Tag Archives: pole building concrete footing

Are Concrete Piers OK in Earthquake Areas?

Welcome to Ask the Pole Barn Guru – where you can ask questions about building topics, with answers posted on Mondays. With many questions to answer, please be patient to watch for yours to come up on a future Monday or Saturday segment. If you want a quick answer, please be sure to answer with a “reply-able” email address.

Email all questions to: PoleBarnGuru@HansenPoleBuildings.com

DEAR POLE BARN GURU:Why are concrete piers not recommended for pole buildings in earthquake areas? YELLING FROM YELM

DEAR YELLING: Part of why I love what I do for a living is I get to learn new things every day. I’d never heard of concrete piers not being recommended for pole buildings in earthquake areas – and have researched it highly, without finding any data to back up the premise.

Post frame (pole) buildings perform admirably in earthquakes as they are very lightweight, as well as flexible, compared to most other construction techniques. The heavier a structure is, the more it will be impacted by seismic forces. Most pole building construction relies upon wooden columns which are embedded in the ground (usually in concrete). A true concrete pier (a hole entirely filled with concrete) with a bracket to attach a column to the pier could prove to be a different story. In the event of a seismic event, the bracket/column connection could very well act as a hinge point.

DEAR POLE BARN GURU:I’m building a Barndominium 36×40 and I wanted to know how should I insulate the walls? Without creating a mold and moisture problem. Should I wrap what type of plastic wrap around the outside of 2×6 outer walls between R-panel? Also on the inside of plastic wrap between Sheetrock walls put R-19? And put R-30 in attic? If I wanted to put tongue and groove piney knot boards on inside walls what should I put up over insulation and 2×6 studs to nail the tongue and groove boards up to? To also help insulate walls?

Do you recommend a certain size a/c and heat pump unit for a 36 x40 barndominum ? Thank you for your help. BARNDOMINIUM BOB

DEAR BOB: As for R-values, without knowing where you are geographically, I can’t speak to what level is appropriate for your specific climactic conditions.

Walls – I would housewrap the outside of my framing, use BIBs insulation, cover the inside with clear plastic for a vapor barrier. If you intend to run the boards vertically on the inside – you can use bookshelf style wall girts to create both the insulation cavity and the support for your inside finish.

Attic – make sure to order trusses with an “energy heel” – deep enough to allow for the full thickness of the insulation to extend to the outside of the building sidewalls.

As for HVAC – your local HVAC experts can recommend the proper size unit for the cubic footage of space you will be conditioning.

Dear Pole Barn Guru: Concrete Footing or Not?

DEAR POLE BARN GURU: I have read much debate about setting the poles in concrete with no “footing” beneath them vs. setting the poles on a concrete footing and back filling with gravel and earth. Seems to be an issue of rot.  What do you recommend? MYSTIFIED IN MAGNOIA

DEAR MYSTIFIED: It seems you and I have been reading the very same posts on advice boards all over the internet!

Let’s start with the “no footing” concept. Typically the soil is not able to resist applied vertical loads when those loads are transferred through the post alone. Therefore, the post is set on some type of a footing, which in the case of post-frame construction is usually concrete.

Footings must be adequate in area (radius squared x pi) to prevent the building from settling under not only the weight of the structure itself, but also the load from snow or minimum live load requirements. They must also be thick enough, to prevent the column from punching through the footing.

Considering even a fairly small span building, with minimum loads requires a footing diameter of 18 inches or more, it is fairly impractical to think of a material other than concrete which could be placed affordably beneath the columns.

On to the “rot” issue. Chapter 23 of the IBC (International Building Code) requires wood in contact with concrete to be either “naturally durable” or pressure-preservative treated. This, in itself, tends to take away credence from the “concrete rots treated wood” faction.

I know every major post frame building company in America. I have yet to have any of them report of having a single “properly treated post” rot off.

The clincher in this is “properly treated post”.

When the first IBC was published in 2000, Section 1805.7.1.2 stated, “Wood poles shall be treated in accordance with AWPA C2 or C4. This language remained the same in the 2003 IBC. The AWPA C2 and C4 standards have been withdrawn, therefore are no longer applicable or referenced standards in later editions of the Code.

In the 2006 IBC, however, things changed. Section 1807.7.1 states, “Wood poles shall be treated in accordance with AWPA U1 for sawn timber posts (Commodity Specification A, Use Category 4B)”. In the 2009 IBC (and repeated for the 2012 edition), the language remained the same, however the referenced section of the Code is now 1807.3.

What this means to you or the average consumer who is shopping for a new pole barn? Everything!

Take a visit to the local lumberyard or big box lumber store. Take a walk through the pressure treated lumber department. Every piece of pressure preservative treated lumber has a tag on it. This tag identified who the pressure treater was, as well as the level of pressure treating. Sadly, most of the pressure treated posts will be treated only to UC-4A…which does NOT meet with the Code requirements for use in pole buildings!

What this means is there are a plethora of buildings which have under treated columns, which is responsible for the rot issues, not the proximity to concrete.

Every time I have someone try to foist the “concrete rots treated wood” story on me, I ask them to show me a single laboratory test, which proves their point. None exist.

The best solution – and my recommendation – use a properly treated post, backfilled with pre-mix concrete in a monolithic pour. Place a minimum of six (and better eight) inches of concrete below the column and eight or more inches up the post (this is known as a bottom collar).

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