Contractors can rely on the specifications and construction documents provided by a project. Then again, they may need to get in the weeds with this stuff.
Some recent standards referenced by the model building codes need clarification. In one case, the 2018 International Building Code has a discrepancy over metal framing, a system used frequently by commercial wall and ceiling contractors.
“You have standards referenced in the code that could create different capacities for the same assembly,” says Patrick W. Ford, P.E., S.E., of the engineering firm raSmith, Brookfield, Wis., and chairman of the American Iron and Steel Institute’s Framing Design Subcommittee for Cold-Formed Steel Framing. “It can become very confusing.”
Yeah. We need to get this straight. But we also need some insights on where codes and standards are heading. This article will help address some key topics.
One Code, Two Standards
These days, metal framing installation standards are written by ASTM International, whose most relevant consensus technical standard is the AC86 10-2021, “Cold-Formed Steel Framing Members—Interior Nonload-Bearing Wall Assemblies.” However, the standards that govern the component products—the studs, joists and hat sections roll formed from sheet steel—are researched and written by AISI, an association of North American steel producers.
AISI standards “have taken the forefront for cold-formed steel framing design,” says Jay Larson, PE, F.ASCE, managing director of AISI’s Construction Technical Program. “They have a greater role [than the ASTM standards] in defining the cold-formed steel products.”
But contractors don’t have to get in the weeds just yet. The Steel Framing Industry Association has a quality assurance and quality control program that certifies cold-formed steel products. By using SFIA-certified steel studs, a contractor has assurance that the components meet AISI’s requirements. After that, the contractor needs abide by ASTM’s installation standards.
But what about this discrepancy in steel framing capacities?
In May, engineers met in Denver for the 2022 Cold-Formed Steel Engineers Institute Expo. At the conference, Ford presented a seminar entitled, “CFS Member Changes per the New Code.” One of his presentation slides said, “How could code officials update their codes and complicate our lives?” The answer: Timing.
The cycles associated with the issuance of new model building codes and new metal stud standards are typically offset. Model building codes are reissued every three years, whereas new AISI standards come out every four or five years, Ford’s presentation said.
As it happens, the 2018 IBC—currently adopted, Ford says, in 26 states—references two different AISI standards in different parts of the code. The 2018 IBC references the AISI S100-16 standard (issued in 2016) and the AISI S240-15 structural framing standard (issued in 2015). The AISI S240-15 references the older AISI S100-12 issued in 2012.
So, the question arises: Which part of the 2018 IBC has control? Both the 2016 AISI S100 and the 2012 AISI S100 are referenced.
“The question certainly affects the framing members the contractors deal with,” Ford says. “It’s not only the design strengths of the framing members, but also what constitutes a legal galvanized coating on the studs.”
The subtle differences in stud capacities between 2012 and 2016 AISI S100 standards could affect a contractor’s bid negatively, since the newer S100-16 requires, in some cases, greater framing assembly capacities. In other words, the contractor may have planned for less material. Then, after the bid has been accepted, he’ll need to purchase more component members to meet the capacity requirements.
The contractor needs to be savvy enough to know the issues, Ford says. Even if the project specifications reference a particular standard, but they do so for the wrong code, a contractor “could end up being called out by the building inspector for his stud framing when he’s really done nothing wrong,” Ford says.
“Depending on the code version,” Ford adds, “he could also run into a coating issue.”
AISI plans to address the complication.
“Our next code update cycle is not until 2027,” Larson says. “[AISI] will be producing updated design standards in 2024 (AISI S100) and 2026 (AISI S220 and S240), but we don’t intend that they be adopted in the IBC until 2027.”
In other words, now is the time—during this respite in standards updates—when contractors can catch up on their understanding of (1) AISI S220 (the interior stud framing standard; the 2020 edition being the latest), (2) AISI S240 (the structural framing standard; the 2020 edition being the latest) and (3) AISI S100 (the design standard for cold-formed steel framing; the S2-20 or 2020 Supplement 2 to the 2016 edition being the latest).
