Space between buildings as a means of preventing the spread of fire. Report D: concluding study on three regions in Vancouver

(1)

Publisher’s version / Version de l'éditeur:

Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.

Questions? Contact the NRC Publications Archive team at

PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information.

https://publications-cnrc.canada.ca/fra/droits

L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

Internal Report (National Research Council of Canada. Division of Building

Research), 1964-05-01

READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.

https://nrc-publications.canada.ca/eng/copyright

NRC Publications Archive Record / Notice des Archives des publications du CNRC :

https://nrc-publications.canada.ca/eng/view/object/?id=7bc4f8ad-972d-4dcb-a648-dd4be0348c96 https://publications-cnrc.canada.ca/fra/voir/objet/?id=7bc4f8ad-972d-4dcb-a648-dd4be0348c96

NRC Publications Archive

Archives des publications du CNRC

For the publisher’s version, please access the DOI link below./ Pour consulter la version de l’éditeur, utilisez le lien DOI ci-dessous.

https://doi.org/10.4224/20337980

Access and use of this website and the material on it are subject to the Terms and Conditions set forth at

Space between buildings as a means of preventing the spread of fire.

Report D: concluding study on three regions in Vancouver

(2)

NATIONAL RESEARCH COUNCIL CANADA

DIVISION O F BUILDING RESEARCH

SPACE BETWEEN BUILDINGS AS A MEANS O F PREVENTING THE SPREAD O F F I R E

R e p o r t D

--

Concluding Study o n T h r e e Regions in Vancouver

P r o f . H. P. Oberlander

Head, Community and Regional Planning,

School of A r c h i t e c t u r e , University of B r i t i s h Columbia

and ,

.

, * ? , ! Y z E D

R. S. F e r g u s o n

Head, Building S t a n d a r d s Section, DBR/NRC

A Joint P r o j e c t of the School of A r c h i t e c t u r e

and the Graduate P r o g r a m in Community and Regional Planning, University of B r i t i s h Columbia

and the

Division of Building R e s e a r c h , National R e s e a r c h Council

I n t e r n a l R e p o r t No. 2 8 3 of the

Division of Building R e s e a r c h

OTTAWA May 1964

(3)

The late Professor Fred L a s s e r r e , as Director of the School of Architecture at the University of British Columbia, was one of the original sponsors of this research project. His contribution i s remembered appreciatively by all con- nected with this Report.

(4)

P R E F A C E

T h i s r e p o r t i s one of a s e r i e s of four which a r e concerned with s p a c e between buildings a s a m e a n s of preventing the s p r e a d of f i r e , which, in t u r n f o r m s p a r t of the m a i n p r o j e c t " P e r f o r m a n c e Standards f o r Space and Site Planning for Residential Development.

"

T h i s p r o j e c t h a s been undertaken for the Division by the School of A r c h i t e c t u r e a t the University of B r i t i s h Columbia. Two r e p o r t s have a l r e a d y been i s s u e d : An Annotated Bibliography o n P e r f o r m a n c e Standards f o r Space and Site Planning f o r Residential Development (NRC 6442) and DBR Internal Report No. 27 3 , "A Study of P e r f o r m a n c e Standards f o r Space and Site Planning f o r Residential Development.

"

T h e l a t t e r contains a d i s c u s s i o n of the f a c t o r s that d e t e r m i n e the spacing of r e s i d e n t i a l buildings. T h i s p r e s e n t s e r i e s of four r e p o r t s , deals with one of t h e s e f a c t o r s

-

f i r e . The o t h e r f a c t o r s , including daylight, noise and p r i v a c y , will be d e a l t with i n subsequent r e p o r t s . When a l l of these r e p o r t s a r e i s s u e d , they will f o r m a complete evaluation of a l l the conditions that m u s t be c o n s i d e r e d i n the planning of r e s i d e n t i a l a r e a s i n Canada.

T h e a u t h o r s of the f i r s t t h r e e r e p o r t s i n this s e r i e s a r e o n the staff of the University of B r i t i s h Columbia. P r o f e s s o r O b e r l a n d e r , b e s i d e s h i s duties on the staff of the School of A r c h i t e c t u r e , i s Head of the Graduate P r o g r a m i n Community and Regional Planning; P r o f e s s o r G e r s o n , a t the t i m e t h e s e r e p o r t s w e r e w r i t t e n , was Acting D i r e c t o r of the School of A r c h i t e c t u r e , and Mr. Goldsworthy was r e s e a r c h a s s i s t a n t to the P r o j e c t . This f o u r t h r e p o r t h a s been p r e p a r e d by P r o f e s s o r Oberlander and R. S t i r l i n g F e r g u s o n , Head of the Building S t a n d a r d s Section of the Division of Building R e s e a r c h . In this r e p o r t they have explained how the regulations i n the National Building Code w e r e i n t e r p r e t e d i n the f i r s t t h r e e studies of regions in Vancouver with

r e s p e c t to building configurations not conside r e d in the Code. T h e p r e s e n t Head of the School of A r c h i t e c t u r e a t UBC, P r o f e s s o r Henry E l d e r , h a s shown m u c h i n t e r e s t i n this p r o j e c t which was initiated under the d i r e c t i o n of his p r e d e c e s s o r , the l a t e P r o f e s s o r

F r e d L a s s e r r e .

T h i s information i s being i s s u e d in the Divisional s e r i e s of

i n t e r n a l r e p o r t s s o that those responsible for the w o r k c a n have the benefit of informed comments p r i o r to publishing i n a m o r e f o r m a l way. Comments will, t h e r e f o r e , b e welcomed and should be s e n t e i t h e r to P r o f e s s o r

Oberlander a t UBC o r to the w r i t e r i n Ottawa. Ottawa

May 1964

R. F. Legget D i r e c t o r , DBR/NRC

(5)

FOREWORD

The unprecedented volume and suburban concentration of

post-war housing has revealed many inadequacies in the use of traditional space and location standards as a b a s i s f o r achieving a high quality of residential communities. In m o s t instances, such standards have m e r e l y allowed housing to be built in a mechanically neat and o r d e r l y fashion. Standards that a r e m o r e flexible and imaginative s e e m e s s e n t i a l i f the next flood of housing is to add m o r e to urban Canada than f u r t h e r volume of accommodation.

Following the w a r , cities and towns became increasingly aware of the value of controlling, through zoning and building bylaws, the individual's use of h i s land f o r the benefit of the whole community. Such bylaws usually r e s t r i c t development with absolute y a r d and height limitations designed to achieve standards of safety, health, amenity and aesthetic appearance. The absolute and one-dimensional nature of these limitations, however, has usually resulted in a monotonous and rigid spacing of buildings.

The main purpose of this r e s e a r c h project i s to d e m o n s t r a t e that adequate space around and between buildings for functional and aesthetic purposes can be achieved with g r e a t e r flexibility through controls usually r e f e r r e d to a s "performance standards. ' I Such standards determine space

between and around buildings by the variety of functions they p e r f o r m and in relation to the s i z e of land and buildings in a given situation.

The value and e a s e of administration of the performance standards has a l r e a d y been demonstrated in industrial and c o m m e r c i a l development.

