First, you need to choose a tree and decide on a position within it for your treehouse. Choose a mature, healthy tree and allow for growth and movement, and keep the structure as lightweight as possible. Consider whether you want your treehouse to be hidden or visible, and make sure it will not disturb other people. Will it be an adult hideaway or children's play area? If you are considering a treehouse for children, keep it close to the ground: 5 feet (1.5 meters) is fine, and seems much higher when you are up there.

The platform, providing a secure foundation for the rest of the structure, is the key element of almost any treehouse. It should be built close to the trunk, with diagonal bracing (galvanized or stainless steel fasteners) for extra strength, if it is not supported by branches or posts. Make sure the platform is level, and keep it balanced centrally around the tree to support uneven loads and reduce swaying.

Once the platform is secure, you need to add the floor. For this you might use exterior plywood sheets or even frame tongue-and-groove floorboards. The walls can either be built in the tree or prefabricated on the ground and then hoisted up into position (for larger treehouses the latter is much easier and safer).

Now that you've built your treehouse, how will you get up there? A simple wooden or rope ladder is fine if the house is not far from the ground, but steps (with handrails) are better for higher treehouses. A rope pulley with a basket is indispensable for hoisting up provisions, whether your treehouse is high or low.

After all the effort involved in designing and building a treehouse, the last thing you want is for it to fall down - especially if you happen to be inside at the time. Remember to check the floors, decks and railings frequently for rot or weakness. Inspect any steps, ladders and walkways, and repair damage immediately.

To learn more, read Building a Treehouse and Home Sweet Treehouse on MotherEarthNews.com.