15

Design and Construction of Building Exits

“BaypTing 073 Jo 43} [Ny OY} TNs S10;VAoTe Po}OT estmsz0q IO ssa[T
Supping op 20} 200g qwofdy w quososdar poysodas seoxe 2009 ath te Oh Fa on 4 wag

NPUNG ZO “WO}IONI}STOO YO"q-J96 JO 6911038 4q vOIY 7

6

o jo
t Jo

{8 [Et jo
[rt [so

wr
a

9%
og

000%
ors

NOILOQULSNOO LSIOf GNV TIVA-AUNOSVM


36° Miscellaneous Publications, National Bureau of Standards

Government office buildings in Washington, D.C., were studied at
the closing hour. Some interesting counts were also made of the
traffic movement during fire drills at the so-called “temporary office
buildings.” These drills were compulsory, and were conducted by the
fire marshal in charge of the buildings. The occupants were not

warned when a drill was to take place. - At the sound of the fire ong .

everyone left the building at a normal rate by exits which had been
assigned to specified floor areas. No attempt was made to form ranks.
Ahigh rate Of discharge for a stairway checked during one of these drills
will be noted in table 19, page 35. A maximum flow condition was
created by closing a stairway ordinarily used, thus adding its entire
Toad to the particular stairway under observation: This stairway
was unusual in that two 5-foot stairways wore connected at an inter-
mediate landing with a:single stairway 7 feet 3% inches wide, producing
a bottle neck in the direction of flow. -

A controlled test of traffic movement on a 36-inch stairway was
made at the National Bureau of Standards. This’ stairwa: was
unenclosed, had @ railing on.one side, treads of 11% inches and risers
of 7 inches, a story height of 13 feet 5 inches, and was constructed
with two landings, each 3 feet square and each one making a 90-
degree turn. A crowd of people was assembled in the hallway at the
top of the stairway and asked to descend as they naturally would
without attempting to run. As will be noted in table 19, page 35, a
maximum rate of discharge of 34 persons per foot of width per minute
was obtained. During ‘this test the number of square feet occupied
Per person averaged 4.1. However, by placing all the people in the
stairway that could be accommodated when there was no motion, but
1.4 square feet was occupied per person.

7. TABULATION OF COUNTS ON STAIRWAY DISCHARGE

The results of the observations on stairways are given in table 19,
Page 35. The average figures in the tables represent a large number of
observations taken not only at different hours of the day, but also on
different days. The column giving the number of persons discharged
per foot of width per minute was calculated by determining the num-

er of persons passing in 1 minute and dividing this number by the
stairway width in feet. _ Thus, on a 3-foot stairway, where 93 people
were discharged in 1 minute, the rate per foot per minute was com-
puted to be 31. If a 22-inch unit were used to compute discharge
a8 is sometimes done, a rate of 93 per 22-inch unit minute would
be obtained where credit for only a single unit was allowed the 36-inch
stairway; if the same 22-inch unit were used and the computation
based on the proportion of 36 inches to 22 inches, the rate would be
57 persons per 22-inch unit per minute. The results obtained in the
Illinois Central and Hudson Terminal studies, table 16, page 31, were
also referred to the rate per foot of width per minute.

8. CHARACTERISTICS OF STAIRWAY DISCHARGE

The varying rates of stairway discharge found, while they bear a
certain relation to stairway width, also indicated that normal dis-
charge rates may vary widely with different occupancies. For any
one stairway with the same class of occupancy using it, the total


32 Miscellaneous Publications; National Bureau of Standards

A very interesting and extensive study of exits in schools was con-
ducted by J. M. Tracy, superintendent of schools, Rochester, N. Y.,
as part of the prompted by the Committee on Safety to Life
of the National Fire Protection Association to determine the efficiency
of exits in such buildings. The individual discharge rate for separate
exits was not recorded id it is not known how these exits were
distributed: on the floor areas. However, the actual time necessary
to empty. building of its occupants during a fire drill was checked
for over 50 schools. An average rate of dischar, ©, assuming all the
exits in the building to be used, was computed for a 22-inch unit
of exit width—that is, a building -heving a total of eight 22-inch
units of exit width, and-discha: 600 pupils in 2 minutes, was
computed to have an average discharge rate of 37.5 pupils per 22-inch

. unit per minute. The results of these studies are given in table 17
low. ;

The results of capacity tests on revolving doors furnished by one
of the_large companies that manufacture such doors, are reproduced
in table 18, page 33.

TABLE 17.—Survey of exits in school buildings, Rochester, N. Y.

Existing a8 Exist a3
exits g °a mise | 2 es
Sella | ae ster] el. | 8s
Behool 52 & = i! school 2 a
gamed 3g) 2) 2 | TE | som) de] | iis
Balad Ae Blggl a | 2 a
3 a g 3 g a H ee
E i EE
é jé*| 2] 2 | 2 & g 8} 21 F <
min} sec min} sec
$s 10 400} 1/20 30 8 18 | 1,550] 2/00 48.0
5 8 600 | 2/ 00 32.5 20 40. 920 |.../ 40 845
9 4 485 |...) 48 43.1 5 ih 580 |...-] 48 65.9
Q 18 662} 2/00 18.3 4 38 609 | 1] 45, 43.5
3 8 681} 1/58 43.6 3 6 625] 1) 40 52.5
3 8 416] 1) 15 45 2 4 275 | 1 | 00. 68.7
6 13 930 | 2] 00 35.7, 5 12 79! 1) 10 $5.5
7 12/ 1,400] 1) 30 7.7 7 Me 500) 1/10 30.6
6 12 730} 1/30 43.3 5 11 | 1,230} 1] 30 45
5 2 834] 2} 40 41.7 5 50 865 j....| 30 34.6
6 RB 4501 1} 30 28.0 8 19 404 30 141
3 8 822) 1) 25 46.0 8 19 875 15 20.4
7] 16] 1,145] 2 | 00 35.8 8} 19] 21 oo 13.3
2 4 260) 1! 05 60.0 4 8 903, 40 67.7
8 13 800] 1; 30 41.0 6 13 | 5.000 ats 61.6
6 15 | 1,536 | 2 | 00 51.2 6 12 530 30 0.4
8 15 | 1,700} 1} 35 715 2 5 40 50 57.6
5) 10} "s3t] 1/05) apy w] ul “67 05 56
5 9.) 1,060 | 2] 35 45.6 4 10 372 45 13.5
6 10 580} 1) 40 34.8 6 24 | 1,639 is Bb
9 % 2) 1 | 35. 33.5, 6 24 | 1,528 15 B.3
3 8 600} 2) 45 42.7 10 16 ‘516 10 |... ——
Pa 48. 600: =| 45 16.6 5 ‘548 4a 77.6
2B 56 | 1,11 -| 30 30.8 7 28 | 1,668 45 340
10 22 | 1, 208, 00 20.5 5 20 | 1,532 10 35.3

ary 02! thine required under normal conditions in September 1027 to empty the buildiigs during fre


Design and Construction of Building Exits 41

necessity is doubted by many authorities. The results obtained in

terms of stairway width, especially where fire towers, horizontal exits,

and other features are not present, are very large in tall structures,

eausing disproportionate amount of space to be devoted to stairways
- as compared with usable floor area.

4, PROBABILITY METHOD

This method secures an answer directly in terms of number of
standard: 2-unit-width stairways by dividing an arbitrary figure
varying with the occupancy, such as 1,000, into the total population
of all floors above the first, with a proviso that.a maximum of only the
6 most densely populated of such floors need be considered. Pro-

‘ vision is. made for taking care of fractions in the result.

The method is direct and simple.. It introduces an element, that
is absent in the preceding ones, namely, a limit as to the probable need
for simultaneous use of the stairways. Other methods have assumed
that all persons on each floor will need egress facilities at once, while
this method infers that such an arrangement is neither practical nor
necessary..

In the case of set-back buildings the method is further complicated
by supplement provisions in order to make it work. In the
ease of high buildings there is a doubt as to whether 6 stories out of
40 are all that need to be considered. The method also makes use of
assumptions as to the influence of type of construction that are not
agreed to by all authorities. In. the case of low buildings of large
floor area the results are so small as to be of questionable value.

5. FLOOR-AREA METHOD

This method presents in tabular form a series of floor areas with
the number of standard 2-unit-width stairways required for each.
The areas vary with the type of construction and class-of occupancy.
They are further modified by the position of a given floor in the
building. The table represents some typical floor such as the third,
with an increase in allowable area per stairway for floors below and a
scale-of percentage reductions for higher floors. Like the probability
method this concedes that it is impracticable to provide a place for
everyone in the stairway enclosure. However, it retains a slight
variation according to height instead of fixing a maximum number of
floors to be considered.

Computations are fairly easy to make. Results do not reach
such large numbers of stairways as to cut down useful area excessively.
However, there appears to be no. consistent relationship between
stairways and number of persons accommodated by them. The
allowance for increase in height is so slight that there is a question
whether it is significant enough to warrant the additional calculations
required. The method, being based on area rather than occupants,
takes no account of varying population within a given occupancy.
Abrupt jumps also occur in the tables at points where floor areas
change.


Design and Construction of Building Exits 9

. Table 4 lists the causes of deaths in 96 year-round and 14 seasonal
hotel fires, as compiled by the National Fire Protection Association.'*

Taste 4.—Causes of loss of life in hotel fires

(NFPA Chart, Jan. 1936)
‘Number of deaths
Sense ‘Year.
Seasonal
round ‘Total
uals | hotels
m 15 39
S| af a
33 0 33
43 3 6
al 0 4
n 0 i
243 40 283
10 1 ML
“ 2 16
BL “4 65
318 87 375

The exits apparently do not share in. the responsibility for loss of
fire in the residential classification, when dwellings are included, to
the same extent as in the public and institutional occupancies.
While fatal fires in hotels end apartment: houses occasionally occur,
it is mainly from the dwellings that the death list is built up and here
carelessness and ignorance, coupled with poor construction, are the
principal factors. There seems to be small possibility of improve-
mnent in the mortality statistics for the home until as a result of
education and improvements in equipment some of these factors are
brought more under control. Certainly no improvement in exit
facilities can affect the number of deaths caused by explosions of
various sorts and burns from the many causes reported m dwelling
statistics. In the case of the multiple dwelling, exits are more of a
factor and the necessity for and benefits from their regulation are
more easily appreciated.

Class 4,. business, as established in the report, Recommended
Minimum Requirements for Fire Resistance in Buildings, includes
factories, warehouses, stores, office buildings, and buil of like
character devoted to business. The loss-of-life record for this classi-
fication. is even less complete than for the other occupancies, except
for dwellings. While there has been some loss of life in office-build-
ing fires it has been relatively sinall; although the records disclose
several fires resulting in heavy property damage. The slight loss of
life is possibly explained by the fact that the majority of office-build-
ing fires apparent, ly start at night when the buildings are unoccupied,
and also, because of the alert population of these buildings, daytime
fires are usually discovered at. an early stage and sufficient warning
is given to enable the occupants to escape. Panic conditions have
not often developed during office-building fires. The National Fire
Protection Association. has compiled a record of 119 fires in office
buildings, 46 of which. caused: property losses of over $5,000.° The

4 Hotel fires, Quart. Nat. Fire Protect, Assn. (Jan. 1930).
0 Quand Nico Bre Prot aacu Cock i920 8


Design and Construction of Building Exits 69

The width of exit doorways at the foot of. exit stairways or at the
head of exit stairways serving basements shall be at the rate of at
least 20 inches * for each unit of exit stairway served.

7-8-2. Hanging of Doors.”

The doors of exit doorways shall swing in the direction of exit travel
and shall be so hung and arranged that they shall not obstruct the
travel along an exit. passageway, stairway, or other required exit;
provided, that a door swung flat against a wall is not considered an
obstruction; and provided, further, that no door shall at any point in
its swing reduce the width of an exit stairway by more than 18 inches.

Except in occupancies coming under class 3, residential, exit door-
ways to a street or an exterior open space leading to a street, shall have
the doors, including the doors of vestibules, so hung as to swing out
wardly when opening; but this requirement shall not be construed to
prohibit the use of doors swinging both inwardly and outwardly or of
doors sliding horizontally when used in shipping and receiving rooms in
occupancies coming under class 4, business, nor in class 5, garages,
hangars, barns, nor of sliding doors when used in connection a
horizontal exit.

Doors leading from rooms occupied by 50 or more persons shall be
hung to swing in the direction of exit travel. .

No door of an exit doorway shall open immediately on a flight of
stairs, but a landing at least the width of the door shall be provided
between such door and such stairs.

7-8-3. Revolving Doors.
Revolving doors may be used as doors in exit doorways, except in

places of assembly, in schools, and in occupancies coming under class
2, institutional,

{1.1 most cases the doorways at the foot of stairways can be made the same width as the stairways and
where ‘possible this should be done. Tt has been ecognized that in straight run flights of stairs some prac-
bya

ms ¢
visions of this chapter. and Toclude doorways required to complete the enclosure of stairways, doorways
Eiging to the exterior of the building which are also classified as “exits”, and doorways opening into
passageways. 5

skis permits the doors of classrooms containing less than 50 persons to swing in either direction at the
tion of the arcbitect. An inwardly swinging door is regarded by some school authorities as giving the
lassroom teacher better control ovet the pupils In ease of fire,
Residential buildings are exempted from the requirement that all exterior exit doors shall swing outwardly.
While this nay represent a possible relaxation in the requirements, in view of current practice it seems to be
Sreasonable one. It takes into account the probability that the occupants will not arrive at the exit doors
ipa crowd, but that opportunity will be afforded for ‘opening the doors before the maximum use of the

y isn 2 5
© Revolving doors are given credit as a means of egress in buildings of certain occupancies when limited
‘use as required by the provisions of section 7-8-4 Certain sdvantagas are claimed over the singing

9

and may possess collapsi vest
that unless properly maintained the probability of collapse at, the time when Beaded is ureertatae For
{these teasons, revolving doors have not been recognized as exits in places of assembly, in schools, in insti
futonel buildings, and at the base of required stairways in all buildings, but their use has not been pro-
hibited for other than exit purposes.
The studies of rate of flow through doorways did not indicate that an increase in width of revolving doors
increased the flow through them to any appreciable extent. ‘The revolving doot {u actual practice is @ 1.
line door, ie, accominodates butt Als of persone. “At tis nore evolving speed 1 person can be accom-
Modated in the space between each 2 leaves of the door, but observations made on these doors in actual
tse indent that this ow | leat steady. “Also unless properly maintained, as the doors beoome worn from
e evolving speed increase, thus hampering a normal ‘persons through the doorway.
aaieee, considerations led to the decision that only part credit should be given revolving doors as means of

To insure safe egress it was decided to limit the total number. of revolving doors that might be used to 50
eteent of the required exit width, and to » fuard against the possibility of the revolving door falling totune-
fon, due either to mechanical faults or to the pressure of a crowd against tho door, itis required that revolys
ing doors be supplemented by swinging doors.



Design and Construction of Building Exits 51

Section 7~2. Kinds of Exits.

- Exits * shall consist of stairways, horizontal exits, passageways,
doorways providing direct exit to a street or to an exterior open
space leading to a street; or ramps, designed, constructed, and ar-
ranged as specified in this’ chapter.

Section 7-3..Mmimum Number of Exits.
7-3-1. Room Doorways.*
Where floor areas are divided into rooms every room: occupied: by
100 or more persons shall have at least 2 doorways as remote from

miThe torm “exits” rolers to the mandatory under recommended minimum
‘Means crotrest provided in adtion to Shoezitsconiained in therecommended minimum require

menteare nor subject to Hations of witb, construction, eto, However, inorder to ish between
uch mune of ress and tie oxito required, ine latter rust bo 0 markod that Tuer functions plainly ve
dent to any oeoupants, | Geter 78) _ Hallways, lobbies, and ordinary roots doorways, except in

are not Means of reaching an exit. Requirements cover-
ing fag the width of pala rvays and Soe ibis ‘ave es Deon tncluded in order fo ieeuateln relationships
cheprear gan be per ted in the diction of ext travel or “bottlo nocksTM wow be creates, thus materiel

roan tion of exit travel or “1 vould bo exeatod thus i

Teducing the egress eflicloney. ‘This principle is elementary.

Fire towers or smokeproof towers have long been regarded as very desirable means of egress and believed
by some to possess certkin advantages not found in the ordinary enclosed stairway. ‘heir principal char.
Seteristiols hat thoy are tescled by tenn Of Vest vestibales ot balconies opening to tbe outer air fo fbat sma
and fre cannot dlsctly enter the stairway from the building itself. Some codes ‘their installation
mosndatory in certain height, However, to give special credit to fire towers seems 1 ogical

a certain amount of exit width toust be provided in aay eveut in order to provide egress for

Tecan yeats many questions have been raised es to the supposed advantages of fire towers, pits

‘have been advanced by competent persons to the effect that these towers, while desirable, do not possess suf-

ficient extra advantage over the stairway to Justify making their use mandatory. They might well

led because of their immunity from smoke in cases w! here the extra expense involved in its construc;

Hop isnot a deciding ‘Where used, the details of constraction for fire towers should be at least equal
to, those recommended in the Building “Exits Code, as approved By the American Standards Associ

‘The term “exit passageway” has @ special Meaning as indicated by the definition. (See p. 46.) Ordl-

i from the base of a. a gtacenyf ine outside of tho building.

Halo includes ooridors such as are frequentiy found in Sheaters and other places of assembly, which furnish

8

‘@ means of getting ‘fro so-called, to
rays, while not in themselves exits, except in sPeolal cases, provide means of r
exit. However, there is a point at which it becomes ne ‘in the interes of etecy to make certs ro
Seed tae Se inert ig er ie ote
: D7
of occupants, should havea in minimam number of exits, the n1 with the class of occu-

uber vi
section deals not only with the minimum number of exits in buildings of different occupancy,
its from different portions of tho building.

“th Iceolatng tho regurenonts fhe room may be takeb as the starting point of travel to the street, A
of 100 persons has be ithe whieh 2 sgom deorars ‘are required. At the rate

of travel estimated through doo inch unit ot ‘Width, 9 room cocupied by
100 persons could be emptied through 2 pe ooras i sin approsiataly ‘minute. This is’ safe interval of

time to be assumed in arriving at emergency re¢ Calculations for the requir red sgeroyate wid!
vided in section 7-8-1 ‘of ts chapter, bat section F-1 is concerned ouly Site the male

expression ‘‘as remote e hrom each other as practicable” is used several times in this report and bas

‘been inserted to give both the desis ulin official some latitude in regard arrangement of

ere ar ee ae et
cea ises oth eat Sg Senn

two situations are presented in ‘white I it ‘ny ‘not be feasible for various ‘reasons t0 Provide such an arrange-

POR

20 POP POP POP
J+} - 700 150 #0

POP
20

POP POP POP POP POR
20 20 20 20 - 20.

Ficunz 1.—Doorways placed “as remote as practicable.”


Design and Construction of Building Exits 49

Type 1. Fully protected—Fully protected construction is that in
which walls are of masonry or of reinforced concrete and the struc-
tural members are of incombustible materials having an ultimate fire
resistance sufficient to withstand the hazard involved in the occu-
pancy, but not less than 4 hours for bearing walls, fire walls, party
walls, piers, columns, trusses, and for girders which support walls;
2% hours for walls and girders not otherwise specified, floors including
beams and girders, for roofs; and in which the degree of fire
resistance for other construction features and the materials acceptable
for the purpose are as given in chapter 11. : .

Type 2. Protected.—-Protected construction is that in which walls
are of masonry or reinforced concrete and the structural members
have an ultimate fire resistance of not less than 4 hours for fire walls
and party walls; 3 hours for bearing walls, piers, trusses other than
roof trusses, and columns and girders supporting walls; 2 hours for
walls, columns, and girders not otherwise specified ; 1} hours for floors,
including beams and girders, roof trusses except as provided for in
section 11~2-3, and for roofs except as provided for in section 11-8-1;
and in which the degree of fire resistance required for other construc-
tion features and the materials acceptable for the purpose are as
given in chapter 11 {of BH14).

Type 8. Heavy timber —Heavy-timber construction is that in which
walls are of masonry or reinforced concrete and the interior framing
is. of timbers, or, in part, of protected steel or reinforced concrete
having an ultimate fire resistance of at least 1 hour, except for roof
trusses as specified in section 11~2-4, the plank floors and roof being
arranged in heavy solid masses and smooth flat surfaces, avoiding
thin sections, sharp projections, and concealed or inaccessible spaces;
and in which the ee of fire resistance required for other con-
struction features and the materials acceptable for the purpose are
as given in chapter 11 (of BH14). .

. Lype 4. Masonry wall and joist—Masonry-wall and joist construc-

~ tion is that not included in type 3 in which the exterior walls are of

masonry or reinforced concrete and the interior framing is partly
or wholly of wood or unprotected iron or steel.

Type 5. Wood frame.—Wood-frame construction is that in which

structural parts and materials are of wood or are dependent upon a
wood frame for support, including construction having an incom-
bustible exterior veneer.
. Type 6. Unprotected metal._—Unprotected-metal construction is that
in which the imposed loads aré carried by an unprotected metal frame
and in which the exterior walls and roof are of sheet metal. or other
incombustible material.

1 The reference to chapter 11 is to the same chapter number in BS BHI4 (1931).


Design and Construction of Building Exits 55

the exit stairways shall have stairs or a stationary iron ladder leading
directly to the street from the story in which such boiler or su
apparatus is located, or some other additional exit by means of an
enclosed stairway or a horizontal exit.
Section 7-4, Location of Exits.

7-4-1. Distance to Exits.

Exits shall be so located that no point in a floor area, room or
space, served by them is more than 100 feet distant from an exit,
measured along the line of travel; provided, that in office buildings,
and in buil sprinklered throughout, this distance shall be not
more than 150 feet.“ In the case of floor areas subdivided into apart-
ments or small rooms, as in office buildings and hotels, the distance

shall be taken from ‘the corridor entrance to such rooms to the
nearest exit.

7-4-2. Distribution of Exits.¥_

Where a floor is required to have 2 exits, they shall be placed as
remote from each other as practicable.

® The requirement the maximum distance which must be traveled to, reach an exit is the chief
tnctor conttaliag tbe location of exits. It is ot maiclgne, to require a certain minimum number of exits;
the building tions must go further and limit the distance traveled to reach an exit in order to locate
af mee immediate reach of the occupants, and thus prevent any serious delay in reaching

dee this distance depends upon the oocupancy; in others, the type of construction controls.
se dna’ of ib et bs been Selected as» practical compromise between the two methods and ss repre-
senting & reasonal i 1am ae might be imposed. Specia} occupancies Possessing unt usual hazards
‘will of course, require shorter dita these distances may well be left to the judgment ofthe building
oficial. A hazard elastin nscationneflor references contained in the Building Exits Code approved by the
* Otis buildings because of the character ofthe aocupancy, the Jow-havard contents ofthe building, and
‘the customary subdivision of the floor areas, are permitted is distance
Bpriablered buildings also bave ben perniittad an tacrease on tho assumption that Aes ie such bulldogs
Will be checked promptly before assuming suficient Donations to eat of the ine of of retreat.

In the case of undivided floor areas, the distance to the exit is measured 8 straight line. In other cases,
the distanoe is measured along the normal pathol travah sae as ooridors af ‘hallways, from the room
snfrunce to the nearest exit

tions to this requirement, #00 soetion 7-3-2,

1; }ropet distribution of exits i very important. Elsewhere maximum distanees from a given point on
the floor are given, but this does not prevent concentrating all stairways near a given polat with the result
thataalghtbecitot by enact Bo vitals his requirement that some experienced oficials advocate

TR,

Z
wa a
L

~y ~ >a

|

Fraune 4.—Distribution of stairways in a building where services are in a central core.



Design and Construction of Building Exits 59

Séction 7-6. Stairways.
7-6-1. Width.
7-6-1-1. Minimum Width.

The minimum unobstructed width of every exit stairway, except
for handrails projecting inward not more than 3% inches on each si de,
shall be not less than 2 units of 22.inches-each; provided, that in in-
stitutional occupancies, exit stairways serving bedridden patients, shall
be not less than 48 inches in width; and provided, further, that in
buildings whose occupancy comes under class 4,. business, or class 5,

garages, hangars, barns, and which are occupied by a single tenant a
and limited in occupancy to 50 persons, and in case of exit stairways
leading to roofs other than roof gardens and similar occupancies, such
width shall.be at least 36 inches.

