ASTM_D_7954_-_D_7954M_-_22a.pdf

Designation:D7954/D7954M22aStandard Practice forMoisture Surveying of Roofing and Waterproofing SystemsUsing Nondestructive Electrical Impedance Scanners1This standard is issued under the fixed designation D7954/D7954M;the number immediately following the designation indicates theyear of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of lastreapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice applies to techniques that use nondestruc-tive electrical impedance(EI)scanners to locate moisture andevaluate the comparative moisture content within insulatedlow-slope roofing and waterproofing systems.1.2 This practice is applicable to roofing and waterproofingsystems wherein insulation is placed above the deck andpositioned underneath and in contact with electrically noncon-ductive single-ply or built-up roofing and waterproofing mem-branes and systems such as coal tar,asphalt,modified bitumen,thermoplastics,spray polyurethane foam,and similar electri-cally nonconductive membrane materials.This practice is alsoapplicable to roofing and waterproofing systems without insu-lation placed above moisture absorbing decks such as wood,concrete,or gypsum,that are in contact with single-ply orbuilt-up roofing and waterproofing membranes as describedabove.1.3 This practice is applicable to roofing and waterproofingsystems incorporating electrically nonconductive rigid boardinsulation made from materials such as organic fibers,perlite,cork,fiberglass,wood-fiber,polyisocyanurate,polystyrene,phenolic foam,composite boards,gypsum substrate boards,and other electrically nonconductive roofing and waterproofingsystems such as spray-applied polyurethane foam.1.4 This practice is not appropriate for all combinations ofmaterials used in roofing and waterproofing systems.1.4.1 Metal and other electrically conductive surface cover-ings and near-surface embedded metallic components are notsuitable for surveying with impedance scanners because of theelectrical conductivity of these materials.1.4.2 This practice is not appropriate for use with blackEPDM,any membranes containing black EPDM,or blackEPDM coatings because black EPDM gives false positivereadings.1.4.3 Aluminum foil on top-faced insulation,roofing,orwaterproofing membranes gives a false positive reading and isnot suitable for surveying with impedance scanners;however,liquid-applied aluminum pigmented emulsified asphalt-basedcoatings shall not normally affect impedance scanner readings.1.4.3.1 This practice is not appropriate for use with alu-minium foil faced modified bitumen membranes,as the elec-trical conductivity of the aluminium foil surface can give falsepositive readings.1.4.4 While their overburden remains in place,this practiceis not appropriate for use with inverted roof membraneassemblies(IRMAs)or protected roof assemblies(PRMAs),which contain above the deck waterproof membrane andoverburden that may include insulation,drainage components,pavers,aggregate,ballast,vegetation,or combinations thereof,because the impedance scanner will not differentiate betweenabove and below the membrane moisture.1.4.5 See A1.4 for some cautionary notes on roofing anoma-lies and limitations that affect the impedance test practice.1.5 Moisture scanners using impedance-based technologyare classified as EI scanners.NOTE1The term capacitance is sometimes used when describingimpedance scanners.Capacitance scanners are purely capacitive as theydo not have a resistive component.Impedance scanners combine bothcapacitance and resistance for testing;thus,they are well suited to themeasurement of different types of materials and constructions found inroofing and waterproofing systems as the combination of both componentsallows for a more versatile testing,calibration,and measurement arrange-ment.1.6 This practice also addresses necessary verification ofimpedance data involving invasive test procedures using coresamples.1.7 This practice addresses two generally accepted scanningtechniques for conducting moisture surveys using electricalimpedance scanners:1.7.1 Technique AContinuous systematic scanning andrecording(see 8.2),and1.7.2 Technique BGrid format scanning and recording(see 8.3).1.8 This practice addresses some meteorological conditionsand limitations for performing impedance inspections.1This practice is under the jurisdiction ofASTM Committee D08 on Roofing andWaterproofing and is the direct responsibility of Subcommittee D08.20 on RoofingMembrane Systems.Current edition approved May 1,2022.Published May 2022.Originallyapproved in 2014.Last previous edition approved in 2022 as D7954/D7954M 22.DOI:10.1520/D7954_D7954M-22A.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization establishe