Anothercommonoutsidewallmaterial that is usedbut not recommended for
food plants is corrugated metal siding installed over an interior metal
framework.Corrugated metaldamageseasilyand is difficult to make rodent
and insectproof.If, however, it is used,the outsidecorrugation must be blocked
and caulked at the foundationand at the top, to preventaccessby rodents,
insects and otherpests. Once insidethe corrugations,pestscan roamup and
downthe wallsat will,findingopeningsinto the plant and so making any pest
control programextremely difficult.Usingcorrugated wall panelsoftenrequires
separate insulation. If that is the case,do not use fiberglass batting. This material
is an attractantfor rodents. Theylike the resinin it and will createnests within
the wallinsulation.Somesuppliersof fiberglass batting will stipulate that their
material will not attract pests.If you use fiberglass battingbe sureto get this
stipulationin writingfromthe supplier. Otherwisematerials suchas urethane,
foamor foamboardare recommended.
Insulated metalpanelsare oftenusedfor exteriorand interiorwallsfor plants
withrefrigerated processingareas. Theyare also usedfor constructing freezer
and coolerstorages. Theyhavethe advantageof beinginterlocking panels,
alreadyinsulatedand can be maderodent and insectproof.These types of walls
are usuallyeasilycleanableand havea goodsanitary cosmetic appearance.
These walls can eitherbe erected againsta framework of beamson the insideof
the wall,or in some instances theyhavebeenobservedwiththe supports
mounted on the outsideof the plantso the interioris free fromany obstructions.
Exterior walls will,at one timeor anotherrequirespenetrationsfor access by
utilities or for otherreasons.Thesepenetrationsshouldbe well planned aheadof
timeand the timingof themcoordinatedwiththe utilityor other services being
taken throughthe wall. Once the penetration has beenmade, it should be used
and sealedthe sameday,if at all possible.Leavingit openovernightwill
probably resultin one or morepests invadingthe wall,which,if it has an
exposed, insulatedor hollowcore, will providethe pestswithan excellent home.10.3 Interiorwalls..
Internalwalls shouldbe imperviousto moisture, easilycleanable,flat, smooth
and resistant to wear,corrosion and impact.In addition,wallsin wet processing
areas should be resistantto watersprays, cleaning compoundsand scrubbing
when used.Thereare a numberof acceptable materialsthat maybe usedon
internal walls. Manyplantswithwet processingareas or processingareas for
microorganism-sensitive products still use ceramic tiles to enhance the
cleanabilityof the walls. Glazedtiles havebeenusedin dairies,breweries and
bottling plants as standard for many years. Thesetype tiles are resistantto blood,
food,acids, alkalis,cleaning compounds, steamand hot water.These walls are
expensive to installbut are easilyand inexpensively maintained.
New materials for wallconstructionare appearingconstantly. Materials
ranging frombakedon enamel-insulated panels,to spray-onresinscoveredwith
188 Handbookof hygiene controlin the foodindustry