does n o t form p a r t o f t h e r e q u i r e d f i r e separation Copyright © NRC 1941 - 2019 World Rights Reserved © CNRC 1941-2019 Droits réservés pour tous pays

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REQUIRED

FIRE

{

T

SEPARATION

FlRE STOP FLAP

n

BY FUSIBLE LINK

Figure C-2 An assembly where t h e membrane provides p a r t o f t h e f i r e separation b u t has a r a t i n g l e s s than an i n t e r s e c t i n g f i r e separation

BAR JOISTS

I

11

VERTICAL FlRE SEPARATION FlRE STOP FLAP

REQU l RE D FlRE SEPARATION

CEILING WITH FlRE RESISTANCE RATING AT LEAST EQUAL TO VERTICAL FlRE SEPARATION

Figure C-3 An assembly where t h e membrane provides p a r t o f t h e f i r e s e p a r a t i o n and i s a t l e a s t equal t o an i n t e r s e c t i ng v e r t i c a l f i r e s e p a r a t i o n Copyright © NRC 1941 - 2019 World Rights Reserved © CNRC 1941-2019 Droits réservés pour tous pays