01442 733 837
Request a Brochure

How big does a tree need to be? Fixing to the tree versus building beside it

The Treehouse Guide Structure and Safety

Whether we fix a treehouse to the tree or build it alongside on its own supports depends mainly on the size and age of the tree. There is a simple rule of thumb we have arrived at over the years.

By Henry Durham. Updated October 2026.

The 60cm rule

In our experience, if a treehouse is going to be supported by braces fixed directly to the tree, the trunk should be at least around 60cm in diameter. If the tree is smaller than that, we recommend stilts or independent supports instead, rather than fixing the structure to the tree.

As a tree matures and reaches a good size, its rate of growth generally slows. That makes building into the tree more practical, and reduces the risk of ongoing movement and adjustment later.

Building around the tree rather than into it

For clients with smaller or younger trees, we often recommend positioning the treehouse next to the tree and supporting it entirely on stilts. The tree’s branches then grow out and over the structure, so you still get the feeling of being up in the trees and connected with nature, with no unnecessary impact on the tree itself.

We recommend the same approach where a tree is covered by a Tree Preservation Order. Keeping the treehouse structurally independent of the host tree is a sensible solution not only for younger trees but also where the tree has extra protection.

The ways a treehouse can be supported

  • A single substantial mature tree
  • Several trees sharing the load
  • A combination of tree supports and ground supported posts
  • Specialised treehouse attachment systems
  • Structural beams and brackets

The right solution depends entirely on the project. Whatever we use has to give the structure stability while allowing the tree to keep growing and moving naturally. This is where experience, careful engineering and an understanding of how trees behave all come together.

Questions people ask

Yes, if the tree is large enough, healthy and structurally suitable. A single mature tree with a trunk of around 60cm or more can carry a treehouse. Smaller trees are better served by building alongside on stilts.

We build the treehouse next to the tree on independent supports. The branches grow over it as the tree matures, and the tree is left to get on with growing.

Often, yes. We keep the structure independent of the protected tree and support it on stilts, so the tree itself is not fixed to or loaded. Planning permission still applies, and the Order may bring additional requirements, so we address both at the start.

More from the guide

Structure and Safety

How we allow for the tree growing and moving

The most important part of any treehouse is not the building. It is the tree. A treehouse has to live alongside something that grows, moves and changes over time, and a good design takes all of that into account from the start.

Structure and Safety

Screw pile foundations: how we build without digging

The first time we used screw piles, it changed the way we build. They look like enormous screws and are mechanically rotated deep into the ground, creating a strong foundation without the need for traditional excavation.

Cost and Budget

How much does a bespoke treehouse cost?

This is usually the first question we are asked, and the honest answer is that it depends on the treehouse you want to create. Our bespoke treehouses start from around £15,000. The final cost can vary a great deal depending on the size, the design, the trees, the access and the level of specification.

Back to the guide