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Addressing disillusionment among young vets WE have been following with interest recent articles on the existing state of the veterinary profession in relation to demographic changes, veterinary well-being, professional identity and disillusionment among young vets. Two of us have recently conducted research among practising veterinary surgeons across a range of different

The transport of water through waterproofing membranes over concrete substrates resulting in water-filled blisters and leaks has been demonstrated by the authors to be caused by osmosis. Although this issue has now been studied for more than a decade, there is currently no industry standard to test for the risk of osmosis in waterproofing membranes. The authors have developed a protocol to measure the osmotic flow and evaluate the risk of osmotic blistering in waterproofing membranes including a standardized osmotic flow rate test, ASTM E96, Standard Test Methods for Water Vapor Transmission of Materials, inverted wet cup vapor permeance testing, and modified ASTM long-term absorption testing. This testing protocol has measured osmotic flow rates and ASTM E96 inverted wet cup vapor permeance for a range of different waterproofing membrane types. The authors propose that this set of testing protocols or another proxy test be adopted by ASTM to determine the risk for osmosis, including thresholds above which a membrane may be deemed “high risk.” To reduce the potential for osmotic blistering over concrete, it is recommended that waterproofing membranes used in inverted roofing assemblies should have an osmotic flow rate near 0.0 g/m2/day when tested using the proposed protocol, an ASTM E96 inverted wet cup vapor permeance less than that of the substrate (i.e., less than 0.1 US perms on a concrete slab), and minimal long-term water absorption uptake. In addition to these thresholds, the long-term aging effects of the membrane should be determined.

As the energy efficiency of buildings improves, the amount of insulation on the exterior of the enclosure will increase because of both energy- and durability-related benefits. There are a large number of papers that have addressed the misconception that exterior insulation increases the durability risk of the enclosure. However, an argument remains concerning the relative performance of low- and high-permeance exterior insulations. RDH Building Science Laboratories has collected nearly two years of field data of full-scale exterior-insulated commercial and residential wall assemblies in side-by-side comparisons. The walls were insulated on the exterior with either low-vapor-permeance extruded polystyrene or high-vapor-permeance mineral wool exterior insulation. The walls were constructed on the north and south orientations of a test hut in a Pacific Northwest climate and were subjected to typical cool, high-humidity wintertime temperatures. The test hut interior relative humidity (RH) was kept at a constant level of 40 % or 50 % (slightly above average for the climate zone) to help determine the performance differences in the assemblies. The test walls were also subjected to intentional controlled wetting events to the exterior surfaces of the structural oriented strand board sheathing to simulate various construction defects and determine the relative rates of drying for the two assemblies. The test walls were compared using measured RH, measured wood moisture content, and the Finnish VTT Technical Research Centre’s mold index. Generally speaking, all of the walls (both mineral wool and extruded polystyrene) performed quite well under normal operating conditions, considering the higher than recommended interior RH conditions. Following the wetting events, the commercial and residential wall assemblies with higher permeance mineral wool continuous insulation generally had improved drying rates.

Prefabricated volumetric modular construction is an approach used by housing providers to quickly provide affordable, temporary, and permanent housing to remote or underserved communities. Modular construction presents unique circumstances for moisture management that conventional construction does not typically encounter, and this is especially important in wet climates. Modular buildings have inherent building characteristics, such as interstitial spaces, that can lead to a higher risk of moisture accumulation. This paper highlights typical sources of moisture in modular construction (providing details of water ingress into modular units during transportation, storage, complexing, and postoccupancy), outlines moisture protection measures throughout all stages of the project, and provides a summary of recommendations for moisture management. It is recommended that moisture management planning, including a robust risk analysis, and the development of a moisture management plan become a standardized process throughout the modular construction industry. The development of a standard or standards could improve the process of delivering dry modules to project sites and improve the quality, consistency, and confidence of modular construction.