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Among the challenges discussed by the group, education ranked top. Other trouble spots appear with complexity of detailing, the International Residential Code (IRC) vs. engineered approaches,
standardization vs. customization of wood products, and changing building codes. Optimism abounded, however, as the panel agreed that education was also a strength of wood frame construction, along with the abundance of product literature and design guidelines, materials testing, and the possible prefabrication of wood components. The group shared their concerns and hopes for the future of wood frame construction; excerpts from the discussion are contained in this article. (Photo: Scott Aitken)Challenges
KEITH: I was going to start with a comment on education. I believe that a major challenge is educating wood engineers. You usually have to train a wood engineer after he is out of school. We spend a lot of our time teaching engineers how to engineer diaphragm-type structures. We publish a lot of literature, and give a lot of seminars.
I don’t know about your experience in college, but I took a wood engineering class, and I designed a truss bridge. I mean, who designs wood bridges? We need people trained to design buildings. And if you look at the structures in the country, the majority of them are residential; the majority of them are wood. And no one really teaches people how to design those. For many years they weren’t designed. But as the new International Building Code (IBC) is being adopted, as we understand more about structural loads, and as we change the way we build buildings, there are more and more projects that are required to be designed.
LAMPE: From an engineering education standpoint, there’s so much focus in college on steel and concrete; wood gets shoved aside. In some ways wood design is a lot more complicated than steel and concrete design. This is because often steel and concrete projects basically line up all the way up and down; yet with wood projects every single floor could be different. You have to trace loads and find load paths and so forth. And in a lot of cases the engineering is just a lot more complicated.
The other thing about wood is that you have to have really good eyes. You have to not only find the fine print in your drawings, but you also have to find the fine print in the codes and in the wood engineering manuals, because everything is in the footnotes. So you have a table that gives you values, but then they’re all modified.
GILSTRAP: We don’t do that at all. (Laughter) In our defense, we have to satisfy many codes. And some jurisdictions haven’t even adopted the I-Codes yet. So we may publish one number in the table and give you seven footnotes to cover different jurisdiction issues. So it’s a struggle.
Back to the topic though, we too spend a tremendous amount of our time educating. Not even just product education, but education on wood design in general. We help designers understand, for instance, how a shear wall or a diaphragm works. It is instrumental in getting our products specified properly. We spend a lot of time educating installers as well. We have Spanish guides; we have English guides—we even tried guides with no text at all, just pictures. These are not hard things for us to do. As a manufacturer, we try to publish a lot of details in our literature and then make it readily available, because we realize you guys can’t put everything on the drawings.
GILDA: Yes! I still think one of the biggest challenges we have, even if we developed all this new technology, is that we still have the same problems effectively communicating our designs to the field. And not just to the framers, but also to the plumbers who are cutting through I- joists, studs, and hold-downs. Our greatest challenge is improving our drawings to communicate effectively to everybody involved in the process.
GILL: I think wood is a wonderful material. It’s my favorite material, actually. It’s the most beautiful, certainly; and versatile. But it takes a lot more attention, a lot more detail, and a lot more care in the field. And it actually gets perceived as less valuable because the fees are generally smaller for wood projects. Not to mention that field observation is less. So, it’s a real challenge, but a great opportunity.
COLLONS: There is a disconnect between the liability that we take on and the quality of the construction. So we’re not getting the fees we need in order to put together good drawings or to be in the field to ensure they are building it correctly. In fact, there are times when we don’t even want to go out to a wood project because we know it’s been completely butchered. We ultimately have to rely on the suppliers that go out to the jobsite to be our eyes and ears—to at least be sure that products are installed correctly.
LAMPE: That comes down to owners’ expectations. You know that the owner just expects that because his is a wood frame building, the fees are going to be smaller, the engineering is going to be easier, and the framing is going to be easier. And, they think it could be done faster.
Yet, there is a lot of detailing that goes into some projects. And from a soft-cost, engineering-fee standpoint it’s a lot more than concrete or a steel project.
GILDA: Wood has always been the Rodney Dangerfield of materials. (Laughter)
We kind of have this split personality with wood. For example, you can have two homes that look identical, and depending on the jurisdiction, one of them may be built per the IRC with no hold-downs, and the other may have been engineered with hold-downs on every single shear wall that is nailed at four inches on center, instead of six inches on center. You know they’re not going to perform the same.
From a builder’s perspective, the one that is built with conventional framing, using the IRC, looks like the greatest deal in the world. They didn’t need to hire an engineer or pay our fees, and they don’t need to pay for the hold-downs.
KEITH: Well, to address this, currently there are several committees trying to rationalize the IRC and to rewrite it. They are striving to base it on engineering. So, in the future, when you use the IRC on a project and I engineer the same project, there won’t be this difference of factor-of-safety of three in performance. But, this is a huge challenge.
