How “NOT” to Build a Tree House

Top 10 Tree House Building Mistakes

1. Choosing a tree without consulting an expert
Building a tree house starts with a foundation analysis. What species is the tree? Where is the tree in its natural life cycle? Is the tree healthy – free of defects, decay, disease? You may not need a professional tree house builder or arborist to look at the tree if you know the basics or research your tree online. But first consider the level of investment you are making in the tree house before bypassing this step to save a few hundred bucks. How much time and money will you spend on the tree house? What is the intrinsic value of your tree? Every ground house starts with the footer inspection and then concrete, and every tree house starts with the tree’s structural grounding, core integrity, and health.

2. Neglecting to have even a reasonably basic tree house plan
It can be fun to build your tree house one board at a time. It certainly gets you started sooner. But this causes a few common mistakes. When there are multiple branches or trunks, your eye-balling methods may deceive you. You may find that in order to pass a main tree house beam where you thought you could, you have to cut a major branch (bad idea). Secondly, most people have trouble sighting level, especially when the grade is sloped. Note that a tree house platform constructed perfectly level will not necessarily be parallel with the ground. This matters because you may find that what you thought was a 10-11′ span may actually be 13′, which would require a stiffer beam and more support. So it’s back to the lumber store to return the 12′ joists and get some 16’s, and now you need 2x10s instead of 2x8s, increasing the weight, cost, and difficulty of the tree house unexpectedly. Even if you can sight level and your beams and spans work out, you may still end up trying to improvise extra tree house attachment points on the fly, which may lead to less than optimal decisions for the tree house and/or the tree. Our advice: climb the tree, take measurements, temporarily mark each beam, draw the tree house platform on paper, and do whatever else it takes to reduce the surprises once you start building.

3. Using too small or the wrong fasteners
Don’t assume that the biggest lag bolt on the shelf at your local big box home improvement retailer is suitable for holding up your tree house. Even a kids tree house with walls, windows, and a roof, will probably use a couple thousand pounds of materials. And then you need to allow for the tree house to also support live loads to cover as many people as can fit up there. It always pays to use the right fastener. Use screws or carraige bolts for places where the tree house will primarily be subject to pullout or tension forces. Use nails where shear forces are primary. Be careful to use approved fasteners for treated lumber. Beware that most of these mistakes will not cause tree house failure in the short term, so you might not necessarily know you made a mistake right away.

4. Using too many fasteners
Never place tree house fasteners too close together in the tree. Remember that trees don’t heal, they seal, or compartmentalize around each wound. If wounds are too close together, the tree may treat them as one wound, which will cause the wood between the fasteners to decay. This will almost certainly cause the tree house to fail. A better approach: Use one, large tree house fastener, instead of multiple smaller ones. I know it’s tempting to use the smaller ones because that’s what you can buy on the shelf, but don’t be lazy with tree house safety.

5. Pinning a beam to a tree
When a tree house beam is pinned to the tree, one of two bad things WILL happen: 1) the beam will restrict growth on that side of the tree, causing it to suffer, or 2) the tree will continue to grow, pushing the beam outward and right off the bolts it was secured with! Eventually, it will fall off and the tree house will fall down. It is advisable to “perch” the beam on a super strong professional tree house fastener like an artificial limb, rather than pinning a beam to the tree.

6. Inadequate stabilization of the platform
The tree house platform should be stable because any movement will wear parts loose over time and become more dangerous. We usually see problems with knee braces not being installed tightly to reduce movement. If the tree house fasteners themselves are moving, you have a big problem because the tree will never seal that wound properly. You will likely see liquid coming from the spot, the wound will remain open, the tree will suffer, and the fastener will get looser and looser and probably fall out.

7. Girdling the tree with rope, cable, or 2x4s
Don’t wrap anything around the tree to support the tree house. You can completely kill the limb or trunk if you do. Even if the tree survives, it will certainly suffer. We see this a lot on zip lines, and when cables or chains are used for tree house supports. We have also seen many people nail short 2x4s into the trunk to space the chains or cables 1.5″ away from the branch or trunk. That will lessen girdling, but it breaks rules #4 and #5. Get the right tree house fasteners to keep your tree happy.

8. Not leaving room for the tree to grow – boxing around
The tree house should only touch the tree where necessary. This means when you frame your beams, joists, rafters, etc., that they all need to allow the tree sufficient room to grow over time and sway in the breeze without rubbing the tree house. If you don’t do this, you risk girdling the tree and reducing the life of your tree house. If you later decide to extend the life of the tree house, your maintenance will be harder, so plan for growth. Ask an expert how fast your tree will grow.

9. Nailing ladder rungs onto the tree trunk
You may have seen a picture of 2×4 ladder rungs each nailed into a tree for tree house access. That is not nice to the tree. As a general rule, no part of the tree house should touch the tree unless it has too. There are many other ways to build a ladder or access the tree house. These types of ladders are repeat offenders for breaking rule #4.

10. Not bothering to preserve natural wood surfaces
Wood, whether pressure treated, cedar, or even bald-cypress has a clock. The sun, rain and snow will cause them to decay and the tree house will look older faster, and need replacement sooner. Commercially produced lumber does not last as long as the old growth forests. Profit drives companies to grow timbers faster, so they don’t build their natural resistance to decay and pests. If your tree house is built with reclaimed lumber, this might not apply, however, treatment will extend the life and beauty of any wood. At a minimum, protect your tree house by applying a clear sealant on the exterior floors, stairs, and railings every 1-3 years.

Questions? Contact Tree Top Builders for more information on safely building tree houses.

111 Responses to “How “NOT” to Build a Tree House”

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  1. Emily Anne says:

    I was wondering is there something to treat a log you want to use as a vertical support so it doesn’t rot. I am planning on building a tree house, around a locust, in the area, several locust and a black walnut came down as a result of a big wind storm and I wanted to use the trunks as a vertical support, but wanted to treat them so they don’t rot. Thanks.

