? The wind exposure of the control buildings was generally lower than that of the problem buildings. Key differences between problem and control buildings is summarized below: This suggested that it is the quantity of wetting at these defects, combined with the drying characteristics of the wall assembly, that determine whether a wall can accommodate the moisture and provide acceptable performance. The data collected in the study indicate that the defects that allowed water to penetrate walls were widespread and appeared on many wall systems. The problems were thought to originate during design and construction activities (due to poor details on drawings) and not as a result of operations and maintenance or defects in the materials. Water enters the wall assembly at details and stays there long enough to initiate rot of wood components. Overall, the results of the study indicate that the primary source of moisture leading to the performance problems was water entering the building from the exterior, rather than interior sources or construction moisture.Ībout 90 % of the problems were thought to be related to interface details between wall components or at penetrations. The table below summarizes these findings multiple attempts at repair are included in the costs, where applicable. Repair costs were used to indicate the severity and extent of damage to each building. Of the problem buildings, almost 50 % were built between 19 another 16 % built in 1994. The sample buildings were to be no more than eight years old. The wall components included various combinations of building paper, OSB, plywood and housewrap. The problem buildings incorporated stucco, wood and vinyl wall types. The actual sample consisted of 37 problem buildings and nine control buildings. Problem buildings were defined as those in which a moisture problem within the walls, decks or exterior framing had resulted in damage requiring $10,000 or more to repair "control" buildings were those which, over a period of at least five years, had not experienced such moisture problems. ? develop a computerized database to manage the input ? establish evaluation criteria and standards ? select samples of "problem" and "control" buildings based on predetermined criteria The research program followed a series of steps: The findings would be used to help identify key aspects of the design, construction and operations and maintenance processes leading to the problems, and to provide a focus for the efforts to resolve these. The objective of this 1996 CMHC study was to examine the relationship between the building envelope problems and their potential causes. The City of Vancouver, the National Standing Committee on Small Buildings and other industry groups have responded to the problem in various ways, and stakeholders have established the Building Envelope Research Consortium (BERC) to monitor this issue. The problems have included water penetration, damage to cladding systems and rotting and decay of wood components. Source (Summary: Over the past ten years, significant numbers of low-rise multi-unit wood frame residential buildings in coastal British Columbia have been plagued with envelope performance problems. Morrison Hershfield Limited, (1998), "Survey of building envelope failures in the coastal climate of British Columbia", Canadian Housing Information Center (CHIC), Technical Series 98-102. Survey of building envelope failures in the coastal climate of British ColumbiaĬanadian Housing Information Center (CHIC), Technical Series 98-102 CRDReference: Morrison Hershfield Limited 1998, Survey of building envelope failures in the coastal climate of British Columbia
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