How to make a wooden post relatively removable from concrete

[Archena]

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

One (tiny) thought: if you do opt for a removable wooden post make sure to include a 'drainage hole' at the bottom.

Possible means: Cut a 1/2 PVC pipe maybe 6 - 12 inches long, stuff it with plastic (bags will work) and make sure one end has an inch of 'poof from the plastic. Before your pour, drill a hole in the bottom of the hole and stick in the PVC - make sure a few inches are above the 'grade'. When you set in the plastic wrapped post push down until you hit that extra resistance.

When it's dry and you've gotten the wood out, pull out the plastic bags. Won't be perfect but it should drain the hole. Water WILL seep in, wood or no, so you want good drainage into the supporting gravel bed.

[Mingy]

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

Pressure treated wood is only pressure treated a cm or two from the surface. If you consult the manufacturer's documentation they'll tell you you have to paint cut surfaces. Any hardware store here which sells the wood also sells the stuff to re-treat cut parts. I think one brand is 'Wolmanizer'.

The depth of concrete you would need would probably depend on the loads and soils.

In any event, I would probably not do what you are trying to do. I have not seen wooden posts embedded in concrete work out that well. I would probably go the steel tube in a tube approach. A steel supplier cold probably tell you what would fit (i.e. a 4" x 1/4" female would fit a 3 1/2" male). If you have a local galvanizing shop its a good idea as it is surprisingly cheap.

I'd embed the 'female' tube in concrete, making sure to fill the tube to ground level. I'd drill a hole to let water out.

[kebwi]

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

Sorry, thanks. I type without thinking sometimes. 'ppreciate all the help.

[Tscarborough]

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

Just do it like I said and move on. No big deal. If you are doing a 6' post, 2' deep, for a 12' post 3', for a 20' post 4'. What matters will be the concrete you pour around it. Make it a spread footing if it is over 10', at least 3-4 foot wide, 1' deep for a 20' post.

[kebwi]

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

Sinking a wooden post (even a pressure treated post) into concrete is not a proper solution any more.

If you want to deal with bending moment using a single post, the preferred solution is a steel angle or channel with the post bolted to it.

Oh, ugh, that's the first I've heard of anything like that. Rats. I've talked to lots of folks about this (like the employees at the lumber yard for example) and no one has mentioned anything like that. Come to think of it, the fence we had put around our entire yard this spring doesn't have those above-ground feet. The posts go into the concrete into the ground.

Gee whiz. There's always an argument that the approach I'm about to take, whatever it is, is wrong. I've been leaning back toward the metal pipe idea anyway, it's just much more expensive and more difficult to work with...and I still don't know what size pipe would be sufficient.

I'll figure something out.

[nissanneill]

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

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.

When I suggested the taper, I was thinking how I would do it, (even though I have a lot of large and sophisticated equipment) as it would be a lot easier to use a power hand planer on the flat sides,
However, if you were using round posts, well, it becomes much more challenging, but I would still use a hand power planer and/or an angle grinder with a coarse sanding disc in it. Plane two opposite sides and then draw the taper that you require on these smooth surfaces and then plane down to your lines. When done, draw your taper for the remaining sides and plane to your lines. It might also be advisable to put a small chamfer on the sharp edges.

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.

If you cut a little off from the bottom of the post, it will slip down very tightly into your concrete and possibly be quite difficult to remove. I would only cut a little off the base if the post became loose in the 'sleeved' base.

kebwi
Treated pine (CCA Copper Chrome Arsenate) or the original terminology in Australia was "Permapine" is pressure treated in a large 'pressure vessel' like a long pressure cooker, and yes, the preservative penetrates all the way through the log, so you don't have to aint" it with anything. The only other preservative that I an familiar with that is applied by brush is Creosote, that black smelly and sometime sticky material.

Neill

[Neil2]

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

"Dont you guys have these over there?"

Yes Al, we do. If fact building codes require these or similar fasteners for fixing posts to concrete. Sinking a wooden post (even a pressure treated post) into concrete is not a proper solution any more.

If you want to deal with bending moment using a single post, the preferred solution is a steel angle or channel with the post bolted to it.

[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!

[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

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.

[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.

[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

[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

[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=en&cp=8&gs_id=7g&xhr=t&q=post+stirrups&biw=1280&bih=828&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.,cf.osb&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi&ei=JYH2T_71D4q6iQfuh9THBg

[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 .