7-6-1-2. Aggregate Width.

Exit stairways shall be supplied in accordance with the following

requirements, using the limitations and assumptions * given in this
chapter.

{jin the opinion of many who have studied the matter, 22 inches can be taken as the width ofa fe of
people In motion. lis origin is sald to be in experience gained in, the Anny. A gatroray we widt
Enches will parm 9 fies of people to move = frly down the start ot the sam les Where
fire drills are commion, the 44-inch width is tho ondeniy movement of 2 files where indivigeals walk
side by side. ‘This width is measured between walls, or frou Wall to center lige of hand rail or balustrade,
In ease sido of the stairway is open.” It's the mvoution of tus ection to prohibit any building consornetid
‘such as beams, columans, chimneys, etc., from encroaching on this space and reducing the required width.
For wide stairways; the fonnding or splaying of omers on landings is considered advantageous in

ating points at which obstruction might occur to the
Honaat as a rot estate eoanpa roar to hat a an fice Dungy oe
it as, fc le, & te company’s 4 Ve 36-inc .
Eefred sutton sufficient for the number of ans allowed a ‘some economy in construction,

re ooculy
hes bat they are not used for such inches is permitted.

The minimum number of stairways "must be aia fo mest sae revious requirements and these stalr~

distributed that the distance traveled to reach joes not exceed the

Sthorwise fined. The fava ‘eeretate widths then computed by Spotbod desoribed in section 7-0-1
and if additional wideh is required the designer is given the ‘option ot providing extra stairways or of in-
‘reaalng tho width of those fou ‘required to fulfill the other two conditions. 1d designers have stated
that the number of stairways inthe majority of buildings is governed by the minimum number and

um distance to an 4s probably trae in having 4 slight density of population,
such as the average ote

Satine
te width take into eosonnt the advantages and disad vantages of the various
methods in-use, ‘The & type of sonstraction of the building does not aflect the aggregate width of stalrways,
The class of occupancy does, however, control the ageregate width of stairways as indicated by the divi-
Slon factors as given on page 60. Buildings in which people sleep or are housed for care or medical treat~
Bel Sn Drovided with greater stairway width for a given population pet floor than buildings housing

Tn biving a th att the division factors, the traMe studies provided valusble information. Those counts were
made for d wore obiained under sufficiently g conditions to give a general
Sversce,” Tbe studies took into seovene ‘not only tho rate of movessont su stairs ut aso the oa capacity of
stair of diferent width Poe 1y ils enabled the eonaunittes to determine whether any slvantage ina
or. "tai using wide stairs in. preference to narrowel

idee iatw bh Doplesiee or are boased for ‘care of any is desirable that the stairs be made

jough to provide a place of efuge for the ‘population if the need arises. On tbe other hand, the otfes
pee cf store, containing 8 Popalation necessarity alert and able-bodied, Jeod ot tse Ie staan 8
refuge ince i anus are fo gain Lauth beadway balore beg discovered sid the cosa

The ‘apkeal ‘sbeh stale bovine etarn Ian dings will sesommodate 94 persons in a 10-oot story helght
‘assuming 2 persons for each tread an: for each 134 square feet of 1d lan
absolute capacity a 0g will paras ate any movement. As a practical matter, however, ts aalialy
t the stairway wil galled upon to aocommodate its full ity, since some of the occupants
Of the lower stories to escape during the first few minutes of the alarm, and thus provide more
for the remain! i population ‘At the rato of flow found im stairways in which people are moving
owt intron i ‘one another, 45 persons can be discharged per minute for each 22 inches

computation for: sO width of exits are given in the ensuing raphs.
in hel 6,000 sauare fet in ara forthe fst 12 stores Inits height
‘stories. The lon per floor, unless Jen he

ea oor mihin te tt, 12stories. | By'this section 360/60 will
for the doors up to and including the oth ere the set back
oocura for this particular case. At the 13t Biot which is 24,000 square feet in area the population would be
my = Mo. hen 240/60~ four Z-inch units of exit stairway Toduired for that fgor and these above,
Teshould be noted, of couree, Coat coucontation of poseialon oo teriatecach te Aen ae ee
aggregate width of exit, stalrways for that floor and, inasmuch as exit width cannot diminish in the direction

of ext travel this would fx the width of the exit stairways from that floor downward to eventual discharge.
Given a hotel butiding 16) stortes ia height and 15,000 square feet in area. An auditorium of 7,500 square
feet is located on the floor. The population on the typical Boors will be 15,000/125, or 120 per floor.



Design and Construction of Building Exits 47

~. Fire door —-A door construction consisting of door, frame, and sill,
which under approved fire-test conditions meets the requirements for
the location-in which it is to be used.

Fire window.—A window consisting of frame, sash, and glazing
which under approved fire-test conditions meets the requirements for
the location in which it is to be used. :

Floor area,—An area enclosed by exterior walls or by walls or parti-
tions having at least 2 hours’ ultimate fire resistance.

Grade —(a) For buildings adjoining 1 street only, the elevation
of the sidewalk at the center of that wall which adjoins street; (b)
for buildings adjoining more than 1 street, the average of the eleva-
tions of the sidewalk at centers of all walls adjoining streets; and (c)
for buildings having no wall adjoining the street, the average level
of the ground (finished surface) adjacent to the exterior walls of the
building. All walls approximately parallel to and not more than 5
feet from a street line are to be considered as adjoining a street.

Hereafter —The time after this code is ado; ted. :

Heretofore.—The time before this code is adopted.

Horizontal exit—The opening or passage between any 2 floor areas,
whether in the same structure or not, by means of a vestibule, by an
open-air balcony or bridge, or through a fire wall or a partition having
an ultimate fire resistance of at least 2 hours.

; Occupied.—As applied to a building, shall be construed as though
followed by the words, “or intended, arranged, or designed. to be
occupied.” .

Place of assembly.—A room, floor area, or building seating or accom-
modating 100 persons or more and used as a place for meetings, per-
formances, and other gatherings.

Required Complying with'a mandatory clause of this chapter.

Self-closing —As applied to a fire door or other opening protective,
means normally closed and equipped with an approved device which
will insure prompt closing after having been openéd.

Sprinklered.—Equipped' with an approved automatic sprinkler
system.

Stairway.—One or more flights of stairs and the necessary landings
and platforms connecting them, which provide a continuous and
uninterrupted passage from 1 story to another in a building or
structure. :

Story—That portion of a building included between a floor and
the floor or roof next above. .

- Street.—A highway or thoroughfare dedicated or devoted to public
use by legal mapping, user, or other lawful manner; and includes
avenue, road, alley, lane, boulevard, terrace, concourse, driveway,

lewalk. -

Theater.—A place of assembly in which movable scenery is used or
moving pictures are shown.

Ultimate fire resistance.—Resistance shown when tested under. the
conditions prescribed in the standard fire test approved by the Ameri-
can Standards Association as “American Standard.”

3. CLASSIFICATIONS

Classifications of buildings by occupancy and by type of construc-
tion are to be found in the report of the Department of Commerce


19

tion of Building Exits

and Construct

jesugn

D

“81489 J0 puo 48 seq07300

o on ° o jo fF |b Soe we or Ono's e
1 on 0 o 0 ci .4 124 vee a 008 2r &
0 oN 0 0 0 eet or oe % 0099 ¥
g ON 0 0 0 ow ye | eo ut 89 003 ‘OT ¥

on 0 0 0 se |e 09 ae 09 our |g
& oN 0 Or 0 Bid g oF 09 on 908 Fe g
z oN, 0 0 40 we | F a sor oF 000'6 @
z on 0 o jo { |e js ee % ott |g
z oN 0 ° 0 % 1s 4 ee a 008 8 9
& oN 0 0 0 8h Ed 9 808 @ oot's 9
T on 0 0 0 gt 99 9
1 oN 0 ° 0 eo yt 06 2
z on iy oO oO ow & 09 sig &. 008 8. 6
z oN 0 oO 0 ow ‘4 09 008 4 0099 6
& oN 0 0 0 oe & oor Te oF 002 ‘St 6
& . o 0 0. a c so 4g we 008 ‘or. or
T of 9 o r fag T 9g ue as 0089. or
& oN 0 oO Oo 68 z ‘98T AIL Ost a a9
é oN $ Yr fs fe Te fs mo ik oe at
.7 0

“ : q cy abs ‘yds
mpi | ON | WIPE] “ON | groaoy | WPI | “ONT
sist a" ox SAE | wore | o$22% an | woe soup | SORE ‘ox spn
Porolanhds 1x0 seq cememreeyy | #8 85020 | donsimdog D | ap angie pune
poredhpog, | Sdvosens | -OAN | shears "

1158—35—4

NOMOAULSNOO TALLSISAW-AUIL
squsmainenau 7129 Burpying juswzindy fo hsnwung— oy G1avy,


Design and Construction.of Building Exits 37

number of persons discharged per unit of time remained nearly con-
stant—that is, with rapid movement necessitating considerable space
between the individuals, the number of people discharged per unit
of time remained the same as when the movement was slower but
therefore denser. This condition has been noted in other tests.

Discharge rates as related to stairway width indicated a number of
possibilities. For average conditions of stairways varying in width
from 3 or 4 feet. up to.6.or 7 feet, the number of persons discharged
might’ be taken as roughly proportional to’ the width of the stairway.
On the other hand, stairways 3 or 4 feet wide appeared to give much
higher rates of discharge per foot of width than those 7 or 8 feet wide,
especially where the wider stairs had no intermediate handrails.
Even where an overflow was waiting to enter a stairway, a condition
existing on the stairway (8 feet 1 inch wide) in the Grand Central
Terminal, as soon as the crowd entered the stair it became scattered
and the discharge rate was therefore reduced. .

Observations of the characteristics of the movement on stairways
showed that the movement was slower end denser on the first half of
any flight than it was on the second half. Increased space between
individuals resulting in faster. movement took place after the inter-
mediate landing was passed. In both flights, the appearance of the
movement under random flow appeared similar. Whenever a rank
of people formed to take up the complete width of the stairway, it
was invariably followed by a lesser number, so the final effect might
be said to resemble series of successive wedge-shaped units dis-
tributed rather evenly over. the length of the flight. Conditions of
maximum flow did not occur unless a number of people were waiting
to enter an exit. .

‘The space occupied per person while moving up or down a stair-
may necessarily varies widely with the speed of the movement.
Table 19, page 35, shows the fluctuation in these figures. Although
under fast discharge a little over 4 square feet is occupied per person,
when ithe discharge ‘is leisurely nearly double this space will be
occupied.

9. RAMPS

Studies on ramps were difficult to make as very few could be
located that were used to anything near capacity. Table 20, below,
lists the results of some 30 observations made on 2 ramps in the

TABLE 20.—Summary of observations of traffic movement on ramps

Number of per-| Number of

per toot of width| occupied pe

Grand Central [Per Mh occupied Per | Di

Terminal track| Width of | tengtn | slope | Area |. Pet minute | person a,
nos. remp travel

Aver- | Maxi | Aver- | Mini-
age | mum | age | mum

ft jin | ot | io sa ft
rinow..| asif BP Bb
lin so) |

&
§

e
e
x
§

Grand Central Terminal used by commuters. Wider ramps: were
also observed in the terminal, but, inasmuch as they never seemed to


68 Miscellaneous Publications, National Bureau of Standards

Credit of 50 percent of a unit shall be allowed for 12 inches or more:
of width added to 1 or more full 22-inch units of doorway width.

The ate width of exit doorways to the outside of a building:
from aisles, lobbies, hallways, or passageways in which a single exit.
stairway discharges shall be at least equal to the width of the exit
stairway. If there is more than one such exit stairway, the exit door-
ways to the outside shall be at least equal: in aggregate width to
three-fourths the combined width of the exit stairways. The aggre-
gate width of the exit doorways shall be further increased at the rate
of 22 inches per 100 persons for any additional persons on the floor
served by such exit doorways.

loorway width. "This would result in a total required width of 2units or 44 inches in the caseshown.
However, beckuse the minimum ‘Buber of doorways! required by section 2-2 would be and because

passageway,
Frbich would make it necessary to add 1 unit of exit width to the width of the stairway, giving a totel of 06
b ay. ‘The other door serving the
ground-floor population would have to be at least 1 unit wide by calculation, but would be further gov-
erned by the requirement of 36 inches minimum width.
In sketch 8, figure 16, 2 stairways discharge into a passageway which also setves a portion of the ground-
Population. Under the requirement the doorway width leading from the passageway would be 3
(44+-44) plus 22 inches for the portion of the ground-floor population served, as explained in the previous
example, This would result in a total of 88 inches, which would. be satisfied by two 44-inch doorways. The
other doorway serving the ground-floor population would be. 36 inches wide as before.

Pa :

20" 200 . 702200 Por 200

’ . s
Fiavre 16.—Ezample for computation of doorway widths.

Zhe Permission for several stairways to discharge into a passageway only three-quarters the combined

Fide of these stairways is an apparent variation of the rule that the exit width should never aleunn vo

the direction of exit travel. Actus

fegeway can discharge at a rate four-thirds as fast as the stairways. In the caso of | stalrway the socernon
‘y stairway whether this-

width were needed for exit purposes or not. In ‘the case of several stairways, however, the sum of their

idth of passageway.
Jn the above examples, occupants have been provided with means of escape involving a combination of
floorways, passageways, and stairways. ‘The width of stairways is determined by the population of upper
floors as set forth in section 7-4-1. The width of the doorways leading from the baildlog is detertatuey sa
{he manner just explained. ‘The width of the passageways connecting those doorways with the beet of the:
Sainrays is governed by the width of the doorways.ssset forth in section 7-9. ‘The width of doorware
entering stalrwaysat any given floor may vary with (ho Population on that floor.
it was noted at the fre drill ofa large building in which the stairway trom the upper floors discharged into
{hehellways sorving the ground foor, thet 8 stoppage occurred at the ground-floor exit door due to the join-
ing of the streams of from the stairway and the ground floor, indicating that, although the exit.
doorway was wide enough for the ground-floor population, its wideh had not besn increased voeare tor ste
Gischarge from the stairway. ‘The stoppage was sufficiont to back up the stream of trailio to suckna cotocy
that the occupants of the stairway were compelled to remain stationary until the dootway hed bess ce seea
and the forward movement down the stairs @ Fesumed. Panic spreads quickly under such condi
“lons and a jam with consequent blocking of the stairway would seam almost inevitable asses of cere a





Design and Construction of Building Exits 7

The floors and ceilings of exit passageways shall have-an ultimate
fire resistance at least equal to that required for the type of construc-
tion of the building in which they occur, but not’ less than 1% hours.

7-9-2-2, Openings.

No openings other than the exit doorways leading into or out of an
exit passageway, ‘and windows to the outer air, be permitted.
Exit doorways, except those from enclosed stairways discharging
into exit passageways and those to the exterior of the building, s
be equipped with approved self-closing fire doors.

7-9-3. Inclined Exit Passageways.

To overcome differences in level within exit passageways gradients
of not.more than 1 foot in 10 feet or flights of stairs having not less
than 3 risers shall be used; provided, that at a doorway leading into
‘an exit passageway or at the foot of an exit stairway, the floor shall
‘be level across the entire width of such passageway and along its length
in the case of the doorway for.a distance of not less than 12 inches on
each side of the doorway, and in the case of an exit stairway for a
distance of not less than 25 inches at the foot of such stairway.

Section 7-10. Hallways.

‘The width © of a hallway shall be at least equal tothe width of the
exit doorway to which it leads.

© Asin the stairway enclosure, it is necessary that the openings in the passageway be kept ata minimum,
An exception to the requirement might be made in the crse of doors to toilet rooms or service closets.
‘# From the very nature of the jeway it is frequently necessary that difference of elevation-be over-
m passogeway leading occupants of the orchestra floor of a theater to level.
Hights of stairs are objectionable for obvious is. Ram)

reasons mss ‘on the other hand, are very desirable, if
space its and the slope can be kept within reasonable limits. In.order to make the walkway safe and
to avotd tripping or falling at doorways or at the foot of stairways, certain level landings are required by
this section as iiustrated in figure 18.
7 pe
| ae cll.
\LEVEL! RAMP LEVEL RAMP CeVEL
1d
g y a)
2
S| eane - g RAMP y RAMP
s 4 4

Fraune 18.—Level landings required on inclined passageways.
© The required width of exit doorways which controls hallway width is given in section 7-6-1.


“70 - Miscellaneous Publications, National Bureau of Standards

Credit for revolving doors serving exit doorways shall be made only
at the rate of ono-half unit of exit width for each door. Such doors
shall not be located immediately at the foot of exit stairways. Such
doors shall not exceed 50 percent of the required width of exit doors
and there shall be at least. one swinging door for each revolving door
in the same general exit opening.

7-8-4, Door Fastenings.!

Fastenings on doors serving exit doorways shall be such that the
doors may be readily opened-from. the inside without the use of keys
during the time when the building is occupied, but this requirement
shall not apply to the doors of rooms where persons are under legal
restraint.
Section 7-9. Exit Passageways.”

7-9-1. Width,

The clear width of exit passageways shall be at least equal to the
width of the exit doorways leading from them to the exterior of
the, building. :

7-9-2. Enclosures.
7-9-2-1, Construction. .

The walls of exit passageways shall have an ultimate fire resistance

of not less than 2 hours. °

RE UNITS 3 UNITS
3 UNITS
POR POR POR
600 600 600
SUNITS SUNITS
13 UNITS
ONITS
d 2 3s

Figure 17.—Ezample for computation of exit passageway wit

£t The survey of exit facilities in buildings revealod that many exit doors are kept locked during the time
“when the bulldings are occupied, and testimony of buldnng offcisis naterian eae practice is extremely
Gifficult to prevent. Nevertheless, the necessity of detecting such violations is of primary importance.
Doorways, passageways, and stairways may be of ample size and properly designed and distributed to
accommodate the popalstion, yet one padlocked exit, door may be sulliciont to dsfent every effort to secare
‘safe and provapt egress. Exit doors are not usually locked in an eflort to invite calamity; they are locked.
2.8 matter of operating convenience or because of Poor maintenance, and it is only by conscientious inspee-
‘tion and the exercise of vigilance on the part of building inspectors and firo marshals, reinforced by severe
Penalties for violations, that such practices can be abolished,

soatrequiting the width of exit passageways to be at lexst equal Yo the width of exit doorways leading from
them to the exteriot-of the building, an attempt was made to simplify the method of desizn and eliminate.
‘any unnecessary computations. It Is obvious that there is no advantage in making te passageway any

ler than the door or doors at the ends and hence, once the exit doorway width hes been established, all

‘that is required is that the passageway shall have the same width.

© ‘The pastageway must provide protection to the occupants fot an interval edequate to evacuate the space
served by the passageway. ‘To do this, the enclosure must have sufficient fire resistance to withstand fane
and smoke penetration for at least the time required to complete the evacuation with some margin of safety
follow for-an interval between the start of the fire.and the sounding of the alarm. This section, which i
‘taken from the Building Code Committee's report entitled “ Recommended Minimum Requirements for
Fire Resistance tn Duildinge”, is intended to provide this protections



Design and Construction of Building Exits 73

~ Rorizontal exits complying with the requirements of this section
may be substituted for stairways or other exits.” _ .
estibules, open-air balconies, or bridges serving as horizontal

exits shall be constructed of incombustible materials and their clear
width shall be at least equal to the width of the exit doorway opening
into them. ce

Doorways or windows opening on, below, or within 10 feet of such
vestibules, balconies, or bridges shall be equipped with approved
self-closing fire doors or approved stationary fire windows.

Where there is a difference in level between the connected floor
areas, gradients of not more than 1 foot in 10 feet shall be provided.
No stairs or steps shall be used in a horizontal exit.”

Section 7-12. Modifications in Required Exit Widths.”

There shell be no reduction in required width along the line of exit
travel, except as specifically permitted in this chapter.

Section 7-13. Exit Designation.”
“ 7-13-1. Exit Signs.

Exits shall be indicated by suitable signs or lights at all times when
the building is occupied. In places of assembly accommodating more
than 100 persons exits shall be plainly marked by approved signs,
sufficiently illuminated when such places are occupied, to be readily
distinguished. a,
~, In places of assembly exit lights and lights used for the illumina-
tion of exit signs and lights for the lighting of halls, corridors, and
any other parts of places of assembly used by the audience, except
‘the general. auditorium lighting, shall be fed independently of the
stage lighting, and shall be controlled only from the lobby or other
convenient place in the front of the house.

In buildings where exit lights or signs or the exits themselves are
not visible from every point in a hallway or undivided floor area,
suitable directional ‘signs indicating the location of the exit shall be
provided.

inthis provision is intended to prevent the substitution of a horizontal exit on a single floor for a stalrwa
through the entire height of the building, Its effect would be to provide a horizontal exit on
floor served by the stairway allowed to be eliminated. Such an arrangement may sometimes be advanta-
‘geous as is shown in the following example: A factory containing 3 floors of 60,000 square feet each has a ite
Frail extending up through the bullding dividing it into 2 approximately equal sections each of which con-
tains 2 stairways, By providing a horizontal exit of suitable size in the wall, 1 stairway can be eliminated
the wall, reducing the total number of stairways in the building trom 4 to 2,

2! Where the bridge or balcony is not enclosed and the climate such as to Involve the possible blocking of
the doors by snow or ice, it is desirable to place the level of the ‘bridge floor below the jovel of the buil
floor by the beignt of an ordinary riser—7}4 inebes. Otherwise the building floor level and the baloony or
bridge-floor level may same.
seconcering reduction in doorway width where the popalation from 2 or more stairways merges, see

18 Adequate exit marking, although often Roplected, is an essential ature to secure safe ogress. This is

Particularly true in those buildings frequented by transients, who cannot be expected to be familiar with
the location of exits,

i ings are held,
Froperly designed and placed exit signs should not detract from the beauty of the fnterior of a church and
there can be no question as to thelr value in promoting safe egress should a fire occur.
cosh? Teauirements of section 7-13-1 are based on the recommendations of the National Electrical Safety

The reasonableness of the requirements for exit designation would seem to beso obvious as to make thelr
{ncorporation in a code unnecessary. Yet the most casual observation will reveal how infrequently the
rovisions are carried out. In these days of high-speed elevators the tenant of the average office pailaing:
tel, oF apartment bouse may not even know the location of the stairway and certainly bas but small
Gocasion to use it to the extent of becoming familiar with it at different floor levels. This fact emphasizes
fhe importance of marking the streot-level door of the stairway so that there can be no mistaking when that
level has been reached. In the confusion attending a fire the occupants might easily follow the stairway
gowns into the basement and lose valuable time in seeking egress to the street uniess the street level was


30 Miscellaneous Publications, National Bureau of Standards

Iv. SURVEY OF TRAFFIC MOVEMENT IN EXITS
1, PROCEDURE

The-rate at which people normally ascend or descend stairways, or
pass through hallways and doorways, is of primary interest to those
responsible for exit design. Knowledge of this rate enables the de-
signer to adjust his exit widths more rationally to the building popu-
lation, and as they should relate to each other if efficiency and economy
are to be secured,

The joint conference already mentioned believed that as a comple-
ment to the survey of current design practice found in buildings erected
within the past 10 years, a survey of traffic movement in exits would
help in pointing the way to more logical conclusions for exit require-
ments.” :

The staff of the Department of Commerce Committee, after com=
pleting the inspection of exits in existing buildings, then proceeded
to secure data.on the movement of people through exits. The
second survey was carried out in much the same manner as the first—
by office and field studies—for it was found that preliminary office
investigation not only contributed largely to the total information but
also revealed those points on which a field investigation might well
be concentrated. . .

The inquiry. was to include: (1) The relation of discharge rate to
exit width; (2) the difference between rate of flow up and down stair-
ways and the relation of rates of flow on stairways to rates on ramps,
on the level, and through doors; and (3) the number of square feet
occupied per person in exits when discharging crowds of people.
It was hoped that sufficient evidence could be secured to answer con-
troversial questions, to check existing data on the. subject, and to
determine what basic facts, if any, had not been developed.

2. SOURCES OF INFORMATION

Many observations have undoubtedly been made on the rate at
which crowds of people normally move thro different types of
exits. ‘The complete data readily available on observed conditions of
this movement are, however, rather meager.