This r e p o r t f o r m s a portion of a continuing study. Following a study of the l i t e r a t u r e (14) a preliminary r e p o r t was p r e p a r e d on the f a c t o r s which determine the spacing of residential buildings (15). This

comprised the full range of community objectives

-

f i r e , daylight., a i r , privacy, view, outdoor s p a c e , traffic and noise.

A m o r e concerted study of prevention of f i r e s p r e a d followed. This field of investigation was chosen because information is m o r e readily available than f o r other community objectives. Means of f i r e prevention based on performance have already been devised and these a r e applied i n Canada's National Building Code. Using the appropriate requirements of the National Building Code of Canada 1960 a s a b a s i s , field surveys of t h r e e developments in Metropolitan Vancouver w e r e made*. The particular aim was to appraise the Code requirements.

*

DBR Internal Reports Nos. 280, 281, and 282, by H . P . Oberlander, W. Gerson and R. D. Goldsworthy

(6)

This study proved to be m o s t rewarding. Since i t w a s the f i r s t study of i t s kind, the r e s u l t s could not have been anticipated. F a m i l i a r i t y with the method, however, has led to confidence that the performance method will in the end provide the d e s i r e d r e s u l t .

It is expected that this fourth r e p o r t will be of special i n t e r e s t to code w r i t e r s and a d m i n i s t r a t o r s since it investigates in detail the many unusual circumstances which. a r i s e and which make the application of a seemingly simple regulation complicated. It explains in detail how the authors interpreted the regulations with r e s p e c t to building configurations which the code w r i t e r s had, f o r quite valid r e a s o n s , not allowed for. A study of this r e p o r t by those who a r e technically concerned can do much to further the understanding and improvement of performance methods of control of f i r e s p r e a d between buildings.

This i s a sufficient reward for the work which has been donel yet it s a t i s f i e s but one of the two objectives of the study. The second one i s m o r e far-reaching. It is the eventual attainment of methods to control space between buildings in a manner that will provide safety and at the s a m e time the n e c e s s a r y flexibility to achieve the g r e a t e s t utilization of space and the g r e a t e s t freedom to e x p r e s s , throughdesign, the fulfilment of space use.

Architects and other designers who r e a d this r e p o r t will begin to r e a d into it a new m o r e definite vocabulary of design. A s c r e e n , opened o r closed, becomes m o r e than an aesthetic device because it can s e r v e in a m e a s u r a b l e capacity a s a f i r e break. One i s encouraged to think that its value a s a sound b a r r i e r c a n be d e t e r - mined quantitatively a s well. Setbacks, window openings and other f a c t o r s a r e enriched with added meaning in the f i r e s p r e a d s e n s e . In this fusion of science and a r c h i t e c t u r e the g e r m of a new idiom may be p r e s e n t . Even s o , it i s only a g e r m . The goals toward which this work leads a r e s t i l l a long way off.

(7)

TABLE O F CONTENTS

P a g e No

.

OBSERVATIONS ON DISTANCE SEPARATIONS

...

1

OBSERVATIONS ON THE PERFORMANCE METHOD

. . .

3

PART 2 T a b l e of S e p a r a t i o n Distances

...

4

Limiting Distance

...

6

SITUATION 1: HEIGHT O F WALL. LENGTH O F WALL. AREA O F OPENINGS

...

( a ) Compartmentation of the Building

...

[ b ) Distribution of Openings

...

( c ) Enclosing Rectangle

...

( d ) S t a i r c a s e E n c l o s u r e s

:

...

( e ) R e c e s s o r Setback in the Wall of 5 ft o r L e s s ( f ) ' R e c e s s o r Setback in the Wall of M o r e than 5 ft Setbacks

...

R e c e s s with openings on t h r e e s i d e s R e c e s s with openings in the r e a r wall only

...

( g ) N o n - f i r e - r e s i s t i v e P r o j e c t i o n s into the Space SITUATION 2: HEIGHT O F ROOF

...

1 3 SITUATION 3: OFFSETS

...

1 3 SITUATION 4: GROUND ELEVATION

...

14

SITUATION 5: ADJACENT WALL NOT PARALLEL

...

1 5 SITUATION 6: STRUCTURAL B A F F L E S

...

16

( a ) Height of Baffle

...

17

( b ) Width of Baffle

...

17

( c ) Openings i n Baffle

...

17

PART 3 Detailed Application of the Findings

...

21

Outline of the Design P r o c e s s

...

21

Stages 1 to 5 E x a m p l e s of Design P r o c e s s

...

22 Stages 1 to 5 CONCLUDING RE MARKS

...

40 CONCLUSIONS A p p r a i s a l of Existing Controls

...

41

Some Suggestions for Improvement i n the National Building Code

...

4 3

...

A Suggested Grading of Space Dimensions _{4 3} REFERENCES AND BIBLIOGRAPHY

...

47

(8)

SPACE BETWEEN BUILDINGS AS A MEANS O F PREVENTING THE SPREAD O F FIRE

Report D

- -

Concluding Study o n T h r e e Regions in Vancouver

H. P. Oberlander and R . S. Ferguson

Reports A, B, and C* contain the on-site m e a s u r e m e n t s pertaining to distance separations for t h r e e blocks of buildings which w e r e surveyed i n Metropolitan Vancouver. In the c a s e of each building

examined the a c t u a l d i s t a n c e was compared with a distance calculated on a performance b a s i s a s applied i n the National Building Code 1960. This e x e r c i s e was useful i n two ways: it revealed d i s c r e p a n c i e s i n the actual and calculated d i s t a n c e s and it s e r v e d a s the f i r s t documented t e s t of the performance method a s applied i n the National Building

Code. Findings with r e s p e c t both to the distances and the application of the method m a y be found complete i n R e p o r t s A to C. F r o m t h e s e , r e a d e r s may draw t h e i r own conclusions.

The authors wish to add t h e i r observations to the information in the preceding t h r e e r e p o r t s and have placed t h e s e together in this s e p a r a t e r e p o r t since these observations a r e based on e x p e r i e n c e with a l l r a t h e r than any one of the study a r e a s . The f i r s t observations a r e on the distance separations and the second observations a r e on the method used.

OBSERVATIONS ON DISTANCE SEPARATIONS

In the c e n t r a l built-up a r e a ( R e p o r t A, DBR Report 280),

indications a r e that the s e p a r a t i o n between buildings did not prevent f i r e s p r e a d but by the expedient of enclosing the s t a i r shafts i n the l a r g e r buildings this danger could be a l m o s t e n t i r e l y overcome. Again i n the suburban a r e a s w h e r e a new group of single houses was examined, i t was shown that the m e a s u r e d distances w e r e quite ample and i n

n e a r l y e v e r y c a s e excessive. H e r e then is a n example i n the field of prevention of f i r e s p r e a d w h e r e the minimum h a s not become the maximum. Comparing the c e n t r a l and outlying study a r e a s , it is

*

(9)

apparent that t h e r e is no consistency of design safety against f i r e spread. This i s a s m a l l sample but, since each of these two a r e a s i s typical, the observation has some significance.

Both a r e a s w e r e developed f r o m the viewpoint of econo- m i c gain and both w e r e developed at t i m e s when the land was subject to controls to prevent f i r e spread.

*

Had both economics and f i r e safety been important determinants and had an adequate method of preventing f i r e s p r e a d been in effect, one can conclude that the resulting designs would have been different. The buildings in the central study a r e a would have been s a f e r and those in the outlying a r e a would have shown g r e a t e r conservation of land.

