I recently read an article in our local paper about old barns. I love old barns. They’re usually red, they look cool, and they contain a certain homey smell – a mixture of hay, grease, manure, leather, and must – that can be found, well, only in old barns. My three brothers and I grew up on a cattle ranch. We had two big old barns and several outbuildings. Some of my favorite memories reside in those places.
Ask the International Building Code (IBC), however, about an old barn and the response will not be so nostalgic: “That derelict collection of sticks is a disgrace to human progress! There isn’t one part or piece that complies with my dictates! The atrocity must die!”
Following is just such an example, from the Skagit Valley Herald, July, 2009 by Elliot Wilson, photos by Mark Malijan. Here is the link. According to the article the Prevedell barn was built in 1915. It recently received a Heritage Barn Preservation Initiative grant. That money plus the owner’s matching funds were spent patching up the foundation and putting on a new roof. Doors, windows, studs and siding were also replaced.
The Prevedell Barn, built 1915.
If you look at the exterior photo carefully, you’ll notice that the barn is in an open field. Meaning that it is subjected to a relatively severe wind exposure, category “C” (open terrain for at least 1/2 mile) . I did a rough calculation and estimate that using today’s code the wind load on this barn would be around 50,000 lbs of sideways force. That’s 22.5 tons racking the building over. And the net uplift (total uplift minus dead weight of roof) would approach 21,000 lbs, some 10.8 tons prying the roof off. This barn does not have one shear wall, one holdown, a drag strut, or even a horizontal diaphragm. There isn’t a single hurricane clip or tie strap. And for 90 of its 94 years it had very little foundation, with only a handful, if any, anchor bolts.
Look at the interior photo and you’ll note that there is no ridge beam. There are no steel plates, bolted gussets, beam hangers, column caps, or any other framing hardware. Rafters appear to be 2×6’s at 2’ spacing, spanning some 20-feet. There are poles and beams holding up the rafters which are connected together with drift pins or dowels. If I calc’d any of those structural members per today’s code they would all fail by at least 100% and in some cases 1,000% or more.
In the same photo, the owner is standing on a hay loft at the eaves level. You can see that it’s loaded with hay. Hay is heavy. Much more than the rough sawn rafters and beams should be able to hold, according to code.
This old barn is built just like the ones on my family’s ranch. One time my dad was cleaning the manure out of our hay barn with his tractor and knocked out a post. There was no beam spanning to the adjacent posts, just a double 2×4 top plate. The roof sagged but didn’t come down. It sat that way for several years, until my dad got around to installing a new post. A few years later some cows knocked out another post. That one was never replaced. The barn still stands today.
I recently did a structural analysis of an old barn that had been converted to migrant worker housing. The owner built a three-story complex of apartments under the roof without a permit and was ratted out by a neighbor. It was my job to verify that the entire shebang was in conformance with the International Building Code (IBC). To begin with, just like all old barns, nothing original came close to meeting code. The apartments actually added a lot of lateral resistance but they, too, did not meet code. Truth be told, my job was impossible. The only way to ensure code compliance was to tear it all down and start over. That would have been infeasible for the owner and would have put a dozen families on the street. So I rolled up my sleeves and did my best, trying, as we used to say on the ranch, to make ice cream out of pig poop.
If that barn would have asked me why, why was I adding all those shear walls, brackets, clips, and all that lumber, I would have been hard pressed to give a sensible answer. I’m well aware that it had been there 50 years and with a little maintenance it would be there 50 more.
If old barns could talk, the Prevedell Barn might offer keen opinion on the travesty that is our IBC. It might say something like, “Now that code there… shee! It ain’t worth the paper it’s writ on. Fer one thing it’s so confounding a feller can’t make heads ner tails of it. And even if he could, with all the concrete and steel it throws around, why, it’s sorta’ like killing flies with a sledgehammer.”
Copyright August 3, 2009. All rights reserved.
Tim Garrison, P.E., The Builder’s Engineer™
Author of “Cracks, Sags, and Dimwits – Lessons to Build On” and “Structural Concepts for the Non-Engineer” available at http://www.ConstructionCalc.com