To complicate matters a bit, more engineers are getting more involved in designing portions of the building. Because builders are finally realizing that if they have a part of a house that doesn’t meet the IRC, they have to have that portion designed by an engineer.
So all of sudden, some structures are partially engineered. It confuses the building officials. That’s a real issue.
Unfortunately, you can’t fully design a $200,000 house, if they’re only going to give you 1 percent—or $2,000—to do that.
GILL: They won’t give you that.
GROMALA: Where are you working?(Laughter)
KEITH: Well, all right, even if you can get $1,000—that’s half a percent—you still can’t fully design it. You’re lucky if you can get a quick grasp of the loads and maybe the basic shear walls.
LAMPE: Going back to all of the different products, another challenge for designers is the evolution of products. For example, one product available today may not be so tomorrow. In contrast, I can specify an A36, 50 ksi steel beam and it will be the same no matter who gives it to me and when it is delivered to the site. If I specify a TJI that’s 11-7/8 inches deep… well, last year it was good for this value, but this year it’s good for that value. And, if I, the contractor, ordered the product from another manufacturer, it could be good for something else.
GROMALA: One of the things we wrestle with as engineers is that we like stability, so we just as soon have the same catalog for 20 years. But our customers want the products to do more and cost less next year. So we are sort of stuck with a constant evolution.
KEITH: One of the problems with the I-joist industry is that nobody is building a commodity. They’re all manufacturing unique and specific I-joists. APA made an attempt some years ago to standardize the I-joist industry, to come up with common standards. The market wasn’t ready for it yet.
COLLONS: Rightly so! I can appreciate that TrusJoist (now part of iLevel by Weyerhaeuser) spends a lot of time and money developing and testing products—for example, creating the profiles for the routed-out pieces of the flanges and developing specific glues—so that they can predict their product’s performance. To try to standardize the product means that any Joe with a router can create an I-joist, and I’m not sure if that’s where I want the industry going, either.
GROMALA: Standardization and the advantages of standardization vs. the company-specific solution is a tough one that we’re wrestling with all the time. The standardization solution stabilizes design options for you. But, the optimization or a company-specific solution gives us the ability to do what Brian asked. He said, I need the suppliers to be the eyes and ears that go out to the jobsite to help me out. And our opinion is that we can’t have it both ways. We can’t go to standardization—which means low cost, bottom dollar—and afford to provide the support network.
And we’ll continue to wrestle with it, and we’ll continue to offer multiple solutions to you. We apologize if it will confuse you a little bit.
GILSTRAP: Can I shift subjects just a little bit?
GOUPIL: Sure.
GILSTRAP: One of the big challenges we’re seeing right now is a result of the requirements in ACI 318, Appendix D. The criteria states that in moderate- to high-seismic zones you have to look at ductility; it says the concrete cannot be the failure mechanism, that you must have a ductile failure of the steel. This effect is having huge impacts on anchors near an edge. I don’t think most of the people understand how this will affect their designs. This is true not just for the hold-downs anchor bolts resisting tension, but the mudsill anchor bolts resisting in-plane and out-of-plane shear forces, too. Have you guys experienced a lot of challenges with that?
KEITH: Something we don’t deal with being wood guys is that we are really above the foundation, but how close to the surface is that? Is that going to happen?
GILSTRAP: It’s happened already; it’s in the code now.
GROMALA: When did this change come to the IBC?
GILSTRAP: The requirements were in the 2000 IBC, but have evolved over the years. In the 2006 IBC, they provided a work-around, which states that you can have a non-ductile failure provided that your demand load is increased by a factor of 2.5. So, anchorage design in moderate- and high-seismic regions per ACI 318 is a big change that engineers should know about as it will likely require larger footings.
Opportunities
GILL: One thing that I have noticed is that a lot of the conversation has been focused on the low end of wood construction—of which there certainly is a lot. But there are also some really high-end houses—in the $6 million to $10 million to $12 million range—as well as other types of wood construction, including museums and schools. In those projects, all these problems go away. Typically I get 2 or 3 percent of the construction costs to do those designs. And the clients want them fully detailed. They want the entire design worked out and resolved. It’s a nice market.
GROMALA: Speaking of large wood construction projects, especially multifamily, residential, and commercial projects, would it be helpful for us to strive to develop either pre-engineered solutions or whole building software?
LAMPE: Let me touch on that real quickly. When engineering a complex wood project, I feel like I need to get real intimate with the plans and the drawings. And the more it’s computerized, the harder it is to do that.
GILDA: I’ve tried some whole building software products. They work well when everything stacks. But, then when the members don’t stack or a shear wall comes down over a window, it’s too hard to control what assumptions are being used by the model. On the contrary, I use the TJ-Beam software religiously to select I-joists. Also, there are a lot of tools that are pretty simple that we use, such as spreadsheets. But, the literature that you guys provide is fantastic.
