At the time of writing, I’m building a treehouse in the garden for my little granddaughter. She’s at an excitement level of 11 out of 10. Like all things worth doing, it’s worth doing properly – but I’ve been worried about hurting the trees when I fix the treehouse to them – so I’ve been doing some research to avoid causing any lasting harm.
You can definitely screw into a tree without hurting it, and the best, safest, and least harmful way to fix a treehouse into a tree is to use a treehouse attachment bolt (TAB) and a floating bracket.
Let’s consider this process in greater detail, and look at what a TAB and floating bracket are, why you need them – and discover some simple steps for installing them.
How Do You Attach a Treehouse To a Tree Without Hurting The Tree?
If done with care and the right equipment, you can screw into a tree without damaging it. This is even the case when you’re attaching a large object like a treehouse.
There are two main rules when it comes to screwing into trees: only make as many holes as you need (in most cases, just the one), and never attempt to fix a treehouse to a smaller tree. The trunk diameter needs to measure at least 12 inches (one foot).
Trees are good at repairing damage to themselves (and yes, drilling a hole is a tree injury); however, we want to minimize any harm by making the least amount of wounds possible. At the same time, we need our treehouses to be super-secure before our kids climb up into them. How do we achieve both these goals?
The best, safest, and least harmful way to fix a treehouse into a tree is to use a treehouse attachment bolt (TAB) and a floating bracket. The TAB is a strong, specialized bolt for fixing treehouses, which reduces the need for lots of holes. The floating bracket fixes onto the TAB, and provides a secure base. We’ll look at both of these items in more detail.
What is a Treehouse Attachment Bolt (TAB)? (And Why You Need One)
The treehouse attachment bolt, generally referred to as a TAB, is a single bolt designed especially for fixing treehouses to living trees. It’s incredibly strong (when fitted correctly), taking between 9000 and 12000 pounds in weight.
Importantly, the TAB is designed to work with compartmentalization. This is the tree’s natural healing process. When it receives a wound (in this case, a drilled hole), the tree protects itself by forming a “wall” around the affected area. This single hole reduces multiple compartmentalized areas.
The TAB also allows for the tree to continue to expand its girth, which it does throughout its lifetime. A spring steel TAB used with a floating bracket also lets the tree move in the wind without fighting against the structure.
TABS come in a few different sizes, but their basic anatomy is the same. There’s the coarse crew that goes into the tree, with a collar in the center that provides the surface area, and finally the stem that holds the support bracket.
Since its introduction in the late 1990s, the TAB has become a popular way to attach a treehouse to a tree (if you search for how to build a treehouse, just about everyone uses a TAB). The simple TAB has now been holding up tree houses across the world for over twenty years.
In 1997, a builder named Jonathan Fairoaks (good name) brought a TAB prototype to the World Treehouse Association Conference. The conference host, Michael Garnier, was so impressed that along with engineer Charley Greenwood (we’re not making these names up) designed the first commercial treehouse tree bolt, the “Garnier Limb”. This eventually evolved into today’s TAB.
How Do You Fix a Treehouse Attachment Bolt (TAB)
Want to know how you fix a TAB to a tree? This short film from Treehousesupplies.com takes you through the process clearly.
You will need:
- The TAB
- A hammer and nail
- A high-torque half-inch drill
- A ratchet (1.875 inch socket) or a large monkey wrench
- A level
- 3 inch self-feeding bit
- 1 ⅛ auger bit
The main points are as follows:
- Choose where you want to mount the TAB. Hammer a nail into this point then remove it, leaving a visible hole.
- Start by making a hole for the TAB collar using the 3 inch drill bit. The depth of the hole depends on the size of the TAB collar. As a rule, it’s an inch for a one-inch collar, two inches for a three-inch collar, and three inches for a six-inch collar. Measure from the cambium not the bark (the cambium is the place where the bark ends and the heartwood begins. The bark itself is not strong and won’t hold the bolt).
- Check that the hole is level.
- Using the auger bit, drill two inches into the tree (for a softwood tree, you may need a different auger bit and to drill an additional four and a half inches).
- Keep the drill running while you pull it out, to clear out the debris.
- Now it’s time to fix the TAB. First measure the hole you’ve drilled to get its exact depth. This makes sure you know exactly when the TAB collar us all the way in.
- Hand turn the TAB as far as you can into the hole.
- When you can’t hand turn it any more, switch to using the ratchet or monkey wrench. You may also need to use a cheater bar.
- Pause before the nut at the end of the TAB is completely tight so you can fix the bracket that holds the beams (more about brackets in a moment).
What is a Floating Bracket? (And Why You Need These Too)
The floating bracket attaches to the TAB. The treehouse beams attach onto this. Why use a floating and not a fixed bracket? Trees move in the wind, and this exerts thousands of pounds of force, which can cause fixed fittings to sheer off. This can damage the tree, the treehouse, and any people or pets in the vicinity.
The bracket is a simple structure that slides over the TAB. It becomes a flexible platform that allows for wind movement, which can be as much as one inch. They consist of a flat plate that attaches to the underside of the treehouse structure.
On top of this is a rectangular frame that looks a bit like a longish handle. This part slides over the TAB, and because it is longer than the TAB stem, allows the bracket to move with the tree.
If you are attaching your treehouse to two trees, use a static bracket for one tree and a floating bracket for the other. If the treehouse is straddling three trees, you’ll need one fixed and two floating. If it’s a major construction that’s fastened to four trees (lucky kids!), all four brackets need to be floating.
How Do You Fix a Floating Bracket?
Like the tree attachment bolt, the floating bracket is straightforward to install. The stem of the TAB is designed to take a floating bracket, so the two parts work easily together.
- You’ve drilled the hole and started to turn in the TAB. Pause before the nut at the end of the TAB is completely tight, as you’ll need to slide the floating bracket over it.
- Slide the floating bracket over the TAB and tighten the nut.
- The beams are then screwed into the flat plate of the floating bracket, from above.
The tree can move freely in the breeze without threatening the structural integrity of the treehouse, or risking causing damage to the tree.
Remember that a second tree’s bracket can be static, but if there’s a third tree involved, two of the three will need floating brackets to allow free movement without strain or pressure. And there you have it: a safe, flexible platform for your treehouse, that’s fastened into the wood with an incredibly sturdy, purpose-made bolt.
So there you have it – you can indeed drill into a tree of at least a foot in width and you won’t damage it, especially if you then fit a TAB and floating bracket so the treehouse fixings don’t break off when the wind blows and the tree moves.
A tree trunk can move up to an inch in even low wind, so fitting a TAB and floating bracket will mean you don’t damage the tree by ripping the bolts out – or damage your treehouse in the process.
But best of all, using these simple fixings will ensure I look like a superhero grandad in front of my granddaughter for building her a great treehouse – so it’s a win-win-win situation. 🙂