That is a tough question. First of all you have to establish a platform in the trees that you will be using for the floor. We used a lot of “found’ materials for the tree house (old rafters, siding and deck boards). Finally we used saplings for the balusters on much of the railings. These items added to the cost substantially. I think that the tree house cost like $70,000.00 and took about five months to build.

There are all kinds of things that one could do to simplify the project. We worked under an architect that provided sketch plans and then we interpreted them to use the materials and spaces we had. It was a great project!
Hope this helps

$70,000.00