Suitability of time domain reflectometry (TDR) for moisture content monitoring in historic building walls

Measuring moisture content in building materials is crucial for the correct diagnosis of buildings pathologies, for the adoption of appropriate intervention measures and for the efficiency evaluation of the treatment solutions applied. There are several different techniques available to measure and monitoring the moisture content in building materials. However, it still remains a great challenge to perform those studies in historical buildings, since minor-destructive techniques are required. Furthermore, if continuous moisture content readings in space are desired, in order to study the moisture transfer phenomenon along the wall thickness, the challenge is even greater. The TDR technique is a relatively new method for measurement of moisture content in building materials with a set of unexplored potentialities capable of satisfying the two mentioned requirements. In this paper, the suitability of the TDR technique to obtain continuous cross-section moisture content profiles has started to be tested on two limestone prototype walls. Each wall was equipped with four TDR probes, designed practically with the same length of the wall thickness and placed at different heights. All the necessary equipment, installation steps, and difficulties are here presented. The preliminary results suggest that the TDR technique is suitable for moisture content monitoring in consolidated porous building materials