The 2021 IBC has just one set of capacity standards to be concerned with: AISI S100-16 with S2-20. For now, make sure your bidders, estimators and project managers keep a close eye on each project’s specifications.
QA/QC Inspection Requirements
When it was released in 2015, AISI S240, “North American Standard for Cold-Formed Steel Framing,” spelled out in Chapter D provisions for quality assurance, quality control and special inspections of cold-formed steel framing.
“As an industry, we decided we needed to take control over the inspection requirements for cold-formed steel framing,” says Jeff Klaiman, PE, principal at ADTEK Engineers, Inc., Fairfax, Va., and chairman of the SFIA Technical Committee and chairman of the AISI Standard Practices Subcommittee of the Committee on Framing Standards.
“Other groups, many not experts in CFS framing, were trying to write that for us into the code,” Klaiman says. “We wanted to make sure that what was being required in the form of inspections was going to be in the best interest of the cold-formed steel framing industry and contractors to produce safe, efficient buildings.”
Thus, AISI S240-15, Chapter D, spelled out what should and should not be inspected and created better expectations for the inspectors. It also made clear which parties are responsible for the types of inspections needed at each phase of construction.
“It created, in my mind, a much smaller list of things that require special inspection,” Klaiman says. “Of course, it’s still up to the building code and the jurisdiction. They can always require more than the standard requires, but at least we set forth the minimums.”
In general, metal framing inspections have become less onerous, even though some contractors, Klaiman says, have a hard time understanding that more QA and QC inspections are required on projects.
“A large contractor understands that, but there are a lot of small contractors and they don’t like having to deal with third-party inspections and critical structures inspections,” Klaiman says. “I don’t blame them for not liking it, but it is just a fact of life. The code and local jurisdictions are requiring it more and more. We cannot stop it, but we are trying to keep it reasonable.”
Contractors must make sure that what’s installed matches the drawings.
“They get flagged all the time because they don’t follow the drawings,” Klaiman says. “I mean, some contractors are very good, and some are not. It’s common for some to use blatantly wrong members, wrong sizes or space the studs 24 inches on center when the specs clearly say to space at 16, or to put one shot in the concrete slab when the specs call for three shots.”
Off-Site Construction, Reliability 2030
What other standards developments should contractors note?
Labor shortages are driving more off-site construction, including panelization and full modular construction, and so codes and standards governing such activities are needed. Klaiman says the development of off-site construction and prefabrication standards—for designers and framers—is big.
“People are looking at how to get QA/QC in a factory,” Klaiman says.
Off-site construction was a huge topic at 2022 CFSEI Expo cited “in nearly every breakout session,” Klaiman says. He says AISI is looking at incorporating off-site construction processes into its standards. And Klaiman says an ICC committee is already developing two standards—one for the design side of off-site construction, and one for QA/QC of the fabrication side.
“At AISI we’re looking at taking control of that ourselves and not letting just a general group of people control us,” Klaiman says.
Another important development is the Reliability 2030 Initiative, a research and standards development program being led by AISI.
“It’s going to bring more economical structures,” Klaiman says. “It’s going to allow us to take into account a building as a system as opposed to just a collection of individual members.”
Larson says that integrated system design will allow for a more economical use of material, lowering the material needs due to redundancies and helping the environment.
“Contractors will often say that when add drywall to the framing, the whole thing stiffens up,” Klaiman says. “They’re right, but the code doesn’t give us any numerical, prescriptive way of accounting for that. And, it specifically says you can’t in certain circumstances.”
The Reliability 2030 Initiative will provide research to account for, within the AISI standards for framing, the benefits of repetitive members, such as sheathing acting as bracing, and of other system effects.
“The research is an expensive undertaking,” Ford says. But hopefully, we will claw back some capacities we’ve lost and get back on some firmer footing with regard to competing materials.”
