Finding Stuff on the Road
Author’s Note: This is part 7 of a series of blogs written from a 6500+ motorcycle trip from WA to Ohio and back. See Blog from Oct. 15th for the beginning…and hang on for the ride!
There are many Building Departments who offer nifty little handouts to property owners who want to design and construct their own post frame buildings. Most of these are one or two page documents and cover a relatively limited number of cases (typically smaller buildings). If one follows their guidelines, a structural Building Permit will be issued (provided the building meets with any other requirements imposed by the Planning and other related jurisdictional departments).
I picked up from one of the states I visited on my trip, a County Construction Code Office 10 page document on how to design a pole building. Most of the document deals with how to design truss carriers (they assume all post frame buildings will have columns every eight feet, with trusses every either two or four feet) to support trusses between columns. The other feature stressed in the document is adequate footings to keep buildings from settling.
There are many things the document overlooks. It gives a description of how to design truss carriers, but not how to attach the carriers to the columns. It gives concrete footing sizes, but fails to address column uplift and overturning due to applied wind loads.
Interesting, of note, all of the footings are greater in size than any concrete “cookie” would ever possibly support!
To learn more about concrete cookies: https://www.hansenpolebuildings.com/blog/2012/08/hurl-yourconcrete-cookies/
Even for a modest sized building (30 feet wide) with generally accepted soil bearing pressure (using 2000 pounds per square foot as the soil bearing capacity), their prescriptive footing requirement takes over 600# of concrete per hole! Not too many people are going to mix up 10 60# bags of sackrete for each hole, so the potential for abuse exists.
Also not addressed by the document are…(and I shudder here) the wall columns, girts or purlins!
What all of these prescriptive requirements got me thinking about was – I wonder if the jurisdiction’s attorneys are aware their Building Departments are putting themselves in the position of being the Designer of Record for buildings constructed using them? Facing reality, if I was to construct a pole building, using the methodology ascribed to be one of these departments, and my building came down, I am thinking my attorney would have a field day with it!
For more information on prescriptive requirements: https://www.hansenpolebuildings.com/blog/2012/02/prescriptive-requirements/
See you tomorrow….for Part 8 in the series of my cycling across the upper U.S.