Windows and Leak-free Performance Monitoring quality from pre-construction to beyond by Eric K. Olson, PE, Emily W. O’Keefe, and Andrew E. Jeffrey, LEED AP Photo © BigStockPhoto.com essential components of ThE BUiLDinG EnCLoSUrE, winDowS aLLow LiGhT To EnTEr anD kEEp wEaThEr oUT. waTEr pEnETraTion pErformanCE, in parTiCULar, Can BE CriTiCaL. arE SpECifiErS GETTinG whaT waS aDvErTiSED? The ability of glazed assemblies to resist wind and weather is quantified by certain criteria, such as thermal efficiency, performance under loads, and resistance to leakage in wind-driven rain conditions. These criteria are assessed through standard certification tests that categorize windows into industry-established ‘performance grades.’ Building owners, contractors, and designers utilize this data to compare different models and manufacturers for selecting the most appropriate window for a building and its anticipated environmental conditions. Since water ingress can lead to significant structural degradation and damage to interior finishes, resistance to its penetration is one of the window’s most critical aspects. Specifiers must consider the validity of the advertised performance levels, and what quality assurance is needed to confirm them. Performance standards When a manufacturer introduces a window to the market and wishes to determine product performance in accordance with industry standards, a representative specimen is sent to an independent certification laboratory for testing. The lab performs testing to establish the window’s performance with respect to certain gateway physical and performance criteria defined in AAMA/WDMA/CSA 101/I.S.2/ A440, North American Fenestration Standard/ Specification for Windows, Doors, and Skylights (NAFS), published jointly by the American Architectural Manufacturers Association, Window and Door Manufacturer’s Association, and the Canadian Standards Association (latest revision issued 2008).1 This specification references test procedures and includes criteria for structural performance and resistance to water penetration and air infiltration. 78 the construction specifier | november 2009