Code watch: Thresholds, skylights, flashing on the docket
The first, and longest, set of code-change hearings for the 2009 edition of the international codes was held Sept. 20-Oct.1 in Orlando, Fla., sponsored by the International Code Council of Falls Church, Va. During the 12 days of hearings, a committee heard a record 2,300 proposals to revise the international codes.
Many proposals deal with energy conservation (see Glass magazine, July, p. 132); numerous others have the potential to affect the fenestration industry. This month we will look at proposals not related to energy conservation.
Window installation and flashing
The 2006 International Residential Code requires exterior windows installed and flashed in accordance with manufacturers’ instructions. The members of the American Architectural Manufacturers Association of Schaumburg, Ill., agree that while it is appropriate for the window manufacturer to provide instructions for installing the window, it is not appropriate for them to have to provide instructions for flashing the window opening. Such a task would be formidable at best given the variety of wall configurations, construction methods such as wood stud, steel stud, concrete block or masonry, and exterior wall coverings such as siding over sheathing, masonry or veneer.
The International Residential Code has a separate section that deals with flashing, including those for window openings. AAMA submitted a proposal that refers the IRC user to that section for flashing reference, instead of requiring the window manufacturer to provide it. The Window and Door Manufacturers Association of Des Plaines, Ill., submitted a similar proposal that would apply to exterior doors as well as exterior windows. AAMA officials will work to have one of these two proposals approved for the next edition of the IRC.
Other proposals that address flashing and installation also are on the table. One requires the use of pan flashing for all windows, while another clarifies that work done to the exterior envelope of a building should not restrict the drainage of incidental moisture from around the window assembly for compliance with the energy conservation code.
A third proposal addresses the window anchoring system. At present, the IRC requires calculations, or the use of some other method of accepted engineering practice, for the installation of window- or door-anchoring systems in substrates not specified by the fenestration manufacturer. All other window and door systems are to be anchored in accordance with published manufacturer’s instructions, to achieve the design pressure specified for the opening.
The new proposal would require testing all window and door anchoring systems to meet the design pressure specified when the wind pressure exceeds 30 pounds per square foot. This proposed revision would also change the requirements for applications requiring additional verification of the system’s ability to withstand the design wind pressure. It would eliminate the option of providing engineering calculations instead of testing when the design pressure exceeds 30 psf.
AAMA will work to retain the option of relying on the manufacturer’s instructions for conditions where the design pressure does not exceed 30 psf. It also is working to continue allowing the use of engineering calculations as an alternate to testing for conditions not addressed by the manufacturer’s instructions, or conditions where the design pressure exceeds 30 psf.
Thresholds at exterior doors
It seems every ICC code-change cycle now includes a proposal that deletes the exception that permits thresholds at exterior doors to be 7 3⁄4 inches higher than the floor outside the door, when the door is not a required exit door and not required to be accessible. Confusion continues to exist within the ICC about the difference between this exception and the exception that permits a 7 3⁄4-inch step down from the top of a threshold at an exterior door to a landing outside the door.
This time, proposals would eliminate the exception for thresholds in the International Building Code and the IRC. AAMA opposes these proposals and will work to retain this provision.
In previous cycles, the AAMA 506 Voluntary Specifications for Hurricane Impact and Cycle Testing of Fenestration Products tag was accepted as evidence of compliance with the impact-resistance requirements of the IRC for windows and glass doors tested and labeled in accordance with AAMA/WDMA/CSA 101/I.S.2/ A440-05. This cycle, a similar proposed change to the IRC for skylights has been submitted. The proposal also requires skylights beyond the scope of AAMA/ WDMA/CSA 101/I.S.2/A440-05 to be tested in accordance with ASTM International’s ASTM E330.
A second proposal would establish a minimum performance grade rating of 20 psf for unit skylights, and would require testing unit skylights to a positive uniform load of 60 psf and negative uniform load of 40 psf. Although the intent of this proposal is to establish a safety factor of three for positive load testing of unit skylights, it would only apply to unit skylights rated for 20 psf. This would create an inconsistency for unit skylights rated at higher performance classes.
