Alex's Tree House
When we moved to a forest in NE Missouri my son, Alex, who was six years old at the time, requested that I build him a tree house. I spent some time studying the different options and scouting trees on our property for just the right combination of size and spacing.
Initially I planned to build a platform in a single tree but found the construction required to ensure sturdy support was a little too involved/expensive. Then I thought about supporting a platform between two trees by attaching beams to the trees and then bolting the platform to them. This sort of construction is fraught with problems, mainly due to the movement of the trees in the wind and as they grow. Finally, after a lot of poking around on the web, I found some adventure travel companies' web sites that had some pictures from their forest canopy tours in Costa Rica and Brazil. I looked carefully at the suspension bridges they erected in the trees. This is what I needed!
Alex's tree house (well, platform, really) is a 4' x 8' platform that is suspended between two trees. I used chains to suspend it, which allows the trees to move in the wind without having much effect on the platform. The chains connect to the corners of the platform's 4"x4" understructure. There are a total of eight pieces of chain used. They connect in pairs so that the platform hangs from four chains with 4 additional chains under the platform to prevent it from swinging.
I was concerned about the safety of anyone playing in or under the tree house so I did some checking into the strength of the hardware that was available locally. In the end I selected hardware that was several times stronger than necessary just to be sure there would be no accidents.
I read a lot of sometimes philosophical stuff about how to attach tree houses to trees and it seemed that screwing into the trunk is accepted as the best way to go because it does the least harm to the tree. I bought eight heavy-duty (1/2" x 8") galvanized screw eyes and screwed them 8" into the tree trunks. This required predrilling the holes and then inserting a piece of pipe in the eye to get enough leverage to turn the screw into the 16" diameter oak trees. Since I was using chain to support the platform, there was no need to get the screw eyes lined up perfectly- I could simply vary the length of chain as needed to level the platform.
I used 1400 lb rated, zinc-plated chain to hang the platform, and lighter chain on the bottom to prevent sway.
I assembled the platform's under-floor frame on the ground, then stood it up on end and connected the upper end to the first tree. Next I lifted the other end and connected it to the second tree. Then I connected the chains on the bottom to stop the platform from swaying. Next I installed the plywood floor and added railings made from 2"x4"s. I sealed all the wood with deck sealer then, finally, I added a rope ladder and the tree house was ready for play time.
Yes, as you would expect, the platform moves a little, but the bottom chains prevent it from swinging more than about 1" in any direction. I could have used just two chains on the bottom, but it would have swayed a lot more.
I don't have a lot of pictures yet, just a couple I took during the install. I'll try to add some that show more detail when the weather warms up a little...
One end showing the attachment to the tree.
Alex tries out the floor beams.
Alex and his friend Mack shortly after completion.
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