A number of. traffic observations have been made in the past by
engineers of railroad companies as an aid in the design of terminal
stations. The Illinois: Central Railroad courteously supplied the
detailed traffic-studies made in connection with the Chicago Terminal
Improvement, summaries of which appear in volumes 25 and 26 of
“the: Proceedings of the American Railway Engineering Association.”
The frm of Jacobs and Davies, Inc., furnished a reprint of a paper by
J. Vipond Davies and J. Hollis Wells, presented before the American

Institute. of Architects at Washington, D. C., December 16, 1909:
‘This paper.contained summaries on traffic counts made at congested
points in New York City as a preliminary step in the Hudson Terminal

le : .

; conference, also had the benefit of studies conducted by the
Committee on Safety to Life of the National Fire Protection Associ-
ation. The findings of this committee are discussed in the Proceedings

¥-Vol. 25, pages 512 to 524 (1924); vol.-28, pages 728 to 734 (1925).



16 Miscellaneous Publications, National Bureau of Standards

‘00H 4ST 09 DE UO soyOUT OCT SLBATEIS UOT ¢

“areas wopoom opisino + “2009 De 38 spus Lows1078 UOULZp
“£0 005 BFF UO » “Supra 043 30 745109 TN} Om ME sIOFBASTGE ¢
o on, eee Ce eee o ° @ t * 060° z
NOMOAULSNOO TWVEE
1 oN 0 0 0 Ha { 08 0089 cd
° on 0 0 0 gB t 6 oos‘ot fe
z oN 0 0 0 g F oor oot |e
& Ox r % t ° % if cc) 006'¢ ’
NOMLOAULSNOO LSIOL CNV 'TIVM-AUNOSVN
1 oN ° ° o | Eo our fe
o eK 0 ° 0 Ge z oor woe fe
0 0K ° o o «6h i jos ou fe
0 ont ° z 0 F z ae 008’ £
z on t) 0 0 o t 96 0076 ¥
z os ° 0 ° ® r out wos’ | F
8 eA o oe ee 4 2} oor aero
z on 0 o ° ® {t ont 000'9 L
9 ox ° 0 ° 4 t 98 eur fe
& x 0 0 ° g fe jf mt ore 18
“a 4" abs
praqesere mapiak | “ON | wAPLA | ON | somoy | MPM | ON | grower | —ggyy | sonore
yo soqainy | pexepupag 919 30 somes | soos) a ‘on supine
syyx0 pe]OZOH sodvos ong — | 7UAN shearers helms war

NOMOAULSNOO TAMSISHU-AULE
sfusmoinsvam pre Burpiing aioe fo fupuung—)y wavy,


22

“Alo S100 puodes PUB ISN} TO 4x0 [eRULTTIONT »
“20H Uy 07 SUM ¢

“AtmO MAGE 0} AmyEIS YOUT-g% T PUL ‘AtuO JOOG PE 04 sABAAITHYS YOUT-Gh g

“é[to 1ooy 132.07 ABAUIS GOUT-SF Ty

“2005 G19 TO ¢
“UTP oy 30 448}oy Tras e4; HI s10;8A9|9 Po}oT osyamLroNI0 HOTTA ¢
“dojyonssa00 Howq-308 jo soTI0}8 £4 BOTY

Miscellaneous Publications, National Bureau of Standards

ice T
sroceeceey 1 jon p-v-e-v-m-] g {| $8 1 Yo { 4 i i o ont oe oop frre tg feseernensery
NOWLOAULSNOO LEIO£ CNV TIVM-AUNOSVN
@ jon tT fo oe & | on 4 cc 02 ‘et 2]
tT JON & fo 9 8 | oF 286 %F O08 &
t Jon o jo. {{%. E jo rd % o0e“er *
T oN 0 oO w & 9 has 8 008 ,
1. jon z jo {% T Yor mm % 0009 ‘
Tt jon o jo cg T }96 18 ve 0082 lo
z jon 0 1 fo i E hoe. a ” {j oo at 9
z [on 0 0 fo % z lw a a 0099 9
z fox ° o-jo. {fe i He f 99r mo oe ‘er 8
. 000
| 00 ‘a8
or 14 4 000 {28
Pha z } ON frereeroer] Cn ee o fo %. | oer Oo vee 000 «12 (rn rns t
st T | 009 “ZT
od 13
“ay 7 TM a abe ads
11007 OL) ON wp | ON | aap | “oN WPIM | ON, jp sou 10015
suoaor deo; | “aod | ior, | 700UE soos | on
perpyuidg 01g jo eou83s}p ware wo TOR, at ‘Sappimg
ape sequin uunmpey_| soi | -eindog . 393
s10;eA0T requozog, | | | S*dv090 oxy, scouts, 1 8100g £q wore 8902p

NOMLOOULENOO TAILSISAY-OAT
squsmesnenou jxe Duspying yopideoy fo huomung—zy wavy,


‘lao umnygutTUTA8 Jo AsoTIWS oars SLATES YOUT-SY e+
*cqoo tanjsowcugs pue wanfaoyipme eas akuaLsjeie OM JO es

[Alto 1009 puooes 0} ya7g Ur03y tz s1yB78 YOUT-gy 10
“peyou espwaseyz0 ssepun ZqypITNg eNs Jo 4uBIOq TAY oy UNE
“WopjonysuoD HouG-408 Jo sep038 Aq wIY:

a
SIOWWASTST ¢
1

oO 0 Or T oo as
0 0 0 g é OF a
'
o fo: jo {8 |e} oor e
i }o ° o fz joo e
o ‘jo oO woe lon g
oO oO 0 09 ¥ oh &
oO 0 0 ic [e 00T &
T 0 0 00 or oo e
ois is ig lee i
6. Jo oo. FB IE Vee &
0 ° oO 0 & ‘sor &
o. }o ° o [es jz e
o jo 0 zo ly Jo e
o |o o TE Hoe g
0 0 o oO .4 Le ,
ojo, yo fH it Nee 8
1
" 4
‘e]
‘ponpmueopaa |e | on He-=-419 Jo o BH | BLE [poterestoseefironnnnnsnen 04) 08 nen
or
: &
4 a a
2005 oN apts | vont aapras | on ‘om
#2003 OL aaPaA sedeose | bromo greue | cosa sod | _ 2000 20H | sone
peste | Sk oe SS oie - ie | eer
‘0g 01 requeoH skemsqeyg | “OURS oHSINGCd |" sro0y Aq wore ssorp | TAPE

18 Miscellaneous Publications, National Bureau of Standards

NOMOAUISNOO HALSISHU-AUL
squuasnevou qure Burpjing jooyss fo Airwung—g wiavy,


Design and Construction of Building Exits 31

of the National Fire Protection Association, particularly those for the
years 1917 and 1918, and in the Quarterly of this association.
Other. studies on the capacity of revolving. doors, efficiency of exits in
schools, and a test.on discharge rate in a large theater completed the
information which was collected and studied before attempting a field
survey.

3. CONCLUSIONS OF PREVIOUS TRAFFIC COUNTS

Suramaries of some of the conclusions reached as a result of the
studies made by the Illinois Central Railroad and those for the
Hudson Terminal are given in table 16, as follows: .

TABLE 16,—Summary of some previous trafic movement observations ~

Slope Number of
Vertical | charged | Direct
Subject of study Width Wigut! | perteor or | ofteavel
. Rise | ‘Tread ‘width per
minute
18 | Up.
‘Btairways of I. C. R. R. 39 | Down.
: 29 | Down.
Ramp of I. C. R. R. Ba
Level passageway of I. 0. Ry 3
Stairways of Hudson Terminal. 20) Up.
Level passageways of Hudson co
‘Btairways of Rapid Transit R. R. 20] Up.
‘Syaaey, Australie: | Down.

The rate at which passengers can pass through doors was also
checked in the Illinois Central study: A double swinging door, each
leaf 3 feet wide and both leaves open, accommodated 117 persons in
1 minute, the movement being in 1 direction only. The same door,
1 leaf locked, accommodated 77 persons in 1 minute. These )
when reduced to discharge rate, show that the 6-foot opening had a
discharge rate of 19 persons per foot of width per minute, while the
3-foot opening had a discharge rate of 26 persons per foot of width
per minute.

Computations made on the number of square feet occupied per
parson on stairways, on ramps, and on Passageways checked in the

linois Central studies gave a figure of 5.7 square feet per person on
the stairways, 10.5 square feet on the ramps, and 11.1 square feet on
level passageways. The Hudson Terminal study noted 10.0 square
feet per person on a level passageway under crowded conditions, the
passageway discharging approximately 30 persons per foot of width
per minute at that time. .

A check of the discharge rate from a theater, made under the
direction of the late Philip A. Mason, when building commissioner
of Hartford, Conn., showed. stairway discharge of 13 persons per
foot of width per minute and a doorway discharge of 32 persons
foot of width per minute. These figures are the average of a number
of observations and represent a normal rate of discharge at the end
of the performance. The theater in question had a capacity of 3,200,
and was filled the night the count was taken.


Design and Construction of Building Exits 13
: 3. FIELD INVESTIGATIONS

The experience gained in the office study indicated that certain
questions which had arisen could be answered only by observation
of conditions in actual buildings. Accordingly, exit measurements
were taken and. géneral exit conditions tabulated for buildings in
Atlanta, Ga., Greenville, S. C., Greensboro, N. C., Roanoke, Va.,
Washi , D.C., Frederick and Baltimore, Md., and Pittsburgh,
Pa. These cities were chosen with a view to covering places varying
in size and sufficiently distributed to give a fair general cross section
of building construction.

The smallest city had no building code. The-codes of the others
ranged from rather sketchy requirements to those as elaborate as in
any city. . .

Buil ling officials in the cities visited rendered valuable assistance
by furnishing plans of buildings erected since 1920. After a study of
the plans, detailed measurements were taken at the dings selected
for inspection. Special attention was given to buil where people
slept or were housed for medical or other care. Buildin; managers
supplemented the field notes in some instances by generously donating
floor plans. . During the building inspection, notes were also kept on
the marking of the exits and on their maintenance. Wherever pos-
sible, figures on the population served by the exits were secured.
Questions were also ed concerning any difficulties experienced
with the exits under normal or emergency conditions. Interviews
with building officials, State labor officials, architects, and school
superintendents further enriched the field notes.

4. TABULATION OF DATA COLLECTED

Much of the information secured is too detailed to warrant publi-
cation here. However, conclusions reached are based on a study of
these plans and the mass of other data that was collected. Summaries
and tables of the more outstanding findings are included for those
particularly interested in exit design. Tables 6 to 14, beginning on
page 14, list some of the points recorded in the field survey. Table 15
gives some general averages obtained: from both the feld and the
office surveys.

_ 5. POPULATION STUDIES.

_ The figures under the heading “Population on typical floors”
given in the tables were obtained in a number of ways. In apartment
buildings the resident manager usually had accurate Knowledge of the
number of people occupying any floor; in hotels an estimate of the
pe ulation on a typical floor was made by counting the number of

and then assuming all rooms to be occupied; itt office buildings,
factories, and schools actual counts were taken’ where possible; in
theaters the number of seats was noted; and in other occupancies
accurate estimates from those in charge of the building were accepted.


72 ~~ Miscellaneous Publications, National Bureau of Standards

Section 7-11. Horizontal Exits.*”

The width ® of horizontal exits shall be determined in the same
manner as the width of exit doorways.

Horizontal exits shall be equipped with at least one approved fire
door; provided, that when located in fire walls or party walls there
shall be an approved fire door on each side of such walls, one of which
shall be a swinging, self-closing fire door. . .

The floor area on either side of a horizontal exit shall be sufficient
to hold the occupants of both floor areas, allowing not less than 3
square feet net clear area per person,

shall be at least one exit accessible to or from the space on
each side of a horizontal exit.

siirorizontal exits are considered to be a very effective means of egress, particularly for those portions of
fpstitutional ocou eles: whe fa caso of emergency, bourladen pation tea te removed from the

‘rea ex] to fire.
The horizontal exit is a most practical device for providing means of egress from one floor area of a building
{0,82 adjoining one, or trom one building to a connecting building. “Equipped with self closing or sete
Ratio Bre doors da joncrom far side of the exit becomes a place of refuge having sufficient fire resistance
{enable the occupants to make their escape in an orderly manner,
Some examples of horizontal exits are given in figure 19.

HOR. are
L-exr c008 (econo, Leis
eeoun FLOR prea Five

Lon tur Saat L woe eur

UpreR Fio0e uprce FLooe
Fraure 19.—Various types of horizontal exits.

Uf all of the effectivenses of the horizontal exit is to be utilized, it is necessary that sufficient clear
be provided on each side to bold all of the occupants of the areas on both sides

.. ‘This space may consist of
‘This is the rinimam
will serve the purpose
istive walls and fire doors

I refuge ide of & horizontal exit it is not contemplated that the
cere per Ry gmain there indefinitely, although to do so may be sale. Access inust bo provided te adantoont
Grits mebich lead to the street as the place of ultimate safety. Such additional exits mey corcetof doorways
Sostat ec roTizontal exits leading to the exterior or to hallways communicating with  ctareay won eae
Zonta! exits leading tos connecting building, or stairways leading to the street many be prewiaee en side
Pf.the horizontal exit. “Whatever the mothod employed access taust Gually be bad tre stairway or ramp

# The minimum and te width of ‘nits is determined in th that fe
exit docrmuzimum ond saeregnte width of horizontal letermined in the same manner as that for

3, From an exit standpoint, provision for a door on each side of fire wall ney provetobeawkward. ‘Two

fre, however, necessary to mest fre-resistance requirements. "A desirabl arrangement would provide

Sresfibale on one side of tho wall so that the occupants will not be Gontronted with thereon opening
‘two doors at almost the same instant.



Design and Construction of Building Exits 57

upon the hallway or lobby, such occupancies shall be provided with
an approved sprinkler system; *’ in buildings whose occupancy comes
under class 2, institutional, at least 1 exit stairway shall discharge
lirectly or through an exit. passageway to the street or to an exterior
open space leading to a street and the remaining stairways may dis-

arge into a hallway or lobby; in buildings of type 1, fully protected.
or type 2, protected construction, occupied as stores and sprinkler
throughout not more than one-half of the exit stairways from upper
floors may discharge into the ground-floor area; provided, that un-
obstructed aisles at least as wide as the stairways are maintained
from such stairways to the exit doorways.

In places of assembly no required exit shall discharge by means of
upward travel through a vertical distance of more 15 feet in
buildings of type 1, fully protected, or type 2, protected construction
nor by more than 6 feet in buildings of other types of construction;
provided, that in places of assembly occupied ‘by not more than 150
Persons such vertical distance shall not be limited.

Where there are 2 or more exit stairways serving floor areas below
grade at least 1 shall lead up directly to the street, or to an exterior
open space or exit passageway leading to a street.

In buildings of other than type 1, fully protected, or type 2, pro-
tected construction, more ‘than two stories high above grade with
roofs having a pitch of 1 foot in 4 feet or less, at least 1 exit stairway
shall continue through the roof.

Section 7-5. Relation of Population to Exits.
7-5-1, Determination of Population,

The number of persons used in determining the necessary exit
facilities on any given floor shall be the actual number * to ocoupy
the floor but in no case less than that determined by dividing the
following areas per person into the gross area * within the perimeter
of the building serving each particular occupancy at the given floor
level; for occupancies not specified the building official shall, by rule,
establish the ratio to be used:

= Provision might well be made to allow the building official to make exemptions in the case of minor
spancies not of great fire hazard,

Bot of great ¥
¥ In many insiantes Hor area are designe to accomtiodate a zed numberof parsons and that number i
customarily stated in the application for the permit. It is the intent of thissection to make use of the actual
‘umber of persons contemplated by the design when itis known, of pathaps is hed by other regalations
such as labor laws.” In casono actual number is stated, or known, the number of persons i, of Course,
determined on the basis of the areas given in this section. ' However, a minimus also provided for regard
leas of what tho design may contemplate in order to tasuro safety. ”
¢,¢ ould be noted particalarly that gross rather than net areas aro tobe used in determining the popu+
eiihe dhattstons este determined i sectfons of the repor foned to the numb
ions of exits as det in sut juent ions of the ‘t are proporti num ber
oft tg to-be acommodated. ‘The determination of the number of oceupants on any floor becomes

then of frst importance in designing exits There are numerous iethods used in godes for making these
ions and very little agreement a3 assumptions. A met! involving least
Jeborious calculation, but which gives results believed to be in reasonable aceord with acrual conditions is

the most useful. based on counts of occupants of buildings of different occupancy should be used by
‘the building official to determine the population. ee
me years ago Rudolph P. Miller, as superintendent of buildings of Manhattan, prepared a tabulation
showing the density of Population in workshops in the city of New York. The tabulation resulted from
Population counts in connection with “exit orders” in 500 workshops and factories. ‘The occupants of
each story of the buildings investigated were determined as accurately as possible and the area. cocapled ‘Per
‘Person computed from the gross area of the story. As might be expected th
‘varit in areas per person ranging from 19 to 560 square feet. ‘This variation is accounted for by the differ-
“etoteu cctec roel alo uo tery et pr aron,otehrepont
1 average for the entire group of buildings in the table was 107 square person, whi
say aly with the average figure of 100 square feet per person ado] ‘by the committee for this
A census of the Equitable Building in New York City, taken in 1924, was made available to the committee
the courtesy of C. T. Coley, operating manager of that building. Here, again, there was a con-
iderable variation, Fanging from 43 Square feet to 250 ‘Square feet per person, but the average was 107.
‘The figures given are based on the net rentable area. When converted into terms of gross area they may
‘ange from 10 to 25 percent higher. On the other hand, they are based on the persons regularly ‘employed



Design.and Construction of Building Exits 5

Taste 1.—Causes of loss of life from fires

{Excluding dwelling fires)
Occupancy
Cause Manufse-) public {Residence | Miscelia-

pane | asembly | balding | neous” | T°!)

404

334

96

76

84

72

6

5

571

1,738

925

64

163

139

178

8,207

From the reports of the New York City Fire Department, Rudolph
P. Miller, a member of the U.S. Department of Commerce Building
Code Committee, prepared an analysis of deaths resulting from fires
in New York City for the years 1920 to 1931, inclusive. The total
number of deaths by fire recorded was 1,453, with a yearly average of
121. Injuries totaled 3,384, with a yearly average of 282. The total
number of deaths by fire in buildings was 1,389, divided among occu-
pancy classifications as shown in table 2.

Tasun 2.—Deaths by fire in buildings in New York City, 1920 to 1981, inclusive
(From reports of New York City Fire Department)

Number | Percentage
Class of occupancy of deaths | ‘of deathe
Residence build
‘Dwellings: 292 21.0
Furnished room houses. 85 61
‘Multiple dwellings (3 or more families 800 a
Hotels, including lodging houses.. 14 10
Clubs... 4 03
Totat 1,195 26.0
7eReviuen tinsace septum)
lum (1 insane asylum) 25 18
‘Hospitals. 5 O38
EY 21
1 1
ories, including brewery and auto repalr shop. 80 58
Moving-picture stiudio (1 esse) 10 oT
Btores.. 5 04
‘Warebouses. B 0.9
Sheds, including pi a 08
no a8
(eee public and private.
ic anc
Biables, including barns 3 ae
Car barn. 1 0.2
36 26
3 02
5 O4
1, 380 100.0



28 Miscellaneous Publications, National Bureau of Standards
11, SPECIAL FORMS OF EXITS

‘The number of iron fire escapes still in use occasioned some surprise.
in this investigation, A further review of buildings having this type
of exit disclosed, however, that many of them had been added as a
supplement to the'existing means of egress to take care of occupancy
changes... Old wings of. buildings now enlarged accounted for a num-
ber of others. However, some recently erected buildings still made
use of fire escapes as one of two means of exit. Testimony of building
officials was ageinst the use of fire escapes on new buildings. A few
officials thought that firemen could. use outside escapes advantageously
when fighting fires. .

~ | The tables of the field survey reveal the limited use of fire towers,
spiral slide chutes, and horizontal exits. If tall buildings in New York
and Philadelphia had heen included, the total number of fire towers
found would undoubtedly be much increased. Opinions solicited on
the use of fire towers as one means of exit as compared with the use of
enclosed stairways for all means of exit in any given building favored
the enclosed stairway. Opponents of the fire tower pointed to the
increased space necessarily deducted from the rentable area where
thesé towers are required; defendants of the fire tower claimed addi-
tional safety over the enclosed stairway. Further study of the rela-
tive value of these two types of exits may be necessary before this ques-
Sion can be conclusively settled. :

Table 6, pages 14-15, lists a spiral chute in one office building of 11
stories-and in’ another of 19 stories. These chutes were unlighted
within the slide. -No check could be made of their performance and
neither had been used under emergency conditions at the date of the
survey. Opinions differed on the advisability of permitting chutes as
one of the two required exits.. One school of thought would allow them
as an additional safeguard after sufficient steirways or horizontal
exits had been provided.

The number of horizontal exits listed was small. Approximately 8
percent of the buildings checked were thus equipped. Of the 8 percent,
the majority could be accounted for in those cases involving exits
between new wings or additions connected to older construction.
Few were found in new buildings, and those that were might be said
to be for convenience such as bridges connecting office or factory build-
ings, rather than as a distinct means of egress. .

_ Confusion often existed as to the amount of credit that should be
given to a horizontal exit when installed on only 1 floor of a multi
storied building—for instance, when a bridge connects 2 buildings on
the fourth story. It has been argued that a horizontal exit on the
fourth floor was of no value to.the occupants of the ninth floor should
a serious fire oceur on the sixth. In line with this reasoning, a number
of those who had studied the question believed that horizontal exits,
if to receive credit as a means of egress, should be provided on all floors.

12. EXIT DESIGNATION

During the survey special attention to exit marking resulted in a
number of interesting disclosures. There was a woeful lack of plainly
indicated street-floor levels within enclosed Stairways running to the
basement. Many stairway doors had exit signs placed flat on the
wall—a position rendering the sign invisible at a short distance down a


64 Miscellaneous Publications, National Bureau of Standards

7-6-2. Construction.
7-6-2-1, Materials.

Stairs and landings of exit stairways shall be constructed of incom-
bustible materials; provided, that combustible materials may be used
for stairs and landings of interior exit stairways in buildings of type 3
heavy-timber construction not over 4 stories in height, in buildi ol
type 4, masonry-wall and joist construction, and of interior an _OX+
terior exit stairways for buildings of type 5, wood-frame construction.
Exit stairways shall have solid treads.

x
®
NN 4
er
: —
N ©1S0b¢ phe perdon20persond mount + |
Bo le a oar cae
$ me ob eede-f
fe] 4--"|
g sr
--4-7" *
aa Cs 35008

1s008 30,600 45.000 — 30,
FLOOR-AREA IN SQUARE FEET
Fieure 14.—Resulis of exits survey compared with curve adopted for hospitals and

‘institutions.

: =

5

i sa

8 be °

as

of eq
6 as ‘200 300400 500 soa 900 "10001100 1200 13001460 i

POPULATION PER FLOOR

Froune 15.—Results ‘of exits. survey compared with curve adopted for places of
assembly.

4 In viow of the fact that stairways are required to be énclosod in partitiods of iicombustible materials, it
Was considered consistent to keep the m: lals of the stairways themselves in harmony with the rest of the
Building. There #2 a point, based on judgment, where combustible materials should be alee oats
‘atural point is that of the height of type 4, masonry-wall and joist construction’ Ress ainee
Donetraetln er elowed for stairs and landings of interior exit stairways in buldings of (ped heer ete
on, not over 4 stories in height, in buildings of type 4, masonry-wall and joist soustrusions oes oy
Bete ft intrarc aatiays renege Gee. poodle fonarurtinW soul be 5 seeson
lor : 7s are req en rere ive. 8s provided in. i
Ye-1, Handrails ate not required to'be of ire reelstioe autcneh: Pre



66 Miscellaneous Publications, National Bureau of Standards

When the width of an exit stairway is 88 inches or more there shall
be an intermediate handrail continuous between landings; provided,
that the number and positions of intermediate handrails shall be such
that.there shall be not more than 66 inches between adjacent hand-
rails; and provided further, that in schools, there shall be an inter-
mediate handrail when the width of the exit stairway exceeds 66
inches.

7-6-3. Enclosures.
7-6-3-1, Construction.

