A treehouse that keeps to a few straight lines and sturdy joints will be more reliable than one full of decorative flourishes. Use a single plank for the floor, a simple frame for the walls, and a steep roof that channels rain away. Stick to hardwoods you can nail or screw—no over‑hanging branches or extra layers. Keep the roof minimal; a single sloped roof with a small overhang is enough to protect the interior. With a clean, functional layout you’ll have a place that feels both wild and safe, and it’ll be easier to maintain and stronger in the long run.