Moisture monitoring of historical buildings by long period temperature measurements

A method is proposed for the moisture analysis of buildings, based on the combination of complementing monitoring techniques. A periodic JR scanning of the whole surface is combined with a visual recording, plus an automatic data logging of the environmental conditions. Thermography allows imaging the temperature pattern, while a long history of thermal hygrometric parameters come available for the fixed measurements at selected points. The used equipment is relatively simple and competitive. A very few thermographic surveys are integrated by several periodic scanning, using an JR pyrometer. The visual monitoring is of great help in rendering results and documenting surface appearance at different seasons. About 20 probes are sufficient to measure thermal hygrometric parameters and evaluate the condensation risk.
A review of algorithms for the moisture testing by thermography and guidelines for the identification of the moisture sources in thick historical buildings is presented. A numerical model has been adopted to simulate the internal thermo-hygrometrical conditions. In such a way, data acquired could be significantly extended and gaps occurred during the data logging has been filled. As case study was identified a North-East Italian ancient church (Duomo of Venzone) destroyed by an earthquake in 1976 and fully restored under the patrol of the cultural heritage authority. A one year round monitoring of the church and tour, according to the proposed procedure, allowed to control the moisture levels both in time and space. This endorsed to
identify the sourèes of the water flux and therefore to suggest the repairing guidelines. Experimental results are reported.