2008-43 Use of Mdu Probes during Determination

The Use and verification of Mdu Probe moisture readings and timber sample analysis by a suitably qualified building expert and laboratory shows the reliability and use of the Mdu Probe System

In this determination the house was refused Certificate of Code Compliance as during the investigation, the government-apppointed expert found a number of problems in the moisture levels and condition of the structural timber building through the installation of the Mdu Probe System (referred to as “invasive moisture readings”, “indicative strength tests” and “Visual Colour Ratings (VCR) [of the timber samples]”. These results were verified by the investigating expert as well as the independent laboratory, and relied upon by the Department of Building and Housing in concluding their decision. An excerpt of the determination decision reads:

“The expert took non-invasive moisture readings at the exterior walls, and two higher readings were recorded at one location. The expert also noted evidence of moisture ingress at one other area. The expert also took 114 invasive moisture readings into the bottom or sill plates of the external framing and 12 readings were higher and 5 much higher than the likely equilibrium moisture levels. The expert also noted that the readings were taken after a prolonged period of minimal rainfall. Indicative strength tests were also taken at each of the 114 investigated locations and low-strength readings were obtained at 15 of these. Visual Colour Ratings (VCR) also indicated that timber at over half of the investigated locations was likely to be damaged and to have lost ¡°cell wall strength¡±. This observation was verified by tests undertaken by an independent testing laboratory on timber samples taken from 4 of the investigated locations. The tests indicated that the timber sample taken from the garage wall framing was moderately treated with boron but had lost structural integrity due to fungal decay. The other 3 samples that were taken from the house wall framing were found to be untreated and 2 of these had also lost structural integrity.”