Structural integrity of a hanging tent platform
Structural integrity of a hanging tent platform
(OP)
I am planning on building a tent platform that will hang from four trees. My plan is a 10'x10' platform constructed with 2x8s with 15" center to center joist spacing. Flooring will be the lightest plywood I can find. Will this platform be structurally sound if hung by all four corners, especially if the strain is not 100% vertical, but more along the lines of 45 deg.? All the platform will hold is a mattress and myself with a simple A-frame covered in shrink which I don't anticipate will add to the weight significantly. I'm planning on using four 1-ton come-alongs in each corner with 3/16 galvanized cable.
My fear is that the horizontal component of the wire strain will prove problematic, but I may be mistaken. Any specific building additions/precautions I need to include?
Any advice would be greatly appreciated.
My fear is that the horizontal component of the wire strain will prove problematic, but I may be mistaken. Any specific building additions/precautions I need to include?
Any advice would be greatly appreciated.






RE: Structural integrity of a hanging tent platform
RE: Structural integrity of a hanging tent platform
If just yourself and a cot/pad/sleeping bag it appears way over-specified. If just yourself (no liability for others!) then you become responsible for your own safety - like a person building a treehouse for himself. Read a few treehouse guidebooks at the the ;ocal Home Depot or Lowes store.
Usual spacing for underfloor reinforcement is 16 inch on-center. Lighter weight will be an outside rim board, then regularly spaced 2x4's across the center. For more rigidity, glue the plywood to the 2x4's, use outdoor-rated plywood - insect proof!
Build it, suspend it a fw inches above the ground from the 4 corners, test it.
RE: Structural integrity of a hanging tent platform
RE: Structural integrity of a hanging tent platform
Buggar-- if, instead of tension cables, I ran the cable through both pieces of wood (and steel corner brackets connecting rim joists) at the corners, would this hold it together? Instead of the tension cables relieving stress would the wood just take on a tensile stress from both ends? As long as the rim joists were properly secured and the wire ran through the bracket as well, the pulling forces on the wood wouldn't be a problem right?
RE: Structural integrity of a hanging tent platform
Seems like the weight of the deck will be a significant component. I don't recall ever hearing about "lightweight plywood". Maybe it's a thing but I would expect the joist framing will be as big or a bigger factor and I don't see the need for 2x8's. I would think mostly 2x4 framing would work. Not sure of why you are using 15" spacing either. Seems like 24" should work fine. Guess there is some "balance" between the plywood contribution and the joist contribution to the weight Maybe by "lightweight" you really mean "thin". Perhaps you have done a comparison of all the combinations. I have not so... that should help.
RE: Structural integrity of a hanging tent platform
RE: Structural integrity of a hanging tent platform
RE: Structural integrity of a hanging tent platform
Anyways, whatever you do, after you build it, maybe give it a good "load test", by throwing something heavy up there and leave it for a few days and see what happens. Maybe do that during a wind storm too just to see what it does. Last thing you want to do is be the guinea pig yourself!
RE: Structural integrity of a hanging tent platform
earthsuntech: hoping to get it 10' up. Simple hanging rope ladder to get in. Hopefully six railing posts total with fishnet or some sort of lightweight rope netting in between. I'm still nailing down the exact spot to put it but as of now it looks like 4 pine trees about 1.5' diameter. I figured I'd live with a little tilting in the wind but hadn't considered extreme or potentially dangerous tilting. No branches above. Planning on tacking some wood strapping vertically around the tree, sawing a small notch into the straps then running the cable around them. Tradeoff as to how high I attach to trees. Higher up means more of a vertical force where cables attach to platform but also means more tilting, less tree strength, etc. will have to look into lightning rod as well.
njlutzwe: definitely will be letting it hang with a heavy load for a day or two before I move up.
RE: Structural integrity of a hanging tent platform
Not sure what you are planning to do in that tent but I wouldn't guess it will involve 4000 lbs of anything.
