at least not yet... This is my first treehouse as a 'pro' (meaning I am hired to build it for a customer) and I'm building it out of metal, suspending it from cables in the upper branches, and a crossbar in a crotch. The second story may be more of a 'multi tree' design using GL type hardware though there will probably be some cable suspension.
This is a single tree design, two stories, the first at 12'-26' is about 15'x30' in a sort of artist's palate shape, with the tree poking through the hole in the middle.
For some reason I find knee bracing and ladders too be unattractive so I am trying to avoid using them, and accessing the platform via a 60' suspension bridge. Actually it is sort of two 30' bridges, there is a tree in the middle, but it only supports one side of the bridge.
The platform moves a lot, it is easy to set the whole thing swinging just by shifting your weight like you're on a swing. The middle crossbar is going to slide around on 1" of UHMW plastic
The cable is 5/16 (and some 3/8) EHS cable rated to over 10,000 lbs. The 7/8 turnbuckles are the weakest link, rated only 7200. The cables attach to the limbs with wedge grips, (with extra wedges so they sit flat on angled branches) and sometimes angled thimble eyes. I estimate the whole treehouse will weigh in at less that 7,000. There are at least 12 cables holding it up in addition to the middle crossbar.
The steel is schedule 40 1.5 in. pipe, notched and welded with a mig welder run off a generator, as it's nowhere near electricity. The whole thing is being constructed in the tree in wind, snow rain, and temps in the teens this week... brr... It's sleeved in 2" pipe at the joints, though will use internal sleeve for handrail, which I am starting next week.
I've been working up there in some pretty major winds and though the platform dances and undulates I haven't seen any evidence of welds cracking.
The pipe is bent using a greenlee 882 fliptop bender, an electric/hydraulic unit small enough to be used in the tree.
Everything is skinned with expanded metal mesh. Maybe covered with some kind of removable mat in the future. I'm trying to keep the it supported at least every 2'.
So far, I've hung cables for the bridge, and the first platform is skinned and ready for a railing.
I'd like to post some pictures, but haven't figured out how to do that.. maybe once I post this I will see the 'attach a file' link..
Haven't seen any mention of angled thimble eyes, has anyone used these before? They are basically made for zipline, etc. industry. capable of supporting almost same weight as cable, but at a 45' angle to the bolt! They seem perfect for what I needed. I've found them in lengths up to 18".
I am mainly an arborist but majored in sculpture at college where I learned to weld and build large outdoor sculpture with recycled material.