Stucco, Thermal Bridging, Head of Wall
What other changes in the works will affect contractors? One significant change coming in the 2021 IBC will impact stucco contractors.
“If they’re applying cement plaster on the exterior of a building, where the sheathing is wood based, they will have to put in a vented airspace or drainage mat,” says Robert Grupe, AWCI’s director of technical services. “They’re looking at adding 3/16 inches of a gap between the water-resistant barrier and the cement plaster itself, although it has yet to be approved.”
Grupe says stucco is a porous material, so a drainage plane provides a second-line defense against water penetrating the stud cavity beyond a water-resistant barrier.
“I’m writing a white paper for AWCI on what this means,” Grupe says. “We’re defining the code and interpreting it, but there are a lot of unanswered questions.”
Another area involves requirements related to thermal bridging. Grupe expects these standards to be added to the energy codes.
Thermal bridging can transfer heat, which can be lost through exterior walls. Grupe says that ASHRAE Standard 90.1, a benchmark for commercial building energy codes, and the International Energy Conservation Code may include tighter requirements on thermal bridging in the future.
“I’m told ASHRAE is looking at it, but I haven’t seen anything definitive on it,” Grupe says. “And I have not done an analysis on where IECC is. The only thing IECC has said that is somewhat significant, and this is my interpretation, involves panelized construction. You may have to analyze for heat loss where panels come together. And if you have a panel or an exterior curtain wall assembly that ties into an exposed concrete column, that interface may also have to be analyzed.”
Another development taking place—a big issue, Ford says—involves the composite slipped head of wall testing assembly. Despite the slipped head of wall assembly being common, the codes and standards only reference a non-slipped head of wall test assembly.
Ford is chairman of the AISI task group trying to get the standard changed, so that both standard non-structural and EQ (equivalent) metal studs used in a composite wall test can be tested “per an applicable real-life situation,” he says.
Interestingly, while ICC refers to AC86 criteria on the issue, and ASTM and AISI also have test standards set, none of them address the slipped head of wall testing issue. But once a revised test standard is defined, and assuming ASTM sets an installation standard, Ford says further work will likely be needed to make the composite slipped head of wall standards align with common field practices.
Resiliency and Sustainability
Codes and standards are always updating. This occurs because of research, better analytical techniques and more enhanced computer simulations.
“The national building codes and the laws say a building has to perform this way and that,” Klaiman says. “And the standards underneath them—like AISI standards for cold-formed steel—instruct architects and engineers, based on what the building codes, laws and local jurisdictions require, what must be done with CFS framing to meet the requirements.”
“As engineers, we get a bad rap from contractors because they sometimes think we over-design this and that,” Klaiman continues. “Honestly, we have very little say, very little judgment that we can make. We have laws and codes and standards with formulas that say what we must do.”
And those standards may be getting stricter.
For example, more discussion is taking place about the resilience of buildings. The idea is that buildings need to remain operable even after extreme events like earthquakes, hurricanes and tornados. Thus, forthcoming standards and codes, sources say, will reflect such resilience objectives, driving future prescriptive and performance codes.
Larson says resilience and performance-based design are coming in at a high level in the standards writing organizations.
The same is true with sustainability.
“When I say sustainability, I mean both energy efficiency and embodied carbon,” Larson says. “They’re being talked about, and they’re working their way initially into the energy codes and eventually into the building codes, I presume.”
So, a lot of change is coming. But for now, contractors need to watch the construction documents and project specifications closely.
“Write any contracts and do any bids in accordance with the standards listed in the project specs and no other,” Ford says. “Then you defer the responsibility for that to where it belongs, which is with the designer of record. It is their job to present contract documents that comply with the proper and current code.”
“If a contractor deals with it himself,” Ford says, “it will be a Herculean task.”
Mark L. Johnson writes for the wall and ceiling industry. He can be reached via linkedin.com/in/markjohnsoncommunications.
