- Author
- Jenkins, D. R. | Mathey, R. G. | Knab, L. I.
- Title
- Moisture Detection in Roofing by Nondestructive Means: A State-of-the-Art Survey.
- Coporate
- National Bureau of Standards, Washington, DC
- Sponsor
- Air Force, Washington, DC
- Report
- NBS TN 1146, July 1981,
- Distribution
- Available from National Technical Information Service
- Keywords
- roofs; moisture content; nondestructive tests; infrared scanners; capacitance meters; radiofrequency pulses; microwave equipment; nuclear radiation; instrument characteristics | nondestructive tests
- Identifiers
- nuclear instruments
- Abstract
- A literature survey is presented of nondestructive evaluation (NDE) methods for detection of moisture in roofing systems. The methods discussed include the use of capacitance-radio frequency instruments, capacitance-microwave instruments, nuclear meters, and thermal infrared scanners. For each method, the principles of operation are reviewed and the measured properties which are affected by moisture are identified. Factors other than moisture which may affect the response of the instruments are also described for each method. These factors produce responses which are similar to those due to moisture and include non-uniformities in the roofing system, roof construction details, and building equipment. The use of each NDE method in actual moisture surveys is reviewed. It is emphasized in the report that the validitity of roofing moisture surveys depends on both a knowledge of the factors noted above and a familiarity with roofing practice. Furthermore, cores of the roofing system at selected points are needed to confirm NDE observations. To define operating conditions for infrared scanners, calculated temperatures of roof surfaces over dry and over wet insulation are presented for representative night and day conditions.