7 Tips for Designing a Backyard Treehouse Like a Pro
‘Treehouse Masters’ host Pete Nelson shares his strategies for building a successful, fun structure in the trees
1. Remember that you’re dealing with trees. Trees grow in girth, so you’ll want to make sure there’s enough space around the tree to allow for expansion. “I would recommend a space of about 6 to 9 inches around each tree,” Nelson says.
Also, trees move — a lot. So you’ll need to consider how the structure will move with the tree. “Movement of branches isn’t always the biggest concern,” Nelson says. “When the core of the tree is moving in the wind, it’s going to exert quite a significant force. So when building, make sure you have a dynamic connection between the structure and trees, rather than purely static connections. Otherwise, your treehouse could get torn apart.”
For example, the treehouse design shown here uses hardware from Nelson’s company. The house sits on a platform that’s connected to the tree by bolts and suspension cables. The tree trunk will grow around the bolts rather than around the house.
Experts recommend using tree attachment bolts, or TABs, for proper security. You also want to make sure you space out your bolts, says arborist and horticulturist Noelle Johnson. Trees adjust to bolts by a process called compartmentalization, which effectively shuts off that particular damaged area of the tree and grows over it, preventing decay from spreading elsewhere. If you put too many bolts in one area, the tree will “compartmentalize the entire section,” Johnson says, “which would cause a large part of the tree to die. “A good rule of thumb is to never have more than one bolt in a square-foot area.
Before you do anything to a tree, you want to consult an arborist who can determine if the species of tree, and its health, will be able to handle bolting.
Zachary Wilder, an arborist at Sonoma Marin Arborists in California, says some species of trees handle bolts and wounds better than others. Something like a redwood or other straight-grained conifer does fine with bolts, he says, while poplars or willows or soft-wooded trees don’t.
Timing is another factor, Wilder says. If the tree is healthy, it should be able to handle the bolt. If it’s not healthy, it may fail to compartmentalize the bolt. All in all, Wilder says bolting is better for the tree than girdling, such as securing a rope or cable around the tree, which can cut off its circulation.
Trees are pretty tough and resilient, Wilder says. He’s found all sorts of things on the insides of trees that got absorbed, such as barbed wire, bolts, nails and even 100-year-old horseshoes.
Also, trees move — a lot. So you’ll need to consider how the structure will move with the tree. “Movement of branches isn’t always the biggest concern,” Nelson says. “When the core of the tree is moving in the wind, it’s going to exert quite a significant force. So when building, make sure you have a dynamic connection between the structure and trees, rather than purely static connections. Otherwise, your treehouse could get torn apart.”
For example, the treehouse design shown here uses hardware from Nelson’s company. The house sits on a platform that’s connected to the tree by bolts and suspension cables. The tree trunk will grow around the bolts rather than around the house.
Experts recommend using tree attachment bolts, or TABs, for proper security. You also want to make sure you space out your bolts, says arborist and horticulturist Noelle Johnson. Trees adjust to bolts by a process called compartmentalization, which effectively shuts off that particular damaged area of the tree and grows over it, preventing decay from spreading elsewhere. If you put too many bolts in one area, the tree will “compartmentalize the entire section,” Johnson says, “which would cause a large part of the tree to die. “A good rule of thumb is to never have more than one bolt in a square-foot area.
Before you do anything to a tree, you want to consult an arborist who can determine if the species of tree, and its health, will be able to handle bolting.
Zachary Wilder, an arborist at Sonoma Marin Arborists in California, says some species of trees handle bolts and wounds better than others. Something like a redwood or other straight-grained conifer does fine with bolts, he says, while poplars or willows or soft-wooded trees don’t.
Timing is another factor, Wilder says. If the tree is healthy, it should be able to handle the bolt. If it’s not healthy, it may fail to compartmentalize the bolt. All in all, Wilder says bolting is better for the tree than girdling, such as securing a rope or cable around the tree, which can cut off its circulation.
