Tag Archives: pressure treated wood

Post Brackets, Cross Bracing, and Pressure Treated Wood

This week the Pole Barn Guru tackles reader questions about a building set into a slope with use of post brackets, the possible use of “cross bracing” for wall girts, and understanding pressure treated wood.

DEAR POLE BARN GURU: I would like to build a 32′ x 48′ 2 story pole building where two of the sides of at least the lower floor are at least partially set into the hillside on the property. I envision the two sides set into the hill to be concrete foundation walls. Sort of a daylight basement. The lower floor would be a woodshop and the upper floor a two bedroom apartment. I am assuming a concrete foundation with Laminated “poles” mounted in brackets as opposed to buried. the “poles” on the two sides set into the hill would be shorter than on the other two sides. With the available space, the two story concept works better than having everything on a single story. Is this even possible? What would a ROM cost for a kit like that cost?


DEAR BILL: Your idea is totally possible. I have done it myself. In my case I had 12 feet of grade change across my building’s 40 foot width. I used ICFs full height on one sidewall and stepping down across rear endwall. Columns on these two walls were mounted using wet set brackets, other two walls had embedded columns. This process could also be used with poured concrete or block walls. We have also developed a system to use columns placed in a permanent wood foundation.

Attached photo is of my own building.

This is being shared with your Hansen Pole Buildings’ Designer who will be reaching out to you shortly.


DEAR POLE BARN GURU: When using bookshelf girts is cross bracing used between posts or are the girts when blocked provide the support? WINSTON in MOULTON

DEAR WINSTON: No cross bracing is required when using bookshelf girts. Once installed (ideally blocked solid to columns at each end) and sheathing (OSB, plywood, structural panels or steel siding) is applied, your wall and girts are more than adequately supported and this assembly is fairly rigid.


DEAR POLE BARN GURU: I read the article regarding treated wood. I am still a little puzzled as to what treating you would use for ground contact purposes, especially the upright poles. Do you have any other articles regarding this subject or have input you could email me? Much appreciated, thank you. KELLY in VICTOR

DEAR KELLY: Pressure preservative treated wood standards can be confusing even for lumber dealers, professional builders and building inspectors. For structural building columns, all end tags should have UC-4B marked on them. UC-4B is for “Heavy Duty” use. This American Wood Preservers Association infographic might prove helpful to understanding proper uses for pressure preservative treated wood: www.awpa.com/images/standards/ResidentialInfographic2020.pdf




Brick Ledge on a Pole Building

Brick Ledge on a Post Frame (Pole) Building

Whilst it would not be my personal preference for finish on a post frame building, there are instances when either aesthetics (trying to match other existing structures), local Planning Departments or HOAs (Home Owner Associations) mandate use of brick or stone exteriors. Whether for a wainscot or covering an entire wall (or walls) if full thickness stone or brick becomes a solution, it must be adequately structurally supported by a footing.

I truly had not given this subject much thought, until reader JASON in COLLEGE STATION wrote:

“Hello, thanks in advance for sharing some of your knowledge and experience with pole barns.

I have been looking at the construction details on your website and have a question about the bottom “skirt board”. Could this detail be designed so that the board does not show below the metal but the metal terminates on a concrete slab that extends a little? I am guessing this is how someone would do it if they needed a brick ledge. If so what is the best way to achieve this?

Thanks again for your advice.”

Jason’s question actually read like a multiple dilemma.

First, a question is hiding a building exterior pressure preservative treated skirt board (aka splash plank). Simple answer is yes, building is already designed so this can be done. Skirt board should be placed per engineer sealed building plans, showing drip edged base trim bottom four inches above grade. This allows for a nominal four inch thick (finished thickness 3-1/2”) sidewalk, driveway, landing or other concreted areas to be poured against exterior of splash plank, coming in ½ inch below bottom of drip edge. Any such pours should be along a grade sloping sufficiently away from building a minimum slope of 2%, to keep water from pooling against building.

For a nominal fee a RDP (Registered Design Professional – engineer or architect) can design an appropriate and structurally adequate support, varying in design due to individual building sites’ frost depths. Using a frost-protected shallow foundation in frost prone regions (read more here: https://www.hansenpolebuildings.com/2017/09/post-frame-frost-walls/), could possibly be part of a design solution, with some sort grade beam, whether it be poured reinforced concrete or properly pressure treated wood. Either will need to be engineered appropriately based upon material weight and strength of  soil to give continuous support.

