Skylight Council Encourages Comments on ICC-ES Requirements in Acceptance Criteria for Skylights
December 23, 2009

The American Architectural Manufacturers Association (AAMA) has forwarded a member's request to parties following work on the International Code Council's (ICC) Evaluation Service (ES) Acceptance Criteria for Glass Glazed Unit Skylights and Sloped Glass Glazing and/or Acceptance Criteria for Plastic Glazed Skylights that they comment on whether or not to delete additional air infiltration tests from Section A3.3 and the deletion of Section A6.2, which currently requires the evaluation reports to indicate compliance with the air infiltration conditions of acceptance.

According to the request from Roger LeBrun, product certification engineer for VELUX America Inc. and a member of the AAMA Skylight Council, "The same minor (but quite important) revision is being made to two similar ICC-ES Skylight Acceptance Criteria, AC16 and AC17. It is intended to correct a misguided change ICC-ES Staff decided to make when they did their last major overhaul for the 2006 codes, regarding the need for additional air leakage testing." (CLICK HERE to see the proposed changes and related documents, as well as a link to the comment form.)

LeBrun explains, "From a unit skylight perspective, the AAMA/WDMA/CSA 101/I.S.2/A440 document referenced in the I-codes specifies that air leakage testing is done on the 'gateway' size only (similar to NFRC 400). At one time, two years ago or so, ICC-ES staff interpreted the codes to require every specific size to meet the air leakage limit, rather than a 'standard' size, and inserted additional testing provisions as part of their overall 2006 IBC/IRC update of the AC16 and AC17 criteria.

"ICC-ES staff further assumed that skylight and TDD air leakage was a function of perimeter length, rather than area, as for operable windows. This assumption did not hold true for the vast majority of skylights that are designed to shed condensation to the outside through weep systems that do not change with size."

According to LeBrun, this posed a problem for two main reasons:

1. "More units and more sizes had to be made, shipped to the lab and tested for air leakage. This is not an insignificant cost in a struggling economy and a suffering industry, and yields no justifiable benefit; and
2. If the weep system that passed on the standard size suddenly was found to be too big for the sizes with lower perimeter-length/area ratios, we would have to redesign products just to satisfy a code misinterpretation by a non-code entity."

LeBrun adds, "By also pointing out that air needs to be replaced in occupied spaces anyway, and that U-factor is also based on a single number, standard size performance rating extended to all similarly-built sizes, it was finally realized by staff that they had overreached on this earlier additional requirement. ICC-ES staff wisely eventually reconsidered and recommended a retraction be approved."

Members of the AAMA Skylight Council agreeing with the proposed changes are urged to file a supporting comment to ensure the changes are implemented. Those who disagree are asked to describe their reasons in detail. There will be no related hearing, since the changes are being balloted to the Evaluation Committee concurrent with the public comment period.

The deadline to comment is January 4, 2010.

CLICK HERE for more information on the proposed changes.

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