Tag Archives: Ag Exempt

Ag Exemptions, Truss Spacing, and Concrete Vapor Barriers

This week the Pole Barn Guru discusses ag exemptions for building permits, the effect of spacing trusses at 12′ or more, and concrete vapor barriers.

DEAR POLE BARN GURU: Do I have to have a permit to build one poll barn on Ag land? DANIEL in PIERSON

Building PermitDEAR DANIEL: Many jurisdictions nationwide exempt true agricultural buildings, on agriculturally zoned land from building permits. A practice I disagree with entirely – as it places these buildings at risk of failure due to under design of critical structural components.

Please read more here: https://www.hansenpolebuildings.com/2011/12/exempt-agricultural-buildings/

To find out if you would need a permit, or not, is going to take a phone call from you to your local Building Department and asking them.


DEAR POLE BARN GURU: Guess this is where to ask questions? We are planning a pole building 40X72 and would like to space the Trusses at 12ft or more? I see you say no problem but what would it take for this? Is it heavier trusses or heavier purlins? Just not sure the requirements for more spacing. Thanks! BRIAN in WARRENSBURG

DEAR BRIAN: You have come to the right place. Changes in truss and column spacing impact more than just having “heavier” trusses. Your entire building structure should be reviewed and sealed by a Registered Professional Engineer to properly incorporate all applicable loads for your site. Just a few possibly affected areas are column footings, column depth and diameter, amount of concrete around base of columns, uplift prevention, wall girts, roof purlins, truss bracing….just to begin with.

Each set of building dimensions and loading condition can have their own best design solution from both economic and functionality aspects. Hansen Pole Buildings’ Instant Pricing system™ allows for nearly instantaneous pricing of various truss spacings – down to fractions of inches!

Please read more about post frame (pole) building truss spacing here: https://www.hansenpolebuildings.com/2011/06/pole-barn-truss-spacing/.


DEAR POLE BARN GURU: Does the vapor barrier under the concrete slab of a pole barn need to cover the poles and splash boards at the perimeter of the concrete? Or do I just lay the vapor barrier on the ground and not up the sides? I am using 10 mil Stego. Thanks for any help! JARROD

DEAR JARROD: You should extend vapor barrier up columns and to top of splash planks.

Information on Stego™ vapor barriers can be found here: https://www.stegoindustries.com/stego-wrap-vapor-barriers



Building Code: It’s Just a Pole Building…Who Cares?

For the most part, obtaining a building permit for a pole barn, or a waiver of the need to obtain one, is very easy. In my humble opinion, far too easy. The reality is… code enforcement agencies generally do NOT require engineering design documents for pole buildings.

Pole buildings are highly stressed, structurally indeterminate structures which mostly rely on wall coverings (wood or metal sheathing) for stability. Even a simple building has a minimum of ten connections and structural elements which require structural analysis to ensure building code compliance.

Among the elements which should be checked are the building columns (posts), the post embedment, the post footing, connection of the trusses to the columns, roof purlins, wall girts, roof and wall sheathing, and the lateral bracing system.

The engineering design analysis of a pole building is closer to an airplane, than a stud framed building. In our case, even a simple, rectangular pole building permit submittal requires seven or eight 24” x 36” blueprint sheets as well as over 100 pages of calculations.

There is no prescriptive building code for pole buildings, much due to the wide range of possible design solutions, as well as the numerous types of buildings which can be built using post frame. Unlike stick frame buildings, where studs are placed every 16 or 24 inches, pole barns can have structural columns anywhere from four to even 20 feet on center!  Building Officials and Plans Examiners are hired to ensure building code compliance and, thereby, public health, safety and welfare. While it seems reasonable for engineering documentation to be required for pole buildings, more often than not, this is not the case. In reality, more than a few code enforcement officers and Building Departments are assisting unknowing clients to circumvent the building code.

Some jurisdictions actually hand out design documents whereby non-compliant, unsafe buildings are allowed to be permitted and constructed! Under structural analysis, these “prescriptive” requirements include overstresses of two, three or even four times the design loads. If an engineer would provide designs such as these, the engineer would lose his (or her) registration!

Non-engineered buildings fall down at an alarming rate. Even a little sprinkle of snow causes failures such as buildings collapsing under less than half the local design snow load. Supposedly this is deemed to be an “Act of God”. In reality, it is building contractors and Building Departments doing less than due diligence.

I heard a story recently about a woman whose building had blown over in a little puff of breeze the day after the contractor left the building site. The woman owned two acres and a llama. The Building Department had done her a favor and given her an Ag Permit. The Ag Permit saved her money and kept her from having to comply with the Building Code. It also kept her out of the “clutches” of the engineers. Some favor. She had absolutely no recourse. The disheartening thing is the collapse could have been prevented by the installation of a few pieces of pressure treated wood the contractor left behind in the scrap pile.

Nearly every state does not enforce the Building Code for all pole buildings. Much of the thought process is, “It’s just a pole building, who cares?” We should all care. When buildings fail, insurance companies pay and premiums go up. I care because under designed non-engineered building failures make it tougher on those of us who do use prudent engineering designs.

In most cases, engineering adds little or nothing to the cost of the overall structures. Engineers are able to eliminate redundant components, which add nothing but take dollars out of the building owner’s pocket.

If you are told your new building is permit or code exempt, a permit will be issued without a thorough structural review, or no engineered drawings are required, you should question as to why? In the end, the life you save…just may be your own.