As most of the deck of the treehouse will be hanging out to one side of the main support tree, I had to figure out a way to support it using the tree itself somehow, and not resorting to additional support posts. The simplest and most evident manner appeared to be using a single main 'outrigger' beam to provide support for the four floor beams away from the tree. This beam would then be supported by two angled brace posts which would then be attached to the trunk of the tree very clost to the base. I decided that this support should be angled in the same direction as the support posts, pretty much 45 degrees from vertical. I constructed four small angle blocks to support this beam (one block for each floor beam supported by it). In addition, I cut a small 1-1/2 inch notch in each floor beam to accommodate a very secure attachment of the main beam to each of these floor beams. Check out the pictures, which shows the detail very well!