windows will also destroyrequiredair pressurerelationshipsnecessary for good
air circulation withinthe facility. In older facilities wherewindows already
exist,they should be sealed.If they cannotbe sealedthen they should at leastbe
fittedwithscreensof 1818 meshor similar materialto keepout insects if
opened. Non-opening windows in interior wallsare permitted,such as in
supervisors' offices, as longas they are non-breakable material. Wire-reinforced
glasswill breakand shatter withsmallpieces.Plexiglas material will also break
intoshards if struckso theseare not recommended for interioror exterior
windows. Windowsills shouldhavea 45Î slopeto prevent the accumulation of
dustand debrisand makethemeasierto clean.
Doorsshould be tightfittingwithless than0.25inches (6 mm)clearanceat
the edges. The doorsshouldbe solid,as shouldthe doorframes.Hollowdoors
and hollowdoorframes can and do become harborageareasfor insectsand
rodents. All doorframesshould be flush withthe wallwithno ledgesabovethe
door.Anydoorwindowsshould be of a polycarbonatematerial and mounted
flushto the door on the sensitive productor processside.The othersideor
exteriorof the doorshould havea sill of 45Î. All doorsshouldbe self-closing
and designedto withstand the use expected. In foodprocessingareasstainless
steeldoorsare alwaysacceptable. Thereare other materialssuchas fiberglass
and fiberglassresinmaterials that are acceptable in sanitaryareas.
7.9.5 Ceilings
Ceilings shouldbe the easy-to-clean typeand shouldbe able to withstand direct
impingementof waterfromhosestations.A ceilingshouldbe a goodreflectorof
lightto helpmake the process areabrightand shiny.It mustbe non-absorbent
and aboveall cleanable.Smoothceilings will allowbetterairflowacross the
ceilingsurfaceand that,in turn,helpsto prevent condensate formation. The
mostsanitary type of ceilingis the walk-on type. Thistype of ceilingcompletely
seals off the trusses and other structural piecesholding up the roof and
connecting the walls. All utilities can be run on the roof side of the ceilingwith
onlyverticaldropsto the equipment below, thus eliminatinghorizontalrunsof
pipein the process area. Theremust be access to the aboveceilingarea, from
outsidethe processroom, in orderto do maintenance on the linesabovethe
ceiling and for pest control. Thespace requires ventilation to reducethe
possibility of condensate formation. In a well-designed and constructed walk-on
ceilingspace, the lightsin the roombelow can be changed fromabovethe
ceiling.Recessed telescopingsprinkler headsare available, eliminating sprinkler
pipesand sprinklerheadsin the processroom.Withthis type,ceilingprocess
pipingchanges, pest control, etc.,can all be carried on overthe process room
without intrusioninto the process roomenvelope.
If at all possible, and the typeof processing allows, the interiorof the roof
becomesthe ceilingmaterial. An example is the concrete doubletee roof
described earlier.The interiorsurfaceof the precastconcretedoubletee can
becomethe ceilingsurface. If this type of ceiling is to be usedin a highmoisture
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