With r e g a r d to the l a t t e r a r e a , the m o r e generous provision of space was obviously for r e a s o n s other than f i r e safety since the distance exceeded the required distances in effect when the buildings w e r e built. F r o m the viewpoint of

controls, there i s no q u a r r e l with this and i t i s perhaps heartening that the minimum has been exceeded voluntarily. The r e a l concern i s that when space does get tight, a s in the central study a r e a , t h e r e i s no way, other than with performance standards,to provide minimum safety. In other w o r d s , up to the present, it s e e m s that the d e s i r e for space r a t h e r than the existing controls has been effective in providing protection against f i r e spread.

Turning to economics one could criticize the disposition of space in both study a r e a s without even knowing the objectives of the spaces other than for f i r e protection. Casual observation on the b a s i s of good design p r a c t i c e indicates that these s p a c e s a r e not tailored to s o m e special use.

If

this i s t r u e , i t is quite probable that the design i s not the m o s t convenient o r economic. This i s a m a t t e r , however, which i s beyond the immediate purpose. It is mentioned, in the f i r s t place, to suggest that t h e r e was no m o r e important r e a s o n that would justify an a r b i t r a r y standard of f i r e safety, and, second, to remind the r e a d e r that this study of f i r e safety is only p a r t of a l a r g e r study concerned with the m e a s u r a b l e aspects of space around buildings. Since minima and maxima have been discussed, it might be pointed out h e r e , i f it i s not already apparent f r o m the foregoing, that what is hoped for i s an optimum which would embrace safety, economics, and utility.

f .

-4 graphic presentation of those controls has been p r e p a r e d and will soon be published for comparative purposes.

(10)

Although only a fraction of the whole problem h a s s o f a r been examined, t h e r e i s encouraging evidence that a rational approach based on performance can be a m o r e p r e c i s e determinant f o r design. If this approach can be utilized to the full, design can be m o r e exact thereby eliminating chance hazards on the one hand and creating the opportunity to conserve space on the other, and so allow for full use with safety a t low cost.

OBSERVATIONS ON THE PERFORMANCE METHOD

Study a r e a No. 3 (Report C, DBR Report 282) highlights the second aspect in which this r e p o r t was useful. It r e v e a l s in a convincing way that the performance method employed i n the National Building Code of Canada i s still i n i t s embryo stages and th.at it could benefit f r o m further study. The p r e m i s e f o r this s y s t e m of control i s theoretical. The variables i t employs a r e those directly re.l.ated to the f i r e hazard. This explains i t s superiority over r u l e of thumb methods. The

distance changes a s the f i r e hazard changes. In the r u l e of thumb s y s t e m the distance remains constant while the hazard changes with the r e s u l t that the distance is r a r e l y c o r r e c t for f i r e safety. T h e r e i s usually either too little o r too much. On the other hand, the p e r - formance method i s accurate only if it can be adapted to the situations which a r e likely to a r i s e . What f o r m s of design i t should be adapted to and how a r e difficult to f o r e s e e and can only finally be proved in practice. In this r e s p e c t the field studies w e r e most useful.

The Code a s s u m e s that buildings a r e disposed horizontally to each other. Study a r e a No. 3 was on sloping ground. It showed clearly that cons ideration should be given in the method to buildings which a r e disposed vertically one to another. This and other problems caused by design variations will be examined in detail i n P a r t 2.

(11)

PART 2

This p a r t is a discussion of the mechanics of applying performance standards to the prevention of f i r e spread between buildings. In the course of the field work, and a s was expected, a number of configurations w e r e encountered which varied f r o m the standard situation ( a plane surface with uniformly distributed openings) for which the Code method was devised. The main variations a r e :

1. The treatment of length and height of wall and a r e a of openings depending on how the openings a r e dis- persed. The important m a t t e r h e r e i s the assumption of a height and a r e a related tothe openings r a t h e r than the wall dimensions when the windows a r e grouped o r d i s p e r s e d unevenly. This assumed portion of the wall i s known a s the enclosing rectangle.

2. Height of the roof. 3 . Wall offsets.

4. Difference in ground elevation between adjacent buildings

.

5. The facing walls of adjacent buildings not parallel. 6. S t r u c t u r a l b a f f l e s .

These s i x special design problems a r e discussed in o r d e r but f i r s t some word of explanation i s warranted concerning the

Table of Separation Distances ( F i g u r e 1) and the "Limiting Distance1' since these a r e not identical with those fo~lnd in the National

Building Code.

Table of S e ~ a r ation Distances

The table of separation distances used in this r e p o r t ( F i g u r e 1) is adapted f r o m the table in DBR Report No. 187 by J.

H.

McGuire (20). This i s the original r e f e r e n c e for the tables in the National Building Code. It differs in f o r m f r o m the one in the Code but in every e s s e n t i a l r e s p e c t the content i s the same. Each u s e s the s a m e dependent variables but the table in DBR Report No. 187 derives minimum separation distances whereas i n the Code this i s one of the indices and percentage of window

(12)

FIGURE 1 S E P A R A T I O N F K O M I\UILDINC; T O BUILDING Width of C o m p a r t m e n t f t 30 40 50 .-.- -- - -- -- 1

70 of window Height of compartment, it openings 70 80 90 100 100 8 0 60 4 0 20 100 8 0 6 0 182 190 40 20 82 86 86 100 8 0 6 0 40 2 0

1

100 60 70 8 0 8 0 6 0 4 0 20 100 8 0 6 0 4 0 184 194 202 20 26 48 - ~..

'

100 8 0 60 7 4 40 20 0 0 9 0 100 120 80 6 0 40 54 92 118 142160 2 0 -- 100 112 172 218 2.56 286 320 346 370 392 414 8 0 96 150 190 226 256 282 308

'

328 338 366 60 80 122 160 190 21.6 238 258 276 292 308 40 54 94 124 118 166 184 202 216 230 242 2 0 2 6 5 0

(lj

70 86 LO2 114 126 136 144 152 - .- 100 118 184 230 276 3 1 ; 348 378 401 428 450 8 0 101, 158 206 246 278 306 334 358 380 402 6 0 80 128 17L 204 236 260 282 302 322 338 4 0 54 98 1124 158 180 202 220 236 252 268 2 0 26 50 70 90 106 l i 8 k 0 142 154 166 -

(13)

openings i s derived. An examination of the two tables will r e v e a l other s i m i l a r differences ( s e e F i g u r e s 2 and 3 ) .

These differences r e s u l t in each table being m o r e accurate than the other in some r e s p e c t s . E a c h i s a c c u r a t e where the values in the indices a r e those r e f e r r e d to. Where it i s n e c e s s a r y to interpolate between these values, s o m e e r r o r i s p r e s e n t . Because of this the table in the Code i s m o r e convenient and m o r e accurate where the distance f r o m the lot line i s known. This i s particularly the c a s e where buildings a r e s m a l l and situated close to the lot line. The other table f r o m DBR Report No. 1 8 7 i s m o r e a c c u r a t e in the c a s e of l a r g e r buildings located further away and is m o r e convenient where the percentage of window opening i s known and it is the distance that i s to be derived. These conditions a r e in fact the ones which generally prevail in the situations to be discussed in this part of this report.

