Moisture Detection with Thermal Imagers

Moisture infiltration is one of the greatest long term threats to buildings and their occupants. As seen in recent hurricane events from Katrina to Sandy, large scale flooding and roof failure cause massive property damage and may even endanger lives. Yet most often it is the after-effects of these major events, along with small, unnoticed water leaks that present long term danger. Leaks from exterior sheathing, or around windows and doors can allow water to seep into wall cavities. Or the condensation of humid air from inside or outside the building can allow moisture problems to build up in outside walls. Insulation and vapor barriers can keep this unwelcome moisture from escaping in a timely manner. Soon enough the building faces threats from decay and pests, while the occupants may suffer respiratory issues due to mold and fungus growth. Energy is wasted as the building's ventilation systems have to make up for the energy lost through wet walls and ceilings. Infrared scans with thermal imagers provide a timely, non-invasive means of ensuring that buildings maintain optimum moisture levels.

How can thermal imagers locate moisture? Through variations in heat patterns. Strictly speaking, infrared cameras can't see moisture directly–they see the affects of moisture on surrounding materials. Moisture transmits heat at a different rate than most dry building materials. This means that as a structure is heating or cooling, areas of significant moisture will show as a different temperature on a thermal imager. If, however, the area being examined is at a constant temperature, then it is likely that the moisture is also at that temperature, and no variation will be seen on the infrared camera. Therefore the temperature of the target area must be changing. The change could be the result of solar loading, or from conditions created through HVAC systems or other heating and cooling methods. So long as these conditions are met, the infrared thermal imager is a profound moisture diagnostic tool. It enables large areas to be scanned quickly and accurately, helping the restoration or indoor air quality contractor identify problem areas without destructive investigation techniques. Once wet areas are identified the contractor can follow up with secondary measurements from a moisture meter. Some moisture meters are even capable of sending their data back to the thermal imager so that all findings are recorded together. (See the Extech MO297, or FLIR MR77 for instance.)

Used in this fashion, thermal imaging technology can detect the moisture conditions which lead to building decay, energy loss, discomfort, and poor health. Homeowners can be assured that their home is functioning in a healthy, safe manner. Property managers can locate the long standing problem areas that lead to energy loss and occupant discomfort. Contractors can quickly and confidently diagnose moisture conditions in a building, earning the trust of their clients. Coupled with a good understanding of how buildings function, the thermal imager is the single best tool for quickly detecting problematic moisture conditions in buildings.

Suggested Thermal Imagers for Detecting Moisture

Thermal imagers intended for detecting moisture problems should meet some minimum criteria. A resolution of 120x120 or higher is recommended. An imager with a higher resolution can scan a larger area or provide more detail than a lower resolution imager. That extra detail is important in seeing the location and extent of the moisture. The infrared camera should be sensitive to at least 0.1º C. Better sensitivity (e.g., 0.05º C) could reveal subtle moisture problems that less sensitive imagers would likely miss. Also available on some imagers are dew point alarms which notify the user when certain conditions in a wall may be conducive to condensation. Other features to consider include connectivity to a moisture meter, and an integrated digital camera for better location identification. Some recommended thermal imagers for detecting moisture are below, or browse all thermal imagers.