This treehouse plan will help you build a 12 wide (flat to flat) treehouse on a single tree. The floor space is 119.25 square feet which may be built into an enclosed treehouse, an open tree platform, or a combination of each. Hardware is specified and suggested materials for siding or roofing are called out, but you can substitute as desired - if you want our advice on which specific bolts you need based on your tree species or design load, then please contact us for support and/or advice. Tips, illustrations, and step by step instructions are included. These plans may be printed on regular 8.5x11 paper. Specialty Treehouse Hardware Needed Includes: (if building something super heavy on top, then please contact us for advice & assistance) (2) TAB 3x9 Treehouse Bolt (2) 1.25" Pipe Bracket (6) 1.25" Lag Bolt (6) 1.25" Knee Brace BracketNote: The number of supports under our platforms will vary depending on the size kit you choose. These plans contain CAD images and instructions to help you build your own treehouse. There are 8 pages of main plans and 7 optional detail sheets to help with trap doors, ladders or stairs, climbing walls, etc... If you have any questions after reading them, you may contact us for extra support. Were here to help!