Post in concrete

john in la · Feb 3, 2016

I think we can all agree a wooden post put in a hole; and refilling the hole with concrete is a no no.
The post rots off right at ground level.

But what about metal?

Lets say you have a 4 inch square hollow post made out of 14 gauge galvanized metal.
How do you feel this will last with one end buried in concrete and used as a post.

If you feel it would last....
What are the advantages/disadvantages of going threw the trouble of filling the inside of the post with concrete up a couple of feet above ground level.

notjustair · Feb 3, 2016

Must be where you live. I use hedge posts and put in one bag of postcrete or flyash. Fill the rest with dirt after it sets. That's how all of my fences here are done. One wood post and four metal between. I just finished putting in another catch pen and did the same with those posts. It will get well pipe on it.

jon f mn · Feb 3, 2016

I would be surprised if a 14ga post lasted very long in your area. 1/4" might be ok.

Geo-TH,In · Feb 3, 2016

John in La, I have a rental house where the previous owner made a TV tower out of two pipe in concrete. Both pipes rusted off at ground level. I put a chain on the pipes and pulled the tower down before it fell on house.

I also have a privacy fence in back yard. The guy who built the fence put the post in concrete. That was 20 years ago. Fence is still up. I put same type post in ground next to kitchen window with bird house on top. This is what the post looked like after being in the ground less time and no concrete.

I sometimes question what I read about posts and concrete. When I made decks at rental property all my posts were put in concrete. No issues like in pic. Perhaps concrete is a good thing if you are using cheap posts. They don't rot off in the ground.

paul · Feb 3, 2016

Wood and concrete are a bad match here too.

Metal post in concrete does well; ip unless you are near livestock, the salt will get the metal.

Filling the post, can you get a rerod inside even, will make something solid and your kids will be mad when they want it moved many decades from now and its about impossible to get out....

Paul

Janicholson · Feb 3, 2016

Metal flange welded to the bottom and anchor bolts into the concrete pier. Jim

john in la · Feb 3, 2016

Its a kit and 14 gauge is my only option.
I found a pole barn kit that the post and trusses are made of 14 gauge galvanized metal.
It is made to bolt the frame work to a slab.

Since I will not have a slab I was wondering about buying longer post and just burying one end in concrete columns like you would a regular pole barn. I can get 10; 12; or 14; foot poles.

john in la · Feb 3, 2016

The post already have a metal flange on the bottom.
I thought about just building a concrete pier and just bolting the post to the top.

My interest in burying the post a few feet is greater wind resistance.
I can get the kit with a stamp for my 112 mph winds but just thinking out ways to make it stronger.

jon f mn · Feb 3, 2016

Just put down concrete pillar, then weld a plate to the post and anchor it to the pillar. That way it's replacable and nothing under ground but concrete.

john in la · Feb 3, 2016

Just what I needed.
Someone to bring me back down to earth so I stop over thinking these things and making them more complicated than they really are.

TKS.

fixerupper · Feb 3, 2016

A wood post in concrete is a death sentence for the pot here too. Seems to me a wood post pulled up out of the dirt and replanted somewhere else will rot quicker.

Ferd · Feb 3, 2016

I'm a general contractor and we do commercial and industrial buildings. The problem that you're going to have is uplift. You need to have enough concrete footing or concrete slab so that your building doesn't lift up during high winds. The building manufacturer should give you an uplift calculation for each one of the columns. That would give you enough information to get a proper size for the footings, or else find an engineer to give you a hand with it. Better than having a disaster later.

Den N Ms · Feb 3, 2016

John,You say the post already have a metal flange on the bottom.
I thought about just building a concrete pier and just bolting the post to the top.

Just dig your holes say 3 1/2' to 4'deep with a 12"-16" auger on a post hole digger then form a square 2x6" box on the top,stake it down level to grade on top.Pour it full of concrete and insert long tie down bolts using a plywood template to match the holes on the metal posts.Then just bolt your post down.

Janicholson · Feb 3, 2016

Diagonal tensioned wire from top of wall to opposite bottom of wall is more effective than the bend over strength of a a pier. Triangulation is superior. At the door, bracing can't get into the way of openings, but using the best and most well places X crossing system makes strong. Jim

newhollandnut · Feb 3, 2016

They make plastic sleeves or caps that you ca slide the post in a come 6" to a foot out of the ground to protect them from rotting. Mainly for post frame building

JerryS · Feb 4, 2016

John, maybe I'm missing something here, but why would your scenario be any different from the millions of chain link fences that use galvanized metal pipes set in concrete? They seem to last many, many years.

john in la · Feb 4, 2016

Yes Jerry.
Hence my question as I do not see a problem.
As on poster said uplift is the thing I am trying to stop.
I figure a concrete column 3 to 4 feet in the ground would have as much strength on uplift as the pole stuck in the ground with concrete around it.

