Mark Zehnal, CPRC, FRSA Director of Technical Services
As a trade association, FRSA has positioned itself as the front-runner when it comes to participation in roofing industry issues in Florida. FRSA staff and volunteer members stay on top of code, licensing, insurance, legal and legislative issues that impact the industry.
Looking to the future of building codes, one of the most important issues to be debated over the past few years came up at the ICC code hearings in Louisville, Kentucky, with the introduction of the newest version of ASCE 7. As we know, the 2012, 2015 I-Codes and the 2014 Florida Building Code are guided by the requirements of ASCE 7-10. If you were around in the early days, then you might remember the chaos that followed moving from ASCE 7-05 to 7-10. The change caught most people off guard and unprepared to deal with it during the 2010 code development process. There was even confusion after the 2010 FBC went into effect in March of 2012, even though changes seemed to be generally modest, with a possible reduction in uplift design pressures in some cases. The single 2007 FBC wind speed map was replaced with three Building Risk Category maps featuring increased wind speeds. The 2007 wind speed conversion tables were replaced with Ultimate Design wind speed (Vult) determined from maps and converted to Nominal Design wind speed (Vasd) by using the Equation 16-32 [ Vasd = Vult√0.6] found in 1609.3.1. The equation uses the square root of 0.6 multiplied by the Vult component which, when rounded to the nearest whole number, equals the Vasd. One might assume that all the disruption could have been avoided if the introduction of the new ASCE 7-10 requirements would have been reported to the industry in advance of the code development process for discussion and dissemination to members.
So, with the old “fool me once” saying echoing in the background, certain industry professionals who’ve heard this proverb and didn’t want to hear the next line “fool me twice,” chose to use this as an opportunity to work together in advance of the 2018 I-Code hearings. Any changes to the 2018 I-Codes wouldn’t directly affect Florida until the 2020 FBC Seventh Edition code development cycle. However, FRSA leadership felt compelled to stand together with other associations in shared opposition that would endure the impact of any changes. Code and technical industry experts including engineers and Ph.D.’s came to the conclusion that the changes created from the adjusted external pressure coefficients would increase the design pressures effecting the building envelope enough to warrant opposition during the I-Code hearings. The elevated pressures for roofing were in the neighborhood of twenty to forty
percent on low slope roofs, with additional attachment zones, and thirty to fifty percent on steep slope roofs. However, on some steep slope roofs, the increase was one hundred percent at the corner zone! In a new construction scenario, the building will need
to be designed to meet the new ASCE requirements which has become a hot topic for the Home Builders Association. For the roofing industry, the major concern is in a reroof scenario, which is regulated by the structural section in both the I-Codes Existing Building Code 707.3.2 and in the Florida Building Code 706.3.2.
706.3.2 Roof diaphragms resisting wind loads in high-wind regions. Where roofing materials are removed from more than 50 percent of the roof diaphragm or section of a building located where the ultimate design wind speed, Vult, is greater than 115 mph, as defined in Section 1609 (the HVHZ shall comply with Section 1620) of the Florida Building Code, Building, roof diaphragms, connections of the roof diaphragm to roof framing members, and roof-to-wall connections shall be evaluated for the wind loads
specified in the Florida Building Code, Building, including wind uplift. If the diaphragms and connections in their current condition are not capable of resisting at least 75 percent of those wind loads, they shall be replaced or strengthened in accordance with the loads specified in the Florida Building Code, Building.
These code sections cover both residential and commercial existing buildings.
Needless to say, the code modifications that were submitted to move the new and improved ASCE 7-16 into the 2018 I-Codes have met unexpected opposition. FRSA participated in the ASCE 7-16 debates that took place during the code administration session and also at the residential and commercial structural sessions. One new requirement ICC has instituted for a new code proposal is that cost impact information as to whether the proposed code change will increase or decrease the cost of construction must be submitted, including proof for either claim. The following was included in one of the residential code modifications:
Cost Impact: Will increase the cost of construction.
Component and cladding loads for roofs on buildings with mean roof heights less than or equal to 60 feet are higher for some roof slopes and zones than similar roof slopes and zones in Table R301.2(2) in the 2015 IRC. Construction costs will increase for roofing products and decking for some areas of the country.
During testimony, FRSA reminded the structural panel members that in accordance with the ICC Existing Building Code 707.3.2 provisions, a building located where the ultimate design wind speed, Vult, is greater than 115 mph, it would be necessary to comply with the building evaluation. The 115 mph zone for Risk Category II Buildings on the map from section 1609 of the International Building Code, spans nineteen states from Maine to the Texas-Mexico border, covering 3,700 miles of coastline not including how far inland the 115 mph designation line falls. Without a doubt, quite a large area with thousands, if not hundreds of thousands of existing buildings that will need to be evaluated before being reroofed.
FRSA offered two options with cost impact analysis for a 2,000 square foot straight gable shingle to shingle reroof with half-inch decking, that includes perimeter reinforcement to meet the presumed increased perimeter and corner pressures.
The first was a reinforcement, which consisted of adding an additional horizontal two-by between the existing trusses at four feet from the outside edge that an intermediate two-by would be connected to so the attachment for the sheathing would be one foot on center between structural members. This would take place on all four sides of both gable planes. Additional pricing includes all necessary hardware, fasteners, two-inch thick wood members, decking, engineering services, general contractor and permits. The cost for the reroof would be $7,000 and perimeter reinforcement cost would be an additional $18,000 for a total of $25,000 for a twenty-square residential reroof.
The second option was to remove the existing half-inch decking and replace it with five-eights CDX which would be around $4,000 in addition to the $7,000 reroof cost. After much deliberation, the panel voted to not approve the code change, however a last minute
assembly action allowed the code mod to be moved to public comment which is still in progress. The fate of this mod is yet-to-be-determined.
At the end of June, FRSA contracted with an engineering firm to perform an evaluation of ASCE 7-16 using ASCE 7-10 as a baseline to determine variations of design wind pressures. FRSA is currently waiting on results that may require further evaluations using earlier versions of ASCE as a baseline. This information is critical to help shape arguments for the ICC final action hearings on the 2018 I-Codes in October.
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