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Fire protection of horizontal service spaces
FIRE PROTECTION
OF HORIZONTAL
SERVICE SPACESbY
L. Konicek and
M.
GalbreathIt is a provision of the National Building Code of Canada 5975
t h a t there be a f i r e separation between a h o r i z o n t a l service space and t h e remainder of the b u i l d i n g where t h e h o r i z o n t a l service space pcne- t r a t e s a required vertical f i r e separation. It follows, t h e r e f o r e , t h a t
where t h e space w i t h i n a j o i s t f l o o r assembly is used as a h o r i z o n t a l
s e r v i c e space p e n e t r a t i n g a v e r t i c a l f i r e separation, thc ceiling con-
s t r u c t i o n m u s t , by i t s e l f , have a f i r e resistance r a t i n g .
The conditions f a r establishing a fire r e s i s t a n c e r a t i n g according t o ASTM f i r e endurance t e s t E l 1 9 are t h a t the t e s t specimen c o n t i n u e to carry any load imposed on it, t h a t no cracks o r fissures occur and t h a t the temperature r i s e above t h e ambient temperature at t h e s t a r t o f t h e t e s t does not exceed a 250°F average of all thermocouples
on the unexposed surface or 325°F a t any one thermocouple.
Type X gypsum wallboard (1) has been shown to stay in p l a c e and c o n t r i b u t e t o one- andtwo-hour fire r e s i s t a n c e r a t i n g s of wood and
steel j o i s t floor assemblies. The temperature w i t h i n the f l o o r space i n t h e s e t e s t s w a s , however, considerably h i g h e r t h a n t h e 250°F temperature r i s e s p e c i f i e d , In addition for the ceiling to meet t h e c o n d i t i o n s f o r a f i r e separation the time at which t h e temperature c r i t e r i a of t h e standard t e s t would be reached must be determined.
E i g h t f i r e endurance t e s t s were carried out on single and m u l t i p l e layers o f Type X gypsum wallboard, combinations of gypsum wall-
b o a r d with air space between, and gypsum wallboard w i t h mineral wool
topping. All specimens were expased to furnace temperatures following
t h e time- temperature curve s p e c i f i e d in t h e ASTM El19 standard t e s t .
Construction of T e s t Specimen
Each o f the e i g h t specimens was designed t o fit DBR's small
E l e c t r i c Furnace (2), which has h o r i z o n t a l dimensions of 3 1
x
33 in. The thickness of the specimens v a r i e d according to t h e combination o f s t r u c t u r a l material used. F i g u r e 1 i s a s k e t c h of t h e specimenSpecimens 1 , 2 and 3 were made of one, two and t h r e e l a y e r s of gypstun wallboard. Specimens 4, 5 and 6 were a combination of t w o layers
of gypsum wallboard w i t h 1 J2-in. and 2-in. a i r space between. The
edges o f These specimens were i n s u l a t e d w i t h ceramic wool to prevent air movement between the laboratory atmosphere and the heated a i r l a y e r .
G y p s u m rvallboard in combination w i t h 3-in. and 6 - i n . t h i c k layers o f h i g h density spun mineral rock wool were used in the c o n s t r u c t i o n o f Specimens 7 and 8. Details o f t h e construction of the specimens a r e
presented in Table I and Figures 2 to 9 inclusive.
Temperature Measurements and Critical Temperature
Temperature was measured by a thermocouple attached to the non- fire exposed surface of the separation. The thermocouple was covered by a standard asbestos pad (Figure 1). The i n i t i a l temperature of The
t e s t e d specimens was 75"F, t h e r e f o r e the c r i t i c a l temperature was 3 2 5 ' ~ .
F i r e T e s t and Results
Furnace temperatures and surface temperatures of each specimen were recorded during t h e tests and plotted in Figures 2 t o 9. The f i r e resistance of each specimen was determined from these diagrams. The r e s u l t s obtained are presented in Table 1.
