• Framing the structure- When building the frame of your tree house, it is definitely easier to work on the ground. Doing this will allow you to use vices and power tools and you don’t have to worry about falling out of the tree! Because the frame is built on a flat wooden surface, you can apply the same principles as you would with building a traditional house.
• Putting up the walls- Plywood is a good choice for walls since it strong and it is available in large sheets. If you do not like the look of plywood, you can use wooden cladding boards. If you go this route, you will need a very rigid frame since boards do not have the same bracing effect as plywood.
• Fitting a Roof- The wood is the most important part of the tree house in terms of durability as it protects the tree house from water damage. Generally, a pitched roof is more attractive than a flat roof and is also easier to waterproof. Having a large overhang and attaching shingles to the roof will protect the walls of the house from water. If you opt for a flat roof, it will need to be covered with a tarred sheet material and sealed with a blowtorch.
• Doors and Windows- When putting doors in a wall, you need to make sure the frame will not twist. An alternative to a door in the wall is a trapdoor in the floor. It is important to put a strong lock on the door to keep out intruders. If you choose to put windows in your tree house, it is advisable to fit them into a suitable frame on the ground and then attach them to the tree house. Putting glass in a tree house window is risky since any twisting could result in the glass shattering. An alternative is to install safety glass or Perpspex. The downfall of Perspex, however, is that is scratches easily and is noisy when it rubs against the wood. This can be especially annoying if you are sleeping over night in your tree house.
References
www.infotoday.com/linkup/lud050106-rubino.shtml
www.thetreehouseguide.com/
www.treehouses.com/treehouse/construction/selectree.html