We’ve all got a favourite tree. Perhaps it's that gnarly oak that you pass on your way to work every day. Or an apple tree that you grew up with. Or a tall London plane tree in your local park. Wherever or whatever it is, chances are you might have even daydreamed about building a treehouse amid its branches.

But can you build a treehouse without harming the tree? And if you can, how do you go about it?

In this blog we take you through some of the tried and tested approaches, tools, and hardware we use at Treetop Co to ensure our treehouses cause no harm to trees.

And this stuff matters. If your treehouse harms the tree, not only does this damage the health of the tree, but it can pose a safety risk to you. A poorly installed treehouse can compromise the health of the tree and leave it vulnerable to disease or storm damage and could ultimately make it unsuitable for use.

Step 1: Know your tree

When it comes to trees and treehouse construction there is no one size fits all approach. Not all trees are a suitable foundation for a treehouse and not all treehouses can fit just any tree. Each tree and build are entirely unique.

Before building a treehouse, it is essential that you carry out an extensive survey of the site that you want to build in. At Treetop Co, we always start by sending boots on the ground to scope out the trees. This means assessing their health, checking for any dead branches, and looking at how they sit in the surrounding landscape. We use cutting edge technology to 3D map the entire tree – this helps us to design treehouses that are nestled into the branches, and placed in the correct way to ensure even loading through the stem of the tree.

Treetop Co 3D treehouse design — Example of Treetop Co’s 3D tree model led design

Not all trees are strong enough to support a treehouse structure. For example, they may be too small, or too old, or growing at too much of an angle. In this case we might opt to build a stilt house that sits adjacent to the tree but is not supported by it. Or we might decide that it's not safe to build a structure of any kind.

Other trees may be suitable for a partially supported treehouse which includes some ground support. The Elmfield treehouse is a good example of this.

Only the strongest and healthiest trees are suitable for a standalone treehouse supported entirely by the tree. That’s why it’s essential that you understand and learn how to read the landscape before you start any build. For inspiration, check out this octagonal beauty that is fully wrapped around the trunk of a sturdy Western Hemlock.

Step 2: Get the load right

OK so you’ve surveyed your land and found a suitable tree. Now you can just build a treehouse, right? Not quite. To ensure your treehouse does not harm the tree and is safe to use you need to calculate what load it can support.

And with wavy branches and organic shapes this is not easy to do.

Let’s start with the weight of the treehouse itself. At Treetop Co we take a systematic approach to this. First, we speak to you to get an accurate picture of the maximum number of children and adults that might be using the structure at the same time. Then factor in weight increase during a heavy snow event in winter. Then we design a structure that can fit that number of people and calculate the weight of the materials required to build it.

Once we’ve got our base weight (people, snow, and materials) we then multiply it by a safety factor of two. This is important. Your tree needs to be able support a structure that is double the maximum use weight. Otherwise, it simply isn’t safe. Nature isn’t always predictable. You need to factor in plenty of wriggle room.

Step 3: Use the right hardware

OK so you’ve got this far – congratulations. Now we are getting to the nerdy bit. Treehouse attachment hardware.

At Treetop Co we use two approaches depending on the type of tree and treehouse.

For smaller treehouses, one option is to use rubber cushioned clamps and cables which allow the structure to sit or hang from the tree’s branches. The rubber cushioning ensures that the tree bark is not damaged by the weight of the treehouse. A great example of this is the Red Treehouse, which hangs amidst a ring of Scots pine trees from steel cables that are slung over the strong upper branches.

However, for most structures we use treehouse attachment bolts. Developed more than 30 years ago in America, these tried and tested bolts have revolutionised treehouse building, offering a safe and strong approach to building.

Treehouse attachment bolts are specially designed for mounting in a living tree. And they are strong too, carrying loads of up to 5 tonnes each! Check out the Ark Treehouse to see how these bolts allowed this funky build to nestle safely between 2 trees.

OK, but doesn’t piercing the bark damage the tree?

Here’s the interesting bit. Inserting a treehouse attachment bolt is very similar to a branch breaking – something that trees are well accustomed to dealing with. As soon the bolt is inserted, the tree begins to heal, using resins and oils to seal the wound. And what’s more, as the bolt closes the hole immediately, no insects or fungal spores can get in so there is very low risk of infection.

The advantage of using a treehouse attachment bolt is that they are designed to keep the wooden structural beams at a safe distance from the tree . This means they do not pinch the tree and instead allow the tree to keep growing, eventually forming a kind of artificial branch as the bolt becomes tighter and tighter.

Importantly, these bolts also allow the tree to move freely. This matters. Not only is it vital for the tree’s health, but it is essential from a safety perspective. Allowing the trees to move naturally means that in high winds the tree can dissipate the increased forces acting on it via its strong root system. If you use rigid attachments which prevent the tree from moving, then the forces will be concentrated on the treehouse and tree branches, leading to an increased risk of damage.

Treehouse attachment bolts are a safe and secure way to attach a structure to the tree

Ready to build?

We hope you’ve found this blog helpful. If you have any questions about treehouses and tree health, we are more than happy to chat with you. Building in harmony with the tree is not straightforward. At Treetop Co it is a skill that we continue to hone through each project we do. There is no one size fits all approach, and the most important consideration is to really read and understand the options that you are working with.

If you would like to discuss options for a treehouse on your land, please get in touch via our contact form or give us a call.

Can you build a treehouse without harming the tree?