Exit stairways in uildings whose occupancies come under class 1,
ublic, class 2, institutional, class 4, business, or class 5, garages,
angars, barns, shall be enclosed with walls or partitions aving an

ultimate fire resistance of at least 2 hours, and in buildings whose
occupancies come under class 3. residential, shall be enclosed with
walls or partitions having an ultimate fire resistance of at least 1
hour; provided, that portions of the enclosure outside the walls of the

ilding shall have an ultimate fire resistance of at least 1 hour. On
buildings not over 45 feet in height the building official may waive the
requirement for enclosure of portions of such stairway outside of the
building walls if all openings in the building walls below or within 10
feet horizontally of such stairways are protected by approved fire
doors or stationary fire windows.

Whenever an exit stairway is so constructed that the several

fights are not directly above one another, the necessary connecting
ways shall be enclosed in partitions, floors, and ceilings of the
same ultimate fire resistance as required for the type of construction
of the building in which they occur but not less than 1 hour in any
case, and openings into such hallways shall be provided with approved
fire doors.
7-6-3-2, Openings.

No openings except the necessary doorways, and windows opening
to the exterior of the building, shall be permitted in exit-stairway
enclosures: Doorways opening into exit stairways shall be equipped
with approved self-closing fire doors } provided, that in schools and
institutional buildings approved automatic fire doors so arranged that
they can be readily closed may be permitted in lieu of self-closing

ich frenclosare of the stairway serves several purposes. It provides a safe line of travel by means of
which the occupants may proceed Protected from the flames; it serves as a barrier to u| ward spread of
to ree peahrevents smoke ttom rising to Bore above und obstructing egress; and it affords Brome seeese

it 9,
Tequiremer ‘aries also with the class of occupancy, being Somewhat
rae ary real, those buildings in which large crowds assemblo or in which the combustibie content i high;
4 Any opening in a stairway. enclosure is admittedly a point of weakness which decreases its efficiency.

in a def ‘erected against fire should be made as

a8 practicable, ‘This is the intent of the requirements of this section,
general Tale in all d i

loors as. in all doorways of stair enclosures except for those
floors whieh open directly to the exterior or into a protected passageway. In schonis aod Petes
Dui ich the sturwate aeeniod ttansively as serviee stats automatic fire doors are per-

iy.
ray
‘altted in order that these doors may stand open to permit traffic to pass easly. However ac safety.

automation aloo the dees ‘Therefore, certain be E

y, 1@ door. Persons must be designated as a part of the fire drills of
fhe buildings to insure thase doors being closed, manually, if necessary aot furnished
the building official that such means are maintaine sow oe simply designated. “onee ust be


Design: and Construction of Building Exits 67

fire. doors when satisfactory evidence is furnished the building official
that adequate devices are installed and maintained for closing such
doors in case of fire; and provided, further, that in buildings not over
three stories in height whose occupancy. comes under class 3, residen-
tial, approved self-closing wood-slab doors of a minimum thickness of
1% inches may be permitted.

7-6-4, Moving Stairs. .

Moving stairs which operate normally in the direction of exit travel.
may be given credit as exit stairways provided they conform to all
requirements of this chapter that are applicable.

Section 7-7. Ramps. . ° .
Ramps serving as exits shall not exceed in slope 1 foot in 10 feet.
amps may be substituted for exit stairways. Ramps serving as
exits shell comply with all the requirements for exit stairways that
are applicable. When a doorway opens into a ramp the floor of the
ramp shall comply with the requirements for inclined exit passage-
ways given in this chapter. .

Ramps shall be provided with an approved nonslip surface.

Section 7~8. Doorways.
7-8-1. Width

No exit doorway shall have a width of less than 36 inches; provided,
that in institutional occupancies doorways serving as exits for bed-
ridden patients shall be not less than 48 inches in width. .

The aggregate width of exit doorways on any floor serving more
than 100 persons shall be not less than at the rate of 22 inches for each
100 persons on that floor.

* The increasing uso of moving stairs in department stores and even in office buildings requires some
recognition of hese devices "They are, however, required to conform to al of the
Teqt

as means of egress, he
‘Visions of this chapter that apply to width, enclosure, and hand rails, if they are to receive credit as reqi
Hairs, Obviously the requirement Yor landings between stores of more than a Given hogar as contained
in section 7-6-2-3 does not apply. Al! moving stairs for which credit is given as constituting -required
‘means of egress should be ofthe horizontal tread type. ‘The cleat type is not recognized as a required means

Ramps are recognized as equal in all respects to a statrway as a means of when meeting the re
quirements of stairways pertaining to width ond enclosure.” Yor certain occupancies such as scheols abd
institutions, they are believed to be more satisfactory and their use in these buildings is recommended.
the character of the walkway surface are important points in the construction
Fihich should be checked carefully by {ne Dallding oe 2 ll be evident from a consideration of
igures on Dage 37, ramps have a rate of discharge between that of stairways and level passageways. Whi
dded recommendation in thoi favor as compared with stairways, it has been considered unwise
farther to complicate the requirements by giving them a special rating.
#1 Extensive studies: ized on page 38, were made on rates of flow through doorways with the obj
of determining an average rate which could be used in calculating the required width of doorways.
studies were made under sufficiently varying conditions and included euough diflereut classes of occupancy
to give results which reprosented a fair average.
sistent with the requirements for stairway width, the ‘aggregate width of doorways has been expressed
in terms of units of 22 inches. | ‘This is regarded as a proper basis of computation since it permits one file
of persons for each unit of width. Although the studies of flow through doorways revealed that travel was
seldom, if ever, in files, yet in buildings in which fire drills are maintained it is essential that the width
Sf Soorways be made to accommodate such methods of ogress, and in other buildings it serves as a factor of
fety.

In speaking of width of doorways, the clear width between jambs is intended. In other words, whena
doorway containing 2 doors has 2: Separate openings ech ‘would be measured separately whileif obese doors
merely meet at the conter without the intervention of a mullion the opening would be measured asa whole.

‘The conclusion from the studies made Dy other agencies and confirmed by the committee's studies Was

that rate of travel through doorways with doors fastened open could be maintained st the rate of 60 persons
minute per 22inch width. This rate was found to be constant up to a width of about 6 feet, beyond
‘which the rate diminish e wider, indicating that 6 feet is at

xit-doorway widths for ground-floor ereas into which no population from upper floors is discharged are.
readily computed. However, when @ portion or all of the upper-floor population-must find its way out
from the bottom of a stairway through aisles in the Boor area as in department stores, or through lobbies,
hallways, or passageways as in office buildings, allowance must be made for this condition.

An skotch 1, Ogure 16, since none of the population of the upper floors passes through the ground-floor
area, theexit-doorway width for the ground-floor area is figured simply at the rate of 100 persons per 22incies


Design and Construction of Building Exits 25
Tanue 15.—Average of evit measurements

Percentage of build-
ings beving— | Average | average | Average
Occupancy ‘Type of construction |———-————| oor ate | width of | “Gitance
istair- | 2ormore| ‘stairway | *2¥89 | “to exit
way. [stairways
Perent:| sqft | in tt
45 ‘8,000 45 86
%| = 2700 8 a
93] 6,500 2 88
100 2, 540 3B J
85 4, 200 42 63
3 2550 40 3
4 8,700 55 63
7 8,900 5 106
58 | 10,600 50 86

Lack of time prevented counts of the population on the floors in
department stores. Only one manager interviewed had ever made
any study of the number of people on any given floor during a rush
period. ‘any had figures on the total number ‘visiting the store
during ® business day, but these figures could not be broken down in
order to estimate the population on any given floor. Numerous
checks on the population in office buildings and department stores
were available through investigations made by the Committee on
Safety to Life of the National Fire Protection Association. Studies
made by engineers in connection with live-load considerations also
furnished some data on population density.

The check on apartment population was made in the better resi-
dential sections. If counts had been made in the tenement districts,
itis believed that the gross area per person would have been materially
lower than that shown in the tables. .

A number of factories visited had notices required by the State
departments of labor which specified the maximum population per-
mitted on any floor. The actual basis for these allowances could not
be obtained from those interviewed.

6. LOCATION AND NUMBER OF EXITS

With but few exceptions, field measureménts revealed that the
maximum distance traveled to reach an exit was less than that per-
mitted in the local building code. These measurements were taken
along the line of travel. In office buildings, for instance, the distance ©
from the door of the office to the stairway was recorded, rather than
the distance to any remote point within the office itself.

‘As most stairways were found to be placed in dead corners or other
areas least rentable, design considerations played an important part
in fixing the distance to exits. It is also possible that the maximum
distenee to exits specified in the code sometimes fixed the design of

‘When compared with the other occupancies, department stores
completely equipped with sprinkler systems showed the greatest dis-
tance of travel to exits. Comparisons between buildings of fire-
resistive construction and other types did not indicate that construc-
tion type had been definitely related to maximum distance to exits.


2 : Miscellaneous Publications, National Bureau of Standards

Upon the completion of its report on fire-resistance requirements,
the committee undertook a study of exit requirements with the
object of developing provisions suitable for building codes. It was

lanned that the two sets of requirements should ‘be used together.
in conducting the study, existing requirements were compared and
tentative provisions were drafted to serve as @ basis for discussion:
These were sent out to a latge number of architects, engineers,
building officials, and other groups, with a request for. expression of
opinion.. The replies indicated wide divergency of views and the
peed for @ greater amount of data upon which conclusions could be
ased.

Early in its work on exits the committee arranged to cooperate
with the Committee on Safety to Life of the National Fire Protection
Association, which is also the Sectional Committee on Building
Exits of the American Standards Association. The latter committee
had considered: the problem over a long period. Its representatives
participated.in joint. conferences and were generous in sharing the
results of their studies. : “

Appreciating the need for more information the joint conference

instituted surveys of existing exit: facilities in buildings, and of the
rate of flow of people through various types of exits. This work was
conducted by John H. Courtney and Harry B. Houghton, associate
engineers at the National Bureau of Standards, and George N
Thompson, secretary to the committee. The results are embodied
in this report. To these are added proposed requirements which
were in process of development when thé Building Code Committee
was discontinued. .
“ To a greater extent than with some’ other features of building
regulations, exit requirements must rest on composite judgment. The
scarcity of fundamental data, the uncertainty of how both fire and
human beings will act under varying conditions, and the great variety
of oceupancies to be dealt with, all tend to create a problem where
divergency of opinion is possible. Experience, good judgment, and
skillful interpretation of such facts as are available become the guides
for arriving at reasonable and acceptable conclusions.

Il. IMPORTANCE. OF FIRE LOSSES
1, PROPERTY LOSS

The burning of buildings and their contents results in property loss
and, much too frequently, in life loss. The property loss was estimated
at approximately $500,000,000 for the year 1930, but dropped to
about $270,000,000 for 1933. This discussion is not concerned with
the property loss, important though it may be, but is concerned with
the life loss because of its relation to the subject of exits.

2. LIFE LOSS

The loss-of-life statistics, unfortunately, are in no sense as complete
as the property-loss figures. Such information as may be gathered
from various sources, however, indicates that the death toll resulti
from fire is an impressive one. The figures obtained by the Unite


Design and Construction of Building Exits —~ 1
- I, INTRODUCTION

If buildings are to be safe for human occupancy adequate exits
are essential. State governments have a legal right to require that
exits shall be suitable in number, size, and location. This power
is generally exercised through local building codes. Inspection of
representative codes discloses that the degree of safety assured occu-
pants of buildings varies widely. There is no apparent reason why
more emphasis should be placed on the subject in one locality than
in another. That such a condition exists seems.to be due partly
to the development of regulations independently in different parts of
the country, partly to the existence of varying ideas on what consti-
tutes reasonable provision for safety, and partly to a lack of informa-
tion on fundamentals.

Some five methods of determining the hecessary stairways for a

iven building are-in current use. These methods all contain desirable

Features, but they tend to become confusing to anyone not a student

of exit design and practice and they have been reported to cause

difficulties for architects, engineers, building officials, and others,

While some maintain that many existing codes are too severe, reduc-

ing unreasonably the rentable area of buildings, numerous deaths by

fire testify to the need of extreme care in lowering present require-
ments,

Fire protection is closely associated with provision for building
exits. This was recognized by the Department of Commerce Building
Code Committee in preparing its report, Recommended Minimum
Requirements for Fire Resistance in Buildings, issued in 1931. The
committee, which has now been discontinued, was responsible for
seven reports dealing with various aspects of building lation that
have been widely used in preparing and revising building codes.
Its membership at the time of its dissolution was as follows:

Wruuam K. Harr, chairman; professor of civil engineering and.director, Labo-
ratory for Testing Materials, Purdue University; member, American Society
of Civil Engineers, American Concrete Institute, and American Society for
Testing Materials

Atbrrt ‘AHN, architect, Detroit, Mich.; fellow, American Institute of Archi-

ects.

Rupourn P. Mruzer, consulting engineer, New York, N. Y.; past president,
Building Officials’ Conference; member, ‘American Society of’ Civil Ean ineers,
American Institute of Consulting Engineers, and American Society for ‘esting

faterials.

Joun A. Newuin, in charge of section of timber mechanics, Forest Products
Laboratory, Forest Service, U. 8. Department of Agriculture, Madison, Wis.;
member, American Society for Testing Materials, and American Society of
Civil Engineers.

Wnt1am Antaur Pane, vice president, Charles T, Wills, Inc., Building Con-

struction, New York, N. Y.; vice president, New York Building Congress.
.l. Wurrremore, chief, engineering mechanics section, National Bureau of
Standards; manager, American Society of Mechanical Engineers; member,
American Society for Testing Materials, American “Association of Engineers.
and American Welding Society.

Josern P, Worcester, consulting engineer, Boston, Mass.; member, American
Society of Civil Engineers, and American Institute of Consulting Engineers,


14 Miscellaneous Publications, National Bureau of Standards

0 oO oO @
Tt T 0
0 T 0 Tt
0 0 jo t
0 oO T Tt
oO oO 0 ca ‘4
oO Oo oO oO T
oO 0 oO 98 t
oO Or oO 6s T cy 000.
0 o fo |e ft feo oes
te e fo |e |r tw one 9
° o fo jo |r | sor 096 ‘9
0 0 oO 8 T oF 009 E
o fo 2 | } on 000 ‘02
o: fo foe |r [so one
o: fo fo |r jos 0088
o fo foe |r |se 006 9
ei
eneteneel gq. [eoeeeees 9 |te
0 0 oO 46 FD
@ ry 08
tee
Jewennenn| g 0 [e-e-=-=-] “fh 98 Te Jaenaennena|annnennnn, 006 QT
° o fo “fe [ey jon (ee 09 56
004 5 0} #6)
000 92 on
096 ‘be m4
e 8 08 st “9 018
% 9 I on fo 0 fp] Cs Cn TO Hens i? | ae 1
aa 4 00F OF ma
oe. eg ae ae
a A a a abs abs
+ Ore | “oN cypras | on | wap | “ON | #10409 | astm | “ON | deoy | sostod Posts “om 4001 soos
Ipexeracridg | nq ouwisre | gore ; . ‘on aang
Crd preg | sedeose ong | ON | stomseas | treyg. | SD 1 81005 £q waze 65035) Pa

NOMLONULSNOO TALLSICIU-AUIL

sqususunspow jut Ourpying aoyffo fo hamuung—g w1avy,


4 Miscellaneous Publications, National Bureau of Standards

the number of deaths in this classification occurring in burning
buildings, but it is obviously somewhat, less than the average figures
cited. "That there is a seasonal trend in the figures is indicated by
the following monthly distribution for the year 1933 of deaths by
conflagration, Continental United States (source, U. 8. Bureau of the
Census):

July__ 54
‘August 2B
Septem! 56
October 113

November

in the winter months, although it might easily be upset by some
major theater disaster having no relation to heating needs. .

Por the 5-year period, 1912 to 1916, inclusive, the State of Illinois
reported 1,511 deaths from fire and burns, 215 of which are listed
under the causes as burned in burning buildings.” :

3. CAUSES OF LOSS OF LIFE BY FIRE

The statistics covering the causes of loss of life by fire in buildings
are admittedly.meagre, due to the fact that no central agency is
charged with the duty of compiling such a record. It is largely
through the efforts of certain State officials and such organizations as
the National Fire Protection Association that information of this
character is available at all. It seems to be a well-established
opinion that certain occupancies suffer greater loss of life by fire than
others, but there is little data to support such a contention. The
late Ira H. Woolson, consulting engineer, National Board of Fire
Underwriters, and. first chairman of the Department of Commerce
Building Code Committee, stated in a paper presented before the
Building Officials’ Conference of America, in 1927, that fires occur at
the rate of something like one a minute, day and night, in the United
States? Fortunately not all of these fires result in loss of life, but it
seems almost impossible with such a frequency of occurrence that
apy one occupancy class Could avoid life loss at one time or another,

Table 1 has been prepared from data published by the National
Fire Protection Association. It does not purport to be a complete
record for the entire country for any given period, but is of consider-
able interest as a representative list of causes. This table lists the
causes of 3,207 deaths from 544 fires involving 104 different occu-
pancies. Dwelling fires are not included because the statistical data
relative to loss of life in dwellings are not readily available.

2 Spo for the Household, Cir BS Ca0r, table, p. 1 (1092)
apt orkof the Nat. Board of Fire Underwiiters, Proc. 18th Annual Meeting of Bldg. Officials’ Confore»ce
«Quart. Kae ire Protect, Assn. (January 1925).


, National Bureau of Standards

Miscellaneous Publicatic

20

o oN ope on jo oy r of od 8 99 'T z
0 on 0 o 2 [tf bo 982, or 08 '¢ z

0 oN 0 0 Fe i % ser a 008 + 4

° oN ° o 8 1b Soe aut or oe |e

0 on 0 poo ° o {% JE Sos oer o 218% z

° oN o j% |9° jo Je Jon Joe $98 a ooo'et fe

° oN fo polo fo 8 YE Hoe 608, a a

° oN “Lo ° o {#@ |t @ ser iy ores &

0 On 1 0 0 is &e 09 000 ‘er g

o oN o OL 0 oF a OF 008 et
° on ° o fo fe [thee ose |e

o oN “lo Oe 9 98 T og 086%

0 oN 0 0 0 8 13 oF 00% 2 a

0 oN 0 ry 0 gm ft 99 082 '¢ e

a on ° 0 0 mit 68 o's fF

9 oN 0 o jo ie fe. ‘ler ome” ly

]) 1 Dy abs
wapim| “on [urpras! “ON | siosoy | TIPLAL |) “ON
. 330 Ta | aosrod sod | 2908,
sora | PoweraHds | joa SA SBHIST | Sox soap | {HITAL | were woID | gar: “ou Buypring,
reimosyo | devon, | “UMN | steares

NOMOQUIENOO LEIO£ GNV TIVMAUNOSVN.
PenaHU0H—susweinsvou jx Burpjing yuowpsndn fo hinuwng— Oy, wav,


U. S. DEPARTMENT OF COMMERCE
DANIEL C. ROPER, Secretary

NATIONAL BUREAU OF STANDARDS
LYMAN J. BRIGGS, Director

NATIONAL BUREAU OF STANDARDS MISCELLANEOUS PUBLICATION M151

DESIGN AND CONSTRUCTION
OF BUILDING EXITS

Issued October 10, 1935

UNITED STATES
GOVERNMENT PRINTING OFFICE,
WASHINGTON + 1935

For asle by the Superintendent of Documents, Washington, D.C. = = Price 10 cents (paper cover)


Design and Construction of Building Exits 43

There is one distinction which helps in building up a method in
dealing with the subject. People who are awake, alert, and in good
physical condition are better able to take care of themselves in such

_an emergency as fire than those who have been just aroused from sleep
or are sick or infirm. The distinction is so obvious that it has been
applied in the case of several of the methods described. There is a
further classification, that of people assembled in such locations as
theaters, assembly halls, and the like. Experience teaches that,
although such people are alert, panic communicates itself much more
readily under such circumstances. ‘There is no interval before the
exits come into full use. The demand is immediate and simultaneous
on the part of all. Such a condition justifies separate treatment.

It now becomes necessary to ‘search for those features of existing
methods that will best, fit the needs of each group of persons or to
develop. new methods. Manifestly, in the case of those asleep, the
sick, aged, and the infirm, the most liberal Brovisions should be made.
They cannot be expected to use the same degree of discretion nor to
move with-as great celerity as the others. Accordingly, it seems wise
to apply the principle of a place for everyone within the stairway en-
closure for this group. However, it was found by actual experiment
in the course ofthe investigations ‘already described that the space
allotted per person in some existing methods that utilize this prin-
ciple ea be reduced. . .

Coming to those awake and alert, a different. problem presents itself.
Here the greatest need and quickest alarm will develop naturally on
the floor where the fire occurs. Other floors may not be involved at
all, or if so, not until a later time because-of the fire resistance of the
building, particularly in its required enclosed shafts and stairways.
On the floor where the fire starts it is possible that panic will develop,
but this would hardly extend. to all floors of the building at once.
Here appears to be a reasonable field for the use of the method of
probable need. As a matter of fact, on reexamining the principal
methods for providing exits, we ‘find that this principle is ra
generally recognized. Some do this directly by a rather drastic
reduction while others do-so indirectly ‘and partially by extremely
liberal reductions in stairway sizes where sprinklers are present. The
net result in all cases is to provide less stairway space than would be
necessary for simultaneous use by all floors.

If this premise is accepted, and.it seems necessary to do so unless
so large an area is allotted to stairways as to make the buil of
doubtful utility, the question arises how much reduction should be
made, or stating it another way, what is a reasonable probability of
the number of floors that will need to be accommodated at one time.
One of the methods described sets a maximum for the 6 most densely
populated floors above the first. While this has a very evident merit
it takes no account of the problem created by high buildings. For
instance, a 7-story building and a 20-story building would each have
facilities for only 6 floors at a time. After reviewing this problem at
length it appears that the probability would be better expressed by
some. other-method. In the case of the lower buildings, flow takes
place ; but. in the case of -high buildings a definite proportion of the

loors should be provided for at all times. As a reasonable assumption,
one-half of the floors above the first was selected and checked back
against values plotted to show the results of the survey of existing


Design and Construction of Building Exits 7

defective construction, violations of ordinance, and Panic. The
exits have played an important part among the causes of deaths and
emphasize the necessity for careful design and proper maintenance of
these facilities. . .

Next in importance to theaters in this class in the number of lives
Jost are the schools. The National Fire Protection Association lists
a. total of 423 lives lost in but 30 fires,” a high average loss per fire
compared with other occupancies. This average is much higher than
would be expected in buildings of daytime occupancy and supposedly
having the advantage of frequent fire drills. However, an examina-
tion of the records of individual fires discloses heavy loss in a few
fires, 4 fires.causing the death of 284 people. The general average
for the recorded school fires is, therefore, considerably less than indi-
cated by the 30 fires mentioned before. As in theaters, the exits in
schools have figured very prominently as a cause of loss of life. The
necessity for a free and unobstructed path of exit has been strikingly
illustrated by several fires, as has also the necessity for proper distri-
bution of exits. One school is reported to have been emptied many
times in a minute and:a half during fire drills, yet 22 lives were lost
when the school burned because the fire drills had never been varied
to provide for the contingency of an exit being blocked.”

‘he following tabulation, prepared from data published by the

National Fire tection Association, gives the causes of loss of life
in 30 school fires."

Cause ‘Deaths
Inadequate exits.
Exit doors open in, barred windows
Exits cut off by fire

w 27
Burns and ignition of clothing. 3
Fire fighting and salvage.. 21
Special hazards. ___ 2

iscellaneous, no data.

,_ The impression is gained from a study of older buildings that those
in which people enter of their own free will, such as office buildings,
stores, etc., have been usually of a better type of construction than
those buildings which they are forced to enter without their consent,
such as schools and certain institutional buildings. This impression
seems to be confirmed by the records of many school fires.
Incomplete records of church fires do not reveal any loss of life in

this country which might be charged to the fact that the buildings
were used as places of assembly, in spite of the frequency of these
fires, which has been reported as 5 per day. Very heavy loss of life,
however, has been reported in 2 church fires in foreign countries. O}
154 recorded fires in churches only 11 occurred while the buildings
were occupied, and in no case was there any difficulty in getting the
occupants out.!?

