Give an objective measurement of damp in all materials. Readings can be obtained on the surface, and at depth. Readings at depth can be taken either by using a radio frequency (RF) signal, or by drilling inspection probe holes. Readings can be expressed as either % wood moisture equivalent (WME) or 60-1000 relative scale (RS). Individual readings in themselves are useful, but normally several readings are required to identify changes from dry to damp over an area. Once damp and dry areas have been identified as a moisture map, a picture starts to build as to the possible cause of the damp, and the likely location of any leak.