While solving leaks and preserving the asset value of exterior wall systems can be challenging, the task is manageable if a few basic principles are remembered and applied.Begin by establishing a reliable leak-reporting/-validation process for observed water infiltration problems. At a minimum, the leak report should include: date, time, floor level, elevation (N/S/E/W), specific location (office No. __), window/wall location (head of 3rd window), and severity (condensation, drips, trickle, continuous flow, serious flood, etc.). Accurate leak data correlated with weather data is a critical first step in planning an effective, efficient survey and remediation project. The scope and cost of the condition assessment, and the design and remediation phases, can be greatly reduced and simplified with accurate, reliable leak-history data.The scope and focus of the survey should be based upon the nature of the leakage problems and the type of construction involved. Due to building heights, the exterior wall investigation process can be both expensive and time-consuming. A visual review using binoculars from ground-level and intermediate roof-/balcony-levels is a good starting point – but is merely cursory. Lift equipment or swing stages are normally necessary to perform inspection, material sampling, and water-testing activities. Expect these access costs to represent 20 to 25 percent of the survey cost. Although full-exterior (100-percent) inspections are sometimes required for forensic or litigation cases, selective (but detailed) inspections on one to two “drops” (typically 30-foot-wide vertical sections of the building exterior accessed via swing stage) on selected elevations can also be successful – and at 20 to 30 percent of the cost of a full survey. The survey should include detailed visual inspection and quantification of each wall system component and their relative condition, placement, attachment, expansion provisions, and joinery. In addition, some of the following testing procedures may be utilized:Sample extraction with dimensional- and material-testing of sealants and gasket materials.Mil thickness testing of coatings and/or paint finishes.Rylem tube-testing of absorption rates on masonry, concrete, stone, or other surfaces.Compression testing of gasket/glass interface in the window system.AAMA 501.3 field static water-infiltration testing.ASTM 783 air infiltration test.ASTM E546-88 test method for frost point of sealed insulating glass.Proper attachment of exterior wall components is critical to performance and safety considerations. The survey should include inspection of structural framing and anchorage conditions at random locations, especially if movement, damage, or distress of any wall components is present. This review may involve removal of interior ceilings or wall finishes for inspection access. In some systems, sectional removal for investigation of construction conditions may be necessary. In others, boroscopes may be used to mitigate demolition and reconstruction costs. It is easy to overspend for testing and inspection procedures. Although valuable investigative tools, the location, scope, and cost of any testing procedures, system demolition, and inspection activities should be validated as to their relevance to resolving observed conditions or problems.Bill Conley is president of the Irving, TX-based Conley Group (www.conleygroup.com).