How to make a wooden post relatively removable from concrete

[kebwi]

Sorry to be posting multiple threads. I prefer one thread per specific topic instead of broad discussions that explore an idea from multiple directions.

That said...

So, the 'ol pressure-treated wooden post in a concrete footing. It's a classic. I'm curious if I can make the post slide in an out of the hole with just enough give to be removable, but tight enough to minimize looseness and sway (to ease pole replacement as the wood wears out every several years). My current idea is to wrap the pole in plastic before pouring the concrete and perhaps giving it a touch of occasional vertical motion while the concrete is setting so it doesn't stick (lift it up a smidge and let it drop back down).

Two questions:

Is this a royally bad idea (the response I expect to get to this thread I suppose)?

What other or additional steps might assist this goal? Should I coat the plastic with something slick (e.g I've heard you can coat the plywood form of a concrete fill with motor oil to make the wood easier to remove). Should I coat the inside (wood) the outside (concrete) or both sides of the plastic (or perhaps between multiple layers of plastic)? Would a slipping agent of this sort make any difference many years later? I'm rather doubtful on this point which obviates any purpose to adding a slipping agent (oil) in the first place.

I was kind of thinking of inserting something thin next to the pole during the pour (masonite or a comparably thick sheet of metal) and then removing it after setting to make a tiny gap so the pole has some room...but the masonite or piece of metal itself could get locked in tight during setting and be too tight to remove after the fact, which would negate the purpose of such an approach.

I know I throw a lot of crazy ideas out on this forum. Any thoughts are, as always, appreciated.

Cheers!

[Jaronimo]

Re: How to make a wooden post relatively removable from concrete

Wrapping the wood in plastic just ensures that it will retain moisture, and rot faster. Even wolmanized will rot like that. It just takes longer

Are you talking about a 4x4 post? Maybe you could get a steel 4x4 post that is slightly larger and then mount the steel in the concrete with a few feet sticking out. Then just slide in the wooden post in to ground level. Fill in the metal tube so its level (inside) with the ground and have a few weepholes at ground level so it does not retain water.

Basically the steel gets inserted 3-4 feet deep in the ground and has the same amount above ground, so the steel acts as a sleeve. Should be pretty strong depending on what gauge steel you use.

[Tscarborough]

Re: How to make a wooden post relatively removable from concrete

Wrap the pole with multiple layers of plastic, you want 1/8" to a 1/4" of slack. You can shim the post after you put it back in. Underneath the pole you will want some gravel for drainage as well.

[kebwi]

Re: How to make a wooden post relatively removable from concrete

Wrapping the wood in plastic just ensures that it will retain moisture, and rot faster. Even wolmanized will rot like that. It just takes longer

I could just use the plastic while pouring the concrete to prevent the wood from sticking to the concrete. Once set, I could remove the pole, take off the plastic, and reinsert the pole. Point taken however.

Are you talking about a 4x4 post? Maybe you could get a steel 4x4 post that is slightly larger and then mount the steel in the concrete with a few feet sticking out. Then just slide in the wooden post in to ground level. Fill in the metal tube so its level (inside) with the ground and have a few weepholes at ground level so it does not retain water.

Not a bad idea, except for potential expense (I see similar things done with PVC, but I can' reconcile the shapes (round hole, square/rectangular peg, you know the deal)).

[kebwi]

Re: How to make a wooden post relatively removable from concrete

Wrap the pole with multiple layers of plastic, you want 1/8" to a 1/4" of slack. You can shim the post after you put it back in. Underneath the pole you will want some gravel for drainage as well.

I had a similar thought. My only concern was that the plastic -- being somewhat compressable -- might tighten up against the pole during pouring/setting so hard that I can' get the pole out...but that was basically the idea I was converging on.

[Laku]

Re: How to make a wooden post relatively removable from concrete

Let the pole sit on a bucket of water before. So It'll be swollen before getting wet from the concrete. Then just proceed as Tscarborough suggested. Idea being that it'll shrink once the concrete has dried and will be easier to remove even if the plastic has been compressed too much.

Other way might be to put one layer of bubble wrap and then normal plastic. That way you should be able to wriggle the pole out.

[kebwi]

Re: How to make a wooden post relatively removable from concrete

Let the pole sit on a bucket of water before. So It'll be swollen before getting wet from the concrete. Then just proceed as Tscarborough suggested. Idea being that it'll shrink once the concrete has dried and will be easier to remove even if the plastic has been compressed too much.

Other way might be to put one layer of bubble wrap and then normal plastic. That way you should be able to wriggle the pole out.

