and other contamination. If a dropped ceil-
ing is installed, it should be constructed as if
it is another floor sealed off from the pro-
cessing area below and should contain utility
runs, air-handling ducts, and fans. Construc-
tion usually includes catwalks so that the
maintenance crew can service the equipment
or lines passing through the area. This area
should be kept pressurized to avoid dust
infiltration. The exposed side of a suspended
ceiling is attractive and easy to clean. Day-
to-day operations beneath the ceiling can
continue in a sanitary and efficient manner
independent of what occurs above the ceil-
ing. Isolation of pipes, electrical, and other
services improves hygiene. Walk-on ceilings
have merit because installation work can be
completed above and below the ceiling
simultaneously.
Ceiling construction should be a smooth
concrete slab of exposed double tees with
caulked joints. If exposed structural steel is
used over processing areas, it should be
enclosed in concrete, granite, or the equiva-
lent to avoid overhead areas that collect dust
and debris or provide rodent runways or
insect harborage. Metal panels should not be
installed because their high heat transfer rate
can cause moisture condensation. Further-
more, the metal expansion and contraction
complicates the maintenance of seals at the
joints, resulting in harborages for insects.
Fiberglass batting should not be installed, as
rodents live and thrive in it. Preferred insula-
tion is Styrofoam, foam glass, and other
insert materials. The hazards of asbestos
prohibit its use.
Floors
Floors may range from plain, sealed
concrete in warehouses to acid brick in high-
impact, high-temperature, high-chemical-
exposure areas. However, plain concrete floors
spall (Graham, 2004) and the exposed aggre-
gate creates protection for microorganisms.
Monolithic floors are gaining in popularity
because they are seamless, easier to apply,
and less expensive than brick or tile. These
floors are both epoxy- and polyurethane-
based and are either rolled or troweled on by
hand. Floors in food facilities should be
impervious to water, free of cracks and
crevices, and resistant to chemicals. Although
tile floors provide an acceptable surface, with
heavy wear, grouting loss can occur, which
results in the penetration of water. Plastic or
asphalt membranes may be laid between the
underlying concrete surface and the tile or
brick. Acid brick floors deserve considera-
tion because of their durability and ease of
replacement in case of breakage and their
reduced moisture accumulation under cracks
and holes. If a concrete floor is retained dur-
ing renovation, it should not be spalled.Processing and design considerations
Appropriate facility design incorporates a
product flow that permits finished items
from making contact with raw materials or
unprocessed products. The ideal flow pro-
vides for raw materials and adjuncts to enter
the process near the receiving dock, flowing
sequentially into the preparation area,
process area, packaging area, and to the
storage. Graham (1991d) has supported this
design flow because it permits proper air
pressure conditions to the overall plant effi-
ciency. Some personnel doors support this
concept because they are designed so that
workers must pass from a “clean” to “less
clean” area. Return to the cleaner area may
require a uniform change and a sanitizing
step, followed by entrance through an air
lock or pressurized vestibule.
Processing equipment should have 1 m of
clear space around it to facilitate mainte-
nance and cleaning. A minimum of 0.5 m of