4-6
CEILING
4-6.1 FUNCTIONS:
The primary functions of the ceiling as a design
e l e m e n t are that it provides visual protection from view of the underside
o f a s t r u c t u r e ; c o n t r o l s the acoustic properties of the space
c o n t a i n i n g t h e c e i I i n g ; a n d may provide a standard of fire resistive
protection to that part of the building and its structure directly
above.
An additional function, that of providing an aesthetically pleasing sur-
f a c e , tends to be regarded as the least important since no definitive
s t a n d a r d s of performance exist, u n l i k e t h o s e f o r f i r e - r e s i s t i v e
construction or acoustics.
T h e ceiling surface often provides a plane which many secondary building
s u b s y s t e m s penetrate.
These include mechanical air distribution diffusers
and griIIes, fire sprinkler systems, electrical alarm systems, lighting
f i x t u r e s , public address speakers, e m e r g e n c y exit signs and occasionalIy
p e n e t r a t i o n s by pipes and ducts exposed to view from remodeling,
p r e s u m a b l y through expedience.
4-6.2 APPEARANCE:
Common deficiencies in ceiling appearance include
pattern staining of dirt accumulating around return air registers,
a c c e n t u a t e d by the introduction of replacement tiIes, often of another
design than the original ceiling.
T h e key to good appearance in ceiling design lies in the reduction of the
n u m b e r of elements permitted to occur in the ceiIing plane and the
i n t e g r a t i o n of those that are exposed into a pattern using simiIar forms,
Many
e.g., square fixtures, air registers, speaker boxes, etc.
manufacturers produce ceiIing assemblies in which the lighting fixtures,
a c o u s t i c tile panels and air diffusers are integrated with a consequent
g a i n in appearance.
4-6.3 FIRE RESISTIVE STANDARDS:
The most stringent performance
r e q u i r e m e n t of a ceiIing system is the need to conform to standards
of
fire-resistive
construction.
T h e National Fire Protection Association defines assemblies
of
materials
of
construction and tests and rates them for fire resistance.
F i r e resistive standards are generally expressed for a complete structure/
c e i l i n g a s s e m b l y , a n d approvals refer to assemblies that are identical in
every detaiI with those tested.
Hence, ceiIing systems are seldom given a
f i r e resistance rating independent of accompanying structure elements.
4 - 6 . 4 REFLECTIVITY:
Where ceilings are to be used to reflect indirect
l i g h t i n g , the reflective values of the ceilings should exceed 80%. Where
this is not required, there is considerable scope for enriching ceiling
s u r f a c e s through the introduction of color and materials.
4-23
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