Expanding foam for post setting?

[Palmetto Bug]

I watched a youtube video of a guy setting a mailbox post using two part expanding foam instead of packing it with cement. Has anyone done this? Would it work on farm gate posts? Does it last? Is there a better option than "Great Stuff" spray can foam?

[mudflat]

I see them setting telephone poles with it.

[AnythingFeathers]

Great stuff is the turd if expanding foam. It has its uses but overall is a cheap product. Great stuff is open cell ( easily crushed and doesn’t last long in the elements)and would not be good for posts in any way. The 2 part foam is closed cell, has more compressive strength, is an easy way, but not real strong, for NON-structural posts- no lateral pressure. The dirt under post would be only real structural element for vertical load only.
So, in short, foam is not a good product for gate posts.

[Saltydog235]

For a mailbox, it’s great. For a gate post, no unless it’s the latch side only.

[Cooney]

That’s the way the DirecTV jacklegs used to set the pole with the little dish on it. Bump it with the he lawnmower and you’d be out of service. It was a great feeling when I called them and told them I no longer needed their services. I hated them worse than any company I’ve ever dealt with.

[Chessbay]

I just did my mailbox with that stuff. My wife smashed into our old mailbox in her car and it was set in concrete……it did not really withstand the crash that well. My son and I were checking out of Lowes with a new post & mailbox and happened to see that expanding foam kit on the way out.

I used it and am pretty sure if you hit the mailbox now, you will total the car and not hurt the post.

It’s solid.

I have no idea what would happen on a gate, so I don’t want to steer you one way or the other, but I’d probably try it. The only thing I could think of that might be different between the two, is that the concrete weighs more. I don’t see how it’s going to hold your post any better. I’m sure someone smarter than me could come up with some cantilevered calc based on the weight difference, but I think depth of post and quality of soil will make the bigger difference.

[scoutlover]

I've been using the expanding foam all over the farm for about 3 years now. It's worked great on everything, including gate posts, but I put H bracing up on all my gates.

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