Volume 9, Issue 6 - June 2008
Stalking the Elusive Water Leak
Uncontrolled water penetration through exterior walls, with consequences ranging from mold infestation to physical damage, has been the subject of numerous investigative studies. The interface between the building’s weather-resistant barrier and the fenestration product is the prime candidate for the weakest link in a building’s potential water leakage.
However, leakage problems are not so likely to be due to faulty window design. Products that meet the standard AAMA/WDMA/CSA 101/I.S. 2/A440-08 and its predecessors must pass water leakage tests of increasing stringency depending on their performance class and performance grade.
But such standards and tests do not account for the more likely culprit: window leakage due to poor installation. In addition, water penetration at or near a fenestration product opening actually may originate from the surrounding construction.
In today’s litigious world, manufacturers and contractors are well-advised to verify the actual installed performance of fenestration products during construction and prior to occupancy of a building. Situations also can arise where a forensic investigation of an actual leakage problem is useful to pinpoint the leakage path.
Two new AAMA field testing standards, scheduled for release this summer, provide the means to assess either of these post-installation performance situations.
Testing Before Occupancy
Per AAMA 502-08, a sealed test chamber is applied to the side of the door or window and pressurized to establish a specified pressure differential across the product and the rough opening that simulates wind pressure. Water then is sprayed against the outside surface from a calibrated spray rack. The entire fenestration product, including the frame, corners, panning, subframe/receptor system, etc. and the adjacent substrate, including the perimeter seals, are tested.
AAMA 502-08 also provides a short-form model specification for the test parameters.
Windows Investigation Testing
AAMA 511-08 provides supplemental guidance for fenestration product investigations conducted according to the seven investigative steps set forth in ASTM E 2128, Standard Guide for Evaluating Water Leakage of Building Walls. The process it outlines begins by describing how to calculate the differential air pressures the suspect specimens experienced during actual wind-driven rain events. This calculated pressure defines the test pressure to which the fenestration product is to be subjected during the actual investigative testing.
The investigative process then moves to actual testing–the protocol for which is similar to that of AAMA 502-08. However, unlike testing performed per AAMA 502-08 or AAMA 503-03, which are based on compliance with a project specification, forensic investigators are required to provide more information than pass/fail criteria. An optional sill dam test, also described in AAMA 511-08, can be used as necessary to investigate the leak path further.
The new documents that provide assistance in this mission may be obtained online from the publication store at www.aamanet.org.
Dean Lewis serves as product certification manager for the American Architectural Manufacturers Association in Schaumburg, Ill. He may be reached at firstname.lastname@example.org. Mr. Lewis’ opinions are solely his own and do not necessarily reflect those of this magazine.