b"1000 Power 8Light Bldg.,KansasCity, Missouri64705 June,1979 ROOFMOISTURESURVEYS Roofmoisturesurveyscanbeofgreatassistancetoanyrooferwho willtakethetimetounderstandwhattheyareandhowtheycanbenefit h~sknowiBd~eoftheroofsystem. Moisturein built-uproofingmaterialshaslongbeenrecognizedas amajorcauseofroofdeteriorationandfailure.Moistureaboveambient inthemembranecauseslossintensilestrengthalongwithblistersand delamination.Moistureaboveambientininsulationcausesrotorganisms toflourishandlossofthermalinsulatingproperties. Moisturecontentaboveambie_ntcanbeeasilydetectedbymodern methodsofdetectingmoisturewithinaroofsyst em.Threesuchmethods are: '-/1.Infra-RedPhotography 2.Radioisotopic 3.Capacitance INFRA-REDPHOTOGRAPHYfromanAir-BornePosition.Temperatureis usedasthemoistureanalog.Thismethoddetectswetinsulation. Differenttonesonathermogramdenotedifferencesintheapparent surfacetemperatureofallobjectsinview.Theamountofelectromagnetic radiationemittedbyasurfaceisnotjust afunctionofitstemperature, butalsoofitsabilitytoemitheatbyradiation. RADIOISOTOPICInspectionDevelopedtoDetectMoistureinInsulation UtilizesaRadioactiveNuclearGauge.Radioactivegaugesdetectbackscatter ofslowmovingneutronsfromcollisionswithhydrogenatoms.The neutronbackscatterisnotactuallyananalogofmoisturebutananalog ofhydrogen.Consequently,adjustmentsofdataarenecessarytocompensateforhydrogencontainingroofingmaterialsbeforeusablemoisture informationis obtained.Oncetheadjustmentstothereadingshavebeen made,it ispossibletodeterminetheareaofwetinsulation. CAPACITANCEisaTestWhichMeasuresChangesintheElectrical PropertiesintheRoofBasedUponMoistureContent.Thedielectric propertychangeisthemoisturea~alogforthecapacitancesystem. Materialsusedinabuilt-uproofhavelowandquiteuniformdielectric constants- roughlyintherangeof2to3.Water,ontheotherhand,is _,,veryhighwithadielectricconstantof81.Asaresult,evenverysmall quantitiesofmoistureinaroofstructurehaveagreateffectonthe"