Pin-less moisture meter comparison to pin-type moisture meters in gypsum board and the effect of backing materials on pin-less readings
17 October 2023
Moisture meters are invaluable tools used in the building inspection industry. Little comparative data is available for pin-type (resistance) verse pin-less (capacitance) moisture meters. There is also a lack of data for pin-less moisture meters in regard to the effect of backing materials on the readings obtained. We present data comparing four common moisture meters used in building inspections and investigate the effect of backing materials on readings in gypsum board. Moisture readings taken by the Trotec and CEM meters correlated well with moisture readings taken with resistance measurements and comparison to gravimetric moisture content. The moisture meters varied in their responses to backing materials with the Trotec showing the smallest effects and the CEM showing the largest. Different moisture meters may be useful in different applications, and inspectors must carefully consider results from pin-less readings to obtain relevant data of moisture investigations.
Issues with percent coverage-based non-viable fungal analysis and new methodology for enumeration- based analysis
10 August 2023
The choices of methodology for analysis of non-viable fungal surface samples are yet to be agreed upon. The two main types of analysis of non-viable fungal (gross fungi) samples can be generally categorised as counting based (enumeration of fungal structures) or categorization based (such as percent coverage estimates or fungal rating categories). We present evidence of flaws in the percent coverage methodology due to a strong dependence on individual analyst’s subjective estimates. By using image analysis and a survey of analysts we show the high variability between analysts’ percent coverage estimates. We also propose an enumeration-based methodology which attempts to address problems in current counting-based methods by using a semi-random grid pattern of fields of view rather than a traverses-based approach.
Mould surface sampling techniques and collection efficiency on paper-faced gypsum board
18 April 2023
Surface sampling techniques for non-viable fungi in building environments are useful tools for investigators in determining hazards to occupants. However, data regarding capture efficiency in this context is limited. Our data demonstrates that collection efficiency of Bio-Tape surface capture medium on paper-faced gypsum board only captures between half and three-quarters of mould present on the surface. Surface sampling using a dry-swab technique showed similar efficiency of capture to tape lift samples. ‘Surface air’ samples had poor collection efficiency and should be avoided where possible in preference to other sampling options. Finally, we propose a sampling strategy based on non-viable microscopy techniques followed by molecular analysis for validation and speciation of samples of interest. Improvements in sampling and data analysis techniques for mould sampling of buildings will aid in providing meaningful results to help building inspectors evaluate health hazards.
Outdoor airborne fungal spores in Queensland, Australia
9 February 2023
We present non-viable fungi concentrations from December 2021 to November 2022 in Queensland, Australia taken from outdoor reference samples collected during mould inspections. Our data indicate an average total mould concentration of approximately 6000 FS/m3 across the December 2021-November 2022 period. Trends in the data indicate higher levels of Aspergillus/Penicillium like spores in the December-May period changing to higher levels of Cladosporium in the July to September period. These data may be useful to mould inspectors in gauging normal mould ecology or unusual spore concentration levels in Queensland, Australia.