I’d personally consider either thin brick, or a cultured stone veneer. Ultimately it will probably be least expensive design solution providing and meeting needed objectives. Framing, including columns and their embedment, will need to be engineered to support added dead loads from thin brick (depending upon pattern and thickness thin brick can weigh nearly seven pounds per square foot). Structural members need to be engineered to have limited deflection. Bookshelf girts might well be part of an engineered design solution: https://www.hansenpolebuildings.com/2011/09/commercial-girts-what-are-they/.




Reader MIKE in ORLANDO writes:

“Dear Pole Barn Guru,

I bought a 38×42 Pole Barn kit from a reputable supplier. The posts are 8″ x 8″ – but do not have the AWPA markings that you describe in your Blog. These posts have a tag stapled to the end that says “SPLASHWOOD, Saltwater Splash Use Only, .80 PCF, Chromated Copper Arsenate (CCA-C), Southern Wood Preserving, Inc,.” and a paragraph of cautions and Consumer Information. I tried to look up this info to see if these posts are AWPA UC4B equivalent but could not find any info on-line.
Are these post acceptable for my Pole Barn construction?

Mike the Pole Barn Guru writes:

Splashwood™ happens to be a registered trademark and brand of Great Southern Wood Preserving, Inc., and was filed December 30, 2004. Great Southern Wood Preserving, Inc., is based in Abbeville, Alabama and was founded in 1970. It has 15 plants located in Alabama, Arkansas, Florida, Georgia, Mississippi, Missouri, Louisiana, Maryland, Virginia, Pennsylvania and Texas with annual revenue of a billion U.S. Dollars.

Pressure-treated wood is treated to various retention levels which are intended to protect the wood for particular applications. Retention levels indicate the amount of preservative retained in the wood in a specific assay zone. In North America, retention is expressed in pounds per cubic foot (pcf).

Retention levels or treating quality procedures are marked on pressure treated wood. The AWPA (American Wood-Preservers’ Association) outlines retention levels required for various applications.

Retention varies with depth in the wood, so preservative penetration also affects wood longevity. In species with large amounts of sapwood, such as southern and red pine, the preservative must penetrate 2.5 inches or 85% of the sapwood to meet standards.  In western species which are predominately heartwood, the wood is incised to ensure a treated shell, and any cut surfaces should be field-treated with a preservative containing at least 2% copper (read more about cut ends of treated lumber here: https://www.hansenpolebuildings.com/2014/09/pressure-treated-lumber-2/).

To meet the Code required standard of UC-4B for structural timbers, takes a retention of 0.60 pcf with CCA. The pressure treatment of your columns exceeds the minimum requirements.


Isolating Pole Barn Poles from Concrete Slabs

Isolating Pole Barn Poles From Concrete Slabs

The fear factor – comes up again and again in construction. Today’s fear is a concrete slab being poured against the poles (columns) of an existing pole barn will cause the columns to decay.

“We have a 25 year old pole barn with 12 main 8×8 poles sunk 8 feet into the ground.

We’d like to pour a concrete slab under the entire building (as it is dirt now).

I was just going to pour the concrete right up to, and around, the poles, but some folks have me thinking that the concrete directly on the wood will create a lot of condensation and moisture and eventually rot/weaken the poles right at the floor.

I hear of people using styrofoam or expansion joint felt as a wrapping for their poles, but all of those discussions relate to avoiding cracks in the concrete from pole movement. My concern is for the poles themselves.

What is an appropriate barrier material to clad the bare poles in, and then pour concrete right up to, that will prevent moisture from collecting on the poles themselves?

Yes, we will be doing a vapor barrier under the concrete – but there will be 12 8×8 holes punched into that vapor barrier which could allow moisture up right into the part of the concrete pad that we don’t want it – the part touching the poles…

All comments and suggestions appreciated.”

Mike the Pole Barn Guru responds:

Properly pressure preservative treated wooden timbers are not only designed to be buried in the ground (with the proper level of pressure treatment being UC-4B), but also are required by Code in cases where wood is in contact with concrete.

So, how is it concrete would cause condensation against the pressure treated wood? Concrete retains a significant amount of interstitial moisture for many years.  This moisture routinely moves in and out of a vapor phase, depending on the temperature and relative humidity.  Placing anything which is reasonably “barrier like” to moisture (which wood is for the short term) can cause moisture to collect under the material in a liquid phase.  This is one reason the wood needs to be pressure treated.

Another reason for the wood to be pressure treated  is concrete is aggressively alkaline.  In the absence of pressure treating (usually acidic), the wood will dry out and its cell structure will be damaged from the exposure to the drying/alkaline condition.  

The reality is there is really no reason to isolate the pressure treated columns from the concrete slab.