.

Where the buildings a r e very s m a l l such a s i s the c a s e with private single family dwellings neither table i s v e r y accurate. This i s a special c a s e which will probably be treated separately in the future.

Limiting Distance

Both the tables ( F i g u r e s 2 and 3 ) give the distance f r o m the building face to the lot line. The table used in this p a r t

( F i g u r e 1) differs f r o m both because the distances have been doubled to equal the total distance between two adjacent buildings. This was done even though it d e p a r t s f r o m the method used in the

Code because it eliminates a s e r i o u s e r r o r which develops with the Code s y s t e m in determining the required space between two buildings which vary greatly i n s i z e . The Code method is the

only known method that i s satisfactory in a legal and administrative sense. The importance of this i s acknowledged but i t i s a m a t t e r which i s of no concern i n this chapter a s this present study deals

solely with the technical problem. It i s not therefore that the legal question i s of l e s s importance but r a t h e r that f i r s t things m u s t be dealt with f i r s t . The decision to use the whole r a t h e r than half the distance affects the examples where m o r e than one building is involved. It does not affect the methods that a r e developed for determining the enclosing rectangle.

Using the modified table of separation distances and the limiting distance a s explained above, the application of the per

-

formance method to six different design situations i s discussed.

(14)

-

7

-

Figure

2

SEPARATION F R O M BUILDING T O BUILDING

(15)

F I G U R E 3

SEPARATION F R O M LOT L I N E

L = length of building face; H = height of building fare,

I

Ann of Exposed Face* sq ft

leas than 300

300 end

but less then

and over

but less than 500 500 and over but lms than 600

and over but less than 800 800 and over but less than 1000 1000 rind over but less thPn 1500

1500 and over but less then 2500 2500 end over but than 3500 3500 and over but than 5000 5000 and over Column 1 Ratio L/H Or less thah 3:l 3 : l to 10:I over 1011 less than 311

;

to lean t h a n 3 : l

;3tr

to

i:;:

less than 3:l

!;elr

to

:

j

:

less then 3 : l :idr to less than 3: 1

:;elr

to

::;:

Jesm then 3:l %:r to

;iji

lean than 3:l :3:r to

:iji

leas then 3 : l to

i:;:

less than 3:l :;Ar to

:

j

:

l e s s t h a n 3 : l 3:l to 10:l over 10:l 2 LIMITING DISTANCE, ft 4 6 10

Permissiblo Area of Unprotected Openhgs 18 in Exporred 20 5 6 9 5 7 9 13 6 30 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 73 75 87 44 48 50 34 47 50 25 35 38 19 22 30 9 15 18 25 12 15 20 11 13 18 10 11 17 8 10 1 4 7 9 13 G 8 11 5 G 9 4 6 8 1 1 4 5 7 3 4 7 3 4 5 6 7 0 32 34 44 23 27 35 21 23 31 18 19 28 15 16 23 12 14 21 9 11 17 7 9 13 6 8 5 7 10 5 6 9 Building 57 63 68 41 45 55 34 37 47 19 32 41 23 25 35 19 22 30 14 16 23 10 12 17 8 10 15 7 8 12 6 7 10 6 8 4 5 7 4 5 7 4 5 7 4 5 6 3 4 6 3 3 5 3 3 5 2 3 5 2 2 4 50 Face, 100 100 100 65 80 100 73 75 87 60 70 80 50 52 60 40 44 50 28 ' 31 40 19 21 34 14 16 23 11 13 19 8 10 15 per 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 88 90 100 62 67 44 48 50 34 37 47 8 11 6 7 10 6 7 10 5 6 8 5 5 8 4 5 7 3 4 7 3 4 6 3 3 6 2 2 5 70 cent 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 7 3 1 0 0 1 0 0 88 90 100 5 0 1 0 0 55 60 1 0 1 1 1 2 100 140 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 LOO 100 100 100 100 100 100 100 100 100 100

(16)

SITUATION 1: HEIGHT O F WALL, LENGTH O F WALL,. AREA O F OPENINGS

(a1 C o m ~ a r tmentation of the Building

It was shown i n the DBR Report; No. 280 that i t i s d e s i r a b l e to subdivide the building into c o m p a r t m e n t s by m e a n s of f i r e -

r e s i s t i v e walls and floors. This m a k e s i t possible to a s s u m e that, for the purpose of space s e p a r a t i o n calculation, e a c h subdivision i s a s e p a r a t e building, thus e a c h c o m p a r t m e n t c a n be t r e a t e d a s a s e p a r a t e r a d i a t o r .

.-..FIRE D I V I S I O N WALL

i

+

I I

[--..FIRE DIVISION FLOOR

I

-.

F i g u r e 4

It i s important to r e m e m b e r that openings a r e considered to be the radiating a r e a s . An opening m a y be defined as any portion of the wall not having the r e q u i r e d f i r e r e s i s t a n c e . This is usually a window o r a door s i n c e , for our p u r p o s e , we have a s s u m e d that the e x t e r i o r walls r e s i s t the pas sage of f i r e until the f i r e d e p a r t m e n t a r r i v e s .

T h e tables of s e p a r a t i o n p r e p a r e d by the Division of Building R e s e a r c h a r e based on the assumption that the openings i n the wall a r e infinitely s m a l l and a r e distributed uniformly. In many c a s e s this approach i s not applicable, for instance, w h e r e the openings a r e concentrated i n only one portion of the facade. H e r e it is m o r e

(17)

There a r e two alternative methods available to cope with this problem. One is contained in "Housing Standards,

1962" Supplement No. 5 to the National Building Code of Canada (24) and the other in #'Fire and Space Separation" ( 3 1 ) by G. J.

Langdon Thomas. The Housing Standards state:

"Where the windows a r e distributed nonuniformly over the face of a building and there is a glazed a r e a that has a width exceeding the limiting distance, the a r e a of wall face to be considered shall be bounded by the ends of the glazed a r e a and a ) finished grade,

b) a floor that i s a one-hour f i r e separation, or c) the ceiling of the uppermost floor area."

Note, however, that the "limiting distanceTt r e f e r r e d to i s the separation to the lot line, and hence is approximately one-half the separation from the building to i t s neighbour ing building.

The second method is known as the "enclosing rectanglett concept and i s described in the following section.

(c) Enclosing Rectangle

The percentage of openings in a wall may be expressed in t e r m s of the rectangle that encloses all the openings in the a r e a of exposure hazard. Such a rectangle i s known a s the "enclosing rectangle. I ' The openings may be spaced a c r o s s the

facade as a number of groups of openings. It i s necessary, therefore, to use another t e r m

-

the "over-all enclosing rectangle. "

./.

OVERALL EP(CL0SING R E C T A N G L E

E N C L ~ S I N ( ~ R E C T A N G L E S

(18)

In the analyses in the previous r e p o r t s the method used was the one that gave the maximum separation requirements. (d) Staircase Enclosures

An enclosed s t a i r i s one which i s contained within suitably f i r e - r e s i s t i v e walls s o that it will not p e r m i t a f i r e , having its origin in one s t o r e y of the s t r u c t u r e , to spread to other storeys. An open s t a i r i s one which will permit the spread of f i r e vertically through the s t r u c t u r e .