    • thb98il1Tr3e says:

      Hello Emily,
      I want to be sure I am understanding you properly. You have trees that have fallen and you would like to use them as supports for your treehouse? If this is the case, you would need to encase the logs (as you call them) if you put them in the ground (i.e. concrete footer, plastic sheath, etc.). But having them outside in the elements (air, rain, humidity, airborne fungus, etc.) it will be hard to prevent them from rotting. Your best solution is to be sure to address the issue at the base and be sure wood doesn’t come in contact with soil where bugs and moisture can cultivate rot. There are many blogs and products on the market for wood rot (i.e. Smith-CPES, Abatron) and harsh chemicals like wood-tar creosote (which I wouldn’t recommend due to its toxicity). There was a recommendation from a client once saying he sprayed anti-freeze on wood to help prevent rot.
      With all that being said, if it is outside in the elements it will be hard to prevent rot from occurring in wood. You can help prolong the life by avoiding direct contact to dirt and sealing it with a clear coat epoxy.
      I hope this helps. Best of luck!

    • brandon says:

      from what I know,locust last a very long time. this is why people like locust fence posts.

  2. Doug Hodgson says:

    So I have built a treehouse on an 8×12 platform. The platform rests on 3 2×10 beams attached to 4 large lodgepole pine trees. Each of these beams have one end screwed to a tree and the othe end resting in a bracket attached to another tree that allows for movement of the trees. In any case, on a windy day the treehouse can move, sometimes up to 3-4 inches. My question is this: Do you have any ideas for how to attach stairs to the treehouse that would also allow for movement without damage to the house or the stairs?

    • thb98il1Tr3e says:

      Hello Doug,

      The best way is to allow one end of the stairs to float. So the top stringer can be made to slide in a contained slot (hopefully with UHMW or another low friction material screwed to stringer and platform). Or, you can rigidly attach the top, but make a small ramp at the bottom that the bottom stringers can slide on.

      This is a difficult task, so a perfect solution takes some thought and effort to create. If you create something and want feedback, please post a photo for us.

      Good luck,
      -Dan

    • Robert Crawford says:

      I have seen stairs made with 4 cables attached to the head and stretched tight to the foot . The treads seemed to be like a 2×12 with cables running through holes near the corner of the tread, with clamps on the cable underneath the tread to hold it level in place. Then you can use cables for the handrails as well

  3. Starkey says:

    Because attaching a platform to our tree is beyond our budget and capabilities, we are building it freestanding around it. The tree is large, healthy, and coniferous. The floor level will be 5-6′ up. How much space should I leave between the tree and the deck?

    • thb98il1Tr3e says:

      Hi Starkey,

      There is no black and white answer, but three principles to consider: movement, growth, and pinching.

      Movement: At 5-6′ above ground, the tree probably moves less than 1/4″ in the wind.

      Growth: North American trees generally grow at 1/8″ to 1/2″ per year. As the tree grows, you may need to enlarge the hole. Try to space joists further away and let decking cantilever so that trimming the hole is easy.

      Pinching: If the space is 3/4″, and a child has fingers in the hole and then the wind blows, it can hurt.

      If the space is 3″ or more, some clients are worried that a foot could slip through. I think a happy medium is about a 1.5″ to 2″ space.

      Good luck!
      -Dan

  4. chris says:

    hey, im building a treehouse and was just wondering would it be okay to use just 6
    5mmx100mm screws on each end of the beams?

    • thb98il1Tr3e says:

      Hello Chris,

      6 screws of 5mm diameter would not be the best choice. It would be better to use fewer, larger fasteners. I don’t know how big your project is, so I can’t make a recommendation without more information. The fastener choice is determined by the expected loads, the type of tree, the desired lifespan of the project, and a few other factors. If you make a sketch of your plan and send it in, then we can help you with more specific advice and provide you with any custom materials you may need.

      Good luck,
      -Dan

  5. Dave says:

    I am using coated lag bolts to attach 2x8s to the tree. Is that ok for the tree? It is the same type of coating for screws used in joining treated lumber.

    Thanks,

    Dave

    • thb98il1Tr3e says:

      Hi Dave, What type of coating is it? There are many coatings approved for use in treated lumber. However, you should be more concerned about the fastener where it passes through treated lumber, than with the coating causing trouble for the tree. I’ve seen galvanized, ceramic, triple zinc, proprietary mixes, and in the new PT lumber, none of them really last that long. Trees generally do not have reaction problems with hardware of any kind, but I am not aware of any scientific studies on the subject. I am just answering based on theory and assessment of the few trees that I have dissected. -Dan

  6. Dex White says:

    Hi. I have a maple that needs to come down, and I want to have the crew leave a 6-foot stump that I can use as a base. Since I don’t have to worry about wind movement, growth, or the health of the tree, do I need to bear in mind any of these concerns about bolts, not-attaching-to-the-tree, etc? Thanks!

    • thb98il1Tr3e says:

      Hello Dex,

      Lots of people build on large stumps and there are pros and cons. To address your question, you can use conventional methods to attach to a stump. The tree is dead, so girdling is not an issue. You can cut notches into the tree with a chainsaw and set beams directly onto the heartwood, something I would never do with a live tree. This will save some money, too, since custom treehouse bolts (TABs) are not cheap – very high quality, but not cheap.

      The downside that I must warn you about is that the stump is dead and will start to decay immediately. I don’t know how many years you’ve got until the trunk will fall over. Some species vary and there are other unknown potential factors. Also, if the wood that your structural members are attached to rots, then the treehouse could still fall before the trunk falls over. When the stump becomes unstable, you can add posts to the ground to help carry the treehouse for a few more years… Good luck, -Dan

  7. Mary Kaye Rios says:

    I’m building a treehouse with a deck and I would like to use branches from cedar trees and other trees that have fallen as posts for the railings. I know cedar is a good wood to use, what about maple, oak and ash? Should I put a water sealant on the posts over the bark or should I strip the bark? I could use treated wood from the lumber store, but I think the tree branches will look better. Will they be strong enough and last long?

    Thanks

    • thb98il1Tr3e says:

      Natural branches generally do not last as long as pressure treated parts for railings. The problem with the smaller parts is that they are mostly sapwood, which rots in a matter of 1-5 years outside for most species. The heartwood, however, can last a very long time. Definitely strip the back before preserving – this eliminates a hiding spot for bugs, and also allows a penetrating stain to change the color, if you prefer.

      One other trick, for safety, is to use a sturdy rail frame (PT wood, locust, white oak, etc…) and install netting as fill, and then put branches over the netting. That way, if a branch rots, people are still safe. Eyes are drawn to the branches instead of the frame.

