How to Build Tree Houses
image by Pole Posiitons by Jane M. Smith 2009, Rock Climb Access Ladder and Tube Slide at http://www.playsetparts.com/store/195/0/index.htm
The simplest tree house is a little more than a platform nailed between two large, horizontal limbs. However, this traditional form of a tree house is now known to be bad for the actual tree. Instead, today's tree houses are built using support poles and 2-inch by 4-inch stock lumber to build a hexagon platform around the trunk. This prevents damage to the tree and provides a safer, more stable platform for your tree house. A spiral tube slide provide an exit from one side, while a molded plastic rock climb provides access to climb up to the main platform. Read on for additional tips on building tree houses.
Use a carpenter's square at the bottom left corner of a 4-feet by 8-feet plywood sheet to determine a 60-degree angle. Snap a chalk line along that angle from the corner of the plywood to the opposite side. Repeat for the bottom right corner. Cut six identical plywood sheets. These will form the platform of the tree house when the angled sides are butted together.
Measure the short, flat side of each sheet of plywood. Cut six lengths of 2-inch by 4-inch stock lumber, mitered at the corners to 60-degree angles to make the inner support frame ring. Cut six more pieces that are eight feet long, mitered at the corners to 60-degree angles to make the outer support frame ring.
Measure the distance along the angled side of the plywood sheets. Cut six pieces with 120 degree included angles at each end to make the support frame ring supports. Attach all the 2 by 4 lumber to connect two sets of two plywood sheets together using 3-inch long, 1/2-inch diameter bolts with matching fender washers and acorn nuts. Do not connect the other two plywood sheets yet.
Lay the plywood platforms around the tree trunk, with the remaining two plywood sheets laid in place. Mark the inner and outer points of the hexagon with metal stakes. Remove the platforms. Run string between the stakes to form the perimeter created by the flat faces of the inner and outer edges of the platform.
Dig one post hole for each point of the inner and outer edges. Fill the bottom six inches of the hole with sharp-sided gravel. Place posts in each hole and back fill with gravel. Hang a plumb bob from a spirit level and adjust posts until they are level and plumb. Brace the posts in the correct position. Make sure that each post will sit across the angles of the corners of the hexagon platform to provide maximum support.
Mix quick-drying concrete in a wheelbarrow and fill the remaining space in each hole. Allow the concrete to dry 3 to 5 days.
Rent a power lift to raise the platforms on top of the posts. Attach the platforms to the posts, using 6-inch long, 3/8-inch diameter lag bolts. Attach the molded plastic rock climb stair to one side of the platform, following manufacturer's instructions and hardware.
Attach the molded plastic spiral tube slide according to manufacturer's instructions and using manufacturer-provided hardware, on the opposite side of the tree house platform from the rock climb stair.
Cut 6 inner and 4 outer walls for the remaining sides of the platform. Miter the edges of each wall to a 60-degree angle. Attach walls to platform using 3/8-inch long, 1/4-inch diameter wood screws. Bend twenty-four L-shaped corner braces from a 90-degree angle to a 120-degree angle. Use two braces in each corner of the inner and outer walls to provide additional support and stability.