December 4, 2013


Load-bearing masonry buildings are a significant portion of the existing building stock; however, adding insulation to the interior side of walls of such masonry buildings in cold, and particularly cold and wet, climates may cause performance and durability problems in some cases. Exterior insulation provides the ideal conditions for building durability; however, many buildings cannot be retrofitted with insulation on the exterior for reasons such as historic preservation, aesthetics, zoning, or space restrictions.

A circa 1917 construction mass masonry building located on a Boston-area university campus was retrofitted with interior polyurethane spray foam insulation; the building is on the National Historic Register. Sensors were installed in the retrofitted walls to measure temperature and moisture conditions within the assembly; interior and exterior boundary conditions were also monitored. Experimental variables included orientation (north and south), spatial location of monitoring, and assembly type (insulated experimental vs. uninsulated control). Hygrothermal simulations were run on the original and retrofitted assemblies using measured site environmental data, both to assess durability risks, and for comparison with the measured data. Durability risks examined included potential for freeze-thaw damage and interstitial condensation. The effect of thermal bridging through structural elements was examined with both cold weather infrared thermography and two-dimensional thermal simulations.