Tag Archives: agriculturally exempt buildings

A Problem Good Structural Engineering Could Solve Part III

Part III, the conclusion by Dr. David Bohnhoff, Phd., P.E., Professor Emeritus at the University of Wisconsin-Madison.

Perhaps only people that engineer buildings understand and appreciate the true dangers and hence insanity of erecting (and then occupying) a structure of absolutely unknown strength.  To structural engineers involved in agricultural building design, NOT following the structural requirements of the governing commercial building code is crazy given the fact that the code sets MINIMUM criteria.  If you aren’t going to engineer a building in accordance with loads considered the MINIMUM for your project, then pray tell, what loads are you going to use????

The IBC, which was adopted (with modification) as the commercial building code in Wisconsin, is a code that is as applicable to agricultural buildings as it is to other commercial buildings.  The WI administration code exemption that allows for the construction of non-structurally engineered farm buildings is outdated.  In many cases, code exemptions for farm buildings are as old as the code themselves.  The first building codes were largely fire codes (much like today’s codes) that were put in place to protect loss of life and property from large conflagrations (e.g. fires that consumed entire villages in some cases).  Since farm buildings were small and located in rural areas where they were isolated from other buildings, there was little concern regarding loss of life and adjacent property when they did burn (which they often did) and hence they were exempted from building codes.  As codes have changed so have farm building exemptions.  While farm buildings are still largely exempt from fire, ventilation and energy codes, they seldom are exempt from electrical and plumbing codes, and some jurisdictions no longer exempt them from structural codes.  The latter recognizes that large farm buildings need to be structurally engineered.  In some jurisdictions (e.g. Arkansas) farm buildings must be designed and constructed in accordance with the governing commercial code, but there is no enforcement (i.e., there is no required plan submittal and no required on-site inspection).

The confusion surrounding the structural design of farm buildings has made it virtually impossible for insurance companies to offer better rates for buildings that are structurally engineered in accordance with a specific code, then for ones that have not been structurally engineered.  To this end, farmers that purchase properly engineered buildings are not getting the break due them, in fact, the more large, non-engineered buildings erected, the higher their rates become.

Builders who sell and erect non-engineered buildings (typically at the expense of reputable companies) have no incentive to change their practice.  Given that insurance companies continue to insure the buildings they erect, why change?  As soon as one of their buildings fails, he/they are right back in the farmer’s yard telling the farmer not to worry as they will take care of him/her like they always have.  They blame the failure on a rare heavy snowfall (or on the truss manufacturer or some other supplier), and then they put up the exact same non-engineered building.  It’s a double win for these builders (two buildings and two pay days).  So why should they change their practice?  Your answer may be “so they don’t get sued”.  To this I ask, when was the last time a hard-working, independent dairy farmer (not a horse farmer) sued a hard-working local builder?  Given that they could go to the same church, have friends in common, or even be related, you can pretty much guess the answer.

Make absolutely no mistake about it, the rash of agricultural building failures is virtually entirely due to the construction of buildings that are not structurally engineered by builders who in many cases could care less.  They are not among the farmers, the reputable builders, the component supplies (who often get blamed for the failures), or the insurance companies who would all benefit by requiring large farm buildings to be structurally engineered.

David R Bohnhoff, Ph.D., P.E.

Emeritus Professor

Biological Systems Engineering Department

460 Henry Mall, Madison WI 53706″

Thank you, Dr. Bohnhoff!

Does Building to Wind Load Matter?

Biking On Down the Highway

Author’s Note: This is part 6 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!

Time for another lumber yard visit.

WindThey are in Michigan (I am really not trying to pick on Michigan). Their statement, “Builders here do not like to have to build to wind loads”!!

Say WHAT???

Last I heard… buildings were to be constructed to resist wind, snow and seismic loads. I was totally unaware of a Michigan exemption against building to support wind loads!

It turns out the majority of the buildings provided by this lumber yard are agriculturally exempt, so they are not designing them for any particular load resistance characteristics.

The 2009 and earlier versions of the IBC (International Building Code) require a design wind speed for all of Michigan of 90 mph (miles per hour). The 2012 Code has bumped this up to 105 mph for Risk Category I buildings (buildings with a low risk to human life in the event of a failure) and 115 mph for Risk Category II (most inhabited structures, like homes).

Clearly ignoring wind loads appears to be an undertaking with a high degree of risk involved.

As a general rule, they provide 6×6 pressure treated columns, regardless of the height of the building, wind speed and exposure and whether the building is fully enclosed with wind rated doors, or partially enclosed.

With structural columns spaced every eight feet, 2×4 Standard & better graded wall girts are placed flat on the outsides of the columns, at 24 inches on center.

Obviously I believe every building should be designed to adequately support all of the loads which are induced – including wind. Also, it is my personal feeling every building should be designed by a RDP (registered design professional – engineer or architect) who should be placing his or her seal on the plans as well as providing complete design calculations to verify the work being produced.

Failure to design for wind loads can only result in the eventual failure of buildings, hopefully without loss of life and/or limb.