  8. Arnold says:

    Dave

    My grandson’s treehouse was built free standing aroung a 40 ft or so now 25 year old tree with the platform about 8 ft above ground level with split tree trunk sections going throught the outer decking. A couple of the trunks, which are 22 to 25 inches in diameter are now close enough to the house (1 1/2 to 2 1/2 Inches) that when they sway in the wind they rub against the upper side wall of the house with the bark wearing. Is there a good would to reduce the wearing and swaying of the trunk section. Thought of putting either a wood spacer (that may need to be reduced in size over time) to snug the trunk to the house or a padded wood spacer or padded material of some sort at the interference points. Do have concerns of the effect this may have on the tree house Please advise.

    Thanks

    Arnie

    • thb98il1Tr3e says:

      Hello Arnie,

      UHMW would be better than wood. But another idea is horse stall matting. Rubber matting of any kind would also be better than wood. We don’t sell much of the stuff but we could cut and sell you a small piece if you don’t want to buy a full sheet at a place like tractor supply. If you want us to ship it to you, please tell us how big of a piece you want. I suggest getting it a little bigger so that you have room to nail it to the treehouse walls around each edge of the tree trunk. The trunk will continue to get bigger.

      Thank you and good luck,
      -Dan

  9. Matt says:

    Hi,

    I am in the middle of building a tree house from a Black and Decker tree house book. I did everything as they said except that they suggested using 2×2 or 2×3 lumber for the wall framing which I could not find. It hadn’t occurred to me at the time to cut the 2×4’s down the middle and now I already have all my walls framed with 2×4’s.

    I was wondering if this is going to be way too heavy. The 8×8 platform seems incredibly sturdy and secure and I plan on using a very light wood siding and sheets of light polycarbonate roof panels.

    Because the walls are already framed I do plan on using them, but I would like to hear your thoughts on the matter.

    Thanks,
    Matt

    • Hello Matt,

      When engineering a treehouse, the live loads (those from people, snow, etc) generally are more significant than the dead loads (those from lumber). If your design is safe with a 2×2 wall, but unsafe with a 2×4 wall, then you have no safety factor for an extra kid or two to climb up, which in my mind is dangerous. Be careful when using cheap off the shelf books to build treehouses. Companies like Black & Decker and television shows like Extreme Makeover are not experts at building treehouses. They are far from it. When we build treehouses, our tree attachment systems are much more robust than anything in that book – you can’t compare the two. I wish I could be more help, but anything I say is more than you’ll get if you try to contact the publisher or author of the book you bought. You get what you pay for. If you want to use the treehouse plans from our supply company, then they will provide unlimited phone or email support for questions like this. We unfortunately can’t offer free support for treehouse plans from other companies, especially companies that don’t know enough about treehouse building to begin with.

      Good luck,
      -Dan

      • Matt says:

        Thanks Dan,

        Thanks for your input! I found this blog through a Google search and was under the impression that you were accepting general questions about tree house construction regardless of what book the plans came from, if any book at all. I didn’t realize this comment section was meant for your customers! Didn’t mean to offend!

        Thanks,
        Matt

        • Emma says:

          As a tree house builder in the planning and research phase, so potential customer, I’ve been reading these comments with interest. My overwhelming impression is that this site considers itself the only source of valid information, and not only that, actively disparages anyone with an idea or alternate source. I would’ve been fine with reading about their own methods and ideas, not try to make themselves look better by making everyone else look bad. I’m not going to be a customer or seeker of feedback from here, plenty of resources and materials work just fine.

          • Hi Emma,

            I’m very sorry to give you that impression. We certainly are not the “only source of valid information.” However, I have a ton of experience that helps me to build treehouses the best possible way, and most of the comments on this blog come from DIYers who don’t have any experience. As a result, most of my comments are helping people to avoid rookie mistakes. If I didn’t call out bad ideas, but let people proceed to build things that do excessive damage to trees or things that are dangerous, then that would be worse than your accusation. My goal is to tell the truth and be helpful, while avoiding condescension.

            As a certified arborist and lifelong carpenter, my analysis is very well informed, but that is definitely not to say that I am the only one who can build a quality treehouse or that I am above critique. In fact, because people really can build their own, we started a supply company called http://www.treehousesupplies.com where you can get plans, hardware, and watch DIY videos for free. I really believe in creativity as long as it is informed by good theory.

            Thanks for the feedback,
            -Dan

  10. Chris says:

    Hello
    Your site is very helpful.
    I am building a 10 x 10 platform on a single tree. Tree diameter is 2.7 ft. I wanted to use 10 ft long 2×10 boards for beams. With beams that long I was wondering if I needed to support them other than attaching them to the tree.
    I plan on having 4 braces (1 at each corner) tied back to the base of the tree.
    Thanks

    • Hi Chris: I hate to say it, but I need more information to give a confident answer. If I make an assumption that you are building with a plan similar to the 10×10 treehouse plan on http://www.treehousesupplies.com, then the 10′ board will have support at the middle and be tied into rim joists which have knee brace support, in which case, a 2×10 should be sufficient. However, I would consider using a 4×10 or 2 2x10s for balance on the TAB. If that’s overkill, then consider downsizing the lumber but using 2 pieces, such as 2 2x8s. The width really does make it fit on the brackets and TABs better. Good luck, -Dan

  11. Alejandro Cordova says:

    I’m planning on building a tree house on four Doug firs. I will build a movable platform first and then the tree house on top of the platform. Will the supports (and consequently the tree house) move in a vertical direction as the tree grows.
    Thanks,
    Alejandro

    • Hello Alejandro,

      The TABs in the tree will always remain at the same height above ground. Tree tissues only elongate at the tips of the branches. The tree will, however, increase in girth and grow around the edges of the bolt over time. Generally, on four trees, we’re using one fixed bracket and 3 floating brackets. This makes the treehouse move with one of the trees (either the biggest or the one closest to the middle), and the other 3 trees can move independently without stressing the platform.

      Good luck,
      -Dan

  12. Seth says:

    Good morning Dan,

    I am in the planning stages of building a treehouse overlooking a pool in our backyard. We have a large Live Oak approximately 20-24″ in diameter. The tree forks \I/ almost evenly around 6 1/2 feet. This is/was the location I was planning for running two 4x6x12′ beams. My question is, and this maybe a dumb one, but can that even fork serve as the rest for the beam?