Evaluation of R e s u l t s
The a p p l i c a t i o n
o f
v a r i o u s materialsin
combination with Type X gypsum wallboard d i d n o t always improve the f i r e performance. The t e s t s indicate t h a t m i n e r a l rock wool, used prima~ily as n h e a t i n s u l a - t i o n , does not add to t h e f i r e resistance of t h e assemblies (Types 7,8), In the case of an a i r layer enclosed between two gypsum wallboards, the f i r e resistance of this assembly can be increased by increasing t h e airl a y e r thickness up to about 2 in. when convection becomes a s i g n i f i c a n t
factor in heat t r a n s f e r . In t h e present s t u d y an increase of from 0 . 5 in. t o 2 in. r e s u l t e d in an increase in t h e f i r e resistance of approximately
15 p e r c e n t .
Application of Results
The results o f t h i s series o f small scale t e s t s will h e l p the
a r c h i t e c t o r designer in the selection of materials o r combinations of
materials applicable to t h e design of a f i r e separation for a h o r i z o n t a l
Acknowledgements
This p r o j e c t was undertaken at t h e r e q u e s t of t h e Steel Industries Fellowship Committee. The work was carried o u t under a
ca-operative program between DBR/NRC and t h e Canadian S t e e l Industries Construction Council, known as the S t e e l I n d u s t r i e s Agreement. The
a u t h o r s w i s h to thank Dr. T.T. L i e f o r valuable comments and
Mr. D. Shearer for carrying out t h e fire t e s t s .
References
1. Canadian Standard Association A82.27-1972 - Gypsum Wallboard.
2. Blanchard, J . A . C . and Marmathy, T.Z., Small-Scale F i r e T e s t
Facilities o f t h e National Research Council,Fire Study No. 1 4 o f the Division of Building Research, Ottawa, November 1969.
S P E C I M E N ' S C R O S S - S E C T I O N
TYPE X GYPSUM WALLBOARD 518"
UM WALLBOARD 518" WALLBOARD 5W WALLBOARD 518" T A B L E 1 T E S T P R O G R A M : D R A W I N G S OF C R O S S - S E C T r O N O F T E S T E D S P E C I M E N S 5 H O W I W G F I R E R E S I S T A N C E P E R I O D
I
)-J
-- I S T A N D A R D A S B E S T O S P A D .- I P L A N O F S P E C I M E N W I T H T H E R M O C O U P L EI T C )
C O V E R E DB Y
S T A N D A R D A S B E S T O S P A D S T A N D A R D T C A S B E S T O S P A D T H I C K N E S S J O F S P E C I M E N C R O S S - S E C T I O N O F SPECIMEN W I T H T H E R M O C O U P L E CTCI C O V E R E D B Y S T A N D A R D A S B E S T O S P A D F I G U R EI
T E S T S P E C I M E N W I T H I N D I C A T E D L O C A T I O N O F T H E R M O C O U P L E A N D S T A N D A R D A S B E S T O S P A D2.
SURFACE TEMPERATURE
TYPE X GYPSUM WALLBOARD
0
0
1 0
20
30
40
5 0
6 0
7
0
J
IME,
M
I N U T E S
F I G U R E 2
S P E C I M E N 1; T Y P I C A L C R O S S - S E C T I O N
W I T H
T E M P E R A T U R E
R E C O R D I N G S
1. FURNACE TEMPERATURE
2.
SURFACE
TEMPERATURE
TYPE X GYPSUM WALLBOARD
0
2
0
40
6 0
8 0
1 0 0
1 2 0
1 4 0
TIME, M I N U T E S
F I G U R E
3
S P E C I M E N 2; T Y P I C A L C R O S S - S E C T I O N W I T H
1 8 0 0
1600
1.
FURNACE
TEMPERATURE
2.
SURFACETEMPERATURE
1 4 0 0
1 2 0 0
TYPE
X
GYPSUM WALLBOARD
1000
8 0 0
6023
400
200
0
0
20
40
6 0
8 0
100
1 2 0
1 4 0
TIME,
M I N U T E S
F I G U R E
4
S P E C
[MEN
3 ; T Y P I C A L
C R O S S - S E C T I O N
W I T H
T E M P E R A T U R E R E C O R D I N G S
1 8 0 0
1 6 0 0
1 4 0 0
TYPE X GYPSUM WALLBOARD
L
