Tag Archives: columns rotting

Dear Pole Barn Guru: Will Treated Wood Rot?

New!  The Pole Barn Guru’s mailbox is overflowing with questions.  Due to high demand, he is answering questions on Saturdays as well as Mondays.

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: I have a pole building reroofed with 1′ overhangs and am wondering if you think I should/need to use closures or something at the eave to seal the ribs. Thanks FREAKING IN FOSTORIA

DEAR FREAKING: I’d recommend the use of form fitted inside closures on top of the eave girt, if you have enclosed overhangs, or on top of the eave girt with open soffits. There should also be form fitted outside closures on top of the roof steel underneath the ridge cap.

This combination will help to keep those nasty little flying critters from joining you inside of your building.

DEAR POLE BARN GURU: water drainage. BUDDY IN HOLLEY

 DEAR BUDDY: Not entirely sure how to best assist you from the two word question.

Assuming your new pole building is not going to be used as a home (in which case I would make entirely different recommendations using a raised wood floor), I’d approach this as for any pole building drainage solution. I would order columns long enough to get the required depth to extend below the frost line, plus make up for any grade change. After the columns were set, I’d bring in good compactable fill to get the elevation of the bottom of any future concrete slab above the highest point of the surrounding grade. Above the high side of the building, a French drain can be installed to divert any natural drainage.

For those who are unfamiliar with French drains, it is when a trench is dug beyond the building perimeter, drain rock is placed in the bottom, then one or more rows of perforated four inch pipe are laid. After placing the pipe, the balance of the trench is filled with drain rock. I hope this helps – if not…please email me more information.

DEAR POLE BARN GURU: My concern with ground contact treated wood is not environmental, it is by experience. Apparently, “treated” can be ambiguous as to what chemical, degree of saturation and retention level the wood has. I had the base of a support structure, in ground contact lumber, show some rot after about 12 years. The structure was on poorly drained soil and that may have been a contributing factor.

I was reading some ag forum topics on pole framed buildings with treated lumber bases and more than one contributor claimed failure at around 20 years, necessitating a restructuring of the foundation. That got me thinking about the concrete footing pillar but perhaps I am being a bit paranoid. MINDFUL IN MICHIGAN

DEAR MINDFUL: Sadly the treated wood, lumberyard and even the pole building industry have not done a very good job ensuring the end users of pressure preservative treated wood get the products which would do the job.

Most “ground contact” treated lumber is really not meant for any type of critical use applications.

I can say I have met or know every major pole barn builder and supplier in the United States, and I have yet to have had a report of any properly pressure preservative treated column ever rotting off. The key is “properly pressure treated”.

Here is an article I wrote earlier which will provide more in depth information:

https://www.hansenpolebuildings.com/blog/2012/10/pressure-treated-posts-2/

Pressure Treated Posts: When Future Building Owners Think They are Engineers

When I was just a little tyke, my Mother used to watch Art Linkletter’s “House Party”. A highlight of his show was the segment, “Kids Say the Darndest Things”.

I have my own version, “Potential Building Owners Say the Darndest Things”.

Our Building Designer Lauri seems to be a magnet for these lately. Here she shares another one….

“Speaking of the poles. I don’t want to sound like a picky little prig or an officious jerk but I do have a requirement about the bottoms of the poles. I don’t know what your standards are for the poles, but I do not want the bottom of the poles sitting in a concrete cup.

When the holes are dug for the poles I would like them to be dug about a foot deeper than needed. Then the bottom of the hole can be filled with at least 6 inches of cracked limestone or 2B river wash stone.

The poles are then set on the stone and an additional 3 or 4 inches of stone are added to the holes. Then set your cardboard casing and fill it with concrete. This method allows for moisture to drain out of the bottom of the pole thus reducing wood rot. If the poles are set deep enough I think you can get away with out using concrete, that is your call, but if you do use concrete the bottoms of the poles have to be able to drain. That is carved in stone.”

Ah, where to even begin?

Let’s talk about pressure treated posts. Rotting fungi need water to work. Other conditions necessary for wood rot to develop include a supply of oxygen and temperatures between 32 and 90 degrees Fahrenheit. (Decay stops below 35 degrees and above 100 degrees.) Wood becomes susceptible to rot if its moisture content exceeds 25 to 30 percent. Keep wood dry, it will literally last for centuries. On the other extreme, if the wood is 100 percent saturated with water, the decay fungi won’t get the oxygen they need. Decay won’t occur, and the wood can last for centuries.

Nowadays building columns are pressure preservative treated for structural in ground use. They are designed to last lifetimes, under the most adverse conditions. If the soil at the site drains well, there is no reason to place rock or gravel beneath or under a column to “drain water away”. If the soil at the site does retain water, any gravel in or around the base actually becomes a collection basin for water, rather than allowing water to drain “off”.  In a quick summary, this customer came up with a poor investment in rock and the labor to dig deeper holes. Plus, this person added chance of the building settling due to inadequate compaction of the stone.

Other previous blogs have covered topics such as the lifespan of pressure treated posts, the need for concrete column backfill to resist settlement, uplift and over turning, as well as why not to use “cardboard casing” (better known as sonotubes).

While I appreciate customers who are concerned about the longevity of their buildings, it is best to leave the structural design of buildings to the experts – registered design professionals (RDP’s).  A RDP (or P.E., i.e. Professional Engineer) has not only the complete educational preparation, but also the decades of experience needed to combine proper structural design and efficiency of materials.