Building a tree house with a focus on the well-being of the tree

My son wanted me to build a suspension bridge to our summer cottage. I liked the thought and decided first to build some platforms. Building a tree house is a topic with a lot of articles on the web. I’m trying to focus on a design that works in relatively medium sized trees and considers the well being of the tree itself.

Background

I’ve built a rope bridge before. It was on a scout camp with nothing to do and ample amounts of hemp rope and wooden planks.  It was fun and surprisingly easy. And as an added bonus, I got to hang around in an harness(?!)

Creation of my first rope bridge in 2013

However, this time I was planning to use wire and a suspension cable to actually make a proper suspension bridge. But before I could get there, I needed to make the platforms, the tree house itself where the bridge would lead.

Initial planning

I did some research on how to attach a treehouse to the tree. The main methods I found were:

  • Bolt the support beams directly to the tree trunk (usually using these special anchors)
  • Bolt anchors and suspend the platform from wires
  • Don’t attach the platform to the tree, rather use beams to support it from the ground.

My issue with all of these were either a) My trees weren’t big enough to survive the massive anchors or b) creating self standing platforms around trees weren’t the “real deal” in my opinion. So I started looking at how this adventure parks that allow you to climb these really high platforms attach them to the trees.

I found out, that using these shims that are spaced equally apart allow for the tree to continue to provide it’s roots with recently photosynthesized sugar through the gaps. Heavy beams are then compressed using threaded rods against the shims. As the tree grows, the installation becomes even sturdier. Note: the shims need to be impregnated wood to stay in place and not rot away.

So I did some sketches to help me buy the right material.

Building a tree house
Initial sketches of the platforms

Being a cheapskate, I was planning to mill my own lumber, but decided I’m not proficient enough yet.

The build

I started the build by attaching the impregnated 2″ x 6″ with two threaded rods on both sides of the tree. Then another set of 2″ x 4″ perpendicularly to the previous set. I had bought nylock bolts, and boy I have to tell you that threading them the whole way was quite a chore.

The first two beams were a bit flimsy and I wasn’t sure would the setup hold, but as soon as I attached the second pair of beams, it the whole setup sturdier in an unbelievable way. I was literally jumping on the beams from joy! My plan worked.

Building a tree house
Two of these modules were created and placed on the beams

Next, I built two of these modules pictured above. It was just a simple case of screwing 2″ x 4″‘s together and making some mitered cuts. I used stainless steel screws but the wood was just plain pine wood without any treatment. I’m not planning to make this a too permanent solution.

Modular construction
The modules being put in place

Placing the modules on the beams and securing them in place with screws, I then measured and cut the two cross beams that’ll be the sides of the hexagon. I carved slots to the main two-by-fours and mitered the ends of the planks. With a single screw to hold the end plank in place, the supports for the decking were in place.

Building a tree house
The carved slots in the main two-by-fours
Side planks
The side planks in place before tidying the ands
Side planks
Side planks fastened with a screw and excess sawed off.

 

building a tree house
The supports for the decking without the side planks in place
Beginning decking
The whole support structure in place, ready for the decking.

I then started the decking. Simply screwing in planks on the support, making cuts to allow for the tree to grow in the middle. I did the final cuts after I had attached the planks, so that the finished platform would be neater.

Building a tree house
Finished decking with the future user checking the site.
Decking
Mind the tree. I tried making the decking around the tree as neat as possible.

First thoughts

Built a tree house
The view from the platform to my initially planned counterpart.

I was then planning to which tree I should build the second platform to house the bridge. The first platform was built on a slope, so that I wouldn’t have to build any ladders, the natural inclination would allow the bridge to span to sufficient heights.

building a tree house
Second platform coming up. Notice the preliminary railings on the first platform.

I started building the second platform, but didn’t get very far when I realized, that the 6m in between the platforms would prove quite a challenge for my bridge. Three meters would probably just as cool for my kids and significantly easier to make.

So I scouted our yard for a better location for me to be building a tree house.

