Tag Archives: agricultural 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 The WI administration code exemption that allows for the construction of non-structurally engineered farm buildings is outdated.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!

Engineered Buildings Part III: Exempt Agricultural Buildings

The International Building Code (IBC) is the primary non-residential United States model building code. Although the code covers all buildings, and has been adopted to varying degrees in all 50 states, most agricultural buildings are not designed in accordance with its provisions. This is because most state and local governments which adopt the IBC exempt “buildings used exclusively for farming purposes” from all building code provisions.

Due to this special agricultural exemption many builders are quick to tell farmers they do not need to have their agricultural buildings engineered. While this is absolutely true, it is foolish.

A consumer deciding they do not need to have their building engineered if it is code exempt, a permit is not required, or their Building Department does not require engineered plans, is no different than deciding you don’t need to wear a seat belt just because no one forces you to wear one.

Many builders or building kit providers will tell clients a fully engineered building costs more. While this may be true for smaller buildings, it is generally not true for larger buildings. Purchasing a large non-engineered building for less than the price of a fully engineered building is likely buying a relatively dangerous building. This results from non-engineered buildings not being balanced in overall design terms.

Engineered structures generally contain components which are either not needed or are larger than needed, unnecessarily driving up building costs. At the same time, non-engineered structures are frequently missing critical components and/or have numerous under-designed components and this places building occupants in grave danger.

Keep in mind building codes establish minimum performance levels for buildings. These include built in safety factors, which insure properly designed buildings meet minimum performance standards. Any statement implying properly engineered buildings are over-designed is likely to just not be true.

I believe all buildings should be fully engineered. Non-engineered buildings needlessly endanger those who occupy them. A lack of building engineering is responsible for countless animal deaths every year, as well as millions of dollars in damage to building contents.

With respect to a consumer, I highly recommend asking for written confirmation their building is designed to meet IBC structural performance criteria. This written document should be structural plans and calculations “wet signed and sealed” by a qualified registered professional engineer (not a photo copy), and should be specific to the address where the building will be constructed.

Be extremely leery of builders who erect buildings designed and supplied by a local lumber yard. The “engineering” of many “lumber yard” building kits is often quite limited or even non-existent. It is also important to understand just because a purchase includes nice looking plan drawings does not mean the building has been properly engineered.

Every time a large storm brings down buildings, the construction industry takes a hit as code officials, insurance companies and consumers begin to question building system integrity. Insurance premiums go up on all structures, even those which are fully-engineered.

What should be of major concern is the sheer number and steady increase in large building failures. This occurring should not surprise anyone. Double structure size will double component numbers, and this alone approximately doubles structure failure probability.

From a consumer safety perspective, large building failures are more a concern than small building failures because there is generally a greater potential for loss of life in larger facilities. In response, some individuals have suggested code exemptions for low risk buildings be terminated, at least for larger structures. I am not for more government intervention but buildings are not failing due to a building code exemption.  They are failing because they are not properly engineered and/or constructed.

Invariably, when reports of another non-engineered building failure surface, someone will exclaim “they sure don’t build them like they used to.” My typical response is, “Be thankful, because past generation buildings do not come close to modern fully-engineered building performance levels.”

The sheer size of many of today’s buildings, distances they clearspan and loads they can withstand make them true engineering marvels. The low per square foot cost of pole buildings is a reflection of efficient material usage. This efficiency, when coupled with their durability makes the modern, fully engineering pole building probably the world’s most environmentally friendly or “greenest” structures.

My advice, whether your building is “ag exempt” or not, at a minimum, purchase a building which is fully engineered.  Insist your pole building is designed to codes using the loading values for the building site.  Don’t cheap out.  Be safe… not sorry.