High Density Foam for Setting Posts

Pole Barn Guru Blog

This is just wrong – in so many ways….

As my loyal readers know, I try to read every posting I can on the ‘net regarding pole buildings. Sadly, more than a few of them are downright scary.

These are excerpts from a recent chat room posting:

“I built this barn last year. I did 80% + of the construction working alone not including the shingles, rock veneer and the vinyl siding. From experience (building a larger barn alone in 2001) I knew how much work there was in encasing the 6×6 posts in concrete. When I built the larger barn I mixed all of the concrete in a tractor mounted 3 point pto mixer. I mean from gravel, sand and cement. The benefit of doing it this way was I could back the tractor up to the hole and dump the concrete directly down the hole.

This time, while I was looking for admixtures online to add to possibly help eliminate future water problems rotting the post I happened onto a 2 part high density foam. To make a long story short I ended up setting all of the posts in this high density foam in lieu of concrete.

The advantage for me is I could set a post by myself using a very simple system of temporary braces to hold the posts for 15 minutes until the foam set up. I used 4 braces per post. The temporary braces were merely 2×2 lengths (8 feet long) of wood with cheap broom hangers screwed into each end and merely set in place by one hand when the post is plum.

When I say high density foam, I mean a foam that takes a claw hammer to penetrate after it sets up. You can’t dig it out with your hand.

The disadvantage is the cost of the foam is higher than concrete. I think I spent about $500 more doing it this way than concrete. It was worth it to me. I justified spending more money because I’m already savings thousands of dollars in labor costs plus I don’t have to work with the heavy concrete.

I not only liked the ease of one man setting all of the posts, but that it really helps eliminate post rotting problems for many years. The foam is really sticky and encapsulates the wood thus waterproofing it. Utility companies use the foam to set poles so I say it’s pretty good stuff.”

In my humble opinion, there are people who will go through a lot of effort, and spend more money, to get an inferior result. There is a reason registered design professionals (RDPs – architects and engineers) exist – and it isn’t just to have someone to spend money on. Same with the Building Code – it keeps people from doing otherwise stupid stuff, or even worse injuring (or killing) themselves or others.

On a sidebar – this particular DIYer was somewhere he did not have to get a Building Permit, so there was no plan checker or inspector involved to save him from himself.

Now, let’s examine some of the highlights….

Mixing concrete from scratch in a mixer would be time consuming as well as costly in the efforts to acquire and have delivered relatively small quantities of aggregate (rock), sand and cement.

Pole Barn FootingPersonally, I would stand and brace all of the columns, call the redi-mix company and pour all of the holes at one time. Rather than spending 15 minutes per hole waiting on foam to set up, even a good sized building can be poured in an hour or less.

The writer admits to the foam being more costly by about $500. There is no way this offsets any amount of labor costs.

Water is not going to cause decay in a properly pressure preservative treated column. Read more about pressure treating requirements at: https://www.hansenpolebuildings.com/blog/2012/10/pressure-treated-posts-2/

Utilities use this high density foam to set poles. Utility poles do not support the downward weight of a building, nor are the subjected to having to withstand wind loads of 85 mph (miles per hour) or more, often pushing against hundreds of square feet of building wall and roof surface.

Depending upon the manufacturer and the product, these high density foams might require a claw hammer to penetrate after setting up, however the compressive strength is only about 4% of what concrete would supply. And this is why the Building Codes do not specify high density foam as an alternative to concrete, as either a footing beneath a column, or to backfill the space between the column and the surrounding undisturbed native soils.

This is not to say alternative products cannot or should not be used in construction.  I am the first one to promote new and innovative uses and materials.  However the validity of the application needs to be somehow proven as a viable alternative.

Here’s to hoping the writer’s new pole barn never has to try to withstand high wind or snow loads.

14 thoughts on “High Density Foam for Setting Posts

  1. *cringe*
    “Utility companies use the foam to set poles so I say it’s pretty good stuff.” True, but the manufacturer only lists utility poles and outdoor lighting as appropriate uses for this product. Might the structural forces be different for a pole barn than a utility pole? (My forehead hurts from head-slaps.) Perhaps the company should include a disclaimer, i.e. “WARNING: Do not hold the wrong end of a chainsaw.” (yes… I have actually seen that label). Quick! Get me a lawyer!

    Reply
    1. Bob ~

      This is like comparing fruit and vegetables (they both grow in a garden is their commonality)…..with a utility pole, the only area subjected to wind loads is the pole itself. With a building, it is the distance 1/2 way to the next column, in each direction, for both the wall and the roof.

