Tag Archives: pressure treated lumber

More Thoughts on Polyurethane Foam

More Thoughts on High Density Polyurethane Foam for Column Backfill

Reader STEPHEN contributes a question regarding high density polyurethane foam for column backfill:

“Hello, I have this question I would like to pass along to the “pole barn Guru” to be answered, I doubt I will get the answer I need in the time frame, but I think its going to come up more often, so  I am guessing now is a good time to ask.

With the idea of burying a 6x6x14 into concrete, the risk of Rot is very high. At a cost of about 50$ per post,  you want to protect your investment,  so many people are using a 6x6x10 and using the Study-wall brackets, but that drives up the cost to about 80$

So my question is, has anyone looked into using the new polyurethane instead of concrete?


Stephen ~

Hopefully this response will prove to be timely in regards to your project.

Mike the Pole Barn Guru responds:

Let us begin with a discussing to overcome a fear of a “risk of rot is very high”. Actual field studies have proven an ability of properly pressure treated lumber to withstand decaying forces for greater than human lifespans: https://www.hansenpolebuildings.com/2017/12/will-poles-rot-off/. Trick, of course, is finding properly pressure preservative treated timbers. Five years ago I penned this article for a post frame industry magazine: https://www.hansenpolebuildings.com/2014/05/building-code-3/. Little has changed since then – lumber dealers and big box stores continue to sell pressure treated timbers without advising consumers as to what those timbers can actually be used for.

Now let’s discuss using high density polyurethane foam for setting columns, rather than concrete. At this year’s National Frame Building Association Expo there were several vendors promoting using their high density foam for setting posts – all of them having experience only from setting of utility poles. Utility poles carry a minimal downward load, so their holes are barely larger than column diameters, making calling for a pre-mix concrete truck impractical. Lateral loads on utility poles are also minimal as compared to columns in a post frame building, so a little high density foam easily provides a solution (and sets up quickly – allowing crews to move expediently from pole to pole).

Here is some more reading on this subject: https://www.hansenpolebuildings.com/2014/02/high-density-foam/.

Besides not being Code conforming, there is an issue of cost. Your suggested product provided at The Home Depot will provide a volume equal to five 80 pound bags of concrete (or 1/10th of a yard) for $37.63 or $376.30 per yard. With pre-mix concrete prices being roughly $100 a yard, concrete being Code conforming and not contributing to decay any more than would high density foam, it seems to me to be a no brainer.

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.

TimberSIL® – A Great Idea?

Great Ideas May Not Always Bring Great Results

Much ado has been made about alternatives to CCA (Chromated Copper Arsenate) pressure preservative treated lumber. CCA has been used to pressure treat lumber since the 1940s. Since the 1970s, the majority of the wood used in outdoor residential settings (as well as pole buildings) has been CCA-treated wood. Effective December 31, 2003, no wood treater or manufacturer may treat wood with CCA for residential uses, with certain exceptions.

Treated Wood StampThis resulted in a plethora of alternative pressure preservative treatment chemicals being introduced which, on the surface, sound like a veritable alphabet soup – ACQ, CA-B, CA-C, MCA, etc.

Although not used for preservation of timbers for structural in ground use, there have been some interesting alternatives, not all of which have necessarily worked in all cases.

Brad Pitt’s Make It Right Foundation has built 100 energy-efficient and eco-friendly houses in New Orleans to replace homes damaged by Hurricane Katrina. Unfortunately, the organization believes that some of the wood it used is now rotting, reports The New Orleans Advocate.

The organization used TimberSIL®, an innovative glass-infused wood product produced by a South Carolina manufacturer, to build porches and outside steps. The absence of chromated copper arsenate and other chemicals typically used to prevent rot and decay was a selling point for Make It Right.

“Instead of treating the wood with toxic chemicals, it’s actually infused with sand, or silica, such that it takes on the properties of treated lumber,” Tom Darden, the executive director of Make It Right, said in a 2010 interview. “At the end of its life cycle, which is estimated to be about 300 years, it can be mulched and composted, believe it or not.”

Unfortunately, Make It Right has found TimberSIL® can’t stand the moisture in the balmy city and has turned dark gray and begun falling apart. The organization has replaced wood in 30 homes and is considering legal action. TimberSIL® has reportedly caused trouble for at least one other client: a project in Western Massachusetts which had to be repaired when the builders found the wood retained too much moisture and couldn’t hold paint.