Other than fear (False Expectations About Reality).

For more reading on longevity of pressure preservative treated lumber, please read: https://www.hansenpolebuildings.com/2017/12/will-poles-rot-off/.


Perma Column vs. Pressure Treated

Hansen Pole Buildings’ Designer Rick has been working with a client who has a nose for knowledge – and I thank both of them for sharing information with me, so I can pay it forward. This particular client is weighing the use of Perma Columns against the more traditional design solution for post frame (pole building) foundations – where a pressure preservative treated wood column is embedded into the ground.

As the good folks at Perma Column state on their website:

“Perma-Columns are five foot precast concrete columns that keep wood out of the ground, ensuring your building’s foundation will never rot. They are the first product to combine the economy of post frame construction with the durability of a concrete foundation. Simple installation. No waiting on concrete trucks. No treated wood in the ground.”

Our good client has done his research and found the following article, “Long-Term Durability of Pressure-Treated Wood in a Severe Test Site”, which was published in Advances in Civil Engineering Materials in 2013.

For those who are interested in numerous pages of reading, the article can be found here: https://www.fpl.fs.fed.us/documnts/pdf2013/fpl_2013_lebow001.pdf

Rather like a so-so book I have read a portion of it and then skipped to the ending, the authors of the article conclude:

treated post“Long-term post and lumber durability tests provide insight into the expected durability of wood products that have been treated to AWPA standards and properly handled during construction. This review of the durability data from a test site in southern Mississippi indicates that the expected durability of creosote-treated wood is in excess of 50 years, and that of wood treated with pentachlorophenol, ACZA, or CCA exceeds 60 years. No failures have occurred in lumber specimens treated to intermediate or high retentions of pentachlorophenol, ACZA, or CCA formulations. The expected durability of specimens treated with copper naphthenate was more difficult to interpret because of conflicting results between tests with lumber and post specimens. However, the post specimens indicated durability in excess of 60 years, even at retentions substantially below those currently used commercially. Some caution is needed in extrapolating the durability observed in these test specimens to in-service structures, as the specimens are not subjected to the same mechanical loads or potential damage during construction. Conversely, comparison of the results from this site to reports from other locations suggests that these results might underestimate potential durability in more northern climates.”

In lay terms – the probability of any of us who are living adults today seeing a non-abused, properly pressure preservative treated wood column ever rot off, is not impossible, but highly unlikely.

Dear Guru? Use Galvanized Nails or Not?

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 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 was at the hardware store at lunch, buying galvanized nails, was told that the galvanized nails cause the pressure treated wood to degrade and the nails to pull out??????   Is that right? I also visited my local Menard’s and was given the same answer from them. PERPLEXED

DEAR PERPLEXED: One of the REQUIRED choices for nails into pressure preservative treated wood, under the Building Codes, are hot dipped (HD) galvanized nails. If a nail (galvanized or not) is through siding or roofing into untreated lumber, and not properly driven, water may seep in around the nail, causing wood degradation. I’ve researched every source I know, and have been unable to find any documentation which backs up what appears to be merely a rural myth.

DEAR POLE BARN GURU: What do you recommend as far as ice or snow guards for a metal roof? We had a couple of big snow storms last winter and the snow and ice from one slid down and ripped the gutters off one side of the roof. Don’t want to have to replace them again.

4/12 pitch in the Kansas City area. SLIPPERY SLOPE

DEAR SLIPPERY: After researching I found your particular building is designed with the roof truss load adjusted for the roofing being a slick surface (so the snow slides off). This is very typically for steel roofs. Any snow or ice guards, which prevent snow from sliding off of your roof, could end up overloading the trusses. You might consider one of several available methods of melting the snow at the edges of your roof.  Read about them here: https://www.hansenpolebuildings.com/blog/2013/04/hotedge/

Southern Yellow Pine

I do a lot of research on most everything I blog about.  I want you to have the most solid and recent information, along with my advice as to how to put it to best use.  I found this recently at www.spib.org: “The Family owned and publicly traded companies that choose to use the SPIB logo on their Products represent the best of the lumber producers. They have made a clear choice to provide their customers with a range of products with an emphasis on quality. Their products are produced from an abundant, renewable resource that requires a minimum of energy to produce, is sustainable, and is locally available. Customers choose their products because they understand value.”

From one of the largest pressure treated wood companies in the U.S., “Industry experts say Southern Yellow Pine’s density makes it the strongest softwood structural lumber species.” Changes may be a coming as earlier this year the Southern Pine Inspection Bureau (SPIB) sent shock waves through the construction industry when it revealed it had submitted new, substantially lower design values for visually graded southern pine dimension lumber to the American Lumber Standard Committee (ALSC) for review.