+ School Fires, Nat. Fire Protect. Assn,

40 Peabody School fire, School Fires, Nat. Fire Protect. Assn.

41 School Fires, Nat. Fire Protect. Assn,
4 Church fires, Quart, Nat. Fire Protect, Assn, (Jan. 1928).


6 Miscellaneous Publications, National Bureau of Standards

The 64 deaths, making up the difference between the deaths result-
ing from fires in buildings and the totel deaths from fire, are reported
as having occurred in or in connection with ships, launches, barges,
scows, motorboats, automobiles on street, airplanes, railroad car,
ferry-house, subway, elevated railway, auto service station, watch-
men’s shanties, storage yard, yard, street, manhole in. street, or
@ bonfire. 2 vee

Class 1, public, as established in the report, Recommended Mini-
mum Requirements for Fire Resistance in Buildings,’ including city
halls, churches, schools, theaters, and’ recreational buildings and
structures, is charged with a large total loss of life, The nature of
the occupancy with its densé population and susceptibility to panics
accounts to'a considerable extent for the large total.

Theaters have probably the most complete record of loss of any
single occupancy due to the fact that loss of life when it does occur
in theaters is of such size as to receive unusual publicity and conse-
quently becomes a matter of casy record. The National Fire Pro-
tection Association has published a record® of lives lost in theater
fires during the period 1797 to 1930 in the United States, Europe, and
Asia. The records are not complete, particularly in regard to fires
in Europe and Asia, but they provide an indication of the extent of the
life loss in theater fires. The total deaths for the 133-year period is
epproximately 12,000, and of this total the United States is charged
with 1,671. :

It was reported some years ago that fires were occurring in theaters
at the rate of 2 per day. It should be borne in mind that the life
loss in theaters cannot be measured by the number of fires nor by the
intensity or destructive effects of the fire. There are records of
heavy loss of life in theaters in which there has been little if any fire,
the deaths being due entirely to the development of panic conditions
followed by a rush for the exits. _ An idea of the dense occupancy of
theaters and the possibilities for the development of panic conditions
may be gained from the reported seating capacity of the theaters of
the Borough of Manhattan, New York City. For the year 1930
there were reported to be 301 theaters and moving-picture theaters
in this Porough alone with a total seating capacity for 356,623
persons.’

An analysis of the causes of 2,426 deaths in 50 theater fires is given
below: *

Cause Deaths
Inadequate exits and panic.
Rapid spread of fire okt off
Jumped to death from windows.

Burned by inflammable film. 10

Burned by open flame 1

Fire fighting___ ld

No definite data_ 1,197
Total___

The record of individual theater fires presents a long list of deaths
due to improperly designed and inadequate exits, poor maintenance,

5 BS BHI (1931).
See eT Be Caen y

ae eas? een Se
‘ Sa Pee ee Be een ot Mane fan, City of New York, Annual Report (1930).


56 Miscellaneous Publications, National Bureau of Standards

. Where more than 2 exits are required, they shall be distributed as

formly as practicable within’ or around the floor area, room or

space they are to serve.
7-4-3. Outlets from Exits.%

An exit stairway shall lead either directly or through an exit pas-
sageway to a street or to an exterior open space leading to a street,
except as follows:

In buildings of type 1, fully protected, or type 2, protected construc-
tion, devoted to o ice, or class 3, residential occupancy, such stairway
may terminate in a hallway or lobby; provided that when there are
stores, restaurants, or other business occupancies within or opening

8 definite method ots ex istance as a percentage of the longest wall
fShepullding. ‘This method| ss rtals uadyed seal bitin laatnststees Ae re.
ich layouts woul 40 be Feasonably safe, although the exits are not as remote from each
abl aoe in gris ite isha of pac Stal gt det ord ind hat 0 # bldg
Eroalike, vas 38 inter requirement aggivon,
‘exits only are req {is assumed that ibe 90 placa ake them em conse stoall tbeae-

juired, it to make
eupants of the floor without cea oth th the eats to tb possibility ot being cat, off by
lates a safe, unobstructed path of travel ith from
the starting’ Point ¢ to the street, , Eo tue last eee mtion. of this travel, the path ‘rom ‘the foot of thestalrway to
ich ott geaennay ag Seely cr ake ae ata Set
crews : a
discharge to teak F ‘Pract ical consi

mapee the for direct Hort digcbat considerations, however, suggest modifications of
in certain occupa:
ithe eochonn juirements of use of modern buildings are such that lobbies with plate-lass misdows
pening ito grou Spaces are a desirable feature for for certain ca de hes

floor
practical to: lee bie tobe chased off he sorsee ng pian a fos te poms
req ‘cOmn} ely ls ey of

with the preperation
gro being built with stairways terminalia in lobbies hevine lows and dots So jing upon the first
floor area. O1 Ofiee! gbuldingeand hotel laren ect ie thls type of arrangement, person! haidings

paving a Testanrants, and shops ‘corridors and lobbies
atlas to constinate thera rather than oa Fon. ols oat fe practice has been i recor ied
ye exceptions for office and residential ings, but it has been safeguarded by requiring
sprinkler: for commercial occupancies 01 opening on ‘such corridors: end lobbies. Tt was believed thet

protection “er toa for the safety lost by fe departure from {rom the ideal requirement of a pro-
lected Passageway. Inasmuch se plate glass soon shatters under heat, the expression opening wrote a
eeitidor should be construed Indiude occupancies having windows bat not ‘necessarily doors fn the cor.

oe ‘artis desirable protection in some locations where late-glass windows open upon public lobbies

cqnssts of metal or ot Aver sh butters to cover the glass area. ‘hese shutters operate automadealsy
some form of sensitive

the ui of institutional gosapency at east: one avenue of safety leading directly to the street. soald

be provi Stairways may be permitted to discharge into hallways or lobbies leading
the streots ad tra protection for ‘hese hallways way be Oniftos He one ‘Perini thelr utlleatios a9
01 pen thereon.

see ent sores pena to allow one-half the stairways from the upper floors to dis-
sllow one-half the stairwa 2 a 3
speak asa peta a eat tan uo Pea ay
a gcodur and oomaratively unghectignabla cas the bulatng sof Groves
eBhstruction waa and completa inklered. He rf di discharge to the street ee

(ere again, pref.
erable, but not always practicable. When one-half of the population of the upper hoor ‘that ra way
loor area the widt tt

‘Ways trom the upper floor in or
aces of assembly, dus to the fact that the entire Pulao fe Wietole atone time, a ticularly ox fei
‘bility of Panic conditions. "It is, therefore, extremely desirable that evap bear Edit u
‘eupants be effected without any delays or in ns. For this reason a
of upward travel which will avoid an: yggaltne inline to secare entrance ‘to sisemeye “Appre.
Poke that the nonhre-resistive building offers more opportunity for spread of fre than tho Are-resisnive
Dallding, the distance of upward travel permitted in the goufire-seative baldtne hee Reso eee eee
to To insure egr ess to the street feeding i is belOwr aac at east 1s stairway is is greauired to lea Tead wp directly
E fo @ Dassageway streak THs pro icular ce to densely 0c
tore basenienis, or basslaent ‘workshops, but the principle w avpiicabie

oy
an cmergency line of re retreat in in the event that stairways are cut off below, vision has been made for
single stareay Provision for 2 stairways by meugs of Walch partes cee eee
by way of the roof and fecend Pe a stairway not cut off was considered but has not been required.

TI iow: in present code requirements on. | the role played by stairways lead-
ing to the roof. Some codes Teq all stairways serving the upper stories to continue on through; others
Tequire 2 to go through on the theory that a & person can escape up by 1, cross over the roof, and then descend
through other. ‘Other pvisions, recognize the use of a passager ay from i stairway to another in the

oo

se of tho
nature of their construction. exits survey ybored that stair doors. to roofs are frequently kept
Tocked, and served to emphasize that steko escape are dependable onty are ae resort aod ave not
to be considered in any wav as a substitute for properly soustraerer stairways leading to the street.


Design and Construction of Building Exits 39

The figures for revolving doors do not necessarily represent absolute
capacity. The readings were clocked for those moments -when the
doors appeared to be accommodating people as fast as convenient.

ass only was checked. Observations. of the action of people in
revolving doors led to the belief that the width of the leaf has very
little relation to the number of persons discharged. As might be

- expected, it was exceptional for 2 people to pass through a single
pocket of these doors at the same time. .

Movement through doorways displayed one characteristic in com-
mon with stairways—the tendency Tor those. having a width of about
5 feet or less to have a higher rate of discharge than those over about
8 feet in width. A comparison of the rates of discharge through door-
ways with those up or down stairways shows a faster rate for door-
ways under similar traffic conditions.

‘he figures in tables 19, 20, and 21, giving the summary of obser-
vations of traffic movement in various types of exits, were carefully
considered by the joint conference. Although there were marked
variations in results, probably attributable to the fact that in some
cases the exits were not used to their maximum capacity, the judg-
ment of the conference was that rates of 45 persons per 22-inch unit
per minute for travel down stairways, and 60 persons per 22-inch
unit per minute through doorways, which had been in use on the
basis of earlier observations, were sufficiently confirmed to warrant
their retention in connection with the requirements under develop-
ment. This is equivalent.to a ratio of 4 to 3.as between the flow to be |
expected through doorways and down stairways.

Varying width, story height, and proportions of treads and risers,
coupled with the mental an physioak trats of people, render it-nearly
impossible to obtain other than general averages of discharge rates
from exits.

V. METHODS OF CALCULATING EXIT WIDTH

Several broad controlling principles are utilized to compute the
necessary exit width. These are discussed below:

1, CAPACITY METHOD

This method is based on the theory that sufficient stairways should
be provided at each floor to accommodate all the occupants on that
floor without the necessity of any movement within the stairway.
There are two principal ways of arriving at the necessary stairway
size. In one the total area of landings and stair treads jis obtained
and is divided by a figure representing an assumed area per person.
In the other, 1 person is assumed to stand on every other tread in a
22-inch width, and the area of landings is divided as in the previous
case to give the additional persons that may be included.

Theoretically this provides a safe area of refuge for everyone within
the protective barrier formed by the stairway enclosure. It allows
for the subsequent safe and orderly evacuation of the building with-
out the necessity of forcing aged or infirm people to travel at a rate
beyond their physical capacity. It recognizes that travel down along
series of stairs in high buildings is exhausting even to normal persons.

The knowledge that there is a safe place f is held ini-
ize the poscbility of cea, safe place for everyone is. to mini-


Design and Construction of Building Exits 27

It was pointed out that certain classes of people would. consider a
stairway very tiresome while others would take no notice of fatigue.
On the basis of a limited study, it was therefore suggested that the
treads and risers should be proportioned for the different uses to
which the stairways were subjected. Further study of this question
may-.reveal more rational methods of accomplishing this end than

are. now in common use.

9. STAIRWAY ENCLOSURES
Enclosed stairways could be said to be current: practice, judging

from the large majority found in’ the buildings visited. An open-
exit stairway in office buildings, hotels, and apartments was extremely
rare, those not exceeding 2 or 3 stories in height excepted. In school
buildings about equal percentages of 0; and enclosed stairways
raised a question as .to most favorable design. Many superintend-
ents and teachers preferred the open stairway because of its efficiency
in handling the changes of classes. Although the lerger department
stores visited had enclosed stairways, many of them were used-only
as emergency: exits. Stores of 2 or 3. stories and having a small area
had enclose stairways in but few instances. Despite the questions
raised concerning the efficiency of enclosed stairs for certain occu-
pancies and their increased cost for small buildings, an analysis of
those buildings erected only within the past 5 years bore witness to
the obsolescence of the unenclosed stairway. .

If the definition of an ‘enclosed stairway means ‘that it must be
enclosed from the topmost story to the final discharge to the street,
mapy of the stairways examined: would -be puzzling to classify.
Stairway enclosures found in hotels and office buildin; frequently
terminated at the second floor or a mezzanine from which ornamental
open stairways continued to the street-floor level.

10. EXIT OUTLETS

Where stairway enclosures terminated within the building at the
ground floor, the discharge was either into large corridors, in-some
cases ha small shops on either side, or directly-into a lobby. It
was unusual to find astairway discharging into a: corridor so constructed
as to constitute a protected passageway Jonding to a street, except in
public-occupancy buildings such as theaters.and auditoriums. Stair-
ways discharging directly to the outside at. ground-floor levels. are
greatly in the minority when compared with those discharging inte
ground-floor areas, corridors, or lobbies. Value of street frontage
apparently controlled this factor, as the stairways of most factories
discharged directly to the outside at-the ground floor. Where stair-
ways continued enclosed to’ the basements in apartments, het
and office buildings, many of them discharged directly to the outside.
Some builders claimed that if many building codes were enforced to
the letter re aa wont be too severely penalized when erected under
requirements calling for direct discharge to stréets or to protected
passageways leading to the street.

1158355,


44° Miscellaneous Publications, National Bureau of Standards

buildings: ‘ated as to occupancy. The results showed that
current practices ‘was substantially in-accord with the percentage
chosen. The results were applied also to a number of plans ‘of build-
ings and were submitted to-representativé architects for their opinions
as to their adequacy. Their reaction was favorable. a

In the case. of occupancy involving assembly there is virtually
unanimous agreement in existing methods on the flow principle, that
is, in providing for: the escape of the occupants through exits pro-
portioned to bring about a complete evacuation within @ given maxi-
mum time. There appears to be no reason why this principle should
be altered and it has constituted the basis for dealing with this par-
ticular.group." . .

It will thas be evident that a selection: may be made of those fea-
tures in existing methods that appear to have the most. practical
usefulness when considered in relation to the principal groups consti-
tuting building occupants. No new principle is introduced but a more
logical application is effected. The method of arriving at actual
results in terms of units of exit width depends upon the use of several
simple divisional factors, as will be shown under the particular para-
graphs to follow dealing with details. .

7. CREDIT FOR ELEVATORS

In some methods examined, attempts were made to give a credit
to elevators in computing aggregate exit width. This ‘allowance was
so small, however, as to offer very slight reduction in required stair-
way space. Recognizing the growth in speed and other improve-
ments in elevator construction, special: attention was given to the
part that might be played by elevators in providing exit from build-
mgs. Certainly these devices have the merit of being familiar means
of egress to which people would naturally turn-in time. of need.

It was assumed that automatic push-button elevators would not
be suitable. Although these have a considerable vogue in apartment
houses and small business buildings, their capacity and rate of speed
is not great. Furthermore, they are not subject to a single will as
in the case of an elevator operator, but to demands from many ten-
ants, Their successful functioning in a time of emergency would be
problematical.

The potential usefulness of other passenger elevators appears to
depend on the reliability of the operators and the ability to ths
people at a reasonable rate. Testimony differs on the first point,
some citing dereliction of elevator operators at critical times, while
others point to examples of heroism. The probability of the operators
staying on the job is at best uncertain. The possibilities of power
being cut off, of cars stopping between floors, and of smoke filling
shafts, also have to be considered.

As to the capacity and speed of elevators, one of the methods
examined made use of a formula indicating that 5 elevators were
about equal to one unit of stairway width, the exact relationshi
yarving with the number of persons that could be carried, the speed,
and the height of the building. A stairway of course, traverses the
entire height of the structure and furnishes some accommodations at
each story, while the elevator can serve only 1 floor at a time. With
the modern high-speed elevator, however, running in an enclosed shaft,


26 - Miscellaneous Publications, National Bureau of Standards

The majority of the buildings studied were rovided with two
stairways. A notable exception to this occ in office buildings
where one stairway might be'said to be the rule rather than the
exception. Table 6, pages 14~15, shows that office buildings’ of
uniform - horizontal cross section and tower sections of set-back
construction frequently were provided with a single stairway.

7. STAIRWAY WIDTHS

‘All the tables indicate a great variation in stairway width, even for
nearly identical conditions. Repeated questioning failed ‘to estab-
lish specific reasons for making stairways 40, 41, 42 or 43 inches, or
any ension approximately 4 inches. either way from 44 inches, in

preference to a 44-inch width. Although codes specified certain mini-
mum dimensions for stairway width, variations up to several inches
either side of the minimum were common. Construction details

light account for some of this discrepancy. . .

tairways 36 inches wide were found rather frequently while the
great majority were between 40 and 50 inches. Just what increment:
of width ‘added to, say a 36-inch stairway, increases the capacity of
the stairway was a question which very few of the architects. had
. given any detailed study. - As might be expected, stairways in schools
and department stores were appreciably wider than those in offices,
apartments, or hotels. A number of those interviewed were of the
opinion that for the same aggregate width it was more beneficial to
increase the number of stairways than to increase the width of a
few—that is, three 44-inch stairways resulted in better traffic
conditions than two 66-inch stairways.

8 PROPORTION OF TREADS AND. RISERS

Dimensions of treads and risers measured indicated that the 2 or
3 rules customarily used for proportioning risers and treads are
adhered to very closely. Risers of 7 or 7% inches and treads of 10
and 10% inches far outnumbered ‘any other dimensions. These pro-
portions will be. seen to check the rules that the sum of riser height
and tread width, in inches, shall not be less than 17 %, nor more than
18; that the sum of 2-risers and 1 tread, in inches, shall be not less
than 24, nor more than 25; or that the product of the riser and tread,
in inches, shall fall between 70 and 75. .

The risers in school buildings occupied by small children averaged
around 6 or 6% inches... Opinions of architects and school superin-
tendents on the advisability of this practice fell into 2 groups. One
group claimed that the fatigue was much less where the lower riser
was used; the other group maintained that children were not accus-
tomed to the lower riser in their homes and other buildings, and,
therefore, that it was more logical and less dangerous to use a 7- or
7%-inch riser in this occupancy.

Because of the different uses of stairways, including those in indus-
trial, private, public, and semipublic occupancies, and because of
their position in the plan, the variations of color and materials used,
and the differences in railings and type of nosings, a suggestion was
advanced calling attention to the inadvisability of attempting to design
all stairways under any one rule for proportioning treads and risers,


* Design and Construction of Building Exits 63-

a

bs,

o

UniTs OF STHRWAY WiOTH
3
o

qo 7 19060 20,000 “85,000 30, 35,006
FLOOR AREA IN SQUARE FEET

Fiaure 11.—Results of exits survey compared with curve adopted for schools.

x
8
ES
Ny
o i) sont

3 , pees
8.

me
8 alc Pp o
St

Ge "$000, 70.000 (5,000 25,000 30,000 35,000

15,000 z
FLOOR AREA IN SQUARE FEET

Ficure 12.—Results of exits survey compared with curve adopted for apartments.

8

8

UNITS OF STAIRWAY WIOTH
a

*. °.
2
= =
A pene
Ie
-——
o eo 74608 Sa005 oes

75008 ‘Ba060 ~~ —~“#R008

FLOOR AREA IN SQUARE FEET

Fiaure 13.—Resulis of exits survey compared with curve adopted for hotels and
‘mitorie


Design and Construction of Building Exits 3

States Bureau of the Census indicate an average annual loss of life
from fire and: burns of nearly 7,500 persons.’ Figures from other
sources often quoted are even higher, ranging between ‘ten and fifteen
thousand lives annually, although the evidence to substantiate these
higher figures is lacking. In both cases, the loss of life results from a
eat variety of causes, some only remotely connected with fire.
Nevertheless, the losses are of sufficient proportions to justify a dili-
gent search into the underlying causes of such an apparently needless
waste of human life. : .

The principal difficulty with the statistics commonly quoted in
connection with loss of life by fire is that they are too inclusive. Thus
all manner of deaths which are in any. way, regardless of how remotely,
connected with fire are compiled under the general heading of loss of
life by fire, and the public, which has become accustomed to associate
fires with burning buildings, conjures up a picture of a vast number
of burning buildings in. which these ten or fifteen thousand lives are
lost annually. - It fails from lack of complete information to take into
account the fact that a great many ‘of these deaths result from burns
and scalds received from industrial processes; forest fires; explosions
of vapors, gases, dust, and powder; bonfires; cleaning fluids; matches;
and many other sources which have no connection with burning build-
ings, and, in many cases, which do not result in fires, in the commonly
accepted usage of the term, at all. . .

The impression thus gained has undoubtedly been of assistance in

- the promotion of campaigns for safety to life and protection against
fire and in that connection the misinterpretation of the statistics has
not been important. But where they have resulted in drastic and
unnecessarily restrictive requirements in building codes, it would ap-

ear desirable that they be broken down and the causes of loss of life

yy fire determined as accurately as possible in order to correct the
impression that loss of life by fire means burned to death in a burning
building, or that simply providing a number of stairways or fire
escapes on buildings. will eliminate this loss of life. This is not to
minimize the importance of the statistics but rather, for the purpose
of this.report, to so adjust the data that a more proper relation be-
tween lives lost by fire, lives lost by fire in burning buildings, and the
influence of exits on the number of lives lost in burning buildings can
be established.

Probably the most nearly complete data on loss of life from fire are
those collected by the United States Bureau of the Census. In the
Census reports deaths resulting from fire are segregated into two
classes: ‘‘Conflagration”’, which includes deaths from fires in buildings,
forest fires, deaths under similar conditions, and “Burns”, which
includes deaths due to ignition of clothing or bodily burns without
anything else necessarily being set on fire. For the 5-year period,
1916 to 1920, inclusive, the Census report shows an estimated average
of 1,465 deaths annually for the conflagration classification. For the
9-year period, 1921 to 1929, inclusive, the deaths for this classifica-
tion averaged 1,620 yearly, an increase which corresponds very
closely to the increase in population for these two periods. In more
recent years there has been a slight decline, the figure for 1933 stand-
ing at 1,521. It is difficult to estimate with any degree of exactness

1 Safety for the Household, Cir. BS C397, table 5, p. 9 (1932).
1158_35——-2



7

is

" Design and Construction of Building

“Barpong ous jo ya8yeq Try oN UN SIOeATA 1

oN

perme"

posses o ° cag t 96 povvorsoroee|oneceernees| ggg 6, & poo

NOWLOQUSSNOO IVLEW-CHLOTLOWAND
T OK w |e o {8 |b fo o 201 09's 8
, NOMOMUISNOO L8IOf CNV TIVM-AUNOSVAL
0 wy err eens) o isa | & o8t eeeeeeeniaes emmenenaaad 008 ‘OT & coresereeeneese OT
NOLLOMULSNOO WHAWIL-AAVIH
0 on z o jo |e je Ioe z
° oN 0 1 0 BL 1 a t
0 on 0 1 o 8 {ft z
0 oN ° 0 ° a tt e
oO oN o r 7 +o Tt i
6 oN o o jo |e je &
0 oN 0 0 jo |e le g
oO x 0 T oO 98 r .2
oO oN 0 T 0 SF Tt r
ay
py] “on | maprm| von, | sr0m03) area | “ON | apro oe 2008
ys104 ox. or eotrenatp | Hoszed 324 | reordcs uo | ware ssoup | HO
eso, | PosPHds wRq Came | P58 SOD | Ler tog D | urquaer “ou SUPINE

sqyr0 poquo70—,

odes erg | “UNN| sheaneig

NOMONULSNOO TAMSISHU-CaLL
squamesnspaus pra Busppeng Aiopos fo hunwwng—g xIav,


54 ' Miscellaneous Publications, National Bureau of Standards

outside the building not less than 48 inches wide so located that no
point in such portions is more than 100 feet from such horizontal exit,
ramp, or doorway leading directly outside the building; provided that
in buildings sprinklered throughout this distance may be increased
to 150 feet.
7-3-5. Exits for Places of Assembly.%
7-3-5-1, Rooms,

Every room, tier, baleony, or other space used as a place of as-
sembly shall have.at least two means of exit.
7-3-S-2, Buildings,

P Exits for buildings used as places of assembly shall be supplied as
follows: :

Not less than 2 exits when 600 persons or less are accommodated in
each room, balcony, tier, or other space; not less than'3 exits when
more than 600 but not more than 1,000 persons are accommo-
dated; and not less than 4 exits when more than 1,000 persons are
accommodated, :

7-3-5-3. Separation of Thester Stairways.!!

Exit stairways. serving theaters located in buildings containing
other occupancies shall be separate and independent from the stair-

ways serving other occupancies in the building.
Exit stairways serving theater balconies above the first shall be
separate from other stairways.

7-3-6. Boiler Room Exits.*?

