Industry Moves Closer to Finalizing IRC 2015
August 15, 2013
COLUMN : Code Arena | Codes & Standards
Under a darkening mid-day sky, the 2013 AAMA National Summer Conference came to a close, June 12. As alerts of a pending Midwestern storm mounted, various AAMA board committees and councils hastened to complete their business.
Among those groups was the AAMA Code Action Committee. The CAC’s primary business was to continue discussion and review of the public comments that AAMA will submit in response to committee action taken at the ICC Group B Code Development Hearings in April 2013.
AAMA will submit a public comment for consideration at the ICC Group B Final Action Hearings that clarifies that exterior door assemblies, and not just exterior doors, are to be tested for resistance to design wind pressure. Currently, there is a great deal of confusion regarding this in the International Residential Code. The two test protocols currently referenced in the IRC―AAMA/WDMA/CSA 101/I.S.2/A440 and ASTM E330―both require testing of the entire assembly. This includes frame and hardware, as well as the door slab itself. Testing of just the door slab does not provide adequate indication of the door’s capability to maintain the integrity of the exterior wall under design wind speed conditions. Therefore, it is necessary to clarify that the entire door assembly is to be tested.
AAMA also will submit a public comment to permit the use of AAMA 504 to test the continuity of a water-resistive barrier from an exterior wall assembly through to fenestration that is placed in that assembly. A proposal that would permit the use of AAMA 504 as an exception to the requirement for a water-resistive barrier in an exterior wall was disapproved at the Code Development Hearings. The modification offered by AAMA will be more consistent with the scope of AAMA 504.
Working with the National Sunroom Association, AAMA will also seek to add a reference to AAMA/NSA/NPEA 2100 to the 2015 IRC. This standard defines five different categories of sunrooms and establishes the criteria for each. A Category I sunroom, for example, is thermally isolated from the interior of the home and is only enclosed with insect screening or 0.5 mm plastic film. The space is basically considered to be an outdoor space, with no requirements for air or water resistance of the exterior building envelope other than for fenestration in the walls or roof. At the other end of the spectrum, a Category V sunroom is heated, cooled and open to the interior of the home. The walls and roof of a Category V sunroom must meet all the requirements of the IRC and IECC for a building thermal envelope, as a Category V sunroom basically expands the interior space of the home.
These sunroom categories, along with reference to AAMA/NPEA/NSA 2100, have been incorporated successfully into the Florida Building Code. Their use in the 2015 IRC would help define the criteria for these types of structures in homes all across the country.
The CAC agreed it would not take further action regarding the ICC Group B committee actions for replacement windows in existing residential and commercial construction. These actions
- Window Opening Control Devices will be required on replacement windows placed in openings where they would be required for new construction. Specifically, this means that if an entire window (including sash and frame) is replaced in a single-family home or townhouse, the window must be equipped with a WOCD that complies with ASTM F2090 if: the top of the sill is more than 6 feet above the exterior grade; and the top of the sill is within 2 feet of the interior floor; and the window can be opened more than 4 inches; and the window is not equipped with a window fall prevention device, such as a window guard, that complies with ASTM F2006 or ASTM F2090.
It should be noted that WOCDs are only required if all four of these criteria are met. For example, if the sill of the replacement window is not more than 6 feet above the exterior grade, WOCDs would not be required. Also, the minimum sill height of 2 feet only applies to one- and two-family dwellings and townhouses three stories or less in height that are constructed under the International Residential Code.
- Window Opening Control Devices will be permitted to be used on windows that are also required to be Emergency Escape and Rescue Openings. These windows must still meet the IBC’s size and height-abovethe- floor criteria.
- Replacement windows in one- or two-family homes or townhouses will be exempt from the IRC’s size and height-above-the-floor criteria if the replacement window is the manufacturer’s largest standard size that will fit within the existing opening (frame or rough opening). The operator-type of the replacement window is permitted to be the same as the existing window, or a type that will provide an equal or greater opening.
So, for example, an existing double-hung window in a sleeping room could be replaced with a new doublehung window, even if the unit will result in a smaller opening being provided, if it is the largest standard size double-hung window offered by the manufacturer that fits into the existing opening. The double-hung window could not, however, be replaced with an awning window, unless the opening provided by the awning window was equal or greater than the one provided by the existing double-hung.
Fortunately, the severe weather that struck the Chicago area, June 12, did not cause significant damage. The Chicago area experienced an EF0 tornado, an EF1 tornado, numerous funnels clouds and hail up to 1 ¾ inches in diameter that afternoon and evening. A barn was blown down by the EF0 tornado, which had maximum recorded wind speeds of 85 mph, and a few roofs were damaged or destroyed. The EF1 tornado, which is estimated to have had a maximum wind speed of 90-100 mph, did not intersect with any structures. The maximum recorded wind speed of the EF0 tornado at 85 mph and the estimated maximum wind speed of the EF1 tornado at 90 - 100 mph are comparable to the 90 mph design wind speed used throughout most of the United States under the Allowable Stress Design wind speed model of the 2009 IBC and IRC.
As “codies,” the question we often ask in such a situation is, “Are the current codes adequate?” The intent of the ASD model is that there be no permanent damage after a structure is exposed to the design pressure. A few roofs were damaged or blown off by the EF0 tornado, but it’s possible that these buildings predated the current codes. For uninhabited agricultural buildings, like the barn that collapsed, the design wind pressure under ASD is 82 mph. Thankfully, no human life was lost in this storm. If all tornadoes were like those the Chicago area experienced on June 12, 2013, then perhaps one could argue that “yes, the codes are adequate.”
The thing is: this particular storm was hardly an isolated event in the U.S. Midwestern states. The U.S. Midwestern and Northern Plains states are considered the epicenter of tornado activity.
Ninety-seven percent of the fatalities from these storms, however, are attributed to less than 13 percent of the tornadoes. It’s that 13 percent—the EF4s and EF5s—that needs to be the focus. The design wind speeds used in hurricane-prone parts of the United States would probably not be justified. But, perhaps we should be designing buildings to higher design wind pressures than those used in parts of the country where hurricanes do not occur and where tornadoes are not as common an event as they are in the Midwest.