Trees are pretty tough and resilient, Wilder says. He’s found all sorts of things on the insides of trees that got absorbed, such as barbed wire, bolts, nails and even 100-year-old horseshoes.
2. Do your research. Before you begin any DIY project, you need to have a solid understanding of the construction process and the space in which you’re building. Nelson recommends consulting spanning charts, which can be easily found online.
“These charts will help you understand how far a beam can span from the base of the treehouse,” Nelson says. “For example, a two-by-four can’t span 14 feet, as it won’t be able to support any weight. You’ve got to consult these charts to get a better sense of the type of beams you need to be using. Creating a solid platform for the treehouse is the most important part of building. From there, the sky is the limit.”
“These charts will help you understand how far a beam can span from the base of the treehouse,” Nelson says. “For example, a two-by-four can’t span 14 feet, as it won’t be able to support any weight. You’ve got to consult these charts to get a better sense of the type of beams you need to be using. Creating a solid platform for the treehouse is the most important part of building. From there, the sky is the limit.”
3. Choose the right wood. Nelson remembers being a kid when his dad attempted to build a treehouse for Nelson’s sister and chose the wrong type of wood for the roof. “He was trying to save some cash and decided to use a composite type of wood,” Nelson says. “That didn’t end well. After one rainstorm, the whole thing collapsed from the weight of the water that the wood retained.”
To avoid a similar mistake, Nelson recommends using materials that can survive outdoor elements. “I would recommend a pressure-treated pine or fir, or even a redwood or cedar,” he says.
To avoid a similar mistake, Nelson recommends using materials that can survive outdoor elements. “I would recommend a pressure-treated pine or fir, or even a redwood or cedar,” he says.
4. Watch out for water traps. “Water traps will eat away and rot out the wood, and in a couple months, the wood will no longer be strong,” Nelson says.
To avoid water traps, you need a roof that sheds water off and away from the rest of the structure. “I would recommend a 12- to 15-degree slope shedding away from the treehouse for the best protection,” he says.
5. Build in sections. Nelson recommends building the walls of the treehouse in sections on the ground. “This is the safest way to build entire walls of the treehouse, as it precludes you from hammering 10 feet up in the sky,” he says.
Once you’ve built the walls on the ground, have a friend help you carefully lift them up onto the platform. “Take it from me: It’s much simpler to build on the ground and then lift,” he says.
To avoid water traps, you need a roof that sheds water off and away from the rest of the structure. “I would recommend a 12- to 15-degree slope shedding away from the treehouse for the best protection,” he says.
5. Build in sections. Nelson recommends building the walls of the treehouse in sections on the ground. “This is the safest way to build entire walls of the treehouse, as it precludes you from hammering 10 feet up in the sky,” he says.
Once you’ve built the walls on the ground, have a friend help you carefully lift them up onto the platform. “Take it from me: It’s much simpler to build on the ground and then lift,” he says.
6. Get creative. Don’t confine your design to four walls, a roof and a floor. Let the tree and your imagination guide you to a unique structure. “Last year, I designed a treehouse that was based on Frank Lloyd Wright’s famous architecture style,” Nelson says. “I also recently built a treehouse that was completely framed out with glass windows. I’m now working on a new treehouse that will be a spa in the sky. I’m creating the new Dove Men+Care Elements Treehouse, which is inspired by the freshness of nature. We’re building this really cool shower that will allow you to bathe among the stars.”
7. Communicate with the neighbors. “It’s always a good idea to discuss your building plans with the neighbors, as the treehouse could affect their views or property lines,” Nelson says. “Make sure you have a conversation with them, and don’t forget that everyone loves to help build a treehouse. So if you communicate from the start, you might find yourself a great building partner.”
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But he’s also built many small, more rustic treehouses and tree forts. “I often find that these smaller forts are the type of project that inspires kids to develop a passion for treehouses and for building in general,” Nelson says. “Bottom line is: Anyone can build a treehouse.”
If you’re considering building a backyard treehouse for yourself or your family this summer, here are Nelson’s seven guiding principles.