High-R or super-insulated walls are a common component of high performance housing. However, in cold climates, these walls run the risks of cold-weather condensation, and general durability issues due to reduced heat flow. Two practitioners have been monitoring the moisture performance of several high performance walls, and will share their results. Chris Corson has been examining highly vapor-open walls based on classic European Passive House designs, without the use of plastic foams. Kohta Ueno has been monitoring double stud walls insulated with cellulose and open-cell spray foam for three winters. His monitoring study was followed by disassembly of the walls, to examine conditions in the cavities. The two will talk about their data, whether various assemblies fall on the safer or riskier side, and how to make design choices. Keeping these walls buildable and cost-effective will be another aspect of the discussions.