treehouse
I have a nice tree in my backyard, the base is easily 10+ feet in circumference.
I want to build my son a tree house. More correctly I want to build a tree house with my son.
I was wondering if there is a good site with suggested plans. I am not entirely sure how to tie into the tree trunk, in terms of the trees health and whatnot.
The first branch is 30+ feet up, so it would be just around a nice clean, cylindrical tree body.
The Treehouse Guide is a pretty comprehensive resource. It covers topics from picking out the tree to building code adherence.
You certainly won't want to just sit the beam in the fork of the tree. The tree will move quite a bit and you'd slowly wear through the bark and damage the tree if you do that. Also note that forks aren't always the strongest part of the tree.
What you want to do is have the beam mounted to the tree with hardware that a) allows for lateral movement and b) is offset from the surface of the mark.
They make special hardware just for this. It's typically a huge lag bolt with a spacer than the beam 'rides' in via a slip bracket. Example:
source: http://www.treehousesupplies.com/1_25_Floating_Bracket_p/br-f1.25.htm
Best Answer
A good design would be what @Tester101 suggested. Build a platform around the tree. On one side of the platform could be the tree house. Some examples are here:
http://www.buildeazy.com/plan_links_treehouses.html
There's a good picture of platform around a tree, now just imagine a bigger platform with a tree house on one side of it.