The Treehouse - Setting the joists
With the frame up in the trees, the next job is to drop the remaining joists into the joist hangers on the headers. Each joist gets fastened diagonally through the hangers and into headers on both sides with four 2-inch galvanized screws.
Now, you're wondering, how do you attach the floor frame to the main supports? You don't. You want it to be able to move a bit if it needs to. But this is a heavy thing. It will firmly resist moving on its own. And once the plywood floor panels are down, with only tree sized holes cut in them, that will also limit it's motion. You might think about cabling loosley from one joist to another, around a support. I may still do this, but I haven't yet.