There is no single species that suits every treehouse. The health, size, structure and position of the individual tree usually matter more than what kind of tree it is. Two oaks standing fifty metres apart can have completely different characteristics. That said, after twenty years we have clear views on the trees we meet most often.
Oak
Oak is one of our favourite trees for a treehouse. A mature oak offers real structural strength and a wonderful setting. Oaks are relatively slow growing and long lived, which makes them particularly well suited to a treehouse that is meant to last, and they tend to develop substantial branches and canopies that create lovely spaces among the trees.
Beech
Beech makes a particularly beautiful setting. The dense canopy gives dappled shade in summer and the autumn colour can be spectacular. Beech trees generally have relatively shallow root systems, though, so we take extra care with ground supports and anything installed close to the root zone.
Silver birch and other fast growing trees
Fast growing species such as silver birch need extra thought. It does not mean a treehouse cannot be built in one. It means the tree’s rate of growth and movement has to be built into the design. The diameter, height and flexibility of the tree all matter. A relatively thin tree can move a long way in strong wind, and that movement has to be understood before the structure and its connections are designed.
Ash
At present we do not generally recommend building around ash trees. Many are being affected by ash dieback, which can weaken and eventually kill the tree. The condition and long term stability of an ash needs very careful consideration before anything is built in or near it.
What we check before we build
Every treehouse survey starts with an assessment of the health and condition of the host tree. We look at the species, age, size, overall health, trunk diameter, branch structure, root system, natural movement, wind exposure and the position of neighbouring trees.
We also look closely at the individual branches and limbs. Any branch that appears dead, diseased or shows signs of decay should be inspected and, where necessary, removed by a qualified tree surgeon before construction begins. A dead or weakened branch can fail without warning, and a falling limb can do serious damage to a treehouse and put the people using it at risk.
One lesson from more than two decades of building: you cannot simply look at a tree and assume it will support a treehouse. The tree has to be assessed as part of the design.