    Thanks in advance for you’re advice,
    Seth

    • Hi Seth,

      Firstly, you should assess whether the tree is safe. When a tree splits into 2 roughly even leaders (tree-speak for central trunks), each stem is called “Co-Dominant.” In general, if the shape made by the union is rounded like the letter “U”, then it is more likely to be strong. If the shape is like the letter “V”, then you have to look to see if bark from each side is touching in the center (included bark) which prevents the structural attachment of both sides of the tree. If you see a deep crevice that collects dirt and leaves and has little plants growing in it, then the tree is likely to split and fail. If in doubt, always hire an arborist to assess the tree.

      Assuming that the tree is safe, I have built plenty of platforms in this type of tree. For small platforms, it is a 4-TAB platform, with 2 parallel beams. Each trunk gets 2 TABs on opposite sides. One tree uses a rigid fixed bracket such as a pipe bracket for treehouse and the other tree gets floating brackets for treehouse. Larger or heavier use platforms may need more support.

      I hope this points you in the right direction. Good luck,

      -Dan

  13. Mike says:

    Hi Dan,

    Is there anywhere online where they list beam sizes for span distances? I have two 24″ diameter Douglas Fir trees that are 15′ apart. I planned to use a beam that was 18′ so I have a decent overhang at each of the TAB’s. But I can’t find any place that tells me what size beam I would need for that span.

    Thanks for any advise you can provide.

    Mike

    • Hello Mike,

      Usually I ask our engineer when in doubt and he knows where to get all of that data. I assume you are not working with an engineer, so for common materials like pressure treated lumber, most lumber yards will have tables available if you ask at the lumber sales desk. For engineered beams, I would go to the manufacturer’s website and/or call one of their reps. We use a lot of engineered pressure treated beams these days, where in the past we would fasten two 2x12s together…

      Good luck,
      -Dan

  14. Joy says:

    Hi Dan,
    I’m looking at building a multitude treehouse with the central. tree bing a 2’2″ cedar. The cedar tree is quite healthy but has a slight lean to it. (about 5 degrees) ca you tell me if this would put excessive strain on the tree. The other tree’s that would be used are in the direction of the lean and also at 90 and 140 degrees.
    Thanks,
    Joy

  15. Jim says:

    Dan
    I am ready to put siding on treehouse – need about 300 sq ft
    I don’t want to use any product that might be toxic to grandchildren
    What do you recommend?
    Jim

    • Hi Jim,

      My favorite siding for basic backyard treehouses is T1-11. It is inexpensive and easy to install. There are fancier versions of this if you order through a lumber yard.

      Another option is any type of shiplap or board & batten wood siding, such as cedar, pine, or spruce. These will cost a bit more, take longer to install, but have more character.

      To avoid toxicity, stay clear of pressure treated wood and most preservatives.

      Best Wishes,
      -Dan

  16. Kj says:

    Dan,
    I need to top some trees that have been topped before. There are multiple tops on one and three 20″ tops on the other. I would like to build a platform on. Is this fesable? The trees are green and healthy. Are there any specific building techniques I could use for this perch?

    • Hi Kj,

      This isn’t good for the trees. You probably know that. But the methods of tree attachments will vary according to whether or not you expect the tree to survive at all. How much of the green branch tissue will be removed? If enough remains near the attachment bolts, then our proprietary methods are preferable. If the tree will not have any green left, then it will likely not regrow, and you might as well notch the trunk and bolt beams onto it according to general carpentry principles.

      Good luck,
      -Dan

  17. Jason Underwood says:

    I am building a tree house between two trees with an 8′ x 8′ platform around each tree. One platform will have walls and a covered roof, the other will have spindles and a railing similar to a deck railing. They are planned to be connected with a bridge between them. The platforms will be 7′ above the ground. Are there any concerns with independent movement of the trees wither connected together in this fashion?

    • Jason Underwood says:

      Also, I was planning to support theses platforms with (4) treated posts on each platform, one at each corner.

      • Hi Jason,

        Be sure to add bracing underneath the platforms and/or connect the bridge tension to the trunk of the trees. A tension bridge can pull two treehouses together when people jump in the middle. Our treehouse bridge kits are tension style bridges. But if the bridge is rigid, then you just have to leave enough space for the trees to sway. If you are using 100% ground support for each platform, then just leave a space around each tree trunk so that the trees can move without yanking the structure around. Make sense? Does that help? -Dan

  18. Vono says:

    Hi Dan, I have 3 black walnut trees with about 24″ diameter trunks they are 15feet apart in a triangle shape. Are black walnuts good trees to build on.? They look very healthy but they do drop those baseball size nuts every year.

  19. Chris Williams says:

    I’m hoping to build a platform (maybe 8ft x 6 ft) on a big old conifer that has many branches and so would offer lots of support. Trouble is, the tree is dead, so we plan to cut it down to a stump of about 6 ft tall. I live in New Zealand, so the climate is mild and there are no extremes of cold, no frosts, but warm summers and lots of rain. The timber has not deteriorated and the limbs are incredibly dense. Is this a viable proposition, and would the stumps need treatment? I would really appreciate your ideas, thank you

    • Hello Chris, I can’t promise to you how long the stump will last. The roots may rot underground before the trunk does above ground. I am aware of no research to rest upon that will give you confidence to build on a stump. This is a good time to use posts on the corners… -Dan

  20. Jack Hamrock says:

    Dan, I’m planning on building my first treehouse – I’ve always wanted a medium size house about 15 feet up a tree. Since we got a new property in Fredericksburg Virginia, that’s a possibility now. However, most of the trees around our house are very thin (6-8″ diameter). I have found three trees that could work for the house, though. My favorite tree is (I believe) a healthy Yellow Poplar with a 24″ diameter trunk. The other two trees I like are (again, I believe) White Oak, but with 13″ and 15.6″ trunks, respectively. The smaller of the two aforementioned trees is 11.7 feet away from my favorite, while the larger is about 6 feet away. My desired house would be 11×8′, and built between trees, not around them.

    I will look at the rest of your site to determine how I should build the rest, or simply ask another question. The only real answers I’m looking for are 1) whether a 13″ diameter trunk is thick enough for a White Oak, and 2) which trees of the two smaller ones I mentioned would you recommend I use?

