Friday, April 13, 2012

Water Intrusion: The Technique of a Leak

Finding the source of water intrusion within an older existing building can be exceedingly frustrating. Following a methodical and systematic investigation procedure will manage and organize the process. If the leak is occurring within occupied space, it is critical to interview and obtain information from those individuals directly affected by the circumstance. Is the leak associated with weather, water use, or other activities? If weather related, when did the leak occur relative to the start of the bad weather? Does the leak occur under windy conditions only? Wind driven rain can push water 2 inches up a vertical surface. Does the leak occur consistently in the same spot? Having an understanding of the building’s age, material science, archaic construction techniques, and professional experience brings focus to the investigation.

Visual observation is the single most important diagnostic tool. Are there obvious sources of water intrusion like open windows, broken downspouts, exterior holes in the building shell, or leaking bathroom fixtures? Storm days are often good opportunities to observe the flow of water over a building surface leading to potential sources. After a rain storm, are some exterior surfaces slower to dry? Has the water pooled along horizontal surfaces or against exterior walls? These observations can be made directly by the investigation team or related by maintenance personnel or property owners. Photographs taken before, during, and after a leak provide valuable perspective on the dynamic nature of the leak.

Infrared camera analysis adds another diagnostic layer of evaluation data. Temperature differentials between wet and dry surfaces can collaborate other visual observations. However, a number of varying conditions, not just water, can cause temperature differences between materials or even temperature differences within the same material. For instance, an exterior stucco wall installed over steel studs may have extreme temperature changes as a result of heat conductance through the steel studs with no related water intrusion.

Often it becomes necessary to augment general observations of interior and exterior surfaces with destructive investigation, a method by which the surface materials are sequentially removed to investigate archaic construction methods. As materials are removed, construction techniques can be evaluated for water tight joints. Moisture meters and other hand-held evaluation tools verify the presence of defective conditions. Openings, or wall-lets, are located at corners, abutting materials, complex intersections of structural elements and architectural materials, and/or other commonly known sources of water intrusion.

Reverse investigation in which the leak point is enlarged and video scopes or wires or other tracing devices are inserted in the opening are used to back trace the leak from the point of observation to the source. This method is often a last resort because it involves cutting several observation points in all directions to follow the path of water. With patience, persistence, and a methodical process, water intrusion defects can be located and repaired.