All About Tree Houses

Whether to attach a Yurt Treehouse to Trees or Use Posts

Posted on September 27, 2009 with No Comments

Question From Peter:

“I’m thinking of using 4-5 trees as supports for a 12′ yurt platform. The platform would be only 1-2 feet up from the ground and placed on 2 (very) roughly parallel beams attached to 4 trees (each between 2 trees), with possibly a diagonal beam additionally attached to one of those trees and extending to a fifth tree (for center support).

trees, measurements, and treehouse platform layout

The distance between edge of platform and bark of tree would range from about 6 inches to 5 ft. (if there’s a center beam) or 3 ft. (if there’s not). I’m attaching a site diagram, for your reference. I believe the trees I would be using are pines. Their trunks are between 1 and 1.5 feet in diameter at 1 ft. above the ground, and they are very tall. It looks like their foliage is in the top third.

My questions are these: (3)

1. Would there be movement to worry about that close to the ground? If so, should I use fewer trees and partially support the platform from the ground?

2. Should I support the platform from the ground, regardless of how many trees I use?

3. While I am aware of hardware options, my preference is to use slings and/or lashings to attach the beams to the trees, with a layer underneath the straps to protect the bark. I would take down the yurt and platform on a yearly basis in order to adjust the straps, but otherwise, they would stay up year-round. When I’m gone from the site, I would remove the beams from the trees. Would this work? I’m aware there have been efforts to build treehouses without hardware, but can’t seem to find info about this on the web.”

Thanks for the questions, Peter, and I’ll tell you what I think.

1. If I were you, I would place several buckets upside down around a sample tree in the stand where you will build the treehouse yurts. Then place small boards on top of the buckets so that they run tangentially to the tree around it and are only about a half inch from the bark. Then go out there on a windy day and watch/measure how much the trees move at 1 foot high. They will certainly move, but I don’t believe they will move enough to affect your decision of what type of treehouse attachment to use. The principal is that the lower to the ground you are, the less the trees will move. However, what little movement they make becomes more difficult to stop due to leverage. Even if you theoretically could stop that movement, you might not want to because it will interfere with reactive root growth which strengthens the tree. Typically, I would use a floating bracket for attaching the treehouse to traditional fasteners like garnier limbs, but this is leading into your other questions.

2. If tree friendly construction is your primary goal, then you should consider using 100% ground support instead of attaching to the trees or using removable slings. The holes will damage some small roots, but with careful digging, this damage will be far less than penetrating fasteners. Either way, don’t forget that foot traffic around the treehouse during and after construction is often a much greater threat than using penetrating fasteners. I’ll also mention that you are diverting rainwater that would otherwise fall under the treehouse yurts and affecting where needles will build up over the years, but these issues are not as important as the above.

3. Some Japanese treehouse builders in the late 1990s did not want to penetrate the bark with fasteners, so they used large clamps. I understand that this practice has been found to do less short term damage, but more long term damage to the trees. Plus, it’s hard to get the clamps tight enough not to slide down the tree under the dead load alone… If you are committed enough to sling and resling the trees every year, then it might work out for you that way. Several arboretums in the Philadelphia area have held treehouse building events in the past few years and all of them had rules about not penetrating the trees. In my opinion, some of the non-penetrating methods were more damaging to trees than our normal practice of penetrating. If you go this route, please spend the extra money to get larger, wider, tree saving slings. These will have a greater bearing surface on the bark and will be less likely to cause grooves under the sling. They will also have higher load ratings so they will last longer when left out in the rain & UV. The primary concern, in my mind is that you are making regular work for yourself this way that may not get done enough, or that the slings may do surface damage to the bark a little bit at a time, especially while being taken down and reset, regardless of how careful you are about it.

Please leave a comment here after you consider all of your research and decide what to do. We’d also like to see a picture of your finished treehouse yurts! Thanks, and happy treehouse building, -Dan Wright

I “Pinned” my Treehouse Beam. Now What?

Posted on August 4, 2009 with 2 Comments

Question from Randy, Milford, DE:

“I just “finished” a treehouse for my kids and while looking around on the net, came across your site. After reading over it, I realized that I made a cardinal error and “pinned” one of the support beams to the tree. It is a large Oak and I have a 2 x 12 lag bolted to it with about three 6.5” x ½”. The front half of the treehouse platform is supported by two 2 x 12 beams bolted to two 4 x 6 posts. Obviously, the beam that is pinned to the tree will create problems in the future. Is there a “simple” solution that I could implement to save the tree from trauma and the house from falling down in the future? I can send photos if you would like.
Where are you located?”

First of all Randy, you are not alone. We regularly hear from people just like you who want to support their treehouse in a better way. There are multiple issues here that may be at play. It would help to see a close up photo or two of the area where the treehouse beam and tree connect, and it would help even more if you hire us or a local arborist to inspect it. Sometimes, we see things in person that are not noticed or describes over email/photos.

Options:
1) You can leave it alone and keep an eye on it. It might be okay for a while, and if the tree is growing around the beam, and doesn’t appear to be suffering too much, you may decide to let the tree deal with it. How valuable is your tree? $1000? $25,000? How much did your treehouse cost you to build?

2) You can hoist or jack the treehouse up, detach the beam from the lag bolts, and install a larger fastener such as a garnier limb underneath the beam, and then set the house back down on the larger fastener. This runs a risk, because you already made 3 holes close together, and now you’re adding another one only a few inches below. This is a good move if the wounds in the tree do not coalesce. You could also choose to raise or lower the whole treehouse to prevent the wounds from being so close together.

3) You could permanently suspend each side of the treehouse beam to points higher in the tree. Make sure you are comfortable with cabling and working at that height, and use cable that is rated for at least double the total dead and live load that will be on it. The advantage is that the new wounds will be far from the other ones. But it does mean working higher in the tree, and attaching loads higher in trees means more sway and possibly greater chances of storm damage depending on how high you go up.

4) Your backup plan, if the tree is suffering and #2 or #3 won’t work or the risks aren’t acceptable, is to add two more posts near the tree and a new beam. When you remove the old beam, if possible, don’t remove the lags that go into the tree unless they are loose in their holes. You may cut them flush to the outer bark if desired.

There may be other options or considerations that will come to mind if we can see the tree and treehouse, but we’re likely to choose one of the above.

Welcome to “Ask the Tree House Experts”

Posted on June 20, 2009 with 1 Comment

We plan to use this category to answer all Tree House Questions that you have. Please leave a comment here with your question or email to treetopbuilders@verizon.net. We will then respond publically to all relevant tree house, tree platform, or tree house accessory questions. We are experts in attaching things to trees, and so we probably won’t answer questions about general construction or trees unless we can answer the question in a way that would be interesting to other readers looking for tree house building information.

For Quick answers to common questions, please check out this tree house questions page. Otherwise, ask away and we will respond for everyone to read…