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. Originally these pieces of equipment used a pair of pins pushed into the surface to detect how wet it was, however these caused damage and could only tell you how wet it was on the surface and not deeper into a wall or floor. Although these tools can be useful, we more often use a pin-less technology that uses electrical resistance or radio waves, to check for moisture and can penetrate up to 5cm beyond the surface to check for the actual moisture content within the structure.