Structural and Hygrothermal Field Monitoring of Thick Continuously Insulated Wall Assemblies Utilized in a Multistory Residential Building

There are numerous high-performance wall designs in which most of the insulation is located exterior to the wall framing. These walls are typically constructed with light-gauge metal framing to retain the insulation and support the cladding.

Continuous insulation is prescriptively required to be used with steel-stud construction in climate zones two through eight in order to comply with ASHRAE 90.1-2007 and 2009 IECC standards requirements. Use of continuous insulation significantly minimizes thermal shorts and improves the energy performance of wall assemblies. Using rigid foam insulation to support the cladding is an efficient method for achieving this requirement; however, monitoring of displacements is required for the industry to gain a better understanding of the structural performance of these systems.

This paper will present the initial detailed case study results from a building envelope rehabilitation project where a seven story structure was externally insulated with three inches of continuous extruded polystyrene insulation and clad with stucco. This building is in Vancouver, British Columbia which is located in Climate Zone five. The system’s design used minimal insulation penetrations that included only screw fasteners. In order to better understand the performance characteristics of such a wall, detailed monitoring equipment was installed throughout the building to record dimensional and hygrothermal information for the continuously insulated wall assembly and its components. A description of the building instrumentation plan and performance data will be presented. Finite element predictions on other continuous insulation systems using polyisocyanurate (PIR) rigid foam board and NYSERDA studies will be compared to this actual work.