Disassembly and reassembly

I’m very happy about the fact that I spent some time designing the platforms, as dismantling it was a breeze. Reassembly was as well! However, since the decking was made for a certain width of a tree, it didn’t look that good anymore. I had to scrap some of the pieces and make some new decking planks.

I decided to forgo my “no-ladders” policy, and built the second platform on top of the first where the bridge would then start. This would allow me to make a bridge of approximately 3 meters to another tree.

Building tree house
New location for the first platform
building a tree house
The two platforms finally in place. The railings, ladders and bridge had to be left for next summer.

End of part 1

The summer ended so quickly. I managed to plan and install the two platforms. I still need to build a third and the suspension bridge is still to be planned. The kids love the lower platform already, I haven’t allowed the to climb to the top before I get some railings going on.

21 Replies to “Building a tree house with a focus on the well-being of the tree”

  1. Hi, could you provide pictures or more info on the shims you used against the tree in step 1 of your project here? Thank you for any info, Richard

    1. I was planning to use impregnated wood. Basically round fence posts that are split lengthwise into semi-circles and cut to approx 8″ length. The idea is like the following picture: img_1025.jpg

      1. Hi Helkkl,

        I love the platform and I am looking to create something similar in my garden. For the shims – are these secured to the tree trunk in any way before the beams are installed? Also, for the beams – are these supported onto the shims / trunk by gripping force and friction alone? Do the beams sit on anything or is it the gripping force created by the bolts which supports the platform?

        Thank you in advance for any info, Craig

        1. I used a nylon strap to secure them first around the trunk. Afterwards the beams are just friction/pressure fit to the shims.

          1. Thank you – I did see the note on the nylon strap on your sketch – looks great.

        2. Hi just about to start the tree platform project. I’ve gone m20 threaded rods and nylon lock nuts. What did you use to stop the threaded pole spinning whilst turning the nut

          1. Might be helpful, I found molegrips on one side useful for working at height when you only have the one hand free

      2. What’s the weightimits for something like this when Not Drilling directly into the tree though. 2nd do you think this is a safe idea for a platform 9′ in the air ?

        1. The method I’ve used to attach the platforms is widely used in Adventure parks (Zipline adventure parks(?)) and they quite often say that the weight limit they give is 120kg. Is this the weight limit of the platforms or the ziplines they have, I don’t know.
          So for a kids play, I’d say the platform won’t come down. Will the kids find a way to fall? I’m sure they will. I’m not even trying to make it fool proof, i.e. the smaller kids are only allowed to use it with supervision.

  2. A tree grows out, not up, so you must allow for future growth without choking the tree. The structure needs to be able to move independently from the tree and vice versa. Using an artificial limb (Garnier, or tab) would allow you to do so. Another way would be to suspend from a higher point using swaged steel cables. Helical cones are another option, but anyway. Fantastic work on the beam construction and the joinery!! It truly shows exceptional skill. Feel free to reach out if you want to talk tree house building, or just share ideas!

  3. Are there more parts to your build available? This is a great project, I was hoping to see how it all worked out.

    1. Still waiting for this summer to be able to finish it. Hopefully we get to leave the house due to covid

  4. Still waiting for this summer to be able to finish it. Hopefully we get to leave the house due to covid

  5. Following. I was looking for ideas to build my own platform using 3 tree limbs as the corners. This isn’t want I needed for that but it’s something I may do in the future.

    1. I’ve screwed them with slanted(?) screws to the 2x6s. And the two 2x4s closest to the tree trunk are attached with threaded rods just like the 2x6s

  6. Have you starting on the project?

    I love the idea. I am trying a scaled-down version to create a sitting bench. I am using shims made from the redwood 2x4s. The tree trunk is not round so I am having trouble spacing the shims. The tree is already full grown (about 12″ diameter). How tight are boards with rods?

  7. Hi, I borrowed the idea of this, but along horizontal branches near the trunk instead. It worked out pretty well.

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