The T-bracket is used to hold a spreader beam, to enable width at this end of the treehouse while mounted in a single tree.  The farther you cantilever out past the horizontal member of the bracket, the vertical member of the bracket needs lengthened correspondingly.  At the other end of the treehouse, the floor joists are supported by two beams that are attached to each tree, using the Garnier Limb in the tree with the Floating bracket mounted on the underside of the beam. We don't use Joist Hangers. Instead we stack the joists on top of the beams which is much stronger in this type of structure. 

Here the beam is setting on a GL in the center and supported on each end by a knee brace, which comes back to a GL at the tree on each end. Using this 3 point support you can extend out past the tree greater distances.

This platform is attached to three trees using a T-bracket and two GL's coupled with a Floating bracket.

When you have four trees, this is a simple, good method to use  Each beam is hung from two GL/Floating brackets. It is a good idea to leave the beams and joists long until you have figured out the floor/decking  plan entirely. Nuts with washers can be added to the GL's to control walkoff.

This is a double deck with four GL's supporting each level. Built in China using local labor and materials in 1999.

Here we are doing, on the ground what we will be doing in a single tree.  In the 20" + tree this  platform  is going in, the GL's have to be staggered in height to keep from weakening and girdling the tree. Some being above a particular beam and the others being below in the traditional method of attachment. Also Care has to be taken to be sure the GL's are level or slightly downcast to promote drainage.  However many GL's are used one must be sure to divide the angles evenly around the circumference of the tree.  Plans and parts will be available at a later date.

Theese GL's are rated  4,000 lbs. at 2" out from where they contact the tree.  Here the platform goes out 6 feet and the GL extensions are attached with cable to 2 more GL's higher up in the tree.  A person standing out at 6 feet can make the GL fail if it is not guyed up. The bottom two strands of cable that hold the bridge planking are connected to 2 of the GL's that are supporting the platform, right next to the tree. For bridges up to 30 feet this is all the support needed. This bridge is 90 feet and is suspended from two catenaries . This undertaking is not advised without the help of an engineer.

This platform was built in Florida and we were able to get a building permit. It is 300 sq. ft.  I have 30,000 lbs of water in the barrels. When you build something like this you have to figure, how many people could get on the floor and a bounce factor has to be added as well. Here again, Engineered plans are a must for safety reasons.