Fence posts - Concrete Vs. Foam - What Say you?

[dirtydeed]

Has anyone used the foam mix instead of concrete for fence posts? What was your experience with it?

I have a small fence job to do (dog play area) so I'm using 3"x5" landscape timbers as fence posts. I'm only planning on anchoring the corners, ends and gate posts. The rest of the posts are just going to be backfilled with the soil cuttings from the auger.

The fence will be 4' tall vinyl coated welded wire with two rails (top and bottom). I'm also planning on approx 10' post spacing. Customers dogs (4 of them) probably have a combined weight of 60 lbs...so, they aren't exactly powerhouses.

 

[biketopia]

I haven't personally, but have co-workers who have and are quite impressed. I'd say your plan and use case is probably a good use for it.

 

[Lil Foot]

I have been contemplating the same question for a 2" pipe, 12' to 16' tall, for a bat house.
Bat house is just 3-4 lbs, but pipe is heavy. (galvanized water pipe)
18" to 2' dp hole, 6" to 8" diameter.
Inquiring minds want to know.

 

[jimh406]

Go look at the SWI Fencing videos on YouTube. It might save you some work or give you some hints to do something different. They also have concrete and foam videos.

 

[McMXi]

I have been contemplating the same question for a 2" pipe, 12' to 16' tall, for a bat house.
Bat house is just 3-4 lbs, but pipe is heavy. (galvanized water pipe)
18" to 2' dp hole, 6" to 8" diameter.
Inquiring minds want to know.

I'd dig a lot deeper and larger diameter hole than that, for wind loading if nothing else. Better to overbuild than underbuild ... that's my approach at least. When I start the pole barn build this spring, I'll be digging 4ft holes at least 12" in diameter for the steel pipe uprights.

 

[North Idaho Wolfman]

Has anyone used the foam mix instead of concrete for fence posts? What was your experience with it?

I have a small fence job to do (dog play area) so I'm using 3"x5" landscape timbers as fence posts. I'm only planning on anchoring the corners, ends and gate posts. The rest of the posts are just going to be backfilled with the soil cuttings from the auger.

The fence will be 4' tall vinyl coated welded wire with two rails (top and bottom). I'm also planning on approx 10' post spacing. Customers dogs (4 of them) probably have a combined weight of 60 lbs...so, they aren't exactly powerhouses.

The foam will work fine, I use concrete on gate posts because they will get worked loose with the foam.

 

[North Idaho Wolfman]

I have been contemplating the same question for a 2" pipe, 12' to 16' tall, for a bat house.
Bat house is just 3-4 lbs, but pipe is heavy. (galvanized water pipe)
18" to 2' dp hole, 6" to 8" diameter.
Inquiring minds want to know.

It's two sided.
The foam will bond to the pipe really well, but the wind will work the pole back and forth in the wind, so that could cause you issues?

 

[MapleLeafFarmer]

YMMV... around these parts we would just set regular rnd. posts in the ground and from what you describe every 8' apart would last generations. no foam / concrete / mess and less work. A tensioned galv. wire top/bottom in lieu of rails.

We would get laughed at if we set posts in concrete or foam.

not your orig. question but chucking it out there for consideration. Cheap and easy and will last generations. Strong enough to hold cows in so should work for dogs and IMHO looks pretty darn good.

 

[hedgerow]

There was a time in my area folks like to use concrete on gate, pole barn and corner posts and the concrete would rot the post off. It's no fun to dig out the post that have been set in concrete if you don't have a back hoe handy. We always set high load post deep and back fill them with one inch crusher run lime stone and tamp them well as your back filling them. Never had one get loose and the rock helps drain the water. Had a friend that tried some foam and wasn't happy with it later the posts got loose.

 

[dirtydeed]

Thanks guys.

I'm aware of the issue with concrete and wood. I may skip it all and just put the posts down 30" or so. The 4' wide gates aren't that heavy (besides, with two rails the post can't sag anyway). I already purchased a large swivel caster for the 12 foot wide gate, so there won't be any weight on those posts either.

My concern now is the lack of quality in the posts. I don't know how long they will last.

I'd like to do away with the rails but they were requested by the client.

 

[hedgerow]

Has anyone used the foam mix instead of concrete for fence posts? What was your experience with it?

I have a small fence job to do (dog play area) so I'm using 3"x5" landscape timbers as fence posts. I'm only planning on anchoring the corners, ends and gate posts. The rest of the posts are just going to be backfilled with the soil cuttings from the auger.

The fence will be 4' tall vinyl coated welded wire with two rails (top and bottom). I'm also planning on approx 10' post spacing. Customers dogs (4 of them) probably have a combined weight of 60 lbs...so, they aren't exactly powerhouses.

I know in my area a 3"X5" landscape timbers are only going to last five years before they rot off. Find out where the guys that build field fence for a living buy post and then you have your good source for post. In my area you don't buy posts at the chain farm stores and think there going to last. I have a fair amount of hedge on one farm so I cut my own 100 year post.

 

[GreensvilleJay]

curious... how well does foam last versus freeze-thaw cycles ? Up here we have to go 3.5' down to get past the frost line.

for a good looking, semi temporary fence ,neighbour drove 2" steel fence poles into the ground,10' spacing. then took 4 2by4s ,screwed together making a hollow square 5by5, then slid them down the poles. Makes for a nice 5" square post ,yet can be totally removed easily, weeks or years later

 

[ctfjr]

About 15 years ago I built a large pen for our 2 labs. I used 103 4x4 X 8' long pressure treated wood. The auger dug down at least 30" on most of them, 36" or greater a few. I just backfilled with the dirt that came out of the holes. They were spaced approx 8' apart and turkey wire was strung between them.

The only one that I ever had a problem with was the one I backed into with the tractor. Snapped clean off at the base but hung there by the wire.

It'd still there today tho we sold the house 3 years ago. The new owners use it for their dogs.

 

[McMXi]

There was a time in my area folks like to use concrete on gate, pole barn and corner posts and the concrete would rot the post off.

I've set a lot of posts in concrete in a previous life. We would always put gravel in the bottom of the hole after placing the post. We would slide a piece of plastic sheet over the pole and down onto the gravel to keep the concrete from getting into the gravel, and then pour the concrete. With the end of the pole being in the gravel and not encased in concrete, the moisture could drain out of the post and not rot the bottom out. We found that posts lasted years using this method.

 

[hedgerow]

I've set a lot of posts in concrete in a previous life. We would always put gravel in the bottom of the hole after placing the post. We would slide a piece of plastic sheet over the pole and down onto the gravel to keep the concrete from getting into the gravel, and then pour the concrete. With the end of the pole being in the gravel and not encased in concrete, the moisture could drain out of the post and not rot the bottom out. We found that posts lasted years using this method.

Those key items are why the concrete worked. Any I ever dug out that were rotted off from concrete had no plastic around the post or gravel in the hole. That's why years ago we started using rock to back fill the holes makes a nice tight post and the water has somewhere to go. I have a pole building I put up forty years ago with used telephone poles and back filled the holes with rock and the post are still in great condition. I put all new steel and doors on this building about ten years ago now. Went from slider doors to over head doors. I have a buddy that about ten years ago bought a acreage that had a camper, boat storage business on it. The buildings were pole buildings 60X300 with the post on four foot centers. Yes they were four foot. They were true six by six post buildings were 20-25 years old and the post were set in concrete and every one was rotted off. I forget the crazy number they wanted to replace all of them but it got the price of the acreage down. Slowly but surely he repaired all the post in the building digging them mostly out by hand because it couldn't ever get the buildings totally empty as a lot the customers were year around. I helped some and it was no fun.