I have a 15 year old maple near my garage that's an ideal location for the kids and is already used as a "climbing tree". We just took down some lilacs underneath it which opened up access. One of the lilace was choked out from sunlight, and the other was actively migrating toward the driveway...
So, this tree is subject to some significant winds at least a couple of times a year and we have list large sections of nearby trees. This one had something happen when young and is growing up in a triple trunk split. The trunks are ~7" at 6' high, which is where i'm planning to make the platform. With this above a mulch bed, any falls shouldn't lead to hospital trips...
I've looked at the treehouse mounting bolts and things like https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/pie-in-the-sky-a-treehouse-build/141173/page1/ covered (which was my initial leaning). But this is probably going to be a triangular or hexagonal platform without the additional weight of walls, roof, etc.
I have seen a lot less about using eye bolts and cables to suspend a board or platform, as long as there's room for the cable to hang with a vertical load and not rub the trunk. I think this will also allow for easier leveling (using turnbuckles).
For the TAB type bolts - it seems like it would have less motion. But movement of the trunk could potentially break a bolt or bracket... or cause the platform to come off of the bolt.
For hanging using cable, more platform movement (maybe even causing the platform to strike the tree trunks? maybe just 'unsafer' to be on top of? and steel cable could be a poking or rust hazard for kids?) seems to be the main downside. The biggest plus for me is that the platform could not fall off a single mounting pin this way and it allows for more dynamic movement.
This is the tree.
Marked here is roughly the height (~6' and width (not over 8') I plan for the platform. I'm thinking central 4x6 supports (for stronger eye bolt installation) then additional 2x6 framing and likely plywood decking. My initial plan was Trex-type composite decking for weather resistance, but plywood has strength in multiple directions.,
I'm planning to leave about 3" of free space around the trunks, and have the decking cantilever so that it can be cut back later if / when needed.
Thoughts? Is this a really stupid idea? When I priced stainless 3/4" threaded rod (which is what I was planning to use as "through" mounts with a metal sleeve and bracket under boards) it was pricey and I think more damaging to the tree than single point of entry eye bolts.
This view is looking at the side where I would have a ladder attached to the edge rail and "float" on the mulch bed.