It is important that enclosed s t a i r s need not be considered a s p a r t of the wall for the purpose of space separation calculations.

( e ) Recess o r Setback in the Wall of 5 ft o r L e s s

Since a facade i s often broken up into a number of planes it i s n e c e s s a r y to determine what c a n be considered a plane surface. A convenient assumption i s that any plane s e t back 5 ft o r l e s s f r o m

the main elevation may be considered, f o r the purpose of the calculations, to lie on the same plane a s the face of the building. This a s sumption i s tested i n the analyses of Field Survey A r e a No. 1 (DBR Report 280) and found to be reasonable. That i s , i t makes no appreciable difference to the separation requirements whether the facade i s analyzed a s a

number of planes o r a s one plane located on the plane of reference.

5' OR L E S S ,/ : P L A N E OF R E F E R E N C E Figure

6

:THIS I S A S S U M E D T O B E T H E B U I L D I N G .FACE FOR P U R P O S E S OF C A L C U L A T I O N

(19)

( f ) Recess o r Setback in the Wall of More than 5 ft Setbacks

A setback in the facade reduces the radiation hazard it presents to the exposed building and thus a reduction in the separation requirements i s possible. This i s achieved by considering the elevation in two portions: that p a r t on the plane of reference and the setback portion.

EQUIVALENT RADIATOR

PLANE OF REFERENCE

Figure 7

The portion on the plane of reference i s dealt with in the normal manner. The next ~ t e p i s to s e t up.an "equivalent radiator.

"

That i s , a line joining the exte:rr,al angles a s shown in Figure 7. The openings a r e assumed to lie on this plane and the percentage of openings within the a r e a a r e assumed to be the equivalent radiator. The required spatial separation can then be a s s e s s e d f r o m the table.

Recess with Openings on T h r e e Sides

The basic assumption h e r e i s that all the openings in the r e c e s s a r e radiating at the aperture. Analyses may then proceed a s before, remembering that the r e c e s s may c r e a t e a local concentration of openings necessitating an i n c r e a s e in the

separation requirements a t that point.

Recess with Openings in the Rear Wall Only

-

Calculation of the separation requires the use of a

simple mathematical formula; the procedure i s a s follows. F i r s t , determine the separation assuming that all openings a r e

(20)

radiating at the aperture. The fact that some openings a r e set back f r o m the plane of reference will reduce the intensity of radiation from the elevation and this reduction may be a s s e s s e d from the following formula adapted from " F i r e and Space Separation" (31)

where

s is the fir s t separation requirement, in ft, r is the depth of the r e c e s s in ft, and

f is the factor by which the openings may be reduced. Knowing s and r

,

f may be calculated. The a r e a of openings in the r e c e s s i s then deduced by the resulting factor and the calculations repeated to give the final separation requirements.

(g) Non-fire-resistive Projections into the Space

Separation is defined a s open and unobstructed space. Any element that has a fire resistance of l e s s than three-quarters of an hour and which projects into the space between the two buildings will facilitate the spread of f i r e f r o m the exposing to the exposed building.

In

the analyses contained in the previous reports it i s assumed that the required spatial separation must be measured f r o m the extremity of such a projection. This seems to be an unnecessary hardship.

An

alternative method assumes that there i s no non-fire-resistive element within 4 ft of the exposed building. This i s derived f r o m the "Housing Standards 1962" (24) which state that an element may be 2 ft f r o m the boundary of the lot without necessarily having non-combustible cladding. Doubling this figure will give the approximate relation from building to building rather than from the building to the boundary of the lot. It may be that some other assumptio~l i s n e c e s s a r y but this one i s used.

SITUATION 2: HEIGHT O F ROOF

The roof need only be considered in the calculations i f it contains a habitable space and has openings permitting radiation to endanger the exposed building. The roof space, therefore, i s considered a s an extension of the wall.

SITUATION 3: OFFSETS

Figure 8 shows that a reduction in the separation requirements i s possible i f the buildings a r e offset sufficiently.

(21)

I P L A N O F E X P O S I N G BUILDING

Figure 8

The f i r a t step is to analyze the buildings a s before and determine the separation requirements. This allows one to s e e if any reduction in the separation i s p e r m i s s i b l e due to the offset a s shown in Figure 8.

SITUATION 4: GROUND ELEVATION

It was shown in the previous r e p o r t (DBR Report 282) that a difference in the elevation of two adjacent buildings can result in a reduction of their horizontal separation requirements.

F i r s t determine the horizontal separation requirements by the usual methods. Then draw the two buildings in section showing the difference in elevation and the separations required.

(22)

EXPOSED

I

XPOSINQ UlLDlN Q

*

/i- , R E D U C T I O N I N S E P A R A T I O N R E Q U I R E M E N T S

I

k..

I

..;DUE TO D I F F E R E N C E IN G R O U N D E L E V A T I O

*...

, R E D U C T I O N I N S E P A R A T I O N R E Q U I R E M E N T S

*...

Figure

9

As before, i f the exposed building lies outside the radiation envelope of the exposing building i t i s in no danger.

SITUATION 5: ADJACENT WALL NOT PARALLEL

The c r i t i c a l factor h e r e i s that the separation requirements may be reduced a t the c o r n e r s of the building since f i r e fighting has proved to be e a s i e r at these points. It is f u r t h e r suggested in DBR Internal Report No. 187 (20) that the separations at the c o r n e r s need only be 80 per cent of the spatial separation required at the centre of the compartment under investigation. But radiation also extends in all directions. The s a m e report makes the assumption that radiation past the c o r n e r s of an opening will cease to be c r i t i c a l beyond a

(23)

"...

R E D U C T I O N I N

c o

S E P A R A T I O N FIGURE 10 R E Q U I R E M E N T D U E T O N O N - P A R A L L E L A D J A C E N T W A L L

If no radiation i s allowed to extend around the c o r n e r s it i s only necessary to ensure that t h e r e a r e no openings in the wall closer to the corner t h a ~ l a distance equal to 60 per cent of the separation distance required at the centre of the compartment.

STTUATION

6:

STRU CTTJRAL BAFFLES

A s t r u c t u r a l baffle i s a s c r e e n , fence, or s i m i l a r element a s distinguished f r o m hedges, t r e e s , o r shrubs which a r e considered shrubbery baffles.

For a baffle to be effective i n reducing the spatial separation between buildings it must have a f i r e resistance of at least three-quarters of an hour. That i s , it should r e s i s t

(24)

the radiative h e a t long enough for the f i r e department to a r r i v e . If the b a r r i e r h a s a rating of l e s s than this i t will tend to facilitate the s p r e a d of fire. The effectiveness of the baffle depends on i t s

height, length, percentage of openings, and the location and a r r a n g e m e n t of these openings.

F o r purposes of explanation we consider only one building which i s a s s u m e d to p r e s e n t the governing conditions. We a l s o a s s u m e , for the moment, that the baffle h a s sufficient f i r e r e s i s t a n c e and that i t i s i m p e r f o r a t e . The following explanation c o n s i d e r s t h r e e f a c t o r s : the height of the baffle, the width of the baffle, and the percentage of openings in the baffle.

