Floors in the german speaking part of Europe are - from a global perspective - special, as they contain heat and sound insulation and a screed on top. 

Traditionally a part of the screed moisture content (CM-Meter) was measured to check, if the screed was sufficient dry to lay a flooring on top. For several reasons the evaluation of the measurement result is prone to errors. A better solution is the measurement of humidity at or in the floor, as practiced in the UK, Scandinavia and the USA. 

Essential for the establishment of the new "KRL-Method" was the design of a "measuring box", designed for 3D-Printing. With this box measurement was easy to do and passivly safe.

The links below give more information.