In keeping with Canada’s climate change mitigation goals, the 2012 Ontario Building Code will demand higher levels of insulation than in current practice. Rapid changes to higher RSI levels will force light frame home builders to employ building envelope designs that are hitherto untried, and therefore present risks in terms of durability and efficiency. To address the disparate issues in choosing design options with respect to OBC 2012 requirements and beyond, seventeen wall assembly configurations were analyzed in terms of heat transfer, moisture safety, environmental impact and costs, for new residential housing in Ontario. ASHRAE Standard 160P was used to determine the moisture safety of the wall assemblies. Furthermore, a new technique for analyzing hygrothermal performance was developed where the maximum number of consecutive daily average relative humidity levels that exceeded 80% were quantified and analyzed. An overall normalized score was awarded to each wall to assist stakeholder decision-making processes.