      Reply
  2. Everett Plummer

    Pouring a ring of cement at the very bottom where the poles sit and backfilling the rest of the way up has proved to withstand the most wind and gust loads. Flexibility is more critical to high gust like when the old oak snaps while the young trees bend and flex back. I would not use in on pole buildings. I would use it on posts or fences where there is a 15 minute setup and way less work I am lazy. To spend more for products that save time and backs plus it’s suppose to be stronger and less likely to fail.

    Reply
    1. admin Post author

      The standard Hansen Pole Buildings’ Post Frame embedment design is for a concrete bottom collar, just as you suggest.

      Reply
  3. Let’s let this guy be test case 1 for a new method of construction. Unless there are thousands of installations of this method we will really never know if it works or not. All the laboratory testing in the world does not mean much.. Real world use is what counts. If you look at the foam you can see that it is approximately 4X stronger in shear and compressive strength than native soil. So what if concrete is that strong…it’s the soil that the building rests against. They use foam to lift roads and houses after the concrete has sagged. Before you go slapping your forehead you need to do some research. Just because some dumbass pencil pusher at the IRC doesn’t think foam will work in structural situations doesn’t mean it won’t. Do some testing, make some buildings, and stop blogging about something you know little of. Real engineers, like myself, are annoyed by bloggers and rightfully so. Where is science in this online world of crap? Where is math? Where is testing?

    Reply
    1. Us annoying bloggers, right? Slap us all silly.

      Well, in the case of this annoying blogger you might want to do some research on me before condemning me to the world of the unknowing. I’ve been personally involved in the design and/or construction of somewhere around 20,000 post frame buildings in my career. I joined ASAE (forerunner of ASABE) and ICBO (forerunner of ICC) in 1987 and sat on the ASAE Structures committee which researched and wrote much of the language which is now utilized to design post frame buildings. I’ve also been involved in actual testing of products such as laminated columns and the shear strength of steel panels.

      Moving forward – laboratory testing means a lot, and in the case of systems involving wood, we only get to utilize a design value of 40% of Pult – so there is plenty of safety cushion built in. Testing gives us a basis for safe design. Real world results are all good, until somebody loses an eye….putting up thousands of installations in hopes of avoiding failure is a pretty iffy proposition, especially since Risk Category II structures are being designed for only a once in 50 year probability of their design loads being exceeded. A lot of buildings could perform satisfactorily for years until the one crucial event occurs and leaves a plethora of unhappy flattened building owners.

      The point of the original article was to point out there exists an easier and less expensive design solution which has been proven.

      Reply
  4. Crass Rude Person

    What’s going to give first in the overload scenario? The soil. The average psi of soil is somewhere in the 20 range. Foams are usually 80-100 psi. Just because you’ve put up 20,000 post frame buildings doesn’t mean squat. How do you thing balloon framing or stick framing became approved building methods? It happened because thousands of these structures were built and were deemed sound by engineers. The easier and less expensive design solution is one being peddled by you and your company because that’s all you know. Wood in contact with soil will rot. I’ve seen UC4C .80 pcf CCA rot in under 20 years in Houston, TX. I wonder how many of the 20,000 buildings you built are now structurally compromised by your “design solution”? You are crapping on this guy because he may have built a structure better than you can. If you have so much influence writing all the rules, maybe it’s time to get off your keister and write some new ones. At least do the testing to see if this is a dangerous practice or structurally sound.

    Reply
    1. admin Post author

      Easy – check. Less expensive – check. Now to address your ramble…..

      There are millions of post frame buildings standing across the United States and Canada, so this is not just the 20,000 or so buildings I have been personally involved in. Post frame buildings are highly engineered structures – most probably due to the lack of understanding on the part of many Building Officials who place them under extraordinary scrutiny.

      Wood rot – Houston must have something different in the ground than anywhere else in the world. Numerous tests have been conducted on pressure preservative treated lumber and the end resultant is lumber which has been properly treated is highly unlikely to experience decay.

      While the high density foam might indeed be a terrific design solution, why expend the hours and the tens of thousands of dollars to test its adequacy if it is going to be significantly more expensive than a proven method?

