Tree House Construction
I have clearly stated in a number of places on this web-log that this is not a how-to site, however, since there has been so much interest in tree houses on this site I wanted to include some construction notes. In keeping with the spirit of this site these notes are put here to inspire creative thinking. Please see the observations below and bear in mind that you are responsible for any construction project you undertake.
The two types of construction represented here are examples of two extremes. One represents a timber frame structure that quite literally hangs in a tree and is extensively over built to support the huge tree house my friend Peter Built. The other is a simple backyard tree house that is built using two trusses that are bolted directly to the tree.
Since how a tree house is attached or suspended from the tree is clearly important, allow me to make a couple observations:
First off, if you are really concerned about whether a given tree can support a tree house, you can always do what many people do and build the structure on stilts supported by footings in the ground. If you are thinking about this method, my advise to you is to check with your town building code first. Some towns will not ask you to meet the letter of their building code if a structure is actually built in a tree, but will make you comply with all building codes if a tree house is supported from the ground.
Second, if you are at all concerned about your design, there are quite a few people who design and build tree houses for a living, and you can go that route. I have included some links at the bottom of this page. Further, there are some how-to books out there as well. The ones I have seen are a bit limited, but they are still a resource worth looking at.
Third, it is generally accepted that you can put fastenings directly into a tree without endangering the health of the tree. However, if you have concerns about the health of the tree check with an arborist, many will give good advice a little or no charge.
On to construction notes:
The construction of Peter’s Tree House is completely illustrated in his book Treehouse Chronicles, so I will not reproduce everything here, but I did want to point out three really unusual features.
When Peter Nelson visited and took pictures for his next book about tree houses, he was blown away with how the tree house is suspended. He kept commenting on how unique it is and said that it might be “one of the most unusual” tree houses he had ever photographed. If you do not know who Peter Nelson is, then you just are not that into tree houses.
This is what impressed him: the size of the tree is so great that there is a massive fork in the trunk about thirty feet off the ground. At the fork the trunk is five feet across, three large pieces of flexible PVC pipe were placed through the fork and cables run through them. The tree house is hung from these cables.
The second unusual feature is that the tree house is built using timber frame construction. This added a new dimension to the project because we were able to get Tedd Benson, who is a hero of mine, to write the introduction for the book. If you do not know who Tedd is check out his blog here:http://teddbenson.com/ or you can check out BensonWood Homes at BensonWood.com which is a company that I think is way ahead of the times combining energy efficiency, in many cases recycled timber, and the best of timber frame construction. As I say, Tedd is a hero of mine and getting to work with him on this tree house book was and unexpected delight.
These two illustrations show how the timber frame went together. and the photograph illustrates how all the pieces were cut and assembled on the ground. The parts were then numbered and taken apart so that they could be hoisted up into the tree and re-assembled. The illustrations and photographs from Treehouse Chronicles and are reproduced here with the permission of the publisher, TMC Books.
The third feature I wanted to point out is that the curtain walls that fill the spaces between the timbers needed to be both light and strong, at the same time we wanted them to look like conventional construction. So, instead of wallboard for the interior finish, we used one-quarter inch Luan plywood and instead of using conventional joint compound for the seams, we used automobile bondo. The bondo is stronger and more flexible and is much less likely to crack as the tree house moves in the wind. Somewhere I have a photograph that Peter took of me in my coveralls wearing a respirator and safety glasses and slathering bondo on seams, but I can’t find it.
The second tree house I wanted to feature is one I wrote about building with neighborhood kids in the post “More Treehouse”.
This one was designed to have two pre-fabricated trusses (called “girts” in the drawing below) that were bolted directly to the tree. Floor joists were set on the trusses and a three-quarter-inch plywood floor set on the joists.
The framing was conventional two-by-four and sheathed with tongue-and-groove pine boards in order to maximize the number of kids who could be pounding nails at once, as I pointed out in the original post.
If you are looking for resources check out these links:
The tree house guide, a source for tree house plans.
The book Treehouse Chronicles