Thermal Performance Patterns on Solid Masonry Exterior Walls of Historic Buildings

Abstract

The Parliamentary Precinct in Ottawa, Canada, is comprised of a number of historic buildings that include the House of Commons, the Senate Chamber, the Parliamentary Library, the Peace Tower, and other buildings that pro vide offices for parliamentarians and their staff. The majority of these buildings have exterior walls that are made of solid masonry with thicknesses ranging between 400 mm and 800 mm. In some cases, special wall areas are more than 1200 mm thick and are comprised of various types of masonry materials. With winter design tempera tures of-25°C, more than 170 cm of snowfall, and numerous thaws during the five month heating season, the exterior environmental conditions acting on the exterior wall assemblies of these historic buildings are severe enough to cause masonry and mortar deterioration wherever moisture accumulates during winter months. Infrared thermographic inspections were carried out to locate and identify the causal mechanisms of moisture accumulation within masonry wall assemblies. This paper will discuss the types of thermal patterns produced by various mechanisms of heat loss and identify some of the typical areas where possible masonry deterioration occurs. Knowledge gained from these extensive investigations will be used to de velop a nondestructive test methodology to locate areas of freeze-thaw damage as part of a predictive and preventive maintenance program to reduce preservation costs of these historical structures.