    Thanks, J.S.H.

    • Hello Jack,

      A 13″ white oak is a good candidate for a multi-tree platform, but not a single tree platform. The 20″ poplar is better for a single tree platform. However, it is challenging to use 6-8″ trees for significant loads. I have done it, but it must be done carefully, and I can’t get more specific until we see a sketch of the trees and the desired treehouse to make sure it will work. I can help you with that if you want a building quote. If you are going to build it yourself, you will want to work with Scott: design at treehousesupplies dot com. He can help with basic plans and hardware specifications. We have a 7″ black oak that we tested to 7200 lbs. load with a modified 6×12 TAB bolt. We are watching the tree and it seems good after 14 months. If you use the smaller trees, make sure that Scott or I review what you’re doing so that we can suggest the best attachment method, which may be non-standard. Also, be sure to get the exact diameter measurement at the height where the bolt will be installed before we finalize the plan.

      Good luck,
      -Dan

  21. Terry Gillis says:

    I built a 12 x 12 foot tree house platform and used treated 5/4″ deck boards spaced about 1/4″ apart on 16″ centers.
    A year later we are now ready to add a house on the railed platform. We want the house to be dry and will have windows and doors. What do you suggest I put on the floor? Since it will be laying on the treated deck boards, can I just lay exterior plywood and then put any flooring on top of that? Will the plywood rot because of water working its way across exposed deck boards and end up between the de King and the plywood? The platform will have 2′ exposed walkway (no roof over that part of the platform) all around the house that is centered on the platform.

    • Hi Terry,

      It depends on whether you are going for perfectly dry or not. For 95% of backyard treehouses, you don’t need to worry about water wicking. Here are some hints if you are in the other 5%.

      1. On sides where the wall is on the edge of the tree platform, let sheathing & siding overlap the rim joists.
      2. On sides where the wall is on the interior of the tree platform, use a roof overhang, cut the flashing through or into the decking (like a masonry chimney flashing), or caulk & flash the floor to framing connections.
      3. Caulk the inside framing to wall connection.
      4. good idea to use exterior plywood for the buildup, allowing a 1/4″ to 1/2″ space from the framing, and then put finish flooring over the top. If climate controlling the treehouse, then put flooring paper down just like you would do in a ground house.

      Good luck!
      -Dan

  22. Danny Hylton says:

    Hey. I plan on building my kids their first tree house. I am planning on a 10×16 platform with an additional raised crows nest of 4×4 platform so it will be a fairly large tree house. I have researched and read up on countless sites and books and have seen many different kinds of wood used. I have several mills located in my area and have decided to use green white oak for the entire tree house, structural and finish, with the hopes of adding in eastern red cedar where I can. I cannot find any mill that will cut eastern red cedar of any size for structural purposes; 4x or larger, for me which would have been my first choice based on its weather and bug resistance. I do plan to use oil based stain or paint once complete. Have you or anyone used a majority of green oak and could there be another more reasonable choice of wood to use that would be easier but have the strength as well? I will be completing this project alone and I know that green oak will have massive weight on larger rough cut 2x and 4xs.

    Thanks
    Danny

    • Holy Cow, I’ve never attempted to build a treehouse entirely out of green oak. We have used oak beams, both green and dry (reclaimed). There was this one project in Panama where we used nothing but tropical hardwoods with rare names but similar to mahogany and cumaru. Typically, for cost and weight reasons, we’re switching to PT lumber for joists and using pine or similar for framing. Heartwood white oak is worth the weight for exterior flooring and railings. Most of the time I’ve heard of green white oak, it’s for bending and projects like wine barrels or boats. I would not use something so heavy for wall studs, rafters, siding, etc… unless I had something to prove by using that material exclusively or if it had sentimental value. If you can use cedar for the framing, siding, & trim (and maybe railings too, but white oak makes nice railings too) then this will save a bunch of weight. I know someone who can supply green eastern red cedar – I buy a lot from the guy in various sizes. He grows it in upstate New York and delivers it down to us in PA. If you need a lot of it, then we could send it through our freight account, which gets pretty decent rates based on our volumes… Where are you located? I might know someone closer to you…

      Thank you,
      -Dan

  23. Francisco marriott says:

    Hi,
    I built a treehouse on a large maple (11 x 11 platform, 8 ft above ground ). The platform was stable as I was building it, but now that the walls and rood are finished there is a bit of shaking when kids/adults move inside. Is that shaking normal?

    The frame rests on 4 diagonal beams attached to the trunk at about 45 degree angles, and I built it so there was space for the tree to grow and move.

    Thanks
    Francisco

    • Hi Francisco,

      Normally, all single tree platforms have some rotational movement to them. However, this is unusual because the movement generally reduces as you build. It is most shaky when less wood is attached. As more wood is added, the ratio of the momentum a person can generate to the steady mass of the structure decreases, making it feel more stable. If you doubt the structural integrity of your treehouse, then you could have it evaluated. I would need a video or to visit the site myself to be able to tell you if the movement you are feeling is normal.

      Be safe,
      -Dan

      • Francisco marriott says:

        Hi Dan,

        Thanks for following up. I could try sending you a video but it might be difficult to see. Please feel free to email me to let me know where to send you the video.

        Thanks again,
        Francisco

  24. Jed says:

    Hi Dan, thanks for the article. I’m bought some plans for a tree house that I want to build from treehouseguides.com Before I go out and purchase my supplies, I was wondering if you know anything about their plans, or if you would be willing to take a look at them? The platform seems to – perhaps – violate your rule 5. However, I’m not really clear on what you mean by pinning a beam to a tree. The plans call for building two supports and attaching them to the tree with three 10″x3/4″ lag bolts each.

    Thanks for your time!

    Jed

    • Jed says:

      also, if I buy normal 2x4s and 2x6s from lowes and seal them with Thompson’s sealer, will that be okay? I’m not too keen on using pressure treated lumber around my son!