Nifty. I think the soaking idea occurred to me and then I completely forgot about it...of course, it may never dry out embedded in a tight three foot hole, but it's still a good idea.

[Gulf]

Re: How to make a wooden post relatively removable from concrete

That is all great advice.
I have just a couple of other suggestions. Buy ground contact rated pressure treated posts. Whether or not you put them in a sleeve, do bring the concrete above ground level a few inches. Slope the concrete away from the post and once you have wedged or stabilized the post to your satisfaction, seal the gap with some form of paintable caulk. I am sure that you will want to stain, paint, or seal your post from the weather. You want have to replace that post "every several years". Let your grand kids do that .
Edit: Let me add exterior to that paintable caulk. We use tar down here but we ain't all that particular .

[brickie in oz]

Re: How to make a wooden post relatively removable from concrete

Dont you guys have these over there?



https://www.google.com.au/search?hl=...D4q6iQfuh9THBg

[Ken524]

Re: How to make a wooden post relatively removable from concrete

Hi Al,
Yep, we have those! I was going to suggest using those as well.

The sleeve idea mentioned earlier might work with this product:
Shop Severe Weather 4-in x 4-in x 100-in White Deck Post Sleeve at Lowes.com

When I built the arbor over my patio I used these things:
Shop Simpson Strong-Tie 6 x 6 Standoff Post Base Z-Max at Lowes.com

[nissanneill]

Re: How to make a wooden post relatively removable from concrete

Maybe a better way whether using round or square logs is to plane or cut a slight taper on the bottom, pour the concrete and 'slightly wobble the post before the concrete has set. You might also smear the lower portion of the post with grease so that the concrete doesn't stick!

Neill

[Mingy]

Re: How to make a wooden post relatively removable from concrete

I am a bit curious as to why you want to do this, but I would
1) Make a taper on the post (1/4" to 1/2" on all 4 corners)
2) re-treat the cut parts
3) wrap the thing with plastic before the pour
4) after you remove the post, cut about 1/2" off the bottom
5) retreat the cut

If you just put a square post in, either you won't be able to remove it due to twist or
other issues, or it'll be wobbly after. A tapered socket will 'self tighten'. You may find it a bit challenging to remove the first time.

[kebwi]

Re: How to make a wooden post relatively removable from concrete

Re:



Those won't work for my application. They provide virtually no lateral support, only vertical support, and are used when the pole will receive lateral support from high above, like a suspended deck or a house. My pole is free standing, like a flag pole, and needs considerable lateral strength to be free standing with minimal sway and no possibly of collapse. Furthermore, the entire purpose of the pole is to support a tall stove pipe via horizontal or diagonal rods. The strain the stove pipe exerts will be purely lateral in nature.

I can't imagine those above-ground feet could possibly work for this project. Even six foot fence posts are usually put in the ground for heaven's sake.

The question I *am* curious about is how much of a pole needs to be below ground in concrete for sufficient self-supporting strength. For metal, the typical prescription is 10%, but I have no idea for wood -- I suspect it's considerably more.

I do like the metal sleeve idea however.

[kebwi]

Re: How to make a wooden post relatively removable from concrete

Maybe a better way whether using round or square logs is to plane or cut a slight taper on the bottom, pour the concrete and 'slightly wobble the post before the concrete has set. You might also smear the lower portion of the post with grease so that the concrete doesn't stick!

Neill

Yep, I had the idea of pushing/pulling the post in the concrete to create a slightly pyramidal hole, then shimming it after it sets. And I agree about slicking it up, I'm just not sure what to use, but I agree.

[kebwi]

Re: How to make a wooden post relatively removable from concrete

I am a bit curious as to why you want to do this, but I would
1) Make a taper on the post (1/4" to 1/2" on all 4 corners)
2) re-treat the cut parts
3) wrap the thing with plastic before the pour
4) after you remove the post, cut about 1/2" off the bottom
5) retreat the cut

If you just put a square post in, either you won't be able to remove it due to twist or
other issues, or it'll be wobbly after. A tapered socket will 'self tighten'. You may find it a bit challenging to remove the first time.

It's not a bad idea. Do I need to retreat pressure-treated wood? The "treatement" doesn't go all the way through the wood? I can't just paint the stuff on, it's done in a gigantic kiln or something like that to the best of my understanding...but I thought it went all the way through anyway.

Good idea about the tapered cut. I can considered something along those lines but was a little weary of long precise cuts (1/4" of two or three feet is a precise cut) as I lack the necessary hardware. But I might try something along those lines...the approach has a lot of benefits as you pointed out.

Cheers!