A Brace of Braces

For the past five weeks or so I have been putting in a lot of work helping Jeff out at H2O Composites building canoes. I was working roughly 4 or 5 days a week 9 to 3, then at least 2 or 3 evenings 7 til midnite or so. So finally this weekend I got the second support brace installed, and pulled away the temporary support holding the main platform up. These two braces were fairly fussy, as I had to cut a couple of compound cuts by hand with the chainsaw to fit them in place properly. I still have to trim them slightly to improve their fit to the angled beam holding up the four floor beams, and after that I plan to install an additional cabling system for support. It is nice to see the treehouse up and supported the way it is meant to be. If you take a look at this photo and compare to one in the previous post, you should notice quite a difference with the temporary support removed.

Deck Foundation

As most of the deck of the treehouse will be hanging out to one side of the main support tree, I had to figure out a way to support it using the tree itself somehow, and not resorting to additional support posts. The simplest and most evident manner appeared to be using a single main 'outrigger' beam to provide support for the four floor beams away from the tree. This beam would then be supported by two angled brace posts which would then be attached to the trunk of the tree very clost to the base. I decided that this support should be angled in the same direction as the support posts, pretty much 45 degrees from vertical. I constructed four small angle blocks to support this beam (one block for each floor beam supported by it). In addition, I cut a small 1-1/2 inch notch in each floor beam to accommodate a very secure attachment of the main beam to each of these floor beams. Check out the pictures, which shows the detail very well!

Uncle John's Tree House

While we were up at the cottage on March Break, John decided to repair the tree platform he had built for his children about ten years ago. It was a great time to get together for a beer, do something fun and useful, and let Rudi play with his cousin Natalie for a while. The platform was robustly built off of two white spruces, with a step ladder up, railings around, and a slide off the side. Although it was very well built, It was not designed with a foundation system that would accommodate the growth of the trees, and of course these two little trees packed on quite a bit of girth over the course of their lives. His goal was to rebuild the foundation in a manner that would accommodate all future growth of the trees without causing any futher damage to either the platform, or the trees.

The original foundation was incorporated into the floor joist framework, and consisted of a rectangular box built around the two trees. Over the years, the trunks grew outward into the box, and eventually pulled the box apart. The new foundation consists of two 2x8 beams that are lag bolted into the trunks, one at the front and one at the back of the trees. The joist framework that supports the floor deck now simply rests on these beams, and the beams are free to slide under the joists as the trees grow. The first and second pictures show the right hand tree, along with one of the old floor joists, as well as the two new main beams underneath. Notice on the trunk the depression left by one of the (now removed) 2x6 joists making up a portion of the foundation. The third picture shows both main trunks, as well as the front main beam, two existing floor joists on each side of a new 2x6 floor joist we installed.

Winter Damage

Winter arrived with a fury, and unlike many over the past years, once the snow arrived, it stayed. A week after the first snow, we got dumped on with about 3 inches of wet sticky stuff, which is generally not good for my spruce trees, as it overloads the branches, and in some cases can snap them off

This time around, the only tree to suffer any damage just happened to be the larger of the two trees that I am building the treehouse in, which annoyed me because now there are some openings left in the canopy, making the tree look a bit like a vagrant with missing teeth. I think perhaps when the treehouse building is up in the spring, the missing branches will be less noticeable. Here are a two photos showing the main foundation, draped with a couple of large fallen branches from the spruce. Not a particularly pretty sight!

Bits and Pieces

A few photographs of various parts of the treehouse described in the previous post.




This is a shot of the cantileverd deck edge, with the new 2x8 end beam in place. This was the one that had to be cut at approx 65 degrees, and spans the three deck beams. Lots of fun chalking, guesstimating, cutting, and fitting to get this baby in!




A view from underneath, showing one of the pair of main beams bolted through the tree, two of the deck beams running perpendicular to the main beams (at the extreme left and right of the photograph), and some of the 2x6 floor joists which run in the same direction as the main beams. Note the joist hanger and crossjoist which had to be installed to support the floor close to the tree itself.





Finally, a close up of one of the two sheet metal sliders fastened under the main beams that rest on top of the wooden bracket on the smaller tree. The main beams will creep back and forth across the bracket when the wind picks up, and these metal strips will hopefully reduce the friction and wear on both the beams and the bracket.

Engineering or Art

Yes. Neither. Both. Hey, does it even matter? The following two photographs show the custom wooden bracket attachment to the smaller tree (note the spreader block installed to keep the longer clamp blocks from snapping as the bolts are tightened), and the simple 3/4 inch through-bolt attachment to the larger tree. Evidently the bolt will break at around 14000 lb under tension, so I am guessing there shouldn't be a big problem holding the treehouse up. The wooden bracket on the other hand...... In the spring, I will want about a dozen male volunteers to climb up and walk around the treehouse in a group, and if it doesn't fall down, I thnk it will be fine!

Slow and Steady (Wins the Race?)

Got back to construction after getting a few other home improvement projects started or finished as the case may be. The four floor deck beams that will support the floor joists under the main treehouse have been put in position, and fixed in place with metal framing flanges. It took quite a while to figure out how best to locate and fasten them, since the twin main beam supports will constantly move away from one another over time. The tall sawhorse support is temporary, and will be removed as soon as the permanent support fixed to the tree trunk is designed and installed. I am mulling over a few different design options, as this single brace will have to support a large portion of the treehouse deck frame, which will extend out approximately 10 feet from the main tree. I have finished the design of the staircase which will rise around the smaller tree to a landing platform there, and hope to begin building those, and the platform next week sometime.

Construction Begins!

I imagine there are some of you out there who, for one reason or another, think that I am all talk and no action. I won't claim that this is nowhere from the truth, but I would more realistically describe myself as all talk and a reasonable amount of action when required! On Saturday the 23rd of August, the main support frame went up, and on Sunday, the final adjusment and tightening was done, and it was stained. Have a look! I am very happy with the results, as the beams are completely level and edges upright, and the two main beams support easily my weight as I walked across from one tree to the other to test them out.

Research and Planning

I think I have had sufficient time to research treehouse design and construction. Over the last 6 years or so, I have read (and re-read) about six books completely dedicated to the subject, and more recently visited a number of websites as well. In general, the information I found was very useful, and has certainly cleared up any misconceptions I may have had about the best manner of construction.

It seems the two most basic rules of treehouse construction are to keep potential injury to the tree to a minimum, and to make sure your design accomodates future growth of the tree.

A treehouse should be attached to the tree with the least number of connections (threaded rods, lagbolts, brackets, or wooden clamps) as possible, and these connections should be large enough to easily support the load of the treehouse and its visitors.

With respect to future growth of the tree, any attachments must be designed in such a way that the year by year growth of the tree doesn't end up breaking the supports or "foundation" or pushing the frame away from the tree.

The design I finally decided on will use two trees, the first for a small platform, and the second around which the treehouse will be built, with a walkway between them. This means that the main support frame fixed to the trees could not have a rigid connection. If you look closely at the picture in the next post, you will see that the main support frame is bolted directly through the larger of the two trees, and then just rests on a wooden bracket on the smaller tree, and can slide back and forth as the trees move in the wind.