( a ) Height of Baffle

The f i r s t s t e p i s to analyze the building to d e t e r m i n e the spatial s e p a r a t i o n r e q u i r e m e n t s neglecting the e f f e c t of the s t r u c t u r a l baffle. Since we a r e now concerned with the height of the baffle, the

resulting space envelope i s b e s t shown by sections through the building. The next s t e p i s to place the b a r r i e r , r e m e m b e r i n g that it i s a s s u m e d to be i m p e r f o r a t e , and determine the shielding effect i t offers.

F i g u r e s 11,12 and 13 show the reduction in the s e p a r a t i o n r e q u i r e d due to this shielding.

It i s shown that to effect any reduction for the full height of the building, the baffle m u s t be a t l e a s t a s high a s the top of the uppermost opening.

(b) Width of Baffle

The width of the baffle is analyzed in the s a m e m a n n e r , (Fig. 12).

It i s n e c e s s a r y to make s o m e provi sion for openings i n the baffle since i t i s unlikely that the baffle will always be i m p e r f o r a t e and a p a r t i a l s c r e e n gives s o m e reduction i n the s e p a r a t i o n required.

The method proposed c a n b e s t be d e s c r i b e d by F i g u r e 13.

This method is applicable to any percentage of openings. The example used has a uniform distribution of openings to simplify the

explanation. If the openings a r e concentrated in one portion of the baffle, however, i t i s possible to u s e a method s i m i l a r to that used in analyzing a building wall. That i s , the section containing the openings c r e a t e a local concentration of exposure hazard.

(25)

NO B A F F L E PARTIAL BAFFLE

.='

P A R T I A L BAFFLE .<--.

.

*.**

....

----

I

F U L L BAFFLE ".-...REDUCTION IN S E P A R A T I O N R E Q U I R E M E N T S DUE TO S T R U C T U R A L B X F F L E F I G U R E 11

(26)

E X P O S I N G B U I L D I N G NO BAFFLE

/

-\

/ *

\.

L-

--.

I'

'7.-

C/.

I

b

4--

- - - / -'L.c.: " - * * AREA S H I E L D E D BY B A F F L E P A R T I A L ' B A F F L E R E D U C T I O N I N S E P A R A T I O N DUE T O B A F F L E F U L L B A F F L E F I G U R E 1 2

(27)

E X P O S I N G B U I L D I N G

/-

-\

*-...

.

...

S E P A R A T I O N R E Q U I R E D W l T H S T R U C T U R A L B A F F L E C O N T A I N I N G 100°/0 O P E N I N G S 50°/o ( X 1 \

<-.--.

.

...

-.

-.ye /

--

-

_{- --}

/ / / A - - /

.-.

.

a .

...

S E P A R A T I O N R E Q U I R E D W l T H S T R U C T U R A L B A F F L E C O N T A l N l N G 50'% O P E N I N G S

...

S E P A R A T I O N R E Q U I R E D W l T H S T R U C T U R A L B A F F L E C O N T A I N I N G O.OOO/o O P E N l N G S F I G U R E 1 3

(28)

PART 3

DETAILED APPLICATION OF THE FINDINGS It i s now possible to explain in more detail the method of applying the findings to particular cases. This i s done through the examination of typical residential buildings the size of small apartment structures. The method of analysis outlined in the following pages can be applied to any size and shape of residential building.

The method i s flexible but the technical information available makes the application of the method to small single-family dwellings difficult and, in some cases, impossible. The table of separations used does not consider wall a r e a s of less than 3 0 by 10 ft and percen- tages of openings of less than 20 per cent. The limitations imposed on the analyses have been discussed more fully in previous reports.

OUTLINE

O F THE

DESIGN

PROCESS

To simplify and organize the analyses, the design process i s divided into stages: The following is based on the outline contained in " F i r e and Space Separationtt (31, p. 3) by

G.

J. Langdon Thomas. Stage 1: To determine what part of the facade must be taken into

account in the calculations. Consider ations :

(a) Setback or r e c e s s of 5 ft o r l e s s from the plane of reference. (b) Compartmenting of the building.

( c ) Enclosed s t a i r s .

Stage 2: To determine the a r e a of exposure hazard. Consider ations :

( a ) Concentration of openings.

(b) Over -all enclosing rectangle. ( c ) Enclosing rectangle.

Stage 3: To determine the separation requirements based on the r i s k determined by Stage 2.

Considerations :

(29)

Stage 4: To locate any s p e c i a l a r e a of e x p o s u r e h a z a r d which m a y i n c r e a s e o r d e c r e a s e the s e p a r a t i o n r e q u i r e m e n t s . Consider ations :

( a ) Setback i n the wall of m o r e than 5 ft.

( b ) R e c e s s of m o r e than 5 ft with openings on 2 o r 3 s i d e s . ( c ) R e c e s s of m o r e than 5 ft with openings i n r e a r wall only. ( d ) Non-fire - r e s i s t i v e projections into the space.

Stage 5: To d e t e r m i n e the effect of s p e c i a l conditions. Considerations :

( a ) Height of roof. (b) Offsets.

(c) Difference i n ground elevation. (d) Adjacent wall not p a r a l l e l ( e ) S t r u c t u r a l baffles.

EXAMPLES

O F DESIGN PROCESS

The following a n a l y s i s p r o c e e d s f r o m s t a g e to s t a g e as

suggested i n the above outline. Concern h e r e is with the r e l a t i o n . ship between neighbour ing buildings, t h e r e f o r e , to d e t e r mine t hc-

s p a t i a l s e p a r a t i o n r e q u i r e d between tsvo buildings i t i s n e c e s s a r 1

to analyze both the governing f a c t o r s . This i s c l e a r i n the r e p o r t s of Field Survey A r e a s Nos. 1 , 2 and 3. F o r p u r p o s e s of e x p h - nation only one building was analyzed and i t w a s a s s u m e d that ~t

r e p r e s e n t s the governing conditions.

The b a s i c building used is shown in F i g u r e 14.

(30)

Figure 15 will be modified a s required to illustrate the method of analysis. For example, the analyses will begin with the building shown i n Figure 1 5.

Figure 15

Stage 1: To determine what p a r t of the facade m u s t be taken into account in the calculations.

( a ) The c e n t r e portion of the facade, since i t i s r e c e s s e d not m o r e than 5 f t , may be considered to lie on the planes of reference.

( b ) The building is compartmented horizontally by the f i r e wall to the right of the r e c e s s e d portion. T h e r e f o r e the building m a y be analyzed a s consisting of two portions s e p a r a t e d by the wall.

( c ) Since the s t a i r c a s e on the e x t r e m e right i s enclosed by walls of the appropriate f i r e r e s i s t a n c e , with suitable a c c e s s doors

,

i t m a y be ignored for the purpose of s p a c e separation calculation.

W I D T H O F

(31)

Stage 2: To determine the a r e a of exposure hazard.

( a ) T h e r e i s a concentration of openings in the r e c e s s e d portion of the facade. One method of dealing with such a condition

is contained in "Housing Standards1' Supplement Number 5 to the National Building Code of Canada, Section 4. 34, p. 3 9 . (24) where i t is stated:

"Where the windows a r e distributed non-uniformly over the face of a building and t h e r e i s a glazed a r e a that has a width exceeding the limiting distance, the a r e a of wall face to be considered shall be bounded by the ends of the glazed a r e a and

(a) finished grade,

(b) a floor that is a one-hour f i r e separation, o r

( c ) the ceiling of the uppermost floor a r e a .