Every building, in which steam boilers, or apparatus using or
Producing gas or vapor, ‘are placed below curb level, in addition to

Patients, the feeble-aainded, and hopelesély insane may require special exit facilities and assistance in an
ene

rhe horizontal exit, while it does not always provide a direet means of exit to the exterior of the building,

iprate portion of the bullding fom woah those ogee cates exit leading to the

exterior. Both the tal exit and enclosed ramp are particularly applicable to the institutionel build-

ousing bedridden persons because ofthe facility with which Deds may be transferred from one section

cally unt is eepectaliy to be recotumonded Soscg ofthe diculty of getting eae into stair ex:

7200) 1156 0 of getting such persons into stair

st plac, and the slow movement Gown ists Rose ee as pees ‘With the

‘spread of fire restricted by the walls of the horizontal exit, a much Jonger period of time can be. utilized to
‘evacuate the area on the safe side of the horizontal exit.

‘There is a further necessary limitation of the requirements for institutional occupancies in the ease of
snob Institutions ae prisons and reformatories where escape of occupants must be prevented. In view ofthe
Hedi oats apo wna acre ges uy the onan re elesto th designers of zrtioa:

ne ‘upon whom rest ity for guarding of thelr charges, certifica-
Hon that the exits provided on the plans are sufficient in the judgment of the deiguer oe le

id the responsibl
Prison official might well be made in order to make it clear upon whom the responsibility rests fer this
ture of the building.

2 ‘of assembly may be considered in two groups, one consisting of rooms used as places of assembly,
fhe other of buildings entirely devoted.to places of assembly. As a general proposition, places of assembly
‘are those buildings or rooms in which People congregate for civic, political, social, or r us purposes, Or
for entertai ters. ‘ceoupancy, they area part of
class 1, pul a a large density of population, they are generally con-
sidered aire spe t {minimum number of exits. ‘The i ‘arrangements
of theaters, such as width of aisles, ig between seats, and other details have not been taken up ss they

fall naturally into a chapter on special oceu; Provisions not covered at the time this chapter was
pared: Details conosrning them will bo found fa the Building Brie Code, lint ste oes
American Tentative Standard by the American Standards Association,
enerteater, by definition, is 8 special form of place of assembly in which there is provision for movable
SOUREY, of inl which moving pi are displayed. It presente hazards beyond those customarily met
nother places of assembly. ‘Tho presence of scenery, and of projection booths aud screens, is» special Reo
id rd. Performances are presented while the ‘space is darkened, thus presenting greater
Possibility of panic than in ordinary places of assembly.
In order to avoid any interference with the flow of people {from a theater, the theater stairways need to
dent of any other stairways in the building. It is obvious that with any orrangement of

f stair-
rays in which the use is common to all, the uninterrupted flow of trafic is impostile eek Tike
Toidecu at tho intersection alti tcc ere eee fom of tai in erly discharge ot eared,

8s from a theater is likely to develop panic conditions repsrdinee ye ere hse wick neces eat
, v 01 ‘< ow 3e Bre w
evgenation may be. | To eliminate any such possibility, tree and uniotarurted eit wan tose
a reasonable interpatetan oases {ho raqoreanest by tes baler amoee is gesumed that
wilh a ent is Judgment
adequate safety of the occupants i oocureds y ine


8

&

QUITS OF STAIRWAY WIDTH,

Design and Construction of Building Exits

61

&
iN

8
fe
Ye
a
om

a ee
eo

a

ic Bust:
oP resed

iN
Sas
t

\

aan J

a Re Tee

Foo £0 700
"POPULATION PER FLOOR

Fiaure 6.—Relation between exit width and population per floor.

KS

UUTS OF SiMe MAY wooTHY

Te

a

54

all
Z

pi
ze
a

A
1405
de pet rae
. em CA |
(pero

4 > e
ae ae el
—_

eH ious need int Sunes Fear
Fiaure 7.—Relation between exit width and floor area.

cae aaiees war HPP
. Sapa Tia T"Fpoo

feperint



34 Miscellaneous Publications, National Bureau of Standards

maximum use of exits were extremely difficult to obtain, so to broaden
the field work additional observations were made in New York City
at the Grand Central Terminal, at certain of the subway and elevated
exits, at theaters, and at a number of other points where there was a
likelihood that the exits would be used to capacity, All these obser-
vations were on random conditions of flow.

5. METHODS USED IN MAKING COUNTS

The mechanical details involved in timing the movement and in
ounting the number of people walking through exits were simple.
The time was recorded by a stop watch. The counts were taken by
means of a mechanical hand counter. The probable error involved in
making a count was determined by having 2 observers make concur-
rent checks of the discharge of people through a few typical exits at
a congested period. Several trials showed that the counts differed by
approximately 2 or 3 people for every 300, a difference so small as to
warrant the use of but 1 counter.

It was found preferable also for the observer recording the time
with the stop watch to read the counter, rather than to ask the observer
making the count for the reading thereby momentarily interrupting
® continuous check and probably introducin slight error in the
count as a few people would pass by while the reading was made.
When the exits were filled for periods of several minutes the count
was taken at intervals of 30 seconds; at other times any interval that
gave an apparent maximum flow whether it was 10 or 60 seconds,
was recorded. .

Stairway or ramp disc! was studied in different ways. Where
rates were only checked, both observers stationed themselves at a con-
venient point and counted the number of people passing as they
reached the top or bottom of the exit. The readings were not started
until the stairways or ramps were filled from top to bottom between
handrails.

Observations to determine the number of square feet occupied per
person at the time when people are moving normally up or down
stairways as well as the rate were taken in 2 ways. Where it was.
possible to see the people as they entered a flight of stairs, an indi-
vidual was picked out as he entered the stairway, the count was imme-
diately started at the other end and continued until the person selected
completed the passage.. The count was then stopped and the time
recorded, thus giving the total number of people in the stairway during
the interval required for any 1 Person to traverse it. Where it was
not possible to see the beginning of the discharge, the observer with
the stop watch stationed himself at the other end of the stairway,
whistled as he entered with the crowd as a signal to start the count,
and then walked through the stairway recording the time required to
reach the observer making the count. Naturally, fewer counts are
possible by this second method during any peak period. These
counts were made only when the stairways discharged at what ap-
peared to be capacity. .

A large number of counts were taken of the traffic movement on
stairways ranging in width from 3 to 8 feet. Unfortunately, it was
not found possible in this survey to obtain discharge rates on stairways
whose widths varied by increments of about 6 inches. The relative



74 Miscellaneous Publications, National Bureau of Standards

Exit stairways -shall be so atranged or marked as clearly. to indi-
cate the level at which there is direct exit to a street or to-an exterior
open space leading to a street.

7-13-2. Lighting.

_ Exits and hallways leading to them shall be kept adequately
lighted at all times when the building is occupied.

Artificial light shall’be provided whenever natural light is inade-
quate. . .

In buildings whose Occupancy comes under class 1, public, or
class 2, institutional, the artificial lighting required by this subsection
shall be separate and independent from that serving other parts of
the building,

Section 7-14. Maintenance.”

Exits, and other means of escape when permitted, shall at all times
be maintained in good, safe, usable.condition, and shall at all times
be kept free and clear of obstructions and shall be readily accessible.
Exits shall be kept free from combustible material or. decorations.
No pat of an exit'shall be used for storage. The-space under stairs.
shall be kept clear and free, No fire-extinguishing apparatus, radi-
ator, steam or other riser shall be placed in an exit or in a hallway
leading to it, nor in an aisle of a floor area in which seating accommo-

lation is provided, unless placed in such a manner as not to interfere
with free travel, and unless heating ‘apparatus is guarded by sub-
stantial metal screens.

cms the intent of this section that exits shall at all times be kept in an anobstructed condition and free
from combustible materials, including decorations which may be‘hung ia Stairways or hallways end pro-
Wan a posiible fre hazard.’ ‘There is ot least one instance on record in which such decorations aes shee,
Payers siepied aud not only rendered the stairway impassable but communicated the fire to other por~

ns oF uilding.

Maintenance of exit facilites is one of the moxt difficult provisions of building regulations to enforce
Sheording to building officials. Exit doors are locked; self-closing fre doors are medven wears ‘open posi~
tion; stairwaye and Passafeways are‘utilized for the storage of materials, combustible as well ‘as ineom-

ns.
Daring the survey of exit facilities made in connection with the preparation of egress requirements, the
‘feRdition of the exits was investigated earefully to determine how closely tho mnainteuance peotene hone
Deing carried out. | ‘The conditions were most deplorable. Searcely a building was inspeo

ot, Grow a violation in one form or another, the most conimon being the wedging of self-closing Bre aocse
Say ae ublliztion of stairways and hallways as storage space for cotabustible manteriais. Tt woul seem
that unless frequent and thorough inspections necessary to secure proper administration of code main-
{eranee provisions were carried out, coupled with sufficiently sovere penalties for iniraction al relee, mach
Reaariort, and careful planning hevessary to provide proper exit facilities would be at least paranr
neutralized by inadequate maintenance.


Design and Construction of Building Exits 35

efficiency of stairways, say one 44 and the other 50 inches in width, is
open to question. .

All essential measurements of stairways, ramps, passageways, and
doorways were taken in order to make the necessary computations
for discharge rates. ‘The width of stairways was that measured from
wall to wall rather than the clear width between handrails, the width
for treads included any nosings, and for doorways the actual door
width was recorded. Any peculiarities of movement or conditions
that might make interpretation of test results easier were also noted.

6. CONDITIONS AFFECTING TRAFFIC COUNTS MADE

The counts of traffic movement at the Grand Central Terminal,
where more than 165 separate observations were taken on stairways,
40 on ramps, and more than 50 on gateways, were made during the
morning and. evening rush hours. The points selected for traffic
checks were chosen after a brief study to determine where traffic
appeared to be the greatest. The exits commonly used by commu-
ters—those people who are always in a hurry to get in and out of a
station—proved to have a faster discharge rate than those used by
through passengers, who were, of course, encumbered with baggage and
unfamiliar with the exits. No counts were recorded when any con-
trary movement took place in an exit because of the apparent retard-
ing effect on discharge.

A number of theaters were studied, but.many of the counts made in
them were rejected. Theater patrons, when leaving at the close of a

erformance, usually walked slowly. This leisurely exit is reflected
in the rates of discharge for theater stairways, approximately 13 per-
sons per foot of width per minute as listed in table 19, below, which
coincides with the rate obtained in the study previously mentioned for
e theater in Hartford, Conn.

Tasux 19.—Summary of observations of traffic movement on stairways

Number of | Number of

Slope charged per | S028, ‘
Width Vertical foot of wefan] 26% Diree-
Location f stair ert ‘Per person | tion of | Remarks,
of stairs height | Pet minute thon of
‘Aver-| Max-| Aver-| Min-
Rise | Tread ‘age jimum| age |imum|
ft in. im. | in, | tt | in,
Grand Central Ter-| 8| 1 ll | 18) 9 12 a
. ee 16} 59) 42] Up..
U.S. Census.......-.. 7] au] 7
7 6)
4th stroot Theater, | 8 | 34)
Subway, 4th Street} ¢/0 | 7
and “ith Avenue,
7
7
TH
7
w
TH



50 Miscellaneous. Publications, National Bureau of Standards

Section 7-1. Application of Chapter: ”
“71-4. New Buildings.

- Buildings hereafter erected, except dwellings,” shall be provided
with exit facilities in accordance with the requirements of this chapter.
‘These regulations shall be taken as the minimum necessary for the
conditions stated. For‘unusually hazardous conditions the building
official may order additional exit facilities to assure the safety o:
the occupants. .

7-1-2. Existing Buildings.

Buildings heretofore erected, except dwellings, which are not pro-
vided with exit facilities as prescribed in this chapter for buildings
hereafter erected and in. which the existing exit facilities. are inade-
quate in the judgment of the building official for the safety of the
occupants, shall be provided with such good and sufficient stairways,

'e escapes,” or other means of egress as shall be specified in a written
order by him. - .

7-1-3. Alterations.4

No buildings shall hereafter be altered so as to reduce thé number
or width of exits to less than required for buildings hereafter-erected.

No change of occupancy whether necessitating physical alterations
or not shall be made in any building unless such building conforms
with the requirements of this chapter applying’ to new buildings of
the proposed new use.

repute, chapter purabering as set forth in the report of the Department of Commerce Building Code Com-
mittee entitled “Recommended Practica for Arrangement of Building Codes ” (BS BiB (1925)) Is given on
‘the assumption that tho chapter would be the seventh in a complete series of building-code requirsments,
3No ical way bas been found to require exits in dwellings beyond customarily supplied as
S matter of convenience. It is true that there fs considerable loss of life in such structures. ‘This could be
considerably reduced by attention to proper tion, adequate fire-stopping, proper spacing of heating
Spplianees from combustible construction, ‘and other details of fire protection where a largo of im-
Provemtent is possible over many present buildings, Such details ma; An the report -
inum Requirements for Small Dwelling Construction (BS BHI8 (1932)). A further sug.
gestion made by the committee on fundamental equipment of the President's conference on home balding
‘and home ownership in the conference report entitled “House Design, and Equipment”,
‘was that sprinkler heads placed {in sspecially hazardous locations, stich as over the heater in the basement
and in the kitchen, offered additional security where such measures were practicable.
73 Fire escapes are recognized only as supplementary means of egress for the urpose of this chapter.
Fete used. they should conform in design and construction to the Building Exits Code as approved oy

the-American Standards Associati
8 Testimony

is much more diffiealt
usual solution to this problam in the past and will probably eontinae to be chosen a the easiest on
rm practice condetns the use of fire escapes on new bul bat
the only means of Providing Ssultciont ogress facilities without prohibitive cost. . Because they are an emer-
evior aad but infrequently used, their maintenance is oven neglected. ‘These devices are exposed
snow and ice, and are often inadequately lighted... Fire trom wall openings along the pail of pena
ney render a fre escape useless. For these and other reasons fre escapes are regarded de particulate:
unsatisfactory as a means of egress. -
inch yuide range of remodeling and olteration projeets are continually foing on. Changes in oceapancy

1d ion,
of building officials indicates that the securing
paneer Idings.

De of
must be provided for y. Tn both instances it is proferable that exit facilities should equal those
required for a new bi ing of the same occupancy. While the owner of a building may be put to consider-
‘able inconvenience and expense to meet requirements equal to those for new builc there ap] to
2o reason why the occupants should not be assured the same degree of safety as cosupants of paniden
for the specific purpose. In other words, if the owner wishes to protit from the alteration he shoul

fot expect to do so at the expense of hazard to the tenant. It will frequently happen that the existing exit
facilities aro ample for the use of the new occupancy and therefore no changes Wil be requnea

‘Many occupancy changes do not require physical alterations of the buildings: as, for example, changing
‘a dwelling into @ rooming house. The increase in Population may be sufficient to put the muilding into
Smother occupancy class requiring more exits but when there are no alterations the matter selon sore,
{pine huilding oficial’ attention. | Such changes are so frequent aud the possible hazard so great teenie

bl 30.
shoald be ly provided, as here, that no of of auy kind shall be made unless the
exits are adequate, “All such éasas should be Petar to tie building offal for authority to make the


of Building Exits

ON 0}

Design and Construct

9 'J003 0} 1005 pe wos} SUN
*Aqwo 100g pe oF Sap Aeszye7s [eIUOUTBTIG ¢
*poqon espssoqzo ssoyan Supping jo sasjey [1nj Uns s7OVeA0TT ¢

“MOpoTLayeuGO 3¥q-708 Jo SopI098 Aq VOY 1

sroreteseronecoee 1 Jo o o jo. g E jo. en posssoseed
peurmsojeptn | =| ON 0 o jo & gr }l 06 or Post? flor
NOMOOWLSNOO HAILSISAU-AUIL 10 STIVH ALIO
on Jo ee eC g } }}s0 nn ae 02 ‘or
NOMMOOUISNOO TAMSISAU-AUIE £0 STHOUAHO
° 0 a jo oe T fo rag 8 OO >,
oN 0 T 0 wo T So wr or 08%
NOMLOMULSNOO LSIOf GNY TIVM-AUNOSVIN 40 SATYOLINNOT
on ° ° * t .] ep er » ove'9 “ly
ox ye 0 48 yt He a oot 3
“oy a 4aybe abe
soogoy, [ON symo | PIAL | ON | cromoy | PHA | ON | rece | oozed sea | 2908 _ | POt2 00a |-0n z00Ke .
yHORTI0 019 70 01 oomeisi o}d.h4 wo sops08 ay | -om
Pe Sgt so ‘tramapeeyy | °° 8020 | LoMornaog sae | SoM
# S107 A9TSE sodeose om sceaig 1 8038 £902)

NOMOQULENOO TALLSISAY-AUE LO SAIMOLINAOT
squauounspou p29 snosuDpeosiu fo fhunumng’—gt KIEV,


Design and Construction of Building Exits 53
3,000 square feet or more in area, it shall be provided with at least
2 exit

7-3-3. Floor-Area Exits,

A floor area not having direct exit to a street or to an exterior open
ace leading to a street shall have access to at least 2 exits; provided,
t in the following cases there shall be access to at least 1 exit:

Floor areas 3,000 square feet or less in buildings of type 1, fully
protected, or type 2, protected construction, whose occupancies come
tinder class 3, residential, class 4, business, or class 5, garages, hangars,

AIDS ;

Floor areas 3,000 square feet or less in buildings-of other types of
construction not over 2 stories in height, whose occupancies come
under class 4, business, or class 5, garages, hangars, barns; .

Floor areas 6,000 square feet or less devoted to office occupancy in
buildings of type 1, fully protected, or type 2, protected construction,
when the maximum distance to an exit does not exceed 50 feet;

Floor areas 6,000 square feet or less used for manufacturing pur-
poses in buildings of type 1, fully protected, or type 2, protected con-
struction, when the maximum distance to an exit does not exceed,
50 feet and the buildings are sprinklered throughout.

7-3-4, Exits for Institutional Occupancies.”

For occupancies coming under class 2, institutional, ‘those portions
of a floor area which exceed 3,000 square feet occupied by bedridden
patients shall have a horizontal exit, ramp, or doorway leading directly

® It has been an accepted principle of exit design that in every floor area should be provided
with not less than ents While ee principle is undoubtedly sound, slight ‘modifications result in econ-
omy in construction without, i Dg ty the occupants. Buildings in which people
sleep or-are harbored for care, or in which public assemblies are held, require better exit facilities than
Emply a lowering of sands tthe lotr Rees grace an as ening quarters TRIS doesnot

ly a Stanc for lat ‘group of ings but Tecognize a

‘the two classes. “This distinction is based on the velative ability of the occupants to evacuate the buildings
promptly in an ency. ,

"The provisions of this chapter adhere to the requirement of 2 exits, except in osrtain cages in which itis
‘considered safe to permit a relaxation, Low-hazard occupancies in buildings of fire-resistive construction,
buildings having a slight density of population, and sprinklered factories constitute the only exceptions
that ld be pe within the certain iti

ust not be exceeded. As a check against these requitements, a survey of modern buildings was con-
ducted in several cities to determine current practies in the design of exits. ‘The findings of this survey
indicated that modern architectural practice favored the permitted exceptions.
Floor areas of public and institution Fs should always be provided with pot less than 2 exits,
e

mg been recognized that in very high
ity for most persons to descend to the street by means of stairways, and
must be placed on the elevators.
consideration is the possibility of re-entering at a floor beneath the fire in the case of  fire-
Tesistive building. With the fire-resistive floors and protected openings characteristic of this type of con-
struction such a procedure is practical. Normally, ‘when there (8 but | stairway in a tower, tite wil bo
i .._ ‘The practice of locking doors of stairways so that a person
impairs the usefulness of the stairway, both for service and escape purposes,

‘The maximum of 3,000 square feet, area for residential construction having 1 stairway was set some time
before intensive studies of low-rental housing had been initiated. Some of these studies point to
of an area approximately 10 percent greater in the case of the so-called “‘cross-plan” type having 4 apart-
‘ents to a floor using a common stairway. This is required in order to meet standards of light, ventilation,
minimum room area, privacy, and other factors held to be essential.

% Buildings of institutional occupancy require special provisions for means of egress. A study of records
gyer 8 period of years shows that a large loss of life has occutred in buildings of this class as a result, of fires.
‘The fire records do not state directly that the exits were a contributing eause of loss of life, but the facts
Point to the need for special exit facilities in these buildings. ‘There are many records of institutional fires
in which the occupants have been carried to safety by attendants and firemen, in some cases through win-
dows, indicating that the conventional exits bad been rendered npassable” ‘The mental and p
condition of the occupants is such that the ordinary protected exit adequate for buildings of other occu-
Pancy will not suffice for the institutional building. Helpless children, bedridden and incarcerated

itting 1 ¥ ions
Riered, a was also the probate at otis steerer It has lor
buildings itis a physical impossibili
‘at some dependence



62 Miscellaneous Publications, National Bureau of Standards

cy

yoosefte

a
sy

UNITS OF STAIRWAY WoT

tof
ope Rees Hees co
“pleas eka in squne: Peer

Froure 8.—Resulte of exits survey compared with curve adopted for office buildings.

o

x
§ °
Nn p vat
N pperspit
g ryan
S| aye
3

s at o |
2 Ips
8 geet

S 795 75086 255 Teese 3566

FLooe AREA IN SQUARE PeeT
Fraunz 9.—Results of exits survey compared with curve adopted for stores.

109 ftper pprsan|60 persons per upit_|__—|

UNITS OF STAIRWAY WIDTH

2

Zae08
FLOOR AREA I SQUARE FEET
Fiaurn 10.—Resulis of exits survey compared with curve adopted for factories.


CONTENTS

‘TABLES

1. Causes of loss of life from fires. :

2. Deaths by fire in buildings in New. York City, 1920 to 1931, inclusiv

8. Deaths per fire-

4. Causes of loss of life in hotel fires. =

5, Relation of garage and tenement fires to total in New York City.

6. Summary of exit’ measurements for office buildings.

7. Summary of exit measurements for store buildings.

8. Summary of exit measurements for factory buildings.

9. Summary of exit measurements for school buildings.
10. Summary of exit, measurements for apartment buildings
11. Summary of exit measurements for hotels.
12. Summary of exit measurements for hospitals_
13. Summary of exit measurements for dormito1

halls_-_.
14. Summary of exit measurements for theaters.
15. Average of exit measurements...
16. Summary of some previous traffic movement observations.
17. Survey of exits in school buildings in Rochester, N. Y_.
18. Capacity. tests on revolving doors of certain buildings in New York
vy.

19. Summary of observations of traffic movement on stairways.
20. Summary of observations of traffic movement on ramps_--
21. Summary of observations of traffic movement through gates and door-

ILLUSTRATIONS

1. Doorways placed “‘as remote as practicable”_.__..-.-.------------
2. Doorway location for connecting rooms occupied by 100 or more

4, Distribution of stairways in a building where services are in a central
core...

5. Example for computation of amount of service area alloted to mixed
occupancies____

6, Relation between exit width and population per floor

7 Relation between exit width and floor area.

Results of exits survey compared with curve adopted for office build

. Results of exits survey compared with curve adopted for factories.
11. Results of exits survey compared with curve adopted for schools.
12. Results of exits survey compared with curve adopted for apartments.
13. Results of exits survey compared with curve pted for hotels and

lormitories



42 Miscellaneous Publications, National Bureau of Standards

6. DEVELOPMENT OF A SATISFACTORY METHOD

Each of the methods already described selects certain conditions
which must be fulfilled in order to insure a reasonable degree of safety.
Refuge for all, eseape at a predetermined rate, a combination of the
two, and probable need for simultaneous use, all start with certain
assumptions. and then endeavor to apply mathematics that will accom-
plish the desired result. No method attempts to apply any factor for

ic. Only oné makes assumptions that some exits will-be blocked
ecause of smoke or fire. This, as worked out by means of a formula,
applies not-to the number of stairways but to increase in the aggre-
gate width and there is thus no assurance that the extra allowance
will be transformed into additional stairways. .

Tn view of all the uncertainties involved in the problem, compli-
cated methods and refinements of detail seem scarcely justified. At
the outset it may be pointed out that the needs of probably over 95
percent of all buildings will be covered by the minimum requirement

lor 2 stairways. Perhaps on’a basis of population contain the per-
centage would run ‘somewhat higher, but the necessity for going be-
Yond 2 standard 2-unit-width stairways does not arise in the average

uilding. It may well be kept in mind that most of what follows ap-
plies to the relatively infrequent building of large size, usually of fire-
resistive construction and designed by experienced talent.

