October 2005

Volume 6 Issue 9 October 2005

AAMA Analysis

From Hurricanes to Condensation
Experts Focus on Water Filtration
by Carl Wagus

Final assessment of the damage wrought during the 2004 hurricane season, especially in Florida, is only now nearing completion and takes on a certain urgency in the aftermath of hurricane Katrina. Much is underway to learn how building components can better withstand the one-two punch of wind and water.

For example, the Florida Building Commission (FBC) established a Hurricane Research Advisory Committee (HRAC) composed of FEMA officials, researchers, engineers, academics, material suppliers, builders, code officials and the insurance industry to develop recommendations on building performance. While initial priorities focused on ways to provide stronger wind protection, one of the lessons learned in 2004 is that water penetration from heavy wind-driven rains occurred in more cases than acceptable. This leads to interior water related damage that could have been prevented.

Preventative Measures
Among the recommendations in the HRAC’s consensus report were the following direct excerpts that address water penetration through windows:
• Windows and doors [should] be correctly rated and tested according to ANSI/AAMA 101. [NOTE: Though the report refers to “ANSI/AAMA 101,” in this context it includes any of ANSI/AAMA/
NWWDA 101/I.S. 2-97, AAMA/
WDMA 101/I.S. 2/NAFS-02 or AAMA/CSA/WDMA 101/I.S. 2/A440-05.];
• Water managed window and door installation requirements [should] be developed and the Florida Building Code altered to require them;
• Develop standard[s] for water intrusion appropriate to hurricane-prone regions; and
• Address installation instructions in relation to the recommendations of the FBC’s Product Approval Working Group (PAWG), which require the use of approved manufacturer installation instructions, including attachment requirements.

AAMA is taking these recommendations to heart by launching investigations into the water control performance of windows under hurricane wind and rain-load conditions. The AAMA Southeast Region Hurricane [Water Penetration] Standard Development Task Group is in the early stages of gathering data on real-world indoor-outdoor pressure differentials due to hurricane-force winds, ways to simulate actual time-pressure profiles (wind gusting) and effects of turbulent wind flow.

While it is too early to speculate where this investigation could lead, options include a test method and rating system, which could conceivably take the form of an optional higher water penetration test pressure for hurricane zones than the 15 psf cap placed on water penetration tests under the current industry standards. A design spec to meet higher water resistance requirements or possible installation guidelines may be future considerations. The task group hopes to have a document for preliminary review this fall. From there, it could take another year or more to have a final version.

Assessing Condensation Performance
Although perhaps somewhat less dramatic in nature, condensation resistance of large fenestration units is receiving attention.

The AAMA Condensation Resistance Factor (CRF) test method, AAMA 1503-98, provides the means to rate condensation performance of fenestration products and to predict when and where objectionable condensation will occur. A limitation of this test method is the size constraints of the test chamber. The largest test sample sizes are normally 8-by-8-feet, with a few labs capable of 10-by-10-feet.

However, architects and exterior wall consultants often want to perform a project-specific “condensation assessment” on full scale mock-ups that are two or three stories high and several bays wide (15 to 25 feet is common). Since the AAMA 1503-98 test is limited by size, the consultants often end up writing their own criteria for condensation assessment on these large mock-ups. Others may use AAMA 501.5-98 to investigate condensation tendencies along with the effects of thermal movement on water penetration resistance. But, without the controls and calibration provisions specified in AAMA 1503, temperature variations and humidity fluctuation are a concern. The wide range of size, volume, and configuration means there is no reasonable way to achieve the accuracy of AAMA 1503.

To address this problem, the AAMA Methods of Test Task Group has established a study group to outline the issues associated with condensation testing on full size mock-ups. The group’s objective is to determine if a qualitative procedure can be developed that will provide meaningful data to owners, architects and engineers regarding condensation control.

Water infiltration, which can result in interior damage, is receiving more scrutiny as the industry continues to tighten performance and quality standards for all sorts of applications—from the everyday to the extreme.

Carl Wagus is technical director for the American Architectural Manufacturers Association in Schaumburg, Ill. He may be reached at cwagus@aamanet.org.