Note, however, that the "limiting distance" r e f e r r e d to i s the separation to the lot line and hence is approximately one-half the separation f r o m the building to its neighbouring building

.

- F i g u r e 17

(b) Over-all enclosing rectangle.

(32)

( c ) Enclosing rectangle.

F i g u r e 19

Stage 3: To d e t e r m i n e the s e p a r a t i o n r e q u i r e m e n t s based on the r i s k determined by Stage 2.

F r o m Stage 2a:

F i r s t , d e t e r m i n e the s e p a r a t i o n r e q u i r e m e n t s f o r the e n t i r e portion of the facade under investigation.

Width

. . .

40 ft Height

. . .

20 ft A r e a

. . .

800 s q ft Total a r e a of openings 372 ' ' 372 s q f t P e r c e n t a g e of openings (- x 1000/0). 46. 5% 80 0 Separation r e q u i r e d

. . .

36 ft

The width of the glazed a r e a exceeds one-half this d i s t a n c e , t h e r e f o r e : Width

. . .

30 ft Height

. . .

20 f t A r e a

. . .

600 s q ft Total a r e a of openings 360 ' ' ' ' 360 s q ft P e r c e n t a g e of openings (- x 100o~,$' 60% 600 Separation r e q u i r e d .

.

37 ft F r o m Stage 2b: Width

. . .

40 ft Height

. . .

1 5 ft A r e a

. . .

600 sq f t Total a r e a of openings

. . .

372 s q ft P e r c e n t a g e of openings

.

,

.

,

.

62% Separation r e q u i r e d

.

37 ft

(33)

F r o m Stage 2c: Width

. . .

30 ft Height

. . .

1 5 ft A r e a

. . .

450 sq ft Total a r e a of openings

.

3 6 0 s q ft Percentage of openings

.

8 0 % Separation required

. . .

3 6 ft If these w e r e the only considerations, the total separation required between this building and i t s neighbour would be the maximum value of 3 7 ft.

Stage 4: To locate any special a r e a of exposure hazard which m a y i n c r e a s e o r d e c r e a s e the separation requirements. ( a ) Setback in the wall of m o r e than 5 ft.

The method of solving this problem i s to consider the facade in two portions: the p a r t on the plane of reference, and the p a r t s e t back f r o m the plane of r e f e r e n c e . The f i r s t portion may be analyzed normally. The setback portion r e q u i r e s sub- stitution of an Ifequivalent radiator" as shown in Figure 21.

The openings i n the r e c e s s a r e assumed to lie on this equivalent radiator and the separation requirements a r e a s s e s s e d a s before.

(34)

Assuming S t a g e s 1 , 2 and 3 have been completed f o r t h i s building: P o r t i o n A:

. . .

Width 30 f t

. . .

Height 20 ft A r e a

. . .

600 s q f t T o t a l a r e a of openings

.

360 s q f t P e r c e n t a g e of openings

.

6070

. . .

S e p a r a t i o n r e q u i r e d 37 f t P o r t i o n B: Width

. . .

30 ft Height

. . .

20 ft A r e a

. . .

.

80% S e p a r a t i o n r e q u i r e d

. . .

4 3 f t

The final s e p a r a t i o n r e q u i r e m e n t i s shown i n F i g u r e 22. It i s a s s u m e d that the r a d i a t i o n d o e s not extend around the c o r n e r , i n any a p p r e c i a b l e amount, beyond a 45-degree angle as shown.

(35)

( b ) R e c e s s of m o r e than 5 ft with openings on two o r t h r e e sides: a l l openings in the facade a r e considered to be radiating at the plane of r e f e r e n c e .

F i g u r e 2 3 Width

. . .

50 ft Height

. . .

20 ft A r e a

. . .

1000 s q f t Total a r e a of openings 840 ' 840 s q ft P e r c e n t a g e of openings (- x 1000J0) 840J0 Separation r e q u i r e d 10 00 56.4 ft

( c ) R e c e s s of m o r e than 5 f t with openings in r e a r wall only. The f i r s t s e p a r a t i o n r e q u i r e m e n t should be obtained by assuming that a l l openings a r e radiating at the a p e r t u r e . T h i s may then be reduced by m e a n s of a f o r m u l a b e c a u s e s o m e openings a r e behind the plane of r e f e r e n c e and tend to reduce the intensity at the plane.

(36)

Determine the f i r s t s e p a r a t i o n r e q u i r e m e n t : Width

. . .

50 f t Height

. . .

20 f t A r e a

. . .

1000 s q f t Total a r e a of openings

. . .

600 s q f t

. . .

P e r c e n t a g e of openings 6070

. . .

S e p a r a t i o n r e q u i r e d 47 f t

The a r e a of the openings i n the r e c e s s m a y be reduced b y the factor:

2 2

The a r e a of the openings on the plane of r e f e r e n c e = 240 s q ft; the a r e a of the openings i n the r e c e s s e d portion = 360 s q f t . The a r e a of the openings i n the r e c e s s m a y then be considered to be 0.72 (360) = 260 s q ft.

The total a r e a of openings i s = 260

+

240 = 500 s q ft. 50 0

P e r centage of openings =

-

1000 x 1OOyo = 50% S e p a r a t i o n r e q u i r e d .

.

42 f t

(d) Non-fire-resistive projections into the s p a c e .

This condition is dealt with by a s s u m i n g that a non-fire-resistive projection f r o m the exposing building into the s p a t i a l s e p a r a t i o n will not constitute a h a z a r d i f i t i s 4 ft o r m o r e f r o m the exposed building.

(37)

. . .

Width

. . .

Height

. . .

Area Total a r e a of openings P e r centage of openings Separation required

. .

The projection, however, extends 12 f t f r o m the wall. Therefore the separation required i s 1 2 ft

+

4 ft =

1 6

ft rather than 13 ft a s determined by the calculations.

stage 5: To determine the effect of special conditions

(a) Height of roof

This

is best shown by using two examples:

The f i r s t dealing with roof openings which lie on the plane of reference, and the second with openings s e t back f r o m the plane of reference. Figure

26 . . .

Width Height

.

. . .

Area Total a r e a of openings P e r centage of openings Separation required

. .

(38)

The second example i s analyzed a s a s e t b a c k i n the wall. A S S U M E 10' S I N C E

...

THIS I S AS L O W A S

...

THE T A B L E GOES

T

1

T

A

F i g u r e 27 Width

. . .

50 f t Height

. . .

20 ft A r e a

. . .

. . . .

. . .

6070 S e p a r a t i o n r e q u i r e d

. . .

47 f t P o r t i o n B: Width

. . .

50 f t Height

. . .

1 0 f t A r e a

. . .

.

367, S e p a r a t i o n r e q u i r e d

.

21 f t

(39)

Figure 2 8

(b) Offsets

It was mentioned that a reduction of the separation requirements i s permissible at the c o r n e r s of a building. F i r s t , determine the b o u d a r y a s before:

(40)

Width

. . .

50 _{f t} Height

. . .

20 f t

. . .

A r e a 1000 s q ft Total a r e a of openings

. . . .

600 s q ft P e r c e n t a g e of openings

. . . .

6 0 % Separation required

. . .

4 7 f t

Then, r e d u c e the s e p a r a t i o n s at the c o r n e r s a s shown in F i g u r e 30.

