Treeless Treehouse or Elevated Platform

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Rynomyte
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Joined: Fri Jul 12, 2019 10:28 pm

Treeless Treehouse or Elevated Platform

Post by Rynomyte » Fri Jul 12, 2019 11:08 pm

Hi all. I'm wanting to build a treeless treehouse for my kids. This would essentially be an elevated deck with some fun additions like a fireman's pole, rock climbing wall, and possibly a slide. I'd like to actually build two platforms connected with a suspension bridge of some sort. These platforms would be 8 to 10 feet in the air. My plan is to use 6x6 posts. There would be 4 posts for each platform as these would be built among the trees, not connected to them. My question is what is the best way to anchor the posts to the ground? I've seen everything from burying the posts directly in the ground with no concrete, to burying them in concrete, or pouring a concrete footer and securing the post to the concrete using a wood to concrete post base. I'm leaning towards using the wood to concrete post base so that the post isn't in contact with the ground or concrete. I've read this is the way to go to prevent rot and decay, but you give up some stability with this method. That's why I'm seeking advice. On a platform that tall, if the only thing holding the post is some screws in a somewhat flimsy metal post anchor, will that be stable enough? Seems like it might want to sway, even with cross bracing. I want this thing to be stable enough for adults to climb on. Also, are 6x6 posts the way to go, or would it be better to screw two or three 2x6s together as a post. I've heard warping stories for some of these 4x4 or 6x6 posts. Thanks for reading and I'd appreciate any feedback.

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A. Spruce
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Re: Treeless Treehouse or Elevated Platform

Post by A. Spruce » Sat Jul 13, 2019 12:11 am

Any buried post has the potential for rotting, whether encased in concrete or not. This can be mitigated to an extent by pouring the top of the concrete above ground and crowning it so that water can't collect at the post/concrete union. A buried post will be the most structurally stable, however, you can achieve good structural soundness above ground too, you just have to build it into the structure in the way of cross braces or sheer panels.

Another thing, IMHO, to worry about is treated lumber in contact with the kids. I don't care if today's PT products are considered "safe" to touch or not, it's still not made of sugar and roses, so it's still not good to play around. Just because it doesn't have the arsenic in it, doesn't mean you want your kids touching it. I would opt for painted lumber or go with a high tanin content wood such as redwood or cedar.

I think you'll be fine with either 4x4 or 6x6 posts, no need to laminate anything. Lumber is unstable if it isn't secured well. If you secure one end in a post base and 2/3's up is a deck with walls and a railing at the top, those posts are not going to do anything illicit.
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Shannon
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Re: Treeless Treehouse or Elevated Platform

Post by Shannon » Sat Jul 13, 2019 9:00 am

Build a pair of these "towers" with a suspension bridge between them and anchor the two far ends to post anchors or some other matter to the ground and you have years of fun ahead for the kids and satisfaction of completing the project yourself!
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A. Spruce
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Re: Treeless Treehouse or Elevated Platform

Post by A. Spruce » Sat Jul 13, 2019 11:48 am

I would be cautious of the overall height at which the kids are off the ground, I wouldn't recommend any more than 6' to minimize the risk of injury when one of them falls or jumps off the structure. As Shannon suggests, install an anchor cable off each back corner, these will keep the towers standing upright. You could also use an angle brace from the bottom inside leg to the deck outside leg to brace the towers from leaning towards each other.
If the women don't find you handsome, they should at least find you handy.

DanM
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Re: Treeless Treehouse or Elevated Platform

Post by DanM » Sat Jul 13, 2019 12:18 pm

Personally for each tower I would do one of the posts buried in concrete (with a domed top above ground like spruce described) for added stability and the other three sitting on concrete piers. I'd still add some cross bracing to help stabilize each tower as well, but that one buried post goes a long way towards combattng any swaying of the structure. I like to dig the hole, than add a few inches of gravel for drainage (tamp the gravel down as well), then set the post on top of the gravel, level it, and then add the concrete.

Rynomyte
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Joined: Fri Jul 12, 2019 10:28 pm

Re: Treeless Treehouse or Elevated Platform

Post by Rynomyte » Sat Jul 13, 2019 4:06 pm

Thanks for the responses everyone! All good recommendations. Looking forward to getting this project started!

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