      • Hi again, Jed, – You can do what you’re saying. PT lumber will last longer, however, so keep that in mind. Another option is to buy cedar or redwood. If you’re going to use regular wood such as spruce or pine or fir, then I’d go with a semi transparent or a solid color stain instead of thompsons because the more solid the coating, the longer it should last outdoors. Given the extra labor and cost of stain, you’re not skipping the PT wood to save money, but if you prefer the chemicals in stain or thompsons instead of the chemicals in the PT wood, then you have the option. -Dan

    • Hi Jed,

      Sorry for the late response! I missed your message earlier in the month. Yes, I am familiar with the plans you’re talking about. They are easier to build, but they do not allow room for the tree to expand in girth as it grows. There is a tradeoff, you see, where those plans will be easier to build and cost less for materials, but the tree will suffer more and more as the years go on. Our design style will cost a bit more and be a little harder to install (though we have free DIY install videos), but the damage to the tree and growth interference get less over time, rather than the other way around. So if you want a long term treehouse, I would rethink the direction you are heading. I like that website and it was an inspiration to me before I started Tree Top Builders, but I don’t like the tree attachment methodology that Patrick is suggesting with his plans.

      Best Wishes,
      -Dan

  25. Dan says:

    Hello, I’ve ordered two of your floating TABs and plan on building a square house with two corners supported by trees and two corners supported by posts. My question is should my post and trees both be on the same sides or would it be better if they were diagonal from each other?

    Also wondering if it’s necessary to use treated joists if my house is going to have a roof and water tight walls?

    • Hi!

      I can’t think of a reason where the configuration of attachment points would matter unless there is more to the story…

      Treated joists are less tasty to bees. But you can spray if that becomes a problem in the future.

      If you order the TABs and brackets from our treehouse store (http://www.treehousesupplies.com), then they will offer free support in answering questions like this. You can pick up the phone and call them too at 610.701.2458.

      Good luck,
      -Dan

  26. Ryan Johnson says:

    Hi there. Great website.

    I am in the process of building a 16×10 platform that I will use to support an 8×10 enclosed house . I have built the platform much like any other deck using all PT lumber for beams, joists, deck boards, etc. As I build the house I was planning to use PT lumber for the bottom plates of the walls with flashing and overlaps as needed to shed the water away where the walls meet the platform deck. Do I need to use PT lumber for the studs and rafters inside the enclosed house? What type of plywood should I install over the decking inside the enclosed house for use as a subfloor – does it need to be PT? Thanks.

    • Hi Ryan,

      It sounds like you know what you’re doing. I probably wouldn’t go with PT subfloor, especially since it is going over the top of decking. The flashing is key, and making sure that siding overlaps as much as possible. You can also consider letting the flashing through the decking – sometimes we frame the deck to allow a slot for wall sheathing to pass through, but you’re already past that point.

      Good luck!
      -Dan

  27. Brian says:

    Hello, I’m building a 8×12 platform 8ft off ground
    Planning on 2 2x10x12 glued and screwed together for the main beams.
    Tree is a 35 inch diameter oak
    2x6x8 joist 16″ center
    ? Will 2 4x6s serving as knee braces work 1 on each side of tree?
    Brian

    • Hi Brian,

      We generally use more than 2 knee braces on a single tree platform, but 4×6 is probably a good sized knee brace for this size of treehouse. It’s tough to be precise without knowing what plan you are building from. I know the customer support at http://www.treehousesupplies.com has over 50 different plans to choose from and will help with questions about plans, tree attachment hardware, and accessories. That way you can use something that we know works, rather than reinventing the treehouse!

      Happy building,
      -Dan

  28. christina says:

    Hi Dan,

    I’m wondering if a pine tree is ok to build a tree platform in. It’s the only large tree in our yard but I know pine is a soft wood and we don’t want to damage the tree.

    • Hi Christina,

      We have built many treehouses in pine trees. Some pines are soft while others are a medium density wood. We have built in several species of pine with no problems. There is no reason to believe that building a treehouse would damage a pine tree any more than it would damage another species. Let me know if you need any other help getting started – we have plans, hardware, and offer full service construction.

      Arboreally Yours,
      -Dan

  29. Thomas Boothby says:

    I’m building a tree house in a very large and mature maple tree. The tree is split at the base into four seperate somewhat evenly spaced trunks. These trunks however are at various angles. My question is, is it possible to notch out the tree to secure the floor joists? I planned to use lag bolts in addition to seating the 2×12 in the notch. Appreciate your time.

    • Hello Thomas,

      It is possible to do what you are asking about. In fact, I have seen other people do that. However, it is very bad for the trees to build like this. We design treehouses that require minimal cutting of the tree. Preferably, the only tree damage we do is installing the main bolts and the rest of the structure doesn’t actually contact the tree at all.

      I hope this helps,
      -Dan

  30. Gail Lee says:

    love this dialog, Dan
    I am soon to sell my home (maybe in a year) which has a, what appears to be failing, 125 yo black walnut in the front yard. If in fact my arborist tells me to cut it this spring, I was thinking of having something built in the lower 15-20 ft on a 3′ trunk and 1′ branches. Not sure if I can build a treehouse by permit yet but have you any other ideas for what to perch in those branches until the roots rot? I’ve lived in its shade for 30 years. I can’t bear to just annihilate it. Thanks for your time.

    • Hi Gail,

      I can appreciate your connection to this tree and desire to see it continue in your life somehow. If you build a treehouse in it, keep the project close to the ground 10′ high or less, and be advised that the wood will not last forever and the project will not be safe when the roots rot. Another option for you would be to remove the tree, mill it into lumber, and build something for your home with it – keeping it out of soil contact and weather conditions will preserve the beauty of walnut flooring or furniture for generations…

      Best Wishes,
      -Dan

  31. Adam Mike Lee says:

    How do I determine what size tabs to buy for my platform? My plan is for double 2×6 pressure treated joists on the outside of the two for trees I have, which are 54″ and 48″ diameter and 28 inches part. The platform is about 10’x10′. The other end of the 2×6 joists would have 3-4″ diameter pipe holding the house up. Single story 10’x7′ footprint….perhaps a half length loft .

    • Hi Adam,

      TAB sizes vary according to the design load that they will carry and the hardness of the wood species they are installed into. Given only 100 square feet, and some ground support, it is unlikely that you’ll need the largest size TABs, but I’d rather direct you to our treehouse supplies sister company for some personal correspondence regarding your project. If you make a very simple 2D sketch of the 10×10 area showing a circle where each tree is, then they will be able to size the TABs, spec brackets, and anything else you may have questions about. Hardware questions are answered free.

