Monday, September 27, 2010

How to build a tree house - supports

The next step is to install the 6" x 6" x 10' posts to build the upper levels on. You may need some help with this step as these posts can be very heavy. I used recycled posts that had already been in the ground as a retaining wall for 15 years so I did not want to direct bury them. This ought to keep them solid for at least another 20 years as they should not have direct contact with moisture and they can completely dry out after every rain. I screwed a heavy-duty plastic base on each post that has a hole for the rebar to go through in the middle. This elevates the post off of the concrete to further extend the life of the wood post. Some people choose to bury their posts in the ground with concrete around the posts. I did not want to lose the extra 3' of height and wanted to avoid the posts being in contact with constant moisture in the ground.

If you look closely you can see the plastic bases on top of the concrete footing. I used the future deck boards to hold the posts vertical as they were going up.

We built scaffolding levels as we worked our way up so that we had a safe place to work from. We used the future deck boards so that we were not having to buy extra lumber.

It took us two levels of scaffolding to get up to our 10' high deck level that the tree house will sit on.

The permanent floor joists are bolted in place with 10" x 3/8" bolts. Consult with your local hardware store to see what kind of finish is needed for the bolts with the kind of treated wood you have in your state. For ACQ wood you need galvanized bolts, washers and nuts.

As we build the deck level and the posts become more solidly locked together, the support boards below are removed and used for the upper deck.

The deck is almost finished and the upper deck is bolted to the tree in two locations for stability. We decided to build a lower level because it was such a cool space below the deck.

The deck is complete with 2' cantilever at each end for a total deck space of 8' x 12' Notice how we decided to add diagonal 2x4x10's to make sure the upper deck was solid as a rock. It was pretty safe before the diagonals, but I wanted to make sure that nothing would move once the house portion was added on top of the deck. The diagonals made a huge difference.

Quite a view from up here! 10' is really high. This represents about two weekends of work.


  1. Good afternoon! I'm curious if you finished your treehouse and if so, can you post some pictures? Thanks!

  2. I love how you did this without ever having to damage the trees. It looks pretty great in it's surroundings too! Nicely done!

  3. Hi there! I work for a tree house company called Blue Forest, we have just started a tree house competition and would love you to enter your tree house. It is just a bit of fun, if you are interested, just click on the link and upload a picture... You never know you may win!

  4. Hi. You did a great job I liked your website and your posts. Wish you all good luck.
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