The Treehouse - Finishing the floor
With the floor joists finished, it was time to lay down the rest of the plywood. The middle board had been simple, no trees come up through it, luckily, but the two end pieces needed to be cut to fit around the trees.
You can do this by cutting a cardboard template around the trees, then using it as a stencil to mark the plywood before cutting it with a Sabersaw. This is how I did the front one, shown here. Or you can just measure very carefully from the edges to the tree and transfer those measurements to the plywood, before cutting. That's how I did the one on the other side in the second and third pictures on this page.
The second picture shows the trapdoor on the other side of the platform.
Third picture shows trapdoor open. Note that it is cut to overlay joists and spreaders on all sides so it's a solidly supported and walkable part of the floor when closed.
Be sure to leave a couple of inches of room around the tree so that the platform can move a bit if it needs to.
Once the floor is installed, give it a couple of coats of good wood protector.