In weighing the advantages and disadvantages of each method the
primary consideration, of course, is safety ; but it is spparent that what
constitutes safety cannot be definitely established. It therefore is
fruitless to reject considerations of loss of usable space on the ground
that such considerations have no standing. No one would dispute
that profit should yield to safety where it can be shown that. certain
requirements will provide safety. But where it cannot be so shown it
is legitimate to balance economic considerations against theoretical
assumptions.

Experience is obviously one method of approach, If it could be
shown that certain cities had utilized a particular method of dealing
with egress requirements over a period of ears, that buildings hi
been erected in strict conformity to it, and that maintenance had been
perfect, and if the loss of life in fires where exits were a factor were

nown over the same period, some evidence would exist for or against
a given method. Unfortunately, such evidence is not available in
sufficient detail and over a long enough period to be of much use.

, Another means of approach is to compare exits found in representa-
tive buildings in a number of cities with those demanded by the vari-
ous methods already cited. It may be argued that simply because
certain provisions for exits exist this is not necessarily proof that they
are adequate, yet there is a certain weight in an accumulation of
instances where certain measures have been followed coupled with no
conspicuous trouble. Traditional principles developed by responsible
architects and engineers in the design of buildings are not to be ig-
nored. Such principles may not be susceptible of definite analysis as
to the extent of provisions for safety, but competent designers come
to have a certain “feel” for the right thing arising out of long study of
needs and observations of buildings in actual use. There is further
consideration in that such buildings have been designed with thought
to their economic use and that practical considerations have not been
entirely subordinated to theoretical provisions for safety.


40 .. Miscellaneous Publications, National Bureau of Standards

‘Such a method takes @ large amount ‘of space away from the
rentable area of the building and reductions are resorted to to over-
come this objection by making allowances when the building is sprin-
kled or when: horizontal exits are provided. These devices are not
always:conveniently installed and the arbitrary allowances made for
them may or may not accurately represent their value in replace-
ment of stairway facilities. While it-is true that safety-should be the
first-consideration, thereis a very real question whether the degree of
safety offered by this method is necessary, articularly in low build-
ings where a certain amount of flow out of the building appéars to be
inevitable. . Authorities also maintain that people not stand still
in stairways even in high structures.

2, FLOW METHOD.

This method is based on an assumed rate of flow of people, com-
monly at the rate of 45 persons per 22-inch width per minute down
stairways and of 60 persons through doorways. -It is usually coupled
with an assumed length of time within which it is expedient to evacu-
ate the building. -The object is to get the people out and away from
the threatened aréa in as short a time as possible.

With certain occupancies such as theaters where simultaneous exit
by all is needed and in certain cases where drills are a lar feature
as in schools, the method has many desirable features. It provides a
definite objective.to be-accomplished. The result calls for considera-
bly less stairway width than the preceding method. For compara-
tively low structures the method has an obvious application since it
Fecognizes that flow out of such structures is a natural procedure.
However, its-use is confined to a few occupancies and to buildings of
moderate height. Continuous movement down stairways, especially
in high buildings, cannot be expected without serious effects upon
some of the occupants. Any calculations assuming continuous
orderly movement in such structures runs contrary to observation
and ‘experience.

i » 3. COMBINED METHOD

This method attempts to correct the defects of the capacity and
flow methods through formula intended to apply the flow method to
low buildings and an increasing emphasis upon capacity until this
controls injhigh buildings. The formula contains various factors
involving such features as type of construction, enclosure of openings,

of occupancy, presence of horizontal exits, etc., all of which
affect the final result.

The method offers a means by which definite relationships may be

reserved between height, character of construction, and other
features. It recognizes that people can file out rapidly in low build-
ings and cannot be expected to do so in high ones. And it effects a
transition from one method to the other in a gradual and systematic
manner.

The results reached through application of this formula have never

en entirely satisfactory even to its advocates. The relative
weights assumed for the various factors are empirical. There is a
constant increase in the aggregate stairway width throughout the
building, as the building becomes higher which is a principle whose


Design and Construction of Building Exits 65

" 7-6-2-2 Treads and Risers.

Treads and risers of stairs in exit stairways shall be so proportioned
that the sum of the height of 2 risers, in inches, and the width of 1
tread, in inches, is not less than 24 nor-more than 25; that no riser
shall be greater than 7% inches in height and no tread less than 9
inches in width, exclusive of nosing, eads shall be not less than
12 inches in width where flights of less than 3 risers ‘are permitted.
‘Treads less than. 10 inches wide “ shall have nosings. Treads shall
be of uniform width and risers of uniform height in any 1 flight.

Winders shall not be used in exit stairways.

17-6-2-3. Required Landings.®

No flight of stairs shall have a vertical rise of more than 12 feet
between floors or landings; provided, that in exit stairways in build-
ings whose occupancy comes under class 1, public, such vertical rise
shall not exceed 8 feet.

The length and width of landings shall be not Jess than the width
of exit stairways in whick they occur; provided, in straight runs the

iainimum distance between risers on landings and platforms shall not
be required ‘to be more than 44 inches.
7-6-2-4, Changes in Floor Levels!

In buildings whose occupancy comes under class 1, public, flights
of less than 3 risers shall not be used at entrances or elsewhere in con-
nection with required exits. To overcome lesser differences in level,
gradients not exceeding 1 foot in 10 feet shall be used:

7-6-2-5, Handrails.

Exit stairways shall have enclosing walls or well-secured balustrades
or guards on both sides; when less than 44 inches in width they shall
have handrails on at least 1 side; when 44 inches or more in width,
they shall have handrails on both sides.

si Of the several rules in use for proportioning treads and risers, the one given in this section seems to give
fesults more nearly in agreement with current Practice. ‘The matter of the slope of stairs seems to be a very
important point, affecting as it does, the comfort and safety of the use of thestairs, A high riser and narrow
tread me very hazardous under fire conditions. On the other hand, &
Nery low riser and wide tread rake travel slow and may render the stair as unsafe as risers and treads of the
other extreme. 2 reer baohitzof the Fsers Doing made too high or too low bas boen overcome by fing a

with.
Some recent studies have been made on the relation of tread width to riser height and other features affect
{ng the uso of stairways, “Curves plotted for the three well-known rules for preportionlae frente ned ae
Saino an 90 of to sugeted farvasnglest atin te range of is ordinarily found in
Pc ng a een an vay oly alenily. “ower farther study of the phase of slarwey deign ap
Biistr aeal, tt farther aseusion ofthe sabes, cpoule arise in tho Navermber and Detomber 1083
genes of Architecture entitied Rako, Wiser, and Head" and © Afore Aueat she Stoie Bae een Mees
Anent Stairway Design”, in the January and February 1931 issues of Pencil Porte
sia ‘which wind as they descend thus causing a difference in width between their inner and outer
ends are lso hazardous, because there is no uniform width of tread In any ouestep Asc ores
user must feel his way carefully end the usual rate of descent is slowed up. ‘here is also au coer wmrecre
osstnility of tripping becausé of the varying footing. Windors are frequently graceful in appearance and
it is often desirable to make use of them from an artistic standpoint, particularly in dwellings and monu-
mentel buildings. ‘The requirement given doce not probibit their use on mouumenval stairs, bur does
a he memsarembek tnd it under th it be. horizontally tro
e neasuremeént of tre wi ‘under this requirement means the run as measured izontally from
the face of 1 riser-to Une face of the next, mean °

Aa anbroken length of stalrvay erending for sine  istncesrentes an efecto tgoppess that edi
goneerting to many people snd offers no relief rom the fatigue inoposed ia daseending, Sy breaiog vote
length of travel through the uso of landings, « desirable effect is produced Hoth as tesarde tie spore
steepness and in providing suloome change irom steady descent, The provisions of this section are intended
to accomplish these purposes. The vertical height permitted between landings has been decreased ie ee,
£338 of public buildings because of a greater number of people to be atcommonated and the pester woe
bilitiss of panic in Public gatherings:

4; Short fights of stairs are particularly objectionable and Sights of less than 3 risers should not he per-
mitted in public buildings. When the exits ate crowded, the stairs are not readily visible and tnppioe or
stumbling is likely to occur. Ramps are much more suitable for such’ ‘buildings provided the gradient is
Kept low enough for safe travels °

Handrails are essential in stairways to provide support for persoris descending and It fs desirable that
each filo of persons should have its own support, " .

Ralls also serve as ruides to indicate changes from fight-to landing, change of direction, end proportion
Pf tise to tread in locations where visibility is poor, or where attention lias been Giverted to Giher thee

vel on the stair.


10 Miscellaneous Publications, National Bureau of Standards

record of these fires discloses that less than half originated in. office
rooms. -

Factory fires reveal rather heavy loss of life in the incomplete
records-available. This probably results from the density of popu-
lation and poor maintenance of exits combined with inferior con-
struction and, in some cases, the fire hazard of the contents. Locked
or obstructed exits are mentioned frequently in the reports as causes
of loss of life, and apparently altogether too much dependence has
been Flsced on fire escapes in the past. The loss of life in facto
fires demonstrates most clearly that, regardless of how perfect. build-
ing-code regulations may be, unless such regulations are properly
enforced, particularly the maintenance provisions, they are almost
valueless. A locked exit door may render useless all of the carefully
considered provisions of the building code tending toward safe and
sure egress in a time of emergency. :

Records of department-store fires are too incomplete for the com-
pilation of statistics and the fires involving heavy loss of life have

een too few to make this occupancy stand out prominently in the
records. A casual survey of department stores would at once raise
the quéstion why more fatal fires have not occurred. Certainly the
piles of highly flammable materials, open stairways, and crowded
condition of many of our older: department stores offer excellent
opportunities for , panics, and consequent loss of life. The rela-
tively slight loss of life is probably explained by the fact that as in
office buildings the occupants are alert and fire is discovered before
it has gained any great headway; also, because more attention is
usually given to fire protection of the property than in some other
occupancies, thereby adding to the protection of the occupants.

Class 5, garages, angars, barns, as established in the report, Rec-
ommended Minimum Requirements for Fire Resistance in Buildings,
consists of garages, hangars, stables, barns, and other buildings of
similar occupancy. The class was at one time considered especially
hazardous because of the nature of the contents, particularly the
garages, but as a result of generally thorough regulation is not now
so regarded. In support of this conclusion evidence submitted by
Rudo! ph P. Miller to the Commission for the Revision of the Tene-
ment House Act of New York, July 6, 1927, is presented consisting
of figures from the annual reports of the fire department for 8 years
(sis. f0,,1925, inclusive). The figures for the entire city are given
in table 5.

‘TABLE 5.—Relation of garage and tenement fires to total in New York City

In tene-
In public | In private | In tene- | ments,orig-
Year ‘Total | “garages | garages’| ments | inating is

stores

4, 368 40 7, 054 953
sr 364 139 8,650 924
13,475 331 122 6, 458 991
13, 281 307 us 6,073 1, 059
1, 311 300 58 664
10, 807 93 4,883, 383
10, 158 205 5,052 599
__10, 552 1857 80 3,319 639
98, 774 2,312 46,737 6,412
12,347 239 110 5, 842 802
100 Exe a9 475 65



°52- Miscellaneous Publications, National Bureau of Standards

each other as practicable, at least 1 of which shall lead directly, or
through a corridor or other open space, to an exit and any other door-
way may lead into an adjoining room from which there is access to
an exit or exits.

7-3-2. Ground-Floor Exits.”

When & floor area has direct exit to a street or to an exterior open
space leading to a street and is occupied by 100 or more persons or is
berrergaes tho room with a population of 100 and that with 180. ‘are, however, considered sufficiently safe

Permitting’ of the room doorways to into room ha’ access to an exit allows

ace te tee ore ee me
n ry a , with the en

Raving aodess fo an pert “A corvoct deste for room doorways fro 2 or more tobe eho E,

\ \

100 100 . 100

q YE

Fieure 2.— Doorway location. for connecting rooms occupied by 100 or more persons.

sick round floor exit is one that is so situated that it leads from a floor ot story directly to a street. In
ring 100 persons as the limit beyond which 2 or more exits are required from these floors the samme reason
* is used as in fixing the limit for rooms. if the limit were fixed at any lower figure, many small shops wit
narrow ‘would be required to have 2 front ‘3 8 rear entrance is often impracticable for
tbe Hit Se a, Yi°R. ofthe small population found in these shops even with an area of 3,000 square fet,
‘the limit fixed should be safe under linary conditions.
expression “direct exit to a street” used in this section means that the floor area communicates
Glrectly with the street either by a doorway, or by a short Aight of steps,
<jproughout the chapter certain exits are réquired to lead directly to a street, or to an exterior open spsce
leading to,8 street. ‘This expression is usod to permit the designer to discharge the oocupants into a beet
or court which in turn communicates with the street, either directly or through Properly protectod
Permits desist ‘ie dani ofthe attiieg it assumes tit tae applies eres 10
ry in ign of the buflding. "It assumes same. ‘aD as
facili they shall never diminish in the direction of exit travel.

THEATER

a

PASSAGE WAY courr

Freure 3.—Discharge from a theater "inte @ court, thence through a passageway to
e street.


58. Miscellaneous Publications, National Bureau of Standards

‘Areas per person
Occupancy: (square feet)
Bonee hall, lodge room, and places of assembly. 15

Street ‘floor and sales basement. 30

her floors... 22... _ 60
School, courtroom, and other similar publi 40
ice, factory, and workroom: 100
Hotel and apartment. 125
Institutional______ ~ 150
Warehouse, storage,-and garage. 300

In places of assembly, theaters, dance halls, lodge rooms, and
similar occupancies when seating arrangements are used or con-
templated, ‘the seating capacity shall be established by allowing
6 square feet. per person in that portion occupied by the audience.

‘he population of basements or portions of basements or of mez.
zanine floors shall be determined according to the occupancy.

The population of a mezzanine floor ‘discharging through a floor
below shall be added to the population of such floor.

7-5-2. Population Limited.

It shall be unlawful to occupy any part of a buildi by a greater
number of persons than that for which exits have ging provided in
accordance with this chapter.

inthe Building and do not take into account. visitors, customers, or other transients. ‘This increase in
epultion's probably sulcient to bring the gt ans er Dann Foy Sealy ae an Teas increase in
Tegommended figure of 100 square feet for oles baloney. °

‘The table of areas per person Spplies also to mixed occupancies provided the adjacent corridor areas,
shafts, istributed to the several occupancies in ‘Proper proportions to obtain the
Foss area devoted to any one occupancy. For exaiaple, in figure 6 with 2 ocenpancies on a given

vor Cf 12,000 square feet area, the area devoted exclusi ‘to the 2 occupancies being 4,000 and 6,000 square
feet, the proportion of the remaining 7000 square feat of st utilized by corridors, elevator shafts, and
seas eons, Algeated to each occupancy ‘be 4,000/10,000 and 6,000/10,000, or 800 square feet and 1,200

are foots Teapoot vo.

ALA KITCHEN

OANCE FLOoR RESTAURANT
6000 SQ FT 4000SQ FT

TOTAL AREA = 12,000SQ Fr

Fiaurn 5.—Example for compiitation of amount of service area allotted to mized
occupancies.

i tbe general occupancy contains a minor oecupancy, as, for example, a kitchen in a restaurant, the area
feniaingd in the minor ocenpaney is to be added to the general occupattey and the population neitoenes
by dividing the total area by the area per person for the eral ogeupaney.

rast ba rene cuit facilities for» building have once been designed, tue number of oecupants of that building
Fast be limited to the exit facilities provided, The requirements are thus definitely connected te tana
‘ative sections and insure that penalty provistons in the administrative chepter of the code will aout,


12 Miscellaneous Publications, National Bureau of Standards

Nearly all construction design today makes use of mathematical
formulas applicable to the problem involved. Numerous series of
controlled tests can often be made, and, from the data obtained,
formulas can be evolved which will apply generally. Criteria for the
design of means of egress from buildings present a different problem.
It is impractical to conduct tests of exit discharge that would simulate
actual conditions during a fire. However, experience has dictated
certain necessary requirements, and current practice in exit design can
be reviewed as to performance, desirability, and économic effect. _

The number, location, size, and type of exits seemed to be major
items to investigate. The population or area served by the exits
and the maximum distance traveled to reach an exit were also impor-
tant.. Additional features, such as building height, number of fire
towers, fire escapes, spiral chutes, and horizontal exits, permanent
obstructions in the stairway enclosures, conditions of final discharge
of stairways, size and type of.doors in stairway enclosures, continuity
of stairways, dimensions of treads and risers, and other construction
elements related to exits, had to be noted to complete the picture.

2, SOURCES OF INFORMATION

The desired data were collected in two ways: (1) by an office
study; and (2) by an inspection of buildings in several cities.

As a first approach in the office study, floor’ plans from architec-
tural and technical magazines were inspected for exit facilities. Plans
obtained from architectural and engineering offices likewise furnished
excellent material exemplifying current design practice. Suggestions
solicited from architects, engineers, school superintendents, officials of
hotel chains, theater executives, and others having specialized
knowledge of exit requirements made a valuable contribution as the
collection of material progressed. The restrictions on design of exits
imposed by some of the laws in effect received their share of attention
in ‘the form of a digest of exit regulations in building codes, labor
laws, and tenement-house acts. These were listed and the funda-
mental requirements of each compared.

Additional information was obtained by means of a questionnaire
sent out to some of the leading architectural offices in all parts of the
country and containing, among others, this question: Are the present
code requirements for means of egress too severe or too lax?

The ‘answers to this question indicated that this group believed
almost unanimously that many of the present building regulations
as régards exits were too severe. Some of the general arguments
cited to substantiate this opinion were as follows: That many ordi-
nances have been rushed through after some catastrophe and are ill-
-advised and extreme; that heretofore these requirements have been
worked out in an unscientific manner; that improvenients in buildis
construction such as increased fire resistance and the inclosure 0:
. Stairways now. obviate many of the requirements formerly necessary,

and that more reasonable consideration should be given to the loca-
tion of buildings and to their occupancy. .

But‘ one observer thought that the code requirements were too lax,
referring. to exits in summer hotels. These buildings usually fall out-
side the jurisdiction of municipal building regulation.

This information reflected an important point of view and helped
to make the exit problem clearer.


Vv CONTENTS

APPENDIX

Vi. Means of egress_.-~
Recommendations.

& Definitions._...

3,. Classifications.

Sec. 3-1. Classification of buildings by occupancy-

inpex To RECOMMENDATION:

vise’
: e28 Required: Jandings.

3-2. Classification of buildings by type of construction.
7-1. Application of chapter-

7-1-1. New buildings_-
-1-2, Existing buildings.

7-3-4. Exits for institutional occupant
7-3-5. Exits for places of assembly.
7-3-5-1. Rooms.
7-3-5-2. Buildings.
7-3-5-3. Separation
7-3-6. Boiler-room exits.
7-4, Location of exits.

7-4-2. Distribution of exits.
7-4-3. Outlets from exits...
7-5. Relation of population
7-5-1. Determination of population.
ie 7-5-2. Population limited_.

Ted. But Metrwaye coring £ below gradi
sit stairways serving floor area below grade
7-6-2. Construction...

16-21. Materials
7-6-2-2.. Treads ani

Changes in 1 floor Jevel_

gasgesaeasand


Design and Construction of Building Exits - 33

Tapue 18—Capacity tests on revolving doors of certain buildings in New York City

converted
Atend con’

Direction |4£°24] atena| Atend| Atend [UTE
‘Neme of trate | 57St, | 30min | 45min | 60min] potriy
basis

9 129 176 188

7m 105 163 Bz

152 BA 339 420

‘21 28 398 480

152, 245 355 440

353] 523 | 758. 920,

376

Hotel Commodore.. a ie pts

Total... 2 | 396] 635 sr

. 952

a7

1,84

1,48

620

1,768

109 436

10. 440

29 |. 876

130 227 520°

199 308 796.

329 535 1,316)

164 311 65

1B BB ‘512°

849 1,168

31 416 533 640

310 421 516 688

oui| s7| 1,00] 1328

Commercial Cable Building... wey gl) er) ey les

Total... 67 | 1,006 | 1,564] 2,052] 2,268

Bank of Commerce Building... we) ea

498 | (847 | 1,281 | 1,640 1,902

so] 163] mr] 337 428
T} 100} 197 | Bra | 368 356
- is2| 360] 605} 700 780

* Count made through 1 door only.’ Courtesy Van Kannel Revolving Door Co.
4, FIELD WORK

A review of the tests-on traffic movement, summaries of which have
been enumerated in preceding paragraphs, indicated that certain gaps
in these data could well be closed up by making further counts. It
also appeared desirable to check some of the previous findings, espe-
cially those where but few observations were available. A field survey
was then instituted in Washington, D.C. Traffic counts were taken
at some of the larger Government office buildings, at department
stores, and at theaters. Congested conditions which would produce


INDEX TO
a

“Application of,

LPI

“Approved, definition of
‘Ares

3

Balconies:

iam number
Minimom, ough eens.
eye city st
PE hen
oa
Special Timfstions.~
Doors:

Automatic fire..
Fastonings,

‘Mininum sum
Minimum width.
‘Modifications in required width.
Relation of population to.
Signs...

‘3
BS $8 BBs Be sss

SaBB ssseres aa aaeese S ss Bese eee

Za SS SsQss

i

RECOMMENDATIONS

buildings.
‘In other types of construction.
Fteimam permitted
am
‘Stairs in connection

Exterior near.

