Resistanceto damageis anotherimportant criterionsincethe use of troughsand
other mobile equipment can damage and breakthe surface of the wall,thereby
ruiningthe pestand waterproofing of the wall. Protectivebarriers suchas
bollards and wallguards are recommendedfor areaswherethereis a high
potentialfor damage. If cement blockwalls are erectedin dry areas,the grout
linesshould be shallow to minimize ledges for dust to collect. Through
experience,it has beenfoundthat a strikingtool the shapeof a stainlesssteel
teaspoonworksverywellin creating a shallowgroutline.
In wet areasthe tile or blockshould be constructed using the stackedbond
methodratherthanthe running bondconstruction.Stackedbonding placeseach
cement block or tile directlyabovethe one below it. Thisyieldsa verticalgrout
line so moisture will draindownthe groutline to the floor below. A running
bondconfiguration puts the verticalgroutline of eachcourseof blockdirectlyin
the center of the block below and the blockaboveit. Moisture can and will
accumulateat eachlayerwherethe vertical groutline meetsthe centerof the tile
or blockbelowand can createa growthnichefor microbes.A wordof warning:
if the stackedbond methodis to be used then the construction structural
designersmust be notifiedso the wallcan be reinforcedby eitherfillingthe
center of the blockwithmortaror usingreinforcing rodsthroughthe centerof
the blocks,or bothif the facility is in a highseismiczone.If blockwalls are used
thenthe first two courses of block shouldhavethe centersfilledwithmortar.
Doingthis will not onlyprevent wateror other liquids fromseepingunderthe
block to the area adjacentbut will also prevent insects fromgainingaccessto the
interior of the block wallin casea crackdevelops at the floorwalljunction.
Blockwallsshould also be cappedto preventinsect and rodent infestationin the
center spacesof the block. Walls up to 6 feet (1.8 m) in height shouldbe capped
witha concretecap at an angleof 45Î to 60Î to preventtools,clip boards, etc.,
frombeingplaced on the flat surface. Wallsthat go all the way to the ceilingor
are over6 feet (1.8 m) can be cappedwitha flat concrete slab.All interiorwalls
should be constructedso the wallfloorjuncture has a covewitha radiusof 1±3
inches (25±75mm)to get rid of any crackat the juncture.Jointcracks are very
hardto cleanand can becomeharboragesfor dust,dirt,insects,and bacterial/
fungal growth.
If plainconcrete walls are used(tilt up, precast or poured in place)and lining
or epoxycoatingthemis not considered as in dry processingareas, warehouses,
etc., thena goodgradeof sealershouldbe appliedto preventdusting of the
concrete. Concretedustwill contaminate openproducts or settleon packaging
material, finishedgoodsand equipment.
Walls in newfacilities shouldbe designedwithoutwindows, particularlyin
the raw material storage, preparation, processing, and packaging rooms.
Windowsrequire maintenance and are subject to breakage.Thereshould be
noglassin a food processingfacility. Plantswithexistingwindows in the
subject areas shouldreplaceany glass witha tempered polycarbonatematerial.
The windowsshouldbe sealedto preventopening,whichwill allowinsects,
dust, dirt,odors,and anythingelsepresentin the air intothe facility. Open
138 Handbookof hygiene controlin the foodindustry