A non-penetrating meter can be used to discover vertical migration of water. This device uses the principal of capacitance. When the sensor is placed against a flat surface, pads on the back of the instrument detect moisture to a depth of approximately 5/8 of an inch. Placed against wood, it reflects the content of water as an approximate percentage. When used on other materials, it reflects a reference number for moisture contained in that material, and that reference number allows it to be compared to similar materials that were not affected by water damage.
When more detailed analysis is needed, a penetrating moisture meter is used. This tool is calibrated primarily for wood, but can be used on other materials as well. With various attachments it can measure moisture levels in gypsum drywall, wall paneling, baseboard, interior cavity insulation, hardwood flooring, concrete, etc. The penetrating meter will cause minor damage when used, but those are easily repaired and proper training will assure the best way to use it to minimize its effects.
A thermo-hygrometer measures the temperature and relative humidity present in any given environment. A professional can then take that data and determine the specific humidity, the actual amount of moisture in the air. When evaluating a drying system, a professional must know, understand and use the specific humidity to determine its effectiveness in drying the air, and dry air is needed to achieve dry structure and contents. Tracking and recording the data from the thermo-hygrometer allows the restorer to modify the drying system and take the necessary steps to reduce the levels of moisture in the environment.
Determining the standard level of moisture
A professional will use the proper metering instruments and equipment, and will determine the difference between the measured moisture level and the dry or normal state of building materials. Professional restorers have a thorough understanding of the normal moisture levels of most common building components. Based on the difference between the measured moisture levels and the normal states, the professional determines the appropriate drying times for each material. Areas of the structure that were not affected by the water damage would also be checked to establish the dry standard if possible.