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kebwi 06-24-2012 07:37 AM

Very tall free-standing pole (for stove-pipe support)
 
1 Attachment(s)
It's been absolutely ages since I wrote anything on Forno Bravo.

I want to add a very tall stove-pipe on top of my oven. Please see the attached diagram. I intend to support it with the a brace near the top (and perhaps a second brace near the middle). The brace will attach to a free-standing pole. Since the top of the stove-pipe will be around 21' above the "higher" ground (two-level with retaining wall) and I want to brace it about 4' below the top, I need about 17' of post above the ground. I have about 3' of "hole depth" to work with, as you can see in the diagram. This hole is the gap between a 3' retaining wall and the back of the stove stand. I figure I'll just stand a 20' 4x4 or 4x6 post (pressure treated I would imagine) up in the gap and fill around it with 3' of concrete. I'm extremely weary of merely placing the pole on a metal bracket above ground in the concrete since I can't imagine such a bracket could hold up nearly 17' of post with no side arms or guy-wires.

I have numerous detailed ideas and questions. First, notice in the diagram that the bottom of the hole is concrete, not dirt, since the foundation extends beyond the stand all the way to the retaining wall (minus an inch or two). I figure I'll put a few inches of gravel in the bottom to assist drainage. I also had the idea of wrapping the below-ground portion of the timber in heavy plastic to separate it from the concrete I pour around it. I would then poke holes in the very bottom of the plastic (which will sit against the gravel and won't touch the new concrete) so that any water that gets inside the plastic will drain out the bottom. Does this sound crazy? Does anyone ever wrap wood in plastic before setting it in concrete? Seems to make intuitive sense to me but I can find very few references to such an approach. It would prevent the concrete from seeping water into the wood, prevent the wood from wicking water from the concrete while it sets, and finally, it also might make it possible to lift the entire pole out of the footing to replace it. It may effective "rest" in the footing instead of being locked in, which would make replacement a cinch. Would this work? I'll also extend the new concrete above ground and slope it down away from the post to minimize seepage into the post of course.

Is is possible to "seal" the plastic, above ground, to the post so water can't easily flow down inside the plastic?

In general, what do you think of this? Like I said, I'm not comfortable with placing the pole entirely above ground. I simply can't imagine it would be sturdy. Does that sound like a reasonable concern? Any other thoughts on this overall project? Are there completely different approaches I should consider? One idea I'm kicking around is a metal flagpole, although I doubt my wife will permit something so ugly in the yard.

Any advice at all? At the most basic level, how would you support a very tall stove-pipe with a single free-standing pole and no other supports (no arms or guy-wires or anything since it would clutter up the yard)?

Thanks!

deejayoh 06-24-2012 10:30 AM

Re: Very tall free-standing pole (for stove-pipe support)
 
Hey Keith -
As a fellow Seattlelite, I've read your earlier threads about smoke problems with the neighbor with some interest. For her sake, I hope this is going right on the property line, maybe with some neon orange paint!

Not sure where you are going to get a 20' long piece of timber. If you can find one, it seems like over time it would excert a lot of leverage on the base - which always has risk of rot no matter how much you try to waterproof.

Metal seems like it would work better, and I am not sure how much more ugly factor it has than a piece of pressure treated timber. Either way, maybe for your neighbor you can put a big halide light on top :)

Oh - and you probably think about the need to ground the chimney in some way - it seems like it would be a lightning rod

kebwi 06-24-2012 11:21 AM

Re: Very tall free-standing pole (for stove-pipe support)
 
Quote:

Originally Posted by deejayoh (Post 133741)
Hey Keith -
Oh - and you probably think about the need to ground the chimney in some way - it seems like it would be a lightning rod

Okay, I can honestly admit that notion never once crossed my mind. Wow. I'll look into that. On the other hand, it's pretty far from the house and I would never use it during a storm, which means I wouldn't be standing at its base, so does it really matter if it takes a strike? I suppose that might destroy it huh. Fascinating question worthy of some research.

