Frequently Asked Questions - (FAQ)
Materials
What are good material for the supports?
Regular wood from a building supply store is ideal, as it is of fixed dimension and will have a predictable strength. Self-harvested wood can be used, but is weaker when green and should be milled to reveal any hidden defects that could cause a failure. Support beams should be free of large knots and splits and should not be twisted when viewed along a long edge.
What are good materials for the floor?
Exterior plywood is suitable for use in potentially damp situations and is very strong. It will resist twisting forces, making the floor more rigid. A thickness of ¾" will span joists that are 12" apart. Plywood does not allow drainage or ventilation, so you will need to prevent water running onto areas of the floor that are not roofed, but this is good practice in general and will extend the life of any wood material you use for the floor. Solid wood boards are well suited for floor material. Use a minimum of 1" thickness with joists set 12" apart. Boards are easier to raise into the tree and cut to size than large, heavy sheets of plywood, and will allow air to ventilate the treehouse through gaps in the floor. You can use hardwood flooring in a treehouse, eg oak or maple, for a strong and good looking floor.
What are good materials for the frame?
Regular wood from a building supplier is well suited for framing a treehouse. Oak or other hardwoods can be used to create a timber frame effect, but they will add a lot of weight to the structure.
What are good materials for the walls?
Exterior plywood or boards are both suitable. Boards are usually overlapped to allow rain to run off without penetrating the wall - a technique called shiplapping. If the frame is very lightweight, plywood is useful as a base layer to make the structure much more rigid. This can then be faced with other materials if required. As the wall covering materials are usually non-structural, alternative materials can be used to add visual interest. Woven branches will add a natural look and allow air in to ventilate the treehouse. Shingles (panels of cedar or other straight grained wood) are popular amongst treehouse builders in areas where they are available (UK and USA especially).
What are good materials for the roof?
The roof should be pitched by at least 30 degrees to allow rain to run off easily. A base layer of plywood will add rigidity to the roof, but is usually not enough on its own to protect the treehouse. Shingles or roofing felt/tarpaper are the most common roofing materials. You could thatch the roof if the angle is increased to at least 45 degrees. If you live in an area of high snowfall, a steep roof of 50 degrees or higher is strongly recommended to allow snow to fall off. Snow can be very heavy and could cause a treehouse to collapse.
Should I use glass or plastic in the windows?
Glass is clearer and is scratch resistant, but plastic will not shatter into dangerous fragments if broken, either from the inside by an occupant, or by a falling branch from outside. Special glasses are available which are shatter resistant, similar to those used in vehicle windscreens. If children will be using the treehouse, make sure windows that can fully open are positioned over decked areas of the treehouse in case of a fall.