      Thank you,
      -Dan

  32. Scott Green says:

    I’m building a pair of 15’x12’x10’x12′ trapezoidal platforms between 4 Ponderosa pines, one at 6’6″ and the other almost ground level at about 4″.
    I’m using treated pine wood and a mixture of 2x4s and 2x8s.
    The pines are located at the 4 corners of the trapezoid with trunk diameters ranging from 11″ to well over 18″.
    During high winds, the trees will bend or move a couple of inches even at the 6′ height.
    I can either attach them to the trees, or use 6x6s “inside” the corners of the trapezoid, and not connect to the trees at all.
    What would be the best method to attach these platforms?
    Thank you.
    SG

  33. Josh Zeman says:

    I have a massive oak tree: seven different trunks coming out of the same base, all at an angle. The base must be 5′ in diameter and almost all of the trunks are at least 18″ in diameter. About 15′ up, they all separate enough to make a large open area. I have a lot of building experience (I built my house). I want to make a platform by connecting beams to the trunks. Because the angle of the trunks, i shouldn’t need diagonal support; a few beams should be the whole structure. How do I make sure the beams will limit natural movement, but allow natural growth? If I use Treehouse attachment bolts, with slots, will that be enough to accommodate the natural growth? Is there a better method? Thanks.

    • Hi Josh,

      These types of trees present a lot of intermediate level challenges for a pro treehouse builder. I find that cabled platforms do alright if done properly, but those are advanced techniques. An easier method to understand would be to pass a central beam through the center attached to 2 trees – one fixed bracket and one floating. Then perpendicular joists on top. The joists will need at least 4 other floating attachments which can be slotted brackets or short suspension often works better when trees are leaning like yours. I would like to help you with the specifics, but we would need to see photos showing the lean, a diagram of the spacing of the 7 trunks, and a quick sketch with dimensions of the shape of platform you intend to build. I prefer to use TABs under the central beam, but the other points might use smaller hardware depending on the size and loads on each point.

      I hope this points you in the right direction. I can help more but you’ll need to email the information I mentioned and then I can spec and supply the correct hardware or generate a construction quote if you want us to build the platform and let you take over from there…

      Thank you,
      -Dan

  34. Lauren Terry says:

    I’m planning to build a 13’x14′ platform with a small treehouse on it (about 7’x7′). I’m not sure where exactly the treehouse will be located because there are branches in the way and it’s hard to take accurate measurements without the platform in place. Am I better off building the platform, covering it with decking boards and then figuring out where exactly to put down the plywood subfloor for the treehouse? Or should I decide ahead of time where exactly the treehouse is going to go and put down plywood there instead of decking boards? It would save me 50 sqft of decking. Does it matter if the house plywood subfloor is attached onto the deck or directly onto the joists? Thanks.

    • Hi Lauren,

      We have built treehouses both ways that you are describing. Step #1, Install TABs, beams, & floor joists. Then, the frame is in place to take measurements and you can decide whether to run decking on the whole platform or lay plywood first and then decking around it. The easiest method for beginners is probably to run decking first, then plywood on top. The other way around requires you to visualize where you will allow drainage and where you will need nailers ahead of time.

      Good luck,
      -Dan
      -Dan

  35. C.Z. says:

    Hi,

    I’m interested in building a small tree home between a few cypress trees in the marsh behind my mom’s house. They are about 25-30ft and about 5 or 6ft from the bank in the water. Would it be a bad idea to build in them?

    • Hi C.Z.

      Cypress trees are well adapted to grow near the water, or even in the water. They actually thrive in those locations, where many other trees would not survive. The lumber from cypress is prized for docks and other constantly wet applications. However, at 25-30′ tall, they might not yet have thick enough trunks to install TABs in.

      Best Wishes,
      -Dan

      • Robert Alpizar says:

        Hi there! I was looking to build in between two large Cypress as well. Are Cypress ok to build on… as far as I know they are hollow. The two I have are very large.

        • I have built in cypress and I think they are amazing trees to work in. Have them checked out by a local certified arborist to help determine if they are hollow – that’s a tough condition for me to assess from Pennsylvania! We do travel for work, but we have to be paid 😉

  36. Doug Wilkerson says:

    Building a tree house between three pines. Not sure if they are large enough to support the weight of the build. 10′ x 12′ house with windows and a door. Fourth corner will be a treated pole. How large should each pine tree be for the installation of TABS?

    Thank you,

    Doug

    • Hi Doug,

      Great Question… with a range of answers. The 1×6 or 1×9 TABs should ideally go in trees that are 9″ or greater diameter at the attachment point. The 3×9 TABs in 10″ or greater. The 6×12 TABs in 12″ or greater. You can cheat a bit by modifying the TABs, which we can do in our shop for you if you have a unique situation or slightly smaller tree. I have installed TABs in 6-7″ trees, but this takes a bit of care and precise preparation of the TAB and the predrilled hole.

      Good luck,
      -Dan

  37. Brian Fikes says:

    Hi Dan. I love your site and appreciate the great info.
    I am building a 16×10 platform that will eventually have some sort of structure on part of it. For supports I have two TAB’s at one end and two 4×4 posts on concrete supports at the other. I have two beams of sistered 2×12’s on each side of the tree running 16ft from TAB to support post. My question is about the joists. For most of the 16ft span, from the posts back to the tree, having the joists at 16″OC isn’t an issue. When I come the girth of the tree however, I can’t figure out how to lay the joists since the beam is the only support underneath. Would bracing between the joists (a span of approximately 46″) be sufficient? I obviously didn’t think of this issue in the planning stages!

    • Hi Brian: In that situation, you frame the opening like you would a door in a wall or a skylight in a roof. Add extra joists on the sides of the opening, and put a header to stabilize the short joists – you will still have a joist every 16″, but some of them will be cut. Keep the header at least 4-6″ away from the tree because that is hard to change as the tree grows… -Dan

  38. Alan Cassels says:

    Hi Dan,
    I am on an island off the coast of British Columbia and I am planning to build a treehouse about 10 feet off the ground between two healthy Douglas fir trees that are 2 feet in diameter and 8 feet apart. I plan on using recovered wood from the beach as my two main beams, and they are very healthy fir logs, 18 feet long, 6 inches in diameter and stripped of bark. I want to attach them to the trees by putting in 10 inch lag bolts and attaching foot-long, 1/2 inch turnbuckles between the logs and the lag bolts, (so that I can adjust for level and allow for the trees to sway independently).