I thinking even with bracing 100+ mph wind may push it over at the bolts.
I was just figuring with the pole stuck down in the ground a few feet then filled with concrete to say 3 feet above ground would make for a much stronger post.

Stephen Newell · Feb 4, 2016

It depends on the wood. If you get treated posts that were done right they won't rot off. I often build a pole barn using 4x6 treated timber for the posts.

jon f mn · Feb 4, 2016

I generally start by over thinking too. Glad I could help.

JRSutton · Feb 4, 2016

I'd say it's less a question of "will it last" - and more a question of "why do you need it in concrete".

If a post, regardless of what it's made out of, HAS to be extremely rigid - then by all means use concrete.

If simply planting it in dirt will suffice - don't use concrete.

Something like a post used for a hanging gate - I'd put it in concrete. But regular fence posts - no need.

db4600 · Feb 4, 2016

I cant speak for Louisiana but in MN the fence companies don't set anything in concrete unless they get below frost depth. IE corner posts and gate posts. Even MnDOT drives there stock in with out concrete. For the building code frost depth changes throughout the state. I believe in the neighborhood of 48" to 60" south to north. The steel buildings erected here anchor to a foundation that is frost depth. As Janicholson stated, bracing is your best friend. A good steel building will have tensioning rods with turnbuckles on both wall and roof assembly. Similarly a good post frame building will have adequate wall and roof bracing. The cheaper ones don't. To often cheap wins. If you have adequate anchorage of your vertical members and a good foundation they set on, the bracing is the wind shear key. Don't rely soley on the exterior skin. A 3'-4' poured pier sounds like the right application for your building.

dpendzic · Feb 4, 2016

if you worried about uplift then make the concrete hole a little wider at the bottom than the top---the dirt around the sides will then help keep it down

ss55 · Feb 4, 2016

How large will your building be? 14 gauge 4x4 square steel tubing has .083 inch thick walls. That sounds a bit thin for the posts of a large pole barn. The manufacturer may intend the building to be fastened to a slab with a substantial footing under the perimeter. I would check the manufacturers recommendations.

Is this picture an example of the kit? The trusses look to be well braced, but I don't see any diagonal bracing on the walls or any corners. Is the sheet metal skin intended to be the bracing?

Daryl in PA · Feb 4, 2016

https://permacolumn.com/what-are-perma-columns[/url]

JimS · Feb 4, 2016

I am in a very dry climate, CA, and have similar issues. Furthermore, the new pressure treated posts are a joke. I have replaced them within 5 years both in and out of concrete. I do not set in concrete unless it is stressed, i.e., gates, animal pressure, etc. I have had good luck with steel and utility poles as gate posts.

One thing I have been doing is back filling line posts with dirty pea gravel, the stuff that has fine chips and dust in it. Pour, tamp, and wiggle the post and it sets tight.

jm. · Feb 4, 2016

wood or metal is usually sat in concrete here on the this farm. Pretty much the norm now for 50 + years. Here is a photo of metal post , sat in large hoes with rebar punched cross ways in about 3 ft deep hole. Then after the structure was completed the concrete floor was pored around the post or supports.

Gchase24 · Feb 4, 2016

Metal or wood, good old fashion roofing tar. Coat them well with tar to 4 to 6 inches above ground level then pour concrete or sack/crete in the hole . Neighbor and I both have wooden and metal post in the ground since early eighty's no rot or rusting at ground level.

john in la · Feb 4, 2016

ss55

"Is this picture an example of the kit?"
Yes and No

That is a exact example picture of the "bottom line" kit.
24x30 with trusses 10 foot apart and 10 foot tall walls.
They are using the 26 gauge sheet metal for bracing.

The kit in the picture does not meet my wind code so I need to get the upgraded kit that looks just like this one but has cable bracing added.
You can also get solid rod bracing for a extra cost.

Guy told me you give me your address and we will provide engineer stamped drawing that meet your wind loads.

I'm just looking for a way to make it even stronger.

Post in concrete

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