How do you build stuff in trees? Part 2.
How, but also Why.
I wrote Part 1 exactly a year ago and I’m currently helping Jay with a treehouse on his property in the Sierra Nevada mountains, so it seemed fitting to finally revisit the topic.
I won’t get too deep in the weeds on how-to. I’ve dabbled, but I’m no professional treehouse builder, and pros have written comprehensively on the subject. But, I figured I’d address the more common questions I get from folks unfamiliar with in-tree construction.
Why?
For me, it comes down to:
No foundation digging.
More whimsical.
Even a little elevation is fun and for smaller builds on uneven terrain, the firm footing of healthy trees is easier and more exciting than moving earth or installing posts.
How?
The proper way to build in the trees is to use Garnier Limbs (GLs), otherwise known as Treehouse Attachment Bolts (TABs). (Though for some very light-duty projects, you can pair oversized lag bolts with treehouse hardware.)
The exact application of GLs, along with the beam they hold, or additional braces and supports, will vary according to your project. To install a GL you’ll need a big drill (I’ve used a Milwaukee Hole Hawg, and its cordless variants), an auger bit, a forstner bit (or a specialized 3-in-1 drill bit), a torpedo level to keep the drill bit level, and a pipe wrench to thread the GL into the tree.
What happens when the trees grow?
Trees grow from their tops and out from their center, so an anchor placed at head height will always be at head height. The trunk will eventually grow out and engulf the anchor, but the correct hardware allows for decades of growth and is meant to strengthen as the tree grows around it.
Trees will move, however, and that has to be considered. Floating brackets are used when connecting to multiple trees or branches to allow trees to sway without stressing the structure.
Doesn’t this hurt the tree?
Not really.
In a technical sense, of course, poking holes in a tree isn’t a good thing. But doing so lightly and with care is minimally invasive. Select trees that can carry the load and install your GL cleanly, and the odds of you harming the tree are fairly negligible.
This is a good time to point out that you can hire pros for this stage of the build. If you feel competent in construction but are worried about anchor strength or tree health, you can bring in someone like Michael Garnier to ensure you’ve got a trustworthy platform to build from. That’s what Foster did with his treehouses.
Also, if you only need assistance with project planning, Michael offers design services. Just send him your tree layout. Which brings me to the next question…
How do you measure trees to create a design?
If you’ve just got one or two trees this is less of an issue, but the question comes up when there’s multiple trees to choose from.
The way to map trees or limbs is by measuring a bunch of triangles and logging those measurements on a rough drawing—aka triangulation.
Pick a starting tree and string a tape measure (or shoot a laser) from it to other trees. Continue measuring between all other trees while also logging their approximate diameters. Take as many measurements as possible. The more you have to work from the more you can be certain that your drawing is accurate.
Back at home, use a ruler to redraw your sketch to scale, or mock it up in Sketchup or a similar program. Add the radius to the distance between trees so that you are working from a single center point within the tree to create your map of triangles.
By checking against all your various measurements against one another you should be able to lay out the position of each tree within an acceptable margin of error. I find that even with all the guesswork, I’m rarely off by more than a handful of inches. Plenty good for project planning.
From there, it’s a matter of playing with anchor points and beam spans, which could support the structure you’ve got your eye on.
How do I get up there?
Depends on the height.
For the high stuff you can build from ropes and/or temporary access cables, but that’s going to add a significant level of difficulty.
The better bet is to work from a temporary scaffolding that’s screwed into the tree. Or from ladders. Both of these likely limit your height to 20 feet or so, but that’s more than enough for a good time.
Just be sure to tie off your ladders and use safety ropes when working from them. Standing on a ladder may be easier work than hanging from a harness, but it’s also a surefire way to take a fall when the drill bucks in your hand.
How do I make things level?
I like a laser level for projecting a flat line across a group of trees. But when installing hardware on two sides of the same tree (or if you don’t have a laser level) you’ll want to use a water level.
Will it be strong enough?
A Garnier Limb can hold 3000-8000lbs, depending on the model, the tree, and how it is supported with additional hardware.
Your basic platform might only use a few GLs with beams screwed to a bracket at the end of the perch.
A heavier treehouse that requires additional support might use a GL fixture with a knee brace.
Or a cable supporting the end of the GL’s perch.
Or an even more complicated system of custom metalwork.
All that’s to say is that small builds can be fairly simple and incredibly strong, but the rabbit hole goes deep if you want to scale up.
If there’s any question that your load might exceed the capabilities of the GLs, you can talk with an engineer, or ask the folks who sell the hardware. I know Michael Garnier is always willing to answer questions and assist on projects, as is Pete Nelson, and other talented builders. Many of whom attend Michael’s treehouse industry meetup every year. I’ve found treehouse construction to be an enthusiastic-to-share community. Probably all that whimsy.
Holler if you’ve got questions. Happy to help.