The Salt Building is a significant landmark in the Southeast False Creek neighborhood of Vancouver, BC. The heavy timber industrial structure was built circa 1930 to refine raw salt. Now considered a heritage building, the Salt Building recently underwent a major rehabilitation to be transformed into a commercial building, with restaurant, bakery and cafe.

With the rehabilitation, the interior operating conditions of the building changed from an unconditioned space to a conditioned space. The exterior wall assemblies, which consisted of dimensional lumber clad with horizontal cedar siding installed directly over diagonal shiplap sheathing, needed to be improved to provide adequate protection against rainwater and to incorporate an adequate level of thermal insulation, air barrier and vapour diffusion control. The absence of a moisture barrier in the existing wall assembly and the designation as a heritage building, where the cladding was considered a significant component that needed to be retained, made this a challenging project. Removal of the cladding and upgrading of the exterior portion of the wall was not a viable option.

This paper discusses our innovative design approach to provide the exterior wall assemblies with the appropriate components to control heat, air and moisture flow with a focus on long-term durability. It describes how the walls were upgraded from the inside using spray polyurethane foam and a drainage mat to create a vented air space inboard of the sheathing.  The hygrothermal performance of the remediated innovative wall assemblies was monitored by installing sensors to collect the temperature and moisture content of the wall sheathing and studs at specific locations on the four elevations of the building over a period of two years. This paper presents the monitoring results and discusses the performance implications of the applied strategy in dealing with similar envelope remediation of wood frame heritage buildings.