This lead to a salvo being fired by the two major roll former manufacturer associations in the United States, the Steel Framing Industry Association and the Steel Stud Manufacturers Association. Both of whom have both rolled out code compliance programs in the past year designed to improve confidence in cold-formed steel products.

According to them, “while the lumber industry appears to have become more lax in its monitoring and testing procedures, the steel framing industry has gone to lengths to certify and validate the design values of its products, and to affirm that they comply with International Building Code requirements.

The southern pine situation illustrates what many builders and designers already know: Cold-formed steel framing is not just more stable, durable, strong and uniform than wood framing—it also provides those who use it with an unimpeachable sense of security that they are getting exactly what they pay for.”

The lumber industry conducts strength testing to insure the product being produced, meets the design specifications published for use by architects and engineers. SPIB, along with Timber Products Inspection, found significant reductions in the stiffness, bending and tension strength of visually graded southern pine samples. Much of this is due to quickly grown plantation (or farmed) trees.

The recently tested wood exhibited a departure from the design values last published in 1991. The SPIB has proposed potential reductions in four of the six basic lumber properties—ranging from 20 percent less for tension, to 30 percent less for bending, to 35 percent less for compression. SPIB also proposed a 200,000 psi reduction in the modulus of elasticity for southern pine.

While the cold formed steel industry is quick to throw stones at southern yellow pine lumber, the revision in design values does not affect machine stress rated or machine evaluated southern yellow pine – which is heavily used in the prefabricated wood truss, glu-lam and I joist industries. Nor does the proposal change the design values for any of the other popular North American lumber species, such as Douglas Fir, Hem-Fir or Spruce-Pine-Fir.

Even if cold roll formed steel pole building wall girts and roof purlins were to become less expensive than wood, they are nowhere near as user friendly as lumber. Cut a 2×6 wrong, every lumberyard has a replacement. Cut a steel girt or purlin wrong and scrap metal has been created.

So, my wife who is my best critic of my blogs said to me, “this is great honey, can you translate this for me?”  Sure.  If you live in a part of the country where Southern Yellow Pine is the predominant lumber species, it no longer will be the strongest lumber to build from.  SYP will become cheaper, but it won’t carry the loads.  Many folks are stuck on a certain species of lumber as “the best”.  My caution is, keep an open mind.  You need to look for what is going to “do the trick”, meaning – what will carry the loads for your building needed to provide a safe and strong structure to carry you through many years?  There are many suitable replacements.  You just have to be “open” to them.

How Untreated Wood Decays – Pressure Treated Wood Prevents Decay

I get asked nearly every day about the lifespan of pressure treated wood. Prior to expounding upon the virtues of pressure treatments, it would be helpful to know more about why untreated wood decays. With this information in hand we can see how current chemical treatment methods prevent wood decay.

The following is excerpted from a paper found at www.slideruleera.com

weathered pole barn

Weathered Pole Barn

“All decay of wood is caused by fungi, low forms of plant life that develop and grow from spores just as higher plants do from seed. These microscopic spores abound everywhere in open air. Lodging in favorable places on untreated timber with which they come in contact, they germinate, sending out hyphae, or strands, that spread through the wood. These plant-like growths break down the wood substance, converting it into food required by fungi for development. However, like all forms of plant life, the spores of wood-destroying fungi must have air, suitable moisture and favorable temperature as well as food if they are to develop and grow. Deprived of any one of these four essentials, the spores cannot develop and the wood remains sound, retaining its full strength for many years of useful, low-cost service.

Wood submerged in fresh water cannot decay, because the necessary air is excluded; decay also will not progress in wood with moisture content less than 20 percent of its weight. Advancement of decay is progressively checked as temperatures drop below those generally favorable for plant growth, and all fungus activity stops as freezing temperatures are approached. Progress will resume, however, once favorable climatic conditions are restored. Because it is impractical to exclude air and moisture from, or to control temperatures in, most outdoor or exposed structures, effective preservation is attained by impregnating the wood with chemicals which are poisonous to fungi, insects and marine borers.

Spores of fungi may lie dormant in the crevices of untreated wood for years while conditions for development remain unfavorable, only to spring to life and begin their destructive activities whenever favorable growth conditions are restored.”

In a later blog, I will discuss the treatments for wood to preserve the longevity of posts and other lumber in contact with the ground.  There is an interesting story of the evolution of what “works” and what is “approved”, so stay tuned.