(41)

T h i s m e a n s that two buildings offset in r e l a t i o n to e a c h o t h e r m a y , f o r example, be s i t e d a s follows:

F i g u r e 31

It i s s e e n t h a t the s e p a r a t i o n p e r p e n d i c u l a r to the facing w a l l s i s now 1 8 . 7 5 f t as opposed to the 4'7 ft p r e v i o u s l y r e q u i r e d .

( c ) Difference in ground elevation F i r s t , analyze the building a s before.

(42)

Figure

. . .

Width

. . .

Height

. . .

Area

Total area of openings

.

Per centage of openings Separation required

.

It

is seen in Figure 33 that a difference in ground &levation reduces the horizontal separation required between buildings.

(43)

(d) Adjacent wall not p a r a l l e l

P r e v i o u s analyses show that a reduction of the s e p a r a t i o n r e q u i r e m e n t s i s possible a t the c o r n e r s of the building.

F i g u r e 34 Width

. . .

50 f t Height

. . .

20 f t A r e a

. . .

1000 s q ft T o t a l a r e a of openings

.

600 s q ft P e r c e n t a g e of openings

. . .

6070

. . .

Separation r e q u i r e d 47 ft

Assuming this building to be the governing one, the buildings m a y be sited a s shown i n F i g u r e 35.

(44)

F i g u r e 35

( e ) S t r u c t u r a l baffles

(45)

Figure Width

. . .

50 ft Height

. . .

20 ft A r e a

. . .

1000 s q f t Total a r e a of openings

.

600 sq ft Percentage of openings

. . .

60

70

Separation required

. . . .

4 7 ft

The b a r r i e r i s of f i r e - r e s i s t i v e materials and has 3 3 per cent openings distributed uniformly. The full separation m u s t be maintained where the b a r r i e r provides no shielding. A reduction i s possible i n the a r e a protected by the b a r r i e r .

Separation required for Portion A

....

4 7 ft Separation required for Portion

(46)

E X P O S E D BUILDING

a

B U I L D I N G

(47)

CONCLUDING REMARKS

This r e p o r t concludes the study of f i r e regulations and the f i r s t s p e c i a l study made a s p a r t of the l a r g e r p r o j e c t " P e r formance Standards for Space and Site Planning for Residential Development. I' This project e n c o m p a s s e s broad objectives and a wide scope of i n t e r e s t . A brief review of p r o g r e s s to date is

included h e r e to r e l a t e the specific conclusions to the g e n e r a l objectives.

In the P r e f a c e to the main r e p o r t (DBR Internal Report No. 273) the late P r o f e s s o r L a s s e r r e w r o t e

-

"The rigidity of

c u r r e n t regulations and the limitations they place on the production of v a r i e t y in the layout of residen.tia1 a r e a s has been of m u c h con- c e r n to p l a n n e r s , a r c h i t e c t s , and s o c i a l s c i e n t i s t s . This c o n c e r n prompted the School of A r c h i t e c t u r e a t the University of B r i t i s h Columbia to a r r a n g e with the Division of Building R e s e a r c h of the National R e s e a r c h Council to c a r r y out a n investigation into the c r i t e r i a that might d e t e r m i n e space s t a n d a r d s , facilitating g r e a t e r v a r i e t y in the layout of r e s i d e n t i a l buildings.

"

The m a i n r e p o r t s e t the scene for the m o r e p r e c i s e studies. It identified f i r e , daylight, a i r , noise, p r i v a c y view, t r a f f i c and outdoor s p a c e a s community objectives and i t identified the

dimensions which a r e c r i t i c a l i f outdoor s p a c e i s to be controlled. Finally i t e x p r e s s e d the hope that a f t e r f u r t h e r m o r e concentrated studies i t would be possible to evaluate t h e s e dimensions and p a r t i c u l a r l y to evaluate the effect of an i n c r e a s e o r d e c r e a s e i n any one of the dimensions in t e r m s of f i r e , light and the other community objectives.

F o r example, one of the c r i t i c a l dimensions w a s building offset s. A balcony might be i n t e r p r e t e d in this c l a s s . The balcony might reduce the s p a c e between buildings and s o i n c r e a s e the r i s k of

f i r e s p r e a d but this might be a m a t t e r of s m a l l i m p o r t a n c e to f i r e s p r e a d c o m p a r e d with s a y , the s i z e of window opening. On the other hand, a balcony might be of m a j o r amenity i m p o r t a n c e and s o be v e r y favourably a s s e s s e d f r o m the viewpoint of privacy, view and space. In considering a l l the community objectives t o g e t h e r , a d e s i g n with balconies might p a s s because i t enhances the g e n e r a l good w h e r e a s a rigid s e p a r a t e uncompromising

approach could condemn the d e s i g n u n n e c e s s a r i l y f r o m the f i r e o r s o m e other single point of view.

(48)

Some m a y liken this to a f o r m of horse-trading and c l a i m that it h a s no place i n building regulations. T h i s i s not n e c e s s a r i l y so. One f i r e precaution, for example, p e r m i t s building a r e a to be doubled

i f a s p r i n k l e r s y s t e m is installed even though the s p r i n k l e r s y s t e m i s not connected d i r e c t l y with the i n c r e a s e in the risk. T h e r e is precedent then for trading but of a unilateral kind. So f a r t h e r e i s no precedent for the kind of multilateral trading (providing health benefits to counter f i r e r i s k s ) that i s suggested h e r e .

Yet safety i s never absolute. A regulation i s always a balance between economy and safety and t h e r e i s always the possibility that, for the sake of convenience or economy, c e r t a i n safety regulations might be relaxed. This c i r c u m s t a n c e actually o c c u r s in s o m e building law. It i s a principle of building safety that t h e r e should be two m e a n s of escape f o r the occupants of a building. Many building by-laws using a n eminent authority, the NFPA E x i t s Code, a s a precedent p e r m i t "dead-end" c o r r i d o r s of a limited length f r o m which t h e r e i s only one means of escape. This law which r e q u i r e s two exits for some people and only one for o t h e r s does s o for r e a s o n s of economy and convenience. The time m a y come when the balance of safety and economy m a y make i t advisable to consider the eight functional d e t e r m i n a n t s , identified by this study all together in connection with any o r a l l dimensional limitations.

It was with this hope a s a stimulus that the s u r v e y of the t h r e e blocks in Vancouver was made. This detailed study has proved rewarding and even though it i s only the f i r s t of this s e r i e s and limited to the f i r e aspect t h e r e a r e s o m e conclusions w o r t h recording. As might be expected these have to do with space controls f r o m the viewpoint of f i r e s p r e a d .

The conclusions resulting f r o m this study a r e of t h r e e Icinds: 1. An a p p r a i s a l of existing c o n t r o l s ;

2. Some suggestions f o r improvement of the National Building Code; and

3 . A suggested grading of space dimensions r e f e r r e d to in controls for f i r e spread.

CONCLUSIONS

1. Appraisal of Existing Controls

( a ) A principal observation of a r c h i t e c t s in t h e i r everyday p r a c t i c e i s that yard r e s t r i c t i o n s and setbacks a r e s o inflexible a s to inhibit design. Internal Report NO. 2 7 3 quotes the RAIC Committee of Enquiry on