      Reply
    2. Amen. I’ve seen this in action and it’s good stuff. You cannot buy CCA treated posts where I live and the new (last 15 years) “ground contact” PT lumber absolutely sucks. It rots like a mofo in less than a dozen years. You could drop a CCA PT post in the ground for 25 years easily.
      The soil is indeed the weak link. Plus, I like the foam idea from a sealing standpoint. Closed cell foam is incredibly strong and waterproof. Why are people so effing opinionated about this product? I saw a Sika brand bag of it at Lowes for $10 that replaces (2) 60lb bags of concrete. The math works out fine by my estimation, and especially if I didn’t have access to water, I’d try it in a heartbeat. In fact, I will try it next time and give an honest report.

      Reply
      1. Any lumber properly pressure preservative treated to UC-4B standards is going to last longer than any of us will be around to witness. The problem is, very few retail lumber yards and big boxes inventory it, it usually has to be special ordered in.

        Foam problem – it has a very low compressive strength, so concrete or a material capable of withstanding the downward forces is going to have to be used beneath the columns – just no getting around it. Until you get the ICC to accept foam as an alternative backfill, you are unable to use it for Code compliant buildings.

        Read the 20% of reviews for Sika who give it one star out of five and you might think twice about using it for a building. BTW – one bag of Sika replaces 100# of premix and the price point is about $12.

        Reply
  5. The soil is still the weak link in any pole building. The concrete is WAY in excess of any kind of soil other than bedrock. From an engineering standpoint you have to look at the weakest link. A pole structure will oftentimes fail at the ground level. The building will try to move due to lateral loading (think tornado). The wind pushes against the building which pushes against the soil. It may also pull against the soil during uplift conditions. I seriously doubt either concrete or foam will fail under these conditions prior to the pole snapping off at ground level. The downward force of the building is not only transferred to the soil by point loading of the pole but by adhesive forces of the foam/concrete/post/soil interactions on the sides of the excavation. Although you are not able to use these for calculations of bearing capacity, they are definitely non-trivial and account to a very large amount of additional axial support.

    Wood Rot: Wood will eventually rot but it can take thousands of years of either left completely wet or completely dry. It’s the cycling of wet/dry that causes rot. The wet/dry cycle is what happens 6″ below and 6″ above the soil line. Why not compromise to keep the Code Nazi’s happy by drilling a 4′ deep hole. Put in the wood post and fill it up with concrete 3′. Fill the last foot, and put a container which extends another 6″ up from soil level, with closed cell structural foam. Make sure the foam is protected from sunlight and you should have a system which protects the post from rot and keeps all the code lunatics happy. Can’t we all just get along?

    Reply
    1. We like people who just want to get along 🙂

      In my nearly 40 years in the post frame industry, I can’t say I’ve ever had a building fail at ground line due to any circumstance. I’ve seen buildings pulled out of the ground because the builder failed to adequately follow plans and instructions (holes not deep enough and somebody forgot to concrete the columns in). If I had to pick a weak link it is inadequate truss connections and inadequate bracing of trusses. Had photos come across my desk earlier today of a 12 year-old building with double trusses where one of the two trusses is gone. There is no way in Hades those two trusses were properly nailed together.

      As for rot – I am still waiting on a properly pressure preservative treated column to rot.

      Reply
  6. AS any farmer or fence builder will tell you, you CANNOT place pressure treated lumber in direct contact with concrete! The acids in the concrete/cement interact with the treated materials thus causing a rapidly deteriorating condition. This was discovered and demonstrate by a man named Jack Shepherd, the head of maintenance for Fieldcrest-Canon Towels and Linens in NC. He discovered this on his farm and figured out what to do about it using the simplistic method of wrapping the posts in plastic where they would not come in contract with the cement products. His fencing for cattle and bison lasted for decades with no apparent decay, rot, or breaks. I have since used this to wrap each and every piece of treated lumber which is placed in concrete or cement base material and will come in contact with the grounds or soils of all nature. It’s best to use a 6-8 ply plastic and firmly attach it to the post material to prevent in collection of moisture or rains inside the wrap. AS crude as it seems, duct tape works pretty well.

    Reply
    1. admin Post author

      Well the Building Codes would tend to disagree with this anecdotal “evidence”. Code REQUIRES the use of pressure preservative (or naturally decay resistant) wood in contact with concrete. Very few fence posts are actually pressure preservative treated, at best they are dipped into treatment chemicals (not under pressure) resulting in basically painting the outside surface. Or, under treated materials (such as what you get from the big box stores and most retail lumber yards) has been used incorrectly. Provide for me actual published testing results to prove your case and I will accept them.

      Reply

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