Bear in mind that once constructed it still won't be taller than the house just thirty feet or so away and it'll be much much shorter than the surrounding trees (70 - 100 feet I'd say).

Cheers!

kebwi 06-24-2012 11:31 AM

Re: Very tall free-standing pole (for stove-pipe support)
 
1 Attachment(s)
If you're curious, here's the new stove pipe. The old one, readily observed in old photos, is a single 4', 8" pipe (10" exterior). This one is nine 2' pieces and one 1' piece with a cap, all 7" interior, 9-1/4" exterior (an admittedly pretty unconventional diameter). I calculated the total weight to be about 157 lbs (very close to 16.333 lbs per 2' piece), so the force it will exert on the arch is a little less than me standing on the arch...which I'm pretty sure it would take without much trouble (fingers crossed).

Cheers!

Tscarborough 06-24-2012 12:18 PM

Re: Very tall free-standing pole (for stove-pipe support)
 
Call me crazy but I would just guy it with three wires, twice. One about halfway up, the other at the top.

kebwi 06-24-2012 12:27 PM

Re: Very tall free-standing pole (for stove-pipe support)
 
Quote:

Originally Posted by Tscarborough (Post 133747)
Call me crazy but I would just guy it with three wires, twice. One about halfway up, the other at the top.

I've always appreciated your input Tscar. What would you recommend I attached the wires to? The yard is a pretty odd shape. Plus, we're a little concerned about children getting wrapped up in the wires. I really don't think my wife is going to go for it. :)

Faith In Virginia 06-24-2012 12:48 PM

Re: Very tall free-standing pole (for stove-pipe support)
 
Okay here is one of those off the wall suggestions and you can take it for what it's worth to you.

Take a top rail of a chain link fence. I think they come in 10' sections. one side is necked down so you can easily put two together for 20'. Use three sections to make a tripod securing one pole on each side of the oven base and one in the rear then draw the three together over the top as a mounting location for the top of the chimney.

That's the concept, figure you could run with it from there.

Like I said just an idea.

kebwi 06-24-2012 12:52 PM

Re: Very tall free-standing pole (for stove-pipe support)
 
Quote:

Originally Posted by Faith In Virginia (Post 133750)
Take a top rail of a chain link fence. I think they come in 10' sections. one side is necked down so you can easily put two together for 20'. Use three sections to make a tripod securing one pole on each side of the oven base and one in the rear then draw the three together over the top as a mounting location for the top of the chimney.

Not sure about the whole tripod deal (were you suggesting hanging the chimey under the tripod apex?!), but I have considered something similar to basic galvanized steel pipe (probably in the 2-1/2" to 3" range) as an alternative to the wooden post. That's sort of what I was getting at when I mentioned metal poles in the first post.

I'll think about it. Thanks.

Faith In Virginia 06-24-2012 01:07 PM

Re: Very tall free-standing pole (for stove-pipe support)
 
No not hanging necessarily. But the three poles coming together will make a fairly ridged point above the oven. So you could connect the pipe directly to the three poles for direct contact (no hanging) and the stove pipe will add some extra rigidity to the mix.

You could run the three poles into the ground next to the oven base for superior anchoring. They will run up the sides of the base so they won't be in the way.

I don't think you need anything a big as 2.5 to 3" if you use the tripod. I think the 1.25" or 1.5" top rail (whatever they are) will give you more then enough strength and the flexibility to draw them together over the top.

But like I said just an alternative thought.

kebwi 06-24-2012 01:15 PM

Re: Very tall free-standing pole (for stove-pipe support)
 
Quote:

Originally Posted by Faith In Virginia (Post 133752)
No not hanging necessarily. But the three poles coming together will make a fairly ridged point above the oven. So you could connect the pipe directly to the three poles for direct contact (no hanging) and the stove pipe will add some extra rigidity to the mix.

Ah, I get it. I can imagine the look on my wife's face if I suggest that. I don't think it's gonna work out. Thanks though.


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