Hire relene af wal and partitions
loor area on each si

Fy on

s
SIloIsS

SS R{ess sah aA SHR SIsRS g

asa

88S 88

SPIBAssVaRy RAs

segaus


21

Design and Construction of Building Exits

“Kenaise Bang f
“Barpring aga 30 48}9q TING Og] UNE IOVEARTA +

=| on 1 I eo |t le 19 98 oor |g
| on 0 ° {8 It  }poe ou os vee fe
on 0 ° a |y sfop ozt 08 00 ‘ez, | or
oN 0 t) wie 6 86r cc) oo0'Tt | oF
on ° ° ce iz ay art 9 00's a
on ° t wit wr ser fais ooc‘et fer
on ° 0 ltt Hoe we on jooo'st far
° ee * wet re 008"
x ay |? ° ay ey y be yal ps |
wpra| on [ayia } on [mpi] “on | mpi} von |
4430 we 0} 009,
101 ‘ osied z0d 8011038 “
sbsorg | POPIEHGS emameISP. | Gaaw esau | {O1ASY wo | voxe ss01D | yr ausioee | “Om SarpIIMEE
sure yeqmoruog | sedeos ang | zemoyeng | “stoaseg
NOMLOAWISNOO FAILSISAU-TaLS
squsmainevaus jira burpying qozoy fo hanwung— tT] a1avJ,
“shomeys 0014308 GOUT-08 £ SO wt “squomyzede z qoe0 20} oxqerjeae odeose oxy T pre Ae8:70%8 Tor “TTB YOU}-g BB Jo opys Yow o[quTTEAE skBuATTEIS zy
‘Seatsje3s wopoous opieino Gouy-ee T “&quo ywomes8q TI “sovny (elds » SoH »
-ghou.7ey8 wopooa opfsino youl-ze Z ‘eAeazio}s oOjA308 YOU OS F SEH & “T84 yoUTy w Jo opys qowe ejqeyjuaw sdeasieys Z ¢
“wyaomaieds g Jo} 0149 “epias soqouy ¥¢ Gove aXwameys mopoom € SEHT & “ann rexds 8 oH ¢
“Aeayey8 Topo. “BIOpPE] UO YOU-FT Z 9 “Sayprng om Jo sq3}0q 11M} O49 UNA sIOPRASTEE +
0 on o & T oO Pig at 009 '¢ 14
° oN o | jen joe ost oe 009 z
0 on 0 |w ft 08 oe 8 000% z
° on ° ow it % 200 8 cor z
0 on t) & |r 9 19% st 089 8
0 on o (8 ly Hee ne @ our = de

NOLLONULENOO TNVEE


DESIGN AND CONSTRUCTION OF BUILDING EXITS

ABSTRACT

‘The deplorable loss of life that occurs annually in building fires can be reduced
by providing suitable exits. Building-code requirements vary widely as to how
many exits are needed, what sizes they should be, and how the details concernin;
them should be worked out. To aid those interested in the problem, surveys ot
current, practice in providing exits and of the rates at whic! People can effect
their escape through different kinds of exits have been made. ie methods
employed in the surveys and the results are presented here in detail. To supple-
ment the information thus obtained, opinions have been solicited from numerous

itecta, building officials, fire-protection experts, and others. Five methods
of calculating exit width in current use are discussed. As a useful reference when
local requirements are under consideration, suggested requirements are presented,
together with notes on the reasoning employed in connection with them.

a CONTENTS
Page
- 1
- 2
- 2
i - 2
3. Causes ~ 4
III. Building-exits survey. - i

12

3. Field investigations. 13
4. Tabulation of data 13
5. Population studies. 13
6. Location and numb: 25
7. Stairway widths__._._ 26
8. Propo 26
9. Stairway enclosures. - 27
10. Exit outlets... ..-. - 27
11. Special forms of exits. - 28
12) Exit designation. 1 88
13.- Exit maintenance. - 29
IV: Survey of traffic movement in exits_ - 30
i. Procedure-._.... - 30
2. Sources of information. . ._ - 30
3.. Conclusions of previous traffic counts. - 31
4, Field work. weenne 33
5. Methods used in making counts - 34
6.. Conditions affecting traffic counts made. 35
7. Tabulation of counts on stairway discharge. ” 36
8. Characteristics of stairway discharge. 36
9. Ramps... 37
10. Doorways. 38
Vv: 39
1. Capacity method. 39
2. Flow method. 40
8. Combined method. 40
4, Probability method_ 41
5. Floor-area method... 41
6. Development of a satisfactory, method _ 42
7. Credit for elevators. 44



Design and Construction of Building Exits 45

the conditions are favorable for taking out a considerable number of
people. If an emergency is well sized up by some one in authority,
it can often be met. by taking people from above the floor involved
to a lower floor, from which they can find their way to safety by means
of the stairways. Thus, the elevators do not necessarily have to
descend to the street floor each. time. Such a utilization of them
calls for intelligence and. good discipline, qualities that cannot always
be safely assumed. . . ;
In general, a safer policy appears to be not to give direct credit
to elevators, but to recognizé their availability in high buildings in
the stairway requirements. The presence of these devices makes it
ossible to apply the assumption of. probability with greater confi-
lence. - With some possibility of flow out.of the building down stair-
ways in the case of Now buildings and with modern elevators acting
as a valuable auxiliary in high buildings, proposed stairway require-
ments are considerably strengthened, while in the case of certain
occupancies for which floor space is required in the stairways for the
occupants of all floors, the elevators in use are likely to be of the push-

button variety or else not able to carry a significant number of people
in case of fire. :

. Thanks are due a large number of architects, engineers, building
officials, and others who supplied information and cooperated in
various ways. The procedure employed in the surveys was possible
only because of the courtesy of Buildin managers who permitted
measurements and traffic counts to be taken in buildings under their
jurisdiction. Suggestions and criticism from numerous individuals

elped materially as the work progressed. Data on earlier traffic
counts was supplied by J. Vipond Davies; the Illinois Central Rail-
road; and J. M. Tracy, superintendent of schools, Rochester, N. Y.
Others to whom particular acknowledgment should be mede are
Frank Burton, consulting engineer, Detroit, Mich.; C. Heller, con-
sulting engineer, San Francisco, Calif.; Nolan D. Mitchell, structural
engineer, National Bureau of Standards; and Robert S. Moulton,

technical secretary, National Fire Protection Association, Boston,
8S.


Design and Construction of Building Exits 29

hallway. . Practically no signs existed telling whether any given stair-
way ran to the roof. Numerous office buildings and hotels with
enclosed stairways ending on the second floor possessed no type of
directional sign pointing out. the line of travel from that point to the
ground floor, and, thence to eventual discharge outside of the building.
‘Theater exits stood alone as the only example of efficient exit designa-
tion. Churches displayed an almost complete omission of any exit
signs. Many of them now have apparatus for lantern slides or motion
pictires, involving need for exit designation within the darkened room,

‘13. EXIT MAINTENANCE,

Exit maintenance, or rather lack of proper exit maintenance, proved
to be a serious handicap. to many dings well provided with exits,
Tn one large department store visited the. ound-floor door of an en-
closed stairway was found padlocked. ors opening to the roof
were frequently found locked. Building managers claimed it was
essential to keep certain-doors locked to prevent robberies. The total
number of locked exit doors found would give anyone cause for alarm.

A. very common practice in man: buildings, and apartments
topped the list, was to prop open the fire doors of enclosed: stairways
in an attempt to increase the ventilation. For the sake of easier
communication during congested periods, fire doors in schools and
stores were also found propped open. In one or two instances fire
doors originally install: bad been removed to make communication
easier between floors.

Packing boxes, receptacles, advertising, and articles of all kinds
were found in stairway enclosures, on landings, in hallways and
corridors, and in front of exit doors, or horizontal exits, Xposed
radiators, piping, incinerator chutes, chimneys, columns, and beams
frequently cut down the normal width of stairway enclosures. While
building officials recognized the hazard of blocking exits, or interfering
with the intended Purpose of fire doors, they were unanimous in de-
claring that successful enforcement of provisions dealing with exit
maintenance was one of their most difficult problems,

Building officials also made frequent observations on the exit prob-
lem involved in the remodeling of old buildings. One pointed out that
in his own city many old private residences had been converted into
rooming houses, often without his knowledge and resulting in totally
inadequate exit facilities for the new use. Increase in the population
of a building over that contemplated in the original design of the
exits caused many inspectors unpleasant moments. From the num-
ber of plans examined where additional exits were ordered to comply
with the code, some latitude evidently exists on the part of those
designing exits. One inspector was said to have lost his'job because
he insisted on the number of exits specified by the code. On the other
hand both architects and engineers claimed that the exit provisions
of some codes were almost impossible to interpret without frequent
explanation from the building official, that they hamper design, and
that they were all too often unreasonable and economically unsound.

This summary has touched but briefly on the exit conditions found.
However, taken in connection with other conditions peculiar ‘to indi-
vidual buildings, it furnishes a background of current practice that is
useful in developing rational provisions for exits.


38 Miscellaneous Publications, National Bureau of Standards

be used to capacity, no counts were taken. An attempt to make a
count on a ramp at the Griffith Stadium in Washington, D. C., which
was 17-feet 6 inches wide, proved unsuccessful because the observers
were unable to get anything approaching accurate readings on a
ramp of this width.

Given similar conditions, the discharge rate on ramps was faster
than on stairways. Naturally, the width of stairway treads reduces
the normal 30-inch stride more than a ramp with a slope of 1 in 10
or less, and would therefore result in effecting a slower discharge
tate for the stairway.

10, DOORWAYS.

Table 21, below, lists the average discharge rates for counts made
at gateways, swinging doors, and revolving doors. It should be
borne in mind that these studies were not made to determine the
efficiency of the various types of doors. Most of the counts of traffic
through doorways were taken when the doors were fastened open.
Just how much slower the discharge rate is when doors are swinging,
would require further special study.

At the Grand Central Terminal, the readings were taken at the
gateways as they were opened to let the crowds through that had
been waiting in the concourse; they therefore show a higher rate of
discharge than the doorways in the office buildings or department
stores.

Taste 21.—Summary of observations of trafic movement through gates and doorways

Number of per-
ter
et foot of
. Total width per
Location ‘Type ofexit | Tre minute Remarks
Aver- | Maxi-
age | mum
ft Jin.
Rl oO 4 16
6) 6 B
6] 0 13 18 | Both doors fastened open.
Department store... 5) 8 4 Do.
7. 8. Bureau of Priat .
‘Engraving’ 5) 6 20 Do.
National Geographic Society. K5] 8] B] | Botdydoots operating
U.S. ‘tment of Commeree- e
GS Dppxtment of Commerce 5] 4] 15] 37] Both doors fastened open
‘13 and 114. 5] 0 rs 26
.. 510 6 6
s{o| &] &
and 104 ooo” 510 30 33
U. 8. Census, “6 ballding. 5) 0) 22) 20 | Both doors fastened open
U. 8. Census, “D” building... 5| 0 W ao} poe a
Department store, ‘Washington, 3) 6 oe 12 | Width of single leaf used to
compute discharge rate.
v. 3) 6 12 LR Do.
3] 1 16 21 | Fastened open.
2) 1] B88 Leaves of oot collapsed
ving 0 2 feet
inch each side,



24 Miscellaneous Publications, National Bureau of Standards

“osqe seoqgo 10) 370 Fu B9AI0G ¢

“TART AttooTeq 48 04104 Oxy auTOIEQ Ar9[feI THO SABATTEIE ¢
“poOURT]US SOPNIOUT

“Bore WON §

. ‘39980Y} JO epis Gowo UO ABAITEYS BOI YOUR Ts

“009 De pus pz do Aumesussed 40o}-11 5

% % ° oN ° se fz fo oor |r foe { meme] ooo ‘et
“ * ° oN nn ace Ti oe eee eed 99 FS a
ETT OIRO) ce o on 0 sw |c for fo |e lor 00 ot
ety e ° on ° ° 009 ‘er
006 1 & 2722 “Ac
S ° ° ~~ ye ° S$ umRONE
oe o ° on o o we a
% * & oN or o | ore a
a eT a " abs

coor | umponpay sqyo. | PIA | on |e a804 .

oo) it, pezersrarictg]) Tez0OF yo 109 eousysip Aypedeo Bap0eg ‘wore ss02—) ‘ous
apres beni’ atid “wON omnonre yy
3¥x0 AomDBUT To0y, JOQUION | saduose omg skeareng

NOMLOOUISNOO TAILSISTU-AaId
squsmoinsvam yxe s9v942 fo AsoMUng—Fy WIAYT


8 Miscellaneous Publications, National Bureau of Standards

Class 2, institutional, as established in the report, Recommended
Minimum Requirements for Fire Resistance in Buil , consists of
hospitals, sanitariums, homes for the aged, prisons, and buildings of
similar occupancy. It has helped materially to swell the total of
loss of life by fire in buildings. Poor construction, bad housekeeping,
inadequate and poorly. maintained exit facilities, isolation, frequently
poor fire-fighting equipment, and the character of the occupancy,
including as it does persons kept under restraint, and a lack of enforce-
ment of existing laws in some cases, all. share in the responsibility
for loss of life. :

Class 3, residential, as established by the report, Recommended
Minimum Requirements for Fire Resistance in Buildings, consists of
apartment houses, hotels, tenement houses, lodging houses, dormi-
tories, and dwellings. It would probably show the heaviest loss of
life of any occupancy if available records were complete. But fatal
fires in residence buildings so frequently cause only one or two deaths
that attention is not focused on them’as in the more spectacular
theater or school fire involving heavy loss of life. C. Heller, consulting
engineer, stated in a paper published ’a few years ago: * “By far the
greatest part of the annual lite loss occurs in the many small fires in
which one or two die and which attract only pressing comment.”’
This is shown in table 3, reporting 426 fires recorded by Heller.

Taste 3,—Deaths per fire

Number of deaths—
100r
1 2 3 4 | Stop | JOor
se{ i} as} asf] °
aii} 73] 34} |} 8
ed er es es) 33

Mr. Heller comments also:

At first glance these figures give the impression that the life losses occurring in
dwellings are smaller in number than those in other buildings. ‘This is true only
insofar as the loss per individual: fire is concerned, but not the aggregate loss;
for the fatal dwelling fires over a fixed time outnumber those of all other occu-
pancies combined. In the United States dwelling-house fires, together with flats
and apartments, constitute 65 percent of the total number of fires. The fires
from which ‘the table was compiled are those of which the writer has a record
and which extend.over a period of many years and include such catastrophes as
those occurring’in the Iroquois Theater, the Collingwood School, and the Asch
Building, which greatly add to the total losses in buildings other than dwellings.
It must be remembered also that prominence is generally given only to the more
noteworthy fires, particularly those in which there is heavy life or property loss,
“so that thousands of lesser ones escape unnoticed or are not reported in the fire
records. Were complete statistics available they would show that tne majority
of lives are lost not, as is commonly: supposed, in industrial buildings, theaters,
and places of public assembly, but in the home; that the next greatest losses
occur in institutional buildings (hospitals, orphanages, reformatories, and similar
occupancies) ; and that the victims in both groups are mostly women and children.
In the home, they generally lose their lives as the result of carelessness or ignor-
ance. In institutional buildings, most of the disasters are due to poor eoustruc-

tion and the gross negligence of those in charge, » sad commentary on our syatem
of social organization. :

1M Some fundamentals of safeguarding life from fire, Quart. Nat. Fire Protect. Assn. (Oct. 1922).


60. Miscellaneous Publications, National Bureau of Standards

The a; te number of units of width necessary for exit stair-
ways shall be determined for each floor of a building by dividing
the population of each occupancy on that floor by 30 in the case o:
occupancies coming under class 2, institutional, and class 3, residen-
tial, and by 60 in the case of other occupancies, except as otherwise
specifically provided for in this section.

Exit stairways in places of assembly having the main entrance at
the street level and not communica’ with any other occupancy
in the same building shall be determined on the basis of 100 persons
per unit of exit width. . . .

In determining the aggregate width of exit stairways in any build-
ing, if the result contains 2 Fraction, 12 inches of width shall be added
for a fraction of one-half or less and 1 unit of width for a fraction
greater than one-half.

If the required total number of units of exit width is greater then

e total number of units of exit width for the minimum number of

exit stairways of the minimum permissible width, the additional
width “ shall be provided by additional stairways or by increasing
the width of the minimum number of exit stairways.

7-6-1-3, Changes in Stairway Width,

The width of exit stairways shall not decrease in the direction of
exit travel.
7-6-1-4, Exit Stairways Serving Floor Areas Below Grade.tt

_, The aggregate width of exit stairways serving areas below grade
shall be at least equal to that required for such stairways serving simi-
Jar occupancies above grade in accordance with the provisions of this
chapter.

Pinder section %6-1-2, 120/80=four 22-inch unite, or two 44-inch stairways will be reqnired. At the Sth
Soot wo inch stairways will be required fur the normal population of this floor. Phe portion of the
Auditorium occupied by the audience is 1,300 square feet. ‘This will accommodate 1,800/6 of 217 persons.
Zo secommodate this number of occupants 217/60 or four 22-inch additional units of exit width snust be
Provided from the 6th floor down.

in 8 theater having a population of 1,000 persons in the baleony, the provisions of section 7-6-1-2 would
include it as @ place of assembly having the main entrance at the strest level and the
wrath, would then be computed at the rate of 100 parsons per unit of exit width, tat is) 1
of stairway width would be required. If condit ‘imum distance to an exit were satisfied, two
‘66-inch stairways and two 4tinca stairways or any other grouping using the 10 saeregate units of width
sory fala the condition. The exit doorways for the orchestra population would be computed according
to the provisions of section 7-8-1,

.G3ven a school building 3 stories high and 14,400 square feet in arée. ‘The population per floor will be
sh s00rag or 360 Persons. 360/60, or six 22-inch units of stairway width will be required. These may be
supplied as three 44-nch or two 66-inch stairways, depending on the distance to the exits,

iven a S-story factory, 60,000 square feet in ares. 60,000/100=600 persons per floo’. 600/60-—=tan 22-fnch
Paitfol stairway required which could be satisfied by 4 stairways, 2containing 2 units each and 2 containing
units each.

Given an Sstory department store 30,000 square feet in area, ‘The floor population would .be

+ 30,000/60 oF 500 per Boor. 500/609 units of stairway width would then Dorequired: The sales boo acce
Prob tae aude Brae j000/80= 1,000 persons. °1,000/60= 27 units of stairway width would then be required

rom. the sales

To illustrate the effect of the requirements in the aso of different occapancies and to compare these
pated pnts with current Practice as found in the field sorvey, figuros 6 to 15 on pages 61-64 have been pro-
fod oe golid line representing requirements starts at the minimum set by section 7-3-3. Polat
Enleaied on Sgures 8 to 16 represent actual conditions found in buildings during the survey.
“ g minimum number of exits, see section 7-3; locations of exits, see section 74; relation of
PP tees madlttons of muatoramn a a
gues moon Utions of minimum number of stairways and minimum width of stairways are satisfied, the
‘designer may distribute the compsted width exceeding the minimum in any way ho sees At ss lou othe
Tag ymuM distanoe to an exit fs not exceeded. For example, if 2 stairways of 2 units each would the
Conditions of minimum number of stairways and maximunn distance to an exit, bat the commantnes ee
Guited 6 units of width, an additional stairway coutd be provided, or 1 unit could be added sain? the

Some codes: juire stairways from areas below. le to be increased in width over those required from
areas above grade by amounts Tang irom 50, Too percent ine ey
under this code the widtt Stairs from store basements is ‘Bread, twice that of stairs from
Eebemeat tse Stores mae 2opO0,, Considred fe chi ig ofr ies nee rows bet
“ofmovemont show that for shott distances the rate of low up stalrwagesiorea cece er ees att



76

bles!

Clear space when served by horizontal exits.

Enclstre wheo snkweys trmisavia =
of exit

SRA SI AeR sane g

‘Distribution...
Maximum dist
‘Outlets from exits.
M
‘Maintenance:
‘Combustibie material. ”
‘Obstructions. 4
a
4
68
66,
35
8
BL
59, 67
B
or
50
5
54
rooms. 51
For ground-floor areas. 52
For other floor are 63
For Soatietinal ‘occupancies. 53
bly. a
1

°

Office buildings:
Agrregate exit width,
‘egation of ents...
Minimam number.
Minimum width of exits
Ontlets from exits...

INDEX

‘Adecting taiaimam distance to an exit,
Affecting minimum number of stairw

s

‘Treads and risers.
Stest, definition of ~

3

Minimum width Oren
opulation..

sys for.
and risers, rule for width and height.
u
[Btimate fire resistance, definition of..
mit:
Definition.
‘Width of.

. v
‘Vestibules as part of horizontal exits...

w

Winders prohibited,
Windows:

lows:
Permitted in exit enclosures...
‘Protected where near



APPENDIX

VI. MEANS OF EGRESS
1, RECOMMENDATIONS.

Throughout this study the ultimate object was to determine what
were suitable exit requirements for building codes. It was not in-
tended to produce a complete manual of practice covering all condi-
tions but to find the minimum that appeared to be necessary for the
usual occupancies. As the work proceeded, various tentative require-
ments were drawn up and compared with the results obtained in the
field studies. Eventually, a set of suggested requirements was formu-
lated representing the consensus of the committee,
It was the intention to publish these findings as part of the series of
recommendations issued by the Department of. Commerce Building
‘ode Committee. Before time came for publication, however, the
committee was discontinued. The suggested requirements, therefore,
could not be put out as.one of its series, but there were requests. for
issuance of a document giving the results of the studies and the inter-
retation placed upon them by the committee. . Rather full footnotes
ve been given in connection with the various recommendations to
explain the reasoning leading to specific recommendations and to
illustrate their effect.

2. DEFINITIONS

The following terms shall, for the purpose of this chapter, have the
meanings indicated.
'_ Approved —As applied to a material, device, mode of construction,
or testing agency, means approved by the building official under the
provisions of this code, or by other authority designated by law to give
Approval in the matter in question.

Automatic—aAs applied to a fire door or other protection for.an
opening, means norm: held'in an open Position and automatically

losed y a releasing device thatis actuated vy. abnormal high tempera-
ture or by a rate of rise of temperature exceeding some fixed value.

Dwelling —A building occupied exclusively as a residence for-1 or 2
families or as a boarding or rooming house serving not more than 15
Persons with meals or s] leeping accommodations, or both.

Evxit.—As applied to.a stairway or doorway, means constructed
and arranged as specified in. this chapter:

- Evit passageway. —An enclosed hallway or corridor connecting a
required exit to a street or an open space leading to a street.
. Fire wall—A wall which subdivides a building or separates build-
ings. to restrict the spread of fire, starting at the foundation and ex-
tending through all stories to or above the roof, and having an ulti-
mate resistance of at least 4 hours.

46


48 Miscellaneous Publications, National Bureau of Standards

Building Code Committee entitled Recommended Minimum Re-
quirements for Fire Resistance in Buildings.” ® They are

here prior to the exit requirements themselves in order to define terms
appearing in these requirements and to emphasize the close relation-
ship existing between fire protection and exits. Sections 3~1 and 3-2
of that report are as follows:

Section 3-1. Classification of Buildings by Occupancy.

Buildings or parts of buildings shall be classified by occupancy or
use into the following groups:

Class’ 1.—Public.

Class 2.—Institutional.

Class 3.—Residential.

‘Class 4.—Business.

Class 5.—Garages, hangars, barns.

Each class is intended to embrace buildings or parts of buildings
as hereinafter defined and those of similar character or use. Where
there is any uncertainty as to the classification of a building, the
pdministrative building official shall fix the classification within which
it falls.

Class 1. Public—This classification includes buildings or parts
thereof in which people come together for transaction of public
business; for civic, pe itical, social, or religious purposes; for educa-
tional purposes; or for entertainment or recreation; such as city halls,
churches, schools, theaters, and grandstands.

Class 2. Institutional —This classification includes buildings or
parts thereof in which people are harbored for medical, charitable,
or other care or treatment or in which people are detained for penal
or correctional purposes; such as hospitals, sanitariums, homes for
the aged, prisons, and reformatories, .

Class 8. Residential—This classification includes buildings or
parts thereof in which families or households live or in which sleeping
accommodations are provided, such as apartment. houses, hotels,
dormitories, and dwel .

Class 4. Business—This classification includes buildings or parts
thereof in which goods are manufactured, stored, converted, or sold,
or in. which business or professional services are rendered; such as
factories, warehouses, stores, and office buildings.

Class 6. Garages, hangars, barns.—This classification includes
buildings or parts thereof used for the storage or repair of automotive
vehicles and airplanes, such as public and private garages and hang-

ars; also for the keeping of horses and cattle, such as stables and riding
academies,

Section 3-2. Classification of Buildings by Type of Construction.

Construction shall be classified into 6 general types. according to
fhe character of materials employed and their method of assembly as
lollows:
Type 1. Fully protected.
‘Type 2. Protected,
Tet Me, sy wall acid joist
. Masonry ws .
Type 5. Wood frame. J
Type 6. Unprotected metal.

"BS BHI4 (1931),


Design and Construction of Building Exits 11

‘The tables in. the reports from which the above figures are taken
classify buildings in which fires have occurred into 31 groups. Those
in which the number of fires for 8 years (1918 to 1925, inclusive) has
averaged more than 200, in the order of greatest frequency, are as
follows:

‘The only yearly variations from this order are occasional transpositions
of factories and store buildings in fourth and fifth places, and of
furnished rooms and garages in sixth and seventh places.

’ It is conceded that the number of fires is not the only element enter-
ing into the consideration of the fire hazard. The frequency in rela~
tion to total number of structures of a given occupancy class is im-
portant. The information necessary for a definite conclusion on this
point isnot available. However, in 1925, fires occurred in 11.4 percent
of public garages and 0.6 percent of private garages; for all garages
the percentage was 2.5. In the same year the percentage for tene-
ment houses was 6.5, or more than twice as great as for garages.

Fortunately, the density of population of garages is low, and prop-
erty damage rather than loss of life usually results from fires in such
puildings. The National Fire Protection Association * reports 13
fires in garages involving a loss of 32 lives for the period 1921 to 1928,
The exits do not figure prominently among the causes of loss of life,
these being principally burns and explosions. It seems unlikely that
the capacity of the exits in this.class of occupancy would ever be
severely taxed; the distance to the exits and the proper distribution,
however, are of primary importance in these buildings. With the
increasing use of public garages the necessity for wise regulation of
exit facilities becomes more apparent.

Ill. BUILDING EXITS SURVEY

1, PROCEDURE

At an early meeting of a joint conference consisting of representa-
tives from the Department of Commerce Building Code Committee
and from the Building Exits Code Committee of the American Stand-
ards Association, it was agreed that a study could profitably be
made of exit design practice and performance, especially as it con-
cerned buildings erected within the last 10 years. The staff of the
Department of Commerce committee was therefore asked to conduct
such.a survey to the extent that, time and funds permitted.

The primary object of this survey was to build up a reservoir of
facts about actual exit conditions that could be tapped at the time
when minimum requirements for building exits were being considered.
The value of such data is readily appreciated. :

1 Garage fires, reprinted from Quart. Nat. Fire Protect. Assn. (April-July 1929).
11588858 :