Comparison of Common Flat Roof Moisture Tests

Infrared Flat Roof Moisture Survey Long Wave Imager Infrared Flat Roof Moisture Survey Short Wave Imager Nuclear Flat Roof Moisture Survey Capacitance Flat Roof Moisture Survey
PROPERTY SENSED Temperature differential Temperature differential Relative quantity of Hydrogen Relative current flow
VERIFICATION Invasive necessary Invasive necessary Invasive necessary Invasive necessary
COVERAGE AREA 100% 100% varies depending upon grid size, normally 1% – 4% varies depending upon grid size, normally 1% – 4%
ROOF MEMBRANE TYPE
Built-up – smooth Yes Yes Yes Yes
Built-up – aggregate Yes Yes Yes Yes
Modified Bitumen – smooth Yes Yes Yes Yes
Modified Bitumen – aggregate Yes Yes Yes Yes
Single-ply – smooth No Yes Yes Yes, EXCEPT butyl rubber or EPDM
Single-ply – ballast No No Yes, requires preparation Yes, EXCEPT butyl rubber or EPDM
Spray Applied Foam (SPUF) No Yes Yes, requires preparation Limited
REQUIRED ROOF CONDITIONS
Roof Surface Dry, free of standing water, ice or snow Dry, free of standing water, ice or snow Dry, free of standing water, ice or snow Dry, free of standing water, ice or snow
Weather Sunny, no precipitation day or evening of the Survey Sunny, no precipitation day or evening of the Survey No precipitation the Survey (protect the gauge) No precipitation the Survey (protect the gauge)
Winds <15 mph <15 mph within safe range for personnel within safe range for personnel
Temperature Daytime highs above 40°F Daytime highs above 40°F within safe range for personnel within safe range for personnel
Time of Day Post Sunset Post Sunset Daytime Daytime
APPLICABLE STANDARDS ASTM, Infraspection Institute ASTM, Infraspection Institute ASTM ASTM
LIMITATIONS Not recommended for ballasted or reflective roof surfaces Not recommended for ballasted roofs Collects data from a very small percentage of the roof, can be labor intensive Collects data from a very small percentage of the roof, false positive or negative results possible
BENEFITS 100% of roof covered, usually most cost efficient 100% of roof covered, usually most cost efficient Best for ballasted roofs, less weather restrictions Less weather restrictions

 

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