A tree house can be a wonderland for children and also a peaceful haven for adults. Animal life in your garden will not be used to seeing humans in trees but will eventually accept the tree house as part of their domain. A tree house will give you a great opportunity to view the other residents of your garden behaving naturally.
Tree House Design
Designing a tree house can involve more than simply choosing which branches of a tree might be suitable to build on. In reality, a tree house should be looked at as a threat to the tree--so you must estimate the effects a tree house will have on the tree. Consider the size and design of the tree house because it will put extra weight on the tree. While a healthy young tree might be able to support the weight, should it have to? You must also bear in mind that a tree house may be adversely affected in strong winds. Even a healthy tree has limits to how far it can lean before falling.
In addition to weight concerns, you need to consider how much damage can the tree sustain while you are building your tree house. Generally using a few nails on a tree branch will do little damage--but long term problems can arise. Trees are constantly growing. The weight of your tree house could change the direction in which some branches grow. Although this will not necessarily weaken the branch, it might take the tree to an area where there is insufficient light for the leaves to maintain a good level of photosynthesis. This, in turn, could lead to systemic root failure. Your tree house should be designed in such a way that it has no effect upon the crown of the tree.
Tree House Protection
Just as you want to protect your tree, you also need to protect your tree house. Constant movement in any wooden structure will inevitably weaken it over a short period of time. You will either need to be always making repairs or set the tree house in such a position that the degree of movement is minor. Using the major branches as the main areas of placement for the tree house will reduce movement to a minimum.
For the best effect, you need to build a tree house that is firmly supported from the ground. The tree house can be within the tree while not using the tree for support. Where branches or the trunk of the tree pass through walls or floor you should place flexible collars to close the gaps while allowing the tree free movement. In this way your tree house will be stable in the tree and suffer no damage. Using tree house supports as trellises can introduce a ground level tree room or arbor and opportunities to train roses and vines and disguise the tree altogether.