A new edition of the West Consho-hocken, Pa.-based American National Standard Institute’s ANSI Z97.1 safety glazing standard is finally available. The 2006 IBC and IRC both reference the 1984 edition of this standard. The edition of the U.S. Consumer Product Safety Commission’s CPSC 16 CFR Part 1201, the other safety glazing standard referenced in the codes, is even older, published in 1977.
Traditionally, the use of ANSI Z97.1 was limited to plastic glazing and wired glass only, with all other glazing products in hazardous locations required to comply with CPSC 16 CFR Part 1201. The federal CPSC is not expected to update 16 CFR Part 1201 at any time in the near future, and the recent update of ANSI Z97.1 was intended to prepare that standard to eventually serve as a replacement of the now seriously outdated CPSC 16 CFR Part 1201.
To that end, two proposals would update the edition of ANSI Z97.1 referenced in the international codes and to expand the scope of applications. Although these proposals would still rely solely upon CPSC 16 CFR Part 1201 for glazing in doors and tub and shower enclosures, as required by federal law, it would allow the use of ANSI Z97.1 for other hazardous locations, such as lites of glass greater than 9 square feet in area and door sidelites.
Urban Wildland Interface
A proposal that would require adoption of the International Urban Wildland Interface Code in all areas so designated also was considered. The establishment of a jurisdiction’s own set of rules for construction in urban wildland areas can lead to inconsistent requirements across the country, so establishment of a uniform set of requirements for construction in these areas might be helpful. The 2006 IUWIC requires exterior glazing in these areas to be tempered glass, multilayered glazed panels, glass block or have a fire-protection rating of not less than 20 minutes. The 2006 IUWIC does not restrict the framing material used for glazed assemblies in these areas.
Light and ventilation
Two proposals affect the use of glazed openings for light and ventilation in residences. The first would require mechanical ventilation of all homes, regardless of the amount of natural ventilation provided by operable windows. The second would permit glazed openings used to provide natural light to a home to open to exterior areas under decks, balconies and floor cantilevers 36 inches or more above ground. AAMA officials will work for disapproval of the later proposal, on the basis that 36 inches under a deck or balcony of unspecified depth may not provide sufficient daylight to reach the glazed opening and pass through to the interior of the home.
Two proposals on the table for the IBC would be to permit the use of wind-tunnel testing to determine design wind pressure. While one references an unspecified standard not yet completed—and therefore an unknown entity—the other proposal references the appropriate section of Reston, Va.-based American Society of Civil Engineers’ ASCE 7. This proposal limits the allowed reduction in design wind pressure, when performing wind-tunnel testing, to 80 percent of that provided by calculations performed in accordance with ASCE 7. The basis for the 80 percent limit is not clear, but otherwise it appears this second proposal may be appropriate.
Wood structural panels
Proposals that limit the types of buildings that can be protected by wood structural panels instead of impact-resistant glazed openings, and revise the anchoring requirements for such panels, also will be considered. The 2006 IBC permits the use of wood structural panels as an alternate to impact-resistant glazed openings in all one- and two-story buildings. The first proposal would limit this use of wood structural panels to one- and two-family dwellings, townhouses and assisted living facilities, and would require the use of impact-resistant glazed openings in all other occupancies in wind-borne debris areas.
A second proposal requires pre-drilling wood structural panels for the anchoring hardware needed to attach them to a building. Additionally, it requires permanent installation of the attachment hardware to the building. It also increases the factor of safety on masonry anchors by three; thereby increasing the overall level of protection provided by these panels.
Once the committee and assembly votes on each of these proposals, the results will appear in a report later this fall. Anyone can then submit a public comment on the outcome of any proposal. These public comments will appear on the agenda for the final action hearings of the 2006-2007 ICC code-change cycle. Those hearings are scheduled for May 22-25, 2007, in Rochester, N.Y.