This treehouse was inspired by every child (both young and old) who had a treehouse or dreamed of having one. Its design was based on the premise that adults need a place to have fun with their children so we made every aspect of it large enough for the big kids too. Every kid dreams of having their very own fort or treehouse so we didn't hold anything back.
The exterior of this structure is full of goodies. First, it has two slides that were bought, used, and repurposed specifically for this project. There is a real boat that was painted, buried, and filled with sand and is now being used as a sandbox. You can see several decks at different levels that vary in size. The decking material is repurposed cypress we bought at a mill from the "dollar pile". We planed each piece and ripped them down into various widths. The largest deck doubles as the roof of the lower structure.
At floor level, a mulched play area with a hidden safety feature. Kids fall....a lot! So underneath the mulch are 2" thick exterior grade foam mats to soften their landings!! The interior of the lower structure is used for dad's toys (tools). The framing of both structures is lumber we bought from various individuals on craigslist that were left-overs from their projects. The interior of the actual treehouse has been finished using reclaimed wood from pallets, windows from a thrift store, and railing that had been used in a church and was taken down. We wanted the treehouse to last so the exterior is comprised of HardieBoard and pressure treated lumber. An asphalt shingle roof keeps the rain out.
The start of the process is the planning phase. It all begins with a dream. You've probably heard someone say, "If you can dream it, you can do it". Well, that's true as long as you plan properly. You'll need to first have a design. There are a lot of free plans out there but you can design your own if you desire. Next, you need a location and a tree. You'll also need to make sure your structure doesn't encroach property lines, building setback lines, and adheres to all building codes....you know, just to keep things legal. For this project, we designed our own structures to fit our needs. There weren't any mature trees to support the weight of the treehouse so we put it on stilts above a tree to get the same effect. This has several advantages. Our design isn't limited by the shape and size of any tree, we never have to worry about damaging any tree, and there aren't any worries about our treehouse falling as a result of the tree dying.
Once you have your design, gain approval from your local building department (and homeowners association if applicable), find a good location, then you are ready for the next step which is to commence building.
Per your design, you'll start with building your foundation. Our treehouse footings are four 8x8x20' posts in holes that we dug 5' deep and 2' in diameter. rebar was driven through the posts and concrete was poured...a lot of concrete was poured. For the storage building we set six 4x4 posts in holes that were 3' deep and 1' in diameter. This provided us with an adequate foundation in which to start framing out the two buildings.
We framed these buildings just like you would any house...all to code. We "overbuilt" in some areas such as the floor joists (which are 2x8 beams, 1' on center) because we wanted security, safety, and just wanted it all to be really solid. The size of your treehouse will dictate the best material to use for your project. Pouring footers and framing can each be their own Instructable so this is just a general idea of the steps taken to undertake and complete a project like this.
Once our beams (doubled 2x8s) and joists (2x8s) were installed, the walls went up and the plywood subfloor (4x8x3/4") was put down. This was all pressure treated material fastened with exterior grade screws/bolts/joist hangers.
Once the framing of the walls was completed, we wanted to get it all dried in to protect it from the weather. To do this we purchased Hardie Board as the exterior of the walls. We screwed and glued this to the framing and began framing in the trusses and rafters for both structures. The roof of the treehouse was pretty standard framing, and once completed, we called in a professional roofing company to roof it for safety purposes.
The storage building was a slightly different process because the roof also doubled as a deck. It looks like a flat roof but it actually slopes slightly more than 1/4" every foot. This slope is just enough to shed water but not enough to notice if you are standing on it. Before the decking went on we installed a rubber roofing underlayment, then furring strips, then applied several coats of elastomeric roofing sealer over top of everything. The decking material was then installed. We had previously gone to a local saw mill and rummaged through the "dollar pile" of cypress wood. We managed to get enough decking material for the entire project for pretty cheap that way. We planed each piece and ripped them down to various widths, then installed each row of decking in a random pattern.
Windows were bought at a thrift store for next to no cost. We had actually purchased the windows before framing the walls out and we just incorporated the window sizes into our design to save costs.
When the structures were dried in we were free to take our time with the inside. Electric was ran to both buildings but the storage building's interior was left unfinished as it is just storage for dad's tools. The real effort went into the tree house interior where we gave it a rustic finish. The walls were covered in plywood paneling that was stained to tie it in with the pallet wood trim work. We added a loft inside which ended up being a great design feature to add square footage and another play area. For safety we put up some old railing that was picked up for free at a church that was getting rid of it. For ventilation we installed vents on both gables and put in a small fan. We found laminate wood flooring that was a "special order return" and bought it for 5$ a box which ended up costing about 30 cents per square foot. This was installed and ensures the floors are going to last for a while and can be cleaned super easy.
To complete the project we finished painting and staining the exterior. Our plan was to try to get this to blend in with the surroundings so we chose a dark brown color scheme. The different levels of these two buildings lends itself nicely to adding slides and even a small deck/lower level beneath the treehouse. The floor of the treehouse sits over 13 feet above the ground so we just had to utilize that space for something. This deck area below the treehouse is only accessed by a cargo net. It has a pirate's wheel and spyglass telescope and you can abandon ship via the slide that was installed. Safety was a priority so we laid 2" thick exterior grade foam mats on the ground over the entire area, then put mulch over the top. An old boat was painted, buried, and converted into a sand box. Old oversized tires were bought at a discount and partially buried to create a neat play feature.