A lot of times the "normal" framing size is needed so the floor doesn't feel bouncy. Being suspended like you will, I don't think that is a concern.
About that, (stable "feel") - If the cables are "straight out" (in plan view) I assume you mean they are basically 2 parallel cables. Seems like that will allow some side sway (like a swing). Nothing wrong with that. Just making sure I understand. In that case, I DEF would expect the cables to be continuous between two trees. Seems like the "connection" would be much simpler and the stresses placed on the wood framing would be much less complicated.
RE: Structural integrity of a hanging tent platform
If you haven't ridden a skimpy platform up in the trees in a strong wind, you haven't lived.
RE: Structural integrity of a hanging tent platform
http://www.metoliusclimbing.com/portaledges.html
Dick
RE: Structural integrity of a hanging tent platform
Maybe this would be close - http://earthsunfarms.com/Tree_Platform/
If it were me a fundamental element of my design would be that the wires going into the trees would go under the platform and "cradle" it. Seems like that would reduce stress on the platform and help prevent twisting and tearing. If it were me I'd design an extra solid square 6x6 frame, have the wires go under that and be positioned onto the 6x6 frame with heavy "U" bolts at the corners. Once they were all together you could tension or relax the wires to level the platform. Then designing the top wouldn't be any more complex of a problem than designing a free-standing deck sitting inches off the ground with concrete blocks under the corners.
For railings I'd use some left over sheep and goat fence, I've seen that on glamping setups and it actually looks acceptable and would be more than strong.
RE: Structural integrity of a hanging tent platform
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Structural integrity of a hanging tent platform
Screwman1: buying a portaledge would be too easy! But I do like the idea!
Thanks for all of the help!
RE: Structural integrity of a hanging tent platform
Wouldn't rely on a single bolt to hold the 6x6 frame together, throw some some addt'l hardware in there. Also, I'd use fender washers and double up the nuts with the 2nd one being a nyloc and tightening them against each other. If you want to get picky for press treated lumber you should use galvanized rather zinc coated hardware. You'll easily cut yourself fooling with cut braided metal cable/rope and I'd use something substantial like 1/2 or 5/8. Once the cable is threaded through the eyebolts you can level the platform and seize the cable with a pinching device at the eyebolts. Construction of any kind of platform desired with whatever lumber you like would be easy on a pre-hung frame.
Anyway.........
RE: Structural integrity of a hanging tent platform
Not comfortable with the end condition for those eyebolts.
Lots of eccentricity too (relatively speaking).
Seems like tear-out would be a problem.
treeclimber -
I have three words of advise: free body diagram
RE: Structural integrity of a hanging tent platform
Also thought that running the cable through the beams might be ok but would rule that out due to the same problem with the eyebolts. Hm, I could see any variation of what anybody has mentioned being fine and holding three people for years and then the whole thing being crushed like it was made of toothpicks in heavy winds...
RE: Structural integrity of a hanging tent platform
The real question boils down to understanding what the actual forces are.
That's why I say free body diagram will be essential here.
Totally agree with treeclimber's reply, "store bought" would be too easy!
Looking forward to pics of this!
RE: Structural integrity of a hanging tent platform
Earthsuntech-
Thank you for those diagrams-- very helpful to visualize. "Crushed like it was made in tooth picks in heavy winds"-- maybe I'll have to relocate during storms or maybe that's part of the thrill of being alive!
I'll be back at the land in a little over a week and can get a better idea of the tree orientation I'm working with so I can make a wire cradle work. Will start constructing shortly thereafter-- pics to follow!
RE: Structural integrity of a hanging tent platform
http://earthsunfarms.com/Tree_Platform_2/
RE: Structural integrity of a hanging tent platform
RE: Structural integrity of a hanging tent platform
RE: Structural integrity of a hanging tent platform
RE: Structural integrity of a hanging tent platform