Stalking the Elusive Water Leak
Investigating Leaks Before and After They Occur 
by Dean Lewis

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
The first of these, a revamp of the 2002 edition, is AAMA 502-08, re-titled Voluntary Specification for Field Testing of Newly Installed Fenestration Products. It serves to verify water penetration resistance and air infiltration performance of newly installed fenestration products before building occupancy. The tests should be performed as soon as practical, as this enables the detection and correction of problems before a substantial portion of the project is completed. AAMA 502-08 is intended for use with any window type, door or skylight, but expressly excludes curtainwall, sloped glazing and storefront systems. (There is a separate standard, AAMA 503-03, Voluntary Specification for Field Testing of Storefronts, Curtain Walls and Sloped Glazing Systems, for use with these products.)

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
Often, improper or inadequate investigations of leaks that have occurred in occupied buildings fail to identify the actual source of water penetration. In recognition of the need for a test method to identify leakage paths where water penetration is evident but the source is unknown, AAMA has developed AAMA 511-08, Voluntary Guideline for Forensic Water Penetration Testing of Fenestration Products.

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.

Accredited Investigators
AAMA 502-08 requires that all testing must be performed by an AAMA-accredited testing laboratory, i.e., one recognized as meeting the requirements of AAMA 204-98, Guidelines for AAMA Accreditation of Independent Laboratories Performing On-Site Testing of Fenestration Products. This ensures that the laboratory has the staff, training, experience and calibrated instruments and equipment to perform field testing properly. Beware of any self-proclaimed window tester; ask to see his AAMA certificate of accreditation.

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 dlewis@aamanet.org. Mr. Lewis’ opinions are solely his own and do not necessarily reflect those of this magazine.

DWM
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