I attended a 3-hour IRC (International Residential Code) update class yesterday. The IRC is, in my opinion, a classic example of shooting yourself in the foot.
I’ve written about the IRC before (“When Is Engineering Required Per the 2003 IRC?” blog, http://www.constructioncalc.com). I’ll spare you the chore of clicking around to find that by reprinting the interesting points here:
“I think the code folks have gone overboard in their efforts to eliminate engineering of the simpler things. In fact, I believe those very efforts are the ones causing so much confusion. There are simply too many ways to build a house to say this way doesn’t need engineering but that way does. Trying to make that distinction—that line in the sand between shall be engineered and doesn’t have to be is what this hullabaloo is all about.
I, no stranger to building codes, spent more than a day researching the International Residential Code (IRC) (read: “groping desperately to unravel a hopelessly tangled pile of kite string”) and still am not sure I’ve got this issue completely nailed down. The following, I think, begins to answer the question. I’ve included code references in case some Very Brave Person wants to investigate further.”
... and then my conclusion:
“Now for the solution. I think the code folks ran awry when they invented prescriptive design. Most people aren’t even aware that prescriptive design violates most state’s engineering law, which paraphrased, states that engineering shall be performed only by engineers (also architects in some states). Deciding what beams or shear walls to use is engineering. Period. I don’t care what IRC tables tell you, still, it is engineering. Span tables are a classic example. Say you’ve got a 16 foot garage door header that you size using an IRC span table but fail to notice the footnote that says ‘only applicable to uniform distributed loads’. Most non-engineers don’t even know what this means and won’t care that a girder truss is bringing a huge point load to the mid-span of their header, making it grossly undersized.
I prefer the good old days when the code simply described minimum standards and it was up to designers and code officials to decide when engineering was needed and when not. This required some basic understanding of the code and common sense. I think today’s codes strive extravagantly to eliminate any possibility of someone actually engaging their brain and using common sense. I’m a big fan of common sense. You see, as soon as you try to define things so precisely, so exactly, that common sense is no longer needed, two things happen: 1) Your descriptions become so dense and perplexing, no one can understand them; and 2) People disengage their brains, throwing any attempt at common sense out the window.”
All that was about the 2003 IRC. Now, two code cycles later, we’re facing the 2009. Do you think the code writers paid any attention to me when they concocted this new and improved quagmire? No, they did not.
Rather than paring down and streamlining, they packed in yet more gobbledygook. Take for example the wind and earthquake design sections. The new code greatly expanded these with the intent, I think, to allow all comers to perform lateral analysis and design.
I’m in the structural software business and here’s the feedback I get most often: “Tim, I love your programs because they’re so easy to use. Why don’t you produce one for lateral design? You’d be rich!” My answer today is the same as it’s been for 15 years: “Becoming rich would be fine, however, lateral design is just too complicated. There’s too much judgment involved. To get it right you’d spend more time inputting than if you just did it longhand.”
Yesterday’s instructor, Tim DeVries, a friend and top notch building official, did a fantastic job. He devoted nearly half of the class to the lateral design sections, which is saying something considering all the changes to the energy code, ingress / egress, and other sections. And at the end I’m pretty sure most attendees were significantly befuddled about lateral design. Not because they’re dense or Tim did a poor job, no, quite the contrary, because it’s just too darned complex.
The intent of the IRC is to bypass professional architects and engineers - to allow anyone to design their own residential structure using prescriptive methods. Actually, I’m good with that premise. I’m all for empowerment. However, I strongly believe that wind and earthquake design does not lend itself to prescriptive methods. The alternative is to hire an engineer who, if he is worth his salt, will not shoot himself in the foot with the IRC but instead use the IBC (International Building Code) and thereby save the project a lot of money in the long run.
As I said previously, any one-size-fits-all prescriptive standard will, by necessity, be overly conservative. In these lean and green times, who can afford that?