Home in the Trees

The first step to building a treehouse is to pick a group of trees. McDonald looks for healthy trees that are big and strong enough to support the weight of the structure.

Each trunk should be at least 12 inches across. Trees should be 6 to 12 feet apart. That’s so the weight of the treehouse is spread out across the trees.

McDonald avoids building in trees with shallow roots that can topple over, such as willows and cottonwoods. He also checks for fungus, like mushrooms, growing on trees. That’s a sign of rot, which could weaken trees.

Once he’s chosen a site, McDonald sketches a drawing of the treehouse. He positions windows and outdoor balconies where they’ll provide the best views. The Gardners’ treehouse looks out over their farm with horses, goats, and donkeys.

The team also uses drones to plan the designs. These robots fly around the trees, taking hundreds of photos. Computer software combines the flat images into a 3-D model with exact measurements of the trees. This step improves the accuracy of the plans. It also allows builders to construct some of the structure off-site at their headquarters.

Treehouse construction starts with a platform—the flat ground floor. The rest of the house is built on top.

The downward force of gravity pulls down on the treehouse. Solid steel bolts, called treehouse attachment bolts (TABs), help to secure it to the trees and support its weight. Each TAB can hold up to 10,000 pounds.

Once the Gardners’ treehouse platform was complete, the Nelson crew trucked in walls and other parts they had built off-site. Then they installed the walls and roof, and finished the details of the interior.

Construction took three weeks—then the real fun began. “My favorite thing to do is to have my friends over to the treehouse,” says Anna, now 14. “We have a great time spending the night and having a sleepover.”