Search for a tree that can support the weight of the treehouse plus the weight of any children that will be playing inside the treehouse. It should have sturdy limbs that extend in all directions. These limbs should be level enough and stable enough that the supports for the floor of the treehouse can be leveled.
Create the frame of the floor of the treehouse using the 3-inch wide bamboo poles. Lay these poles across the tree limbs in the shape of a square, rectangle, pentagon, or any shape that makes sense given the tree you are using. Get creative and trim the poles if you must. Use your level to ensure the floor is as horizontally level as you can manage. If you can't reach high enough to position the floor, climb a ladder instead of the tree itself. This will help avoid bending the limbs of the tree unevenly.
After you've adjusted the poles to your satisfaction, use the lashing to secure them together. This is the floor frame of your treehouse. When lashing bamboo poles together, make sure you wrap the lashing around the poles from all possible directions. Pull the lashing as tight as possible. If there is any slack, the poles could come apart while the children are playing in the treehouse. Also last the floor frame to the tree itself for greater stability and safety.
If you're building the treehouse around the main trunk of a tree, you'll have to build an inner frame for the floor of the treehouse around the trunk. Do this in the same manner as you built the outer frame. The inner frame should have roughly the same shape as the outer frame, though some variation is acceptable to accommodate the shape of the trunk. Try to keep the inner frame as close to the trunk as possible but leave enough room to lash the floor poles to the frame. You will need six or eight inches of clearance between the inner frame and the tree trunk, so take this into account.
Use the 1-inch wide poles to form the floor of the treehouse. Trim the poles so they overhang your floor frame by two inches on either side. Lay the poles side by side across the floor frame and lash them in place. Each pole should be lashed to the floor frame on both ends. Also lash each pole to the pole on either side of it. End poles should be lashed to the frame at all possible locations. If you're building around the trunk of the tree, you will have to lash the poles located closer to the center to the inner frame as well.
Construct the frame for the roof of your treehouse. You'll have to first decide where you want the poles that support the roof to go. You can have as few as four support poles or as many as eight around the floor frame. If you're building around the tree trunk, you'll need the same number of poles around the inner floor frame. Lash all poles in their proper places. There should not be more than 6 feet between poles that are next to each other. The vertical poles should end up secured to the floor frame vertically. Don't worry if they go slightly askew. You'll fix that problem in a moment.
Lash 2-inch wide poles horizontally between the tops of the support poles. Each support pole should be connected to the support pole next to it with a horizontal pole. These horizontal poles are the roofing poles. If you're building around the trunk of the tree, you should also connect each support pole its the corresponding support pole along the inner floor frame using a horizontal roofing pole. Trim all poles to size before lashing them in place as it will be difficult to do this later.
Create guard rails around the exterior of the treehouse so children don't fall out of the tree house. Lash 2-inch wide poles to the support poles around the outer edge of the treehouse. These poles should be about three feet off the floor of the treehouse. You may also lash additional guard rails in place one and a half feet off the floor of the treehouse. This is especially useful if younger children will be using the treehouse. Leave a gap of about one foot to accommodate a ladder.
Build the roof of your treehouse by lashing the grass mats over the horizontal roofing poles.
Build a ladder for easier access to your treehouse. Cut two lengths of 3-inch wide bamboo poles long enough to reach from the ground to the floor of your treehouse. Last 8-inch lengths of 2-inch bamboo between the longer poles, creating a ladder. Your ladder rungs should be no more than 12 inches apart. Lash this ladder into place. Make sure to lash it to the frame of the floor of your treehouse and not to the actual floor poles. Once the ladder is secure, the treehouse is ready for use.
Things You Will Need
- 20 bamboo poles, 6 feet long 3 inches wide
- Manual saw
- Lashing cord
- 100 bamboo poles, 10 feet long 1 inch wide
- 40 bamboo poles, 6 feet long 2 inches wide
- Grass matting for the roof of the treehouse
- If you find your support poles are too far apart for your 6-foot roofing poles, you can always look for longer bamboo poles or lash a couple poles together.
- If you want walls for your treehouse, consider using additional grass mats lashed to the roofing poles and the floor frame.
- Waterproof your treehouse by adding a tarp under the grass mat roof.
- If you're unfamiliar with lashing techniques or nervous about lashing at all, you can use screws to secure the poles together. However, make sure the screws do not stick out of the poles or children could end up hurt.
- Larger treehouses or treehouses which will have to bear more weight than two or three children should have additional lateral supports on the floor frame. Add more bamboo to the frame itself if you feel you need the additional strength.