LAMPE: Yes, it’s very valuable.
COLLONS: In fact, when we hire a young engineer, we build his library out of the TrusJoist and Simpson Strong-Tie product catalogues, and the APA manuals. That is the core material, plus a few books that we buy. The 1997 Uniform Building Code was beautifully documented, remember? It had everything in it. Now, in the days of the IBC and referenced standards, we have to go out and spend hundreds of dollars to purchase the materials. It’s a huge expense. So when we can get product catalogues and design guidelines for free, we are happy to put them on our reference shelf.
But there are just not software tools available. Products that perform simple wall stud calculations for a three-story building that cost thousands of dollars to buy are just not worth it. So we all create our own spreadsheets.
I know that the industry is out there. Software companies are developing all these multi-story steel and concrete applications. But, they don’t care about wood, because a wood project is a three-story building. These projects do not generate fees to support or encourage software development; otherwise, everybody would be doing wood design. The wood industry is suffering just because of the limitation of wood.
GILL: I agree that there’s a bias towards concrete and steel in the engineering profession, especially in software development and research. And I think there is a great opportunity for a lot more materials testing. There is much, much, more latent strength in wood that is not being used in our design procedures.
For example, I work with some pole building builders and they show me—they literally take me out and show me buildings with 2 and 3 feet of snow on them that shouldn’t be standing up. And in fact, the buildings would fail if you did the calculations, by a factor of four or five. Yet, they take me out and show them to me, and there they are performing wonderfully. It’s hard to argue with that.
KEITH: One opportunity that I see—and I know that APA and Simpson and I’m sure Weyerhaeuser does, too—is to give seminars to building officials. We have a brown bag lunch series where we’ll supply the lunch entertainment for an hour.
But, there are not enough of us to do that. It is something that local engineering firms should think about: investing the time to prepare a one-hour presentation to give in your local jurisdictions. I know they would appreciate it, because they’re faced with new 2006 I-Codes and don’t have a clue. Of course, the ICC will train them, but the jurisdictions don’t often send their people because it is expensive. But, it would be much nicer if a local engineer came in and explained the significant changes that will affect your projects. Also, if you explain why certain things need to occur in your design, based upon the code changes, you are more likely to get your plans approved.
GOUPIL: To wrap up, I think there is tremendous opportunity in engineered wood panels and assemblies. Pre-fabrication is where much of the market is going, if you look at the construction industry as a whole. If we can get that trend into the wood industry, it would help to eliminate some of the uncertainty of field work, which will only help the quality of the finished product.
KEITH: I think with the cost of engineering going up and the skill level of labor going down, we’ll be forced to use a lot more pre-fabrication in wood construction. Higher quality is achieved because the employees can be trained well. The workers have all the tools they need and they get to work indoors. It will be the way of the future.
Conclusion
LAMPE: I think as wood engineers, it’s important for us to not sell ourselves short, and one of the ways of doing that is through education. We must educate the public and our clients, as well as the jurisdictions with which we work. Just to show them, to educate them, on the value of what they’re getting through our services, as well as the reasons why we’re doing some of the things that we’re doing.
Another way we do that is by setting realistic expectations for the owner from the beginning regarding schedule, fee, and all other aspects of the project.
GILL: I’m really optimistic for the future of wood construction. There are a number of good products that have come out in the last 20 years—which were developed at Simpson and TrusJoist—and I just think it’s going to keep going. I’m not seeing that happening in any other materials.
While there is a bit of catch-up going on in terms of engineering education and public education, I’m sure we’ll all get that done. I think there is a really bright future for wood construction.
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THE PANEL
All photos: Scott Aitken
Bryan Collons, P.E., S.E., is a principal of Issaquah, Wash.-based Collons + Smith Structural Engineers.
Greg Gilda, P.E., S.E., is an associate at the civil and structural engineering firm DCI Engineers, headquartered in Bellevue, Wash.
Gary Gill, P.E., S.E., is a senior engineer located in the Seattle office of the multidiscipline engineering firm Coffman Engineers.
Jeremy J. Gilstrap, M.S., P.E., is the manager of engineering research and development at Simpson Strong-Tie and is located in Pleasanton, Calif.
David S. Gromala, P.E., is the director of codes and product acceptance at iLevel by Weyerhaeuser, and is based in Federal Way, Wash.
Edward L. Keith, P.E., is a senior engineer in the technical services division at the APA - The Engineered Wood Association, and is located in Tacoma, Wash.Brian Lampe, P.E., is a principal at BTL Engineering—a structural engineering consulting firm based in Woodinville, Wash.
HOST
Jennifer Goupil, P.E., is a structural engineer and the editor of Structural Engineer magazine. Photo: Adonis Photography