With more and more pole buildings being used for residential purposes, with alternative sidings to the traditional steel, as well as attached decks, it would behoove some serious research and consideration (in this author’s humble opinion) before utilization of this particular product

Pole Building in Hawaii Using Pressure Treated Wood

LeiOver the past few decades, I’ve been involved in several pole building projects on the Hawaiian Islands, and they all had one thing in common – the use of pressure preservative treated lumber throughout, included the prefabricated wood roof trusses. The use of pressure treated wood has been standard building practice in Hawaii and the building codes require all structural wood framing to be constructed with it.

Just as much as we enjoy ants at a picnic, wood-destroying organisms such as termites and decay fungi are necessary in creating elements which are essential to the balance of the global ecosystem. While termites are needed out in the ecosystem, they are totally unwanted and unwelcome in wood structures.

For overall cost effectiveness and building performance, the majority of North American (and Hawaiian) low rise buildings are built with wood frames, which need protection from termite and decay damage. For design professionals and builders, termites and fungi can present some issues in building with wood. As a solution, pressure treated wood products provide long lasting protection against wood destroying organisms which could wreak havoc on island pole buildings.

In Hawaii’s particularly tough environment, pressure treated wood has performed admirably in field tests and structures built with it have a commendable record in real world use. Treated structural lumber, used correctly, in construction of pole buildings is extremely effective in providing a product which is long lasting and safe from Formosan or other termite damage.

One consideration and frequent question is: can prefabricated wood roof trusses be constructed from pressure treated lumber? In a word – yes. Using most pressure treated wood does not sacrifice truss quality or reliability in any way. Loading conditions are not impacted, so the installation process remains the same. Some methods of pressure treating wood are very corrosive to the steel truss plates and require the use of stainless steel, rather than the industry standard galvanized plate. Also, some lumber species require the wood to be incised, in order to take an adequate level of pressure treatment, so appropriate strength reductions are taken into account in the design process.

With a lifelong efficacy, pressure treated wood offers a built-in protection against Formosan termites and other wood-destroying organisms and provides durable and sustainable post frame buildings for all Hawaiian residents.

Galvanized Nails

I read lots of different forums. A poster on one of the board recently wrote:

I have a quick question concerning nails. I just had a builder build me a pole barn and was wondering about the nails. They used galvanized nails for the skirt board on the bottom but then on the 2×4 strapping they used common nails. Is this acceptable? Or won’t the pressure treat corrode the nails that were shot into the 2×4 strapping?”

My answer was pretty simple:

Per IBC (International Building Code) Section 2304.9.5 fasteners in preservative-treated and fire-retardant-treated wood shall be of hot dipped zinc-coated galvanized steel, stainless steel, silicon bronze or copper. The coating weights for zinc-coated fasteners shall be in accordance with ASTM (American Society for Testing and Materials) A 153.

Even electroplated galvanized nails, which were the predominant fasteners used with CCA (Chromated Copper Arsenate) pressure treated lumber, are not acceptable for use with ACQ (Alkaline Copper Quaternary) and CBA (Copper Boron Azole) pressure treated lumber. The zinc content in the coating of these nails is insufficient for long-term resistance to the corrosive action by the chemistry of some of the new treatments.

The 2×4 “strapping” referenced are 2×4 “barn style” wall girts, which attach to the wall columns and support the siding.

In the event the builder was selling his services as providing a “building code compliant” building or the building required a building permit – the building owner would most certainly have a cause of action against the builder. To my humble opinion – it at least would involve a massive rework on the part of the builder, as all of the siding would need to be removed, in order to fix the problem.

If a building permit was required, shame on the Building Inspector for letting such an obvious violation of the code occur.

Outside of the potential for chemical reaction issues with pressure treated lumber, I’ve always advocated for the use of galvanized nails for all pole building connections. If “brite” nails are used, and the nails are rained on, unsightly rust streaks form on exposed framing members.

For the few dollars the builder above has put in his own pocket, he has risked a possible catastrophic building failure….and if the building were to fail and someone was injured or worse, the builder could easily be criminally liable!