    Any advice on doing so?
    The resulting platform will be 8 feet by 12 feet, and I intend to use steel cables –attached with large lag bolts–up the trees–instead of knee braces to support the platform that will jut out from these two main beams.
    Do you have any quick advice or do you think I’m crazy?

    • Hi Alan,

      I definitely do not think you are crazy. There is nothing wrong with trying to reinvent the wheel if you have lots of time or like a challenge. We have methods we use for suspending loads from cables that we have developed over years. The problem you are likely to have designing this with off the shelf hardware is that your doug firs will keep growing 1/4 to 1/2″ per year, and envelope your cabling quickly, which can lead to metal fatigue. If you change your mind and want to build with TABs, then there are a couple methods that we can show you which will create longer lasting designs. About 80% of our projects are conventionally supported these days (perched beams, knee braces), but cabling remains a viable option when done properly.

      Regards,
      -Dan

  39. Fred Sotcher says:

    Hello Dan, I am planning to build a hexagon platform on top of a old redwood stump. The tree was cut down 75 years or more ago it is 5 feet in diameter and stands three feet high. It appears to be quite solid. The hexagon platform will be 8 feet across and will be supported on 12 inch long pressure treated 4 x 4’s. The 4×4’s will be attached to the stump with (12 ) 1/2 x 10 inch lag bolts and connected to the 4×4 with Simpson ABU44Z Strong Ties. Once the 4×4 are installed I was planning to cut them to length so that I would have a level surface to support the platform. Do you see any problems with the plans?

    • Hi Fred. That’s amazing how long the stumps last, isn’t it? And if you build a treehouse on top with a roof, you’ll be keeping water off which may keep the stump sturdy even longer. The only potential concern is to make sure that the base of the tree near the roots is solid. The roots are thinner than the trunk, and they are underground, so I would expect them to rot first. If the roots are solid, then it won’t tip over and you’re good to go. Good luck, -Dan

  40. Calvin W says:

    Hi Dan,

    We had a 135′ Douglas fir tree die so we had it cut down but we left 25′ stump which planned to build a tree fort around. The diameter of the tree is around 4′ at the base none of the wood that came from the tree was rotting. I wanted to build an enclosed tree fort around the tree and a roof over the top to protect the top from rain etc. However I am now wondering if the root base in a dead tree would support this. Any thoughts on this would be appreciated. I could send you a picture if that would help.

    Thanks,
    Calvin

    • Hi Calvin, unfortunately, I just can’t tell how long a dead tree will remain stable. The structural roots in the 8-12 foot radius around the trunk are dead and will eventually rot, I just don’t know how long it will take. You could use ground support, or cables to further stabilize the treehouse. -Dan

  41. Jeremy says:

    I want to build a treehouse in my back yard which is on a saltwater creek with only skinny loblolly pines. The biggest trees are probably only 2 feet in diameter. Do you think it is possible? My thought was to use several trees at once for support, so if one does die then the treehouse doesn’t collapse. there is a group of 7- 8 about 18in diameter trees that I was considering.

    • Hi Jeremy: the trees sound great! We have built in loblolly pines as small as 12″. They do move a lot in wind or ice conditions, but are generally good trees to attach to. A stand of 7-8 of them around 1′-2′ diameter would surely have possibilities. Good luck! -Dan

  42. Jon Jones says:

    Greetings – I am mid build, the platform is up and secure, but it has more wobble than I’m comfortable with, I’m not sure if I’m over-reacting or if some movement is normal / inevitable.

    The build is on a single large healthy oak, the platform is 8 feet by 10 feet, framed in 2×6 lumber, and sits on top of 2 double plated 2×10 beams supported by a TAB each and knee-braced at 45* down to another TAB below- 4 bolts total, 2 each side of the tree.

    I thought the wobble would dissolve once the frame was decked, but it has not, so I’m open to suggestions or thoughts on how to eliminate this or if I’m just overbuilding. I showed the structure to a general contractor in photos and he laughed and said I could hang my truck from the beams with how braced they are – its just the rotational twist that troubles me.

    Thanks guys!

    • Hi Jon,

      Some rotation will always be present on single tree platforms – even when we build them. The rotation is higher with a high ratio of platform size / tree diameter. Things to reduce rotation include adding more knee braces or adding weight to the platform. Generally the rotation feels bad with just joists, then less bad after decking, then less bad after walls. The weight of a person / weight of platform decreases as you build. Unfortunately, I can’t see if anything is wrong with your platform without being there to check it out, but some movement is to be expected. You can use guy wires to other trees to eliminate rotation, but it’s not necessary if the structure is built properly.

      Good luck,
      -Dan

  43. Rick Schroeder says:

    If I use TABs for 4 trees do I have to have one static anchor and the other three dynamic? Or can they all be dynamic? And if one must be static, which one do I choose?

    • Hi Rick,

      You can use either configuration. I usually pick one as static (master) to create a set position for the house. All else being equal, I would pick the largest tree involved and the tree closest to the center of the platform.

      Good luck!
      -Dan

  44. Brandon Wilson says:

    I am planning to build a treehouse between two large (30″ diameter) Sitka spruce trees on the Oregon coast. I have two 6×14 untreated beams for the 12 foot span between them. I will use TABs to attach the beams and protect them with stain and flashing. I plan to build about 25′ – 30′ up for the floor level. I’m wondering how much sway I need to plan for in the floating brackets. The beams are perpendicular to the breeze that “typically” comes from the ocean but I’m sure I can’t count on that. I’ve read on your site that 6″ seems reasonable nearer the ground. Can I just do the math to project that level of motion further up the tree?

    • Hi Brandon,

      For a more exact guess, I would defer to an arborist or forester on the West Coast – I’ve never sat outside in a wind storm in the northwest USA and watched how far Sitka Spruce tend to bend. However, they look like large, sturdy trees and if they are anything like our Norway Spruce on the east coast, then we seldom see more than 1″ of movement at 10′ high. However, at 25-30′ up, I would allow 4-6″ in any direction. That tends to get into custom brackets attached to TABs, which is something we can help you with at http://www.treehousesupplies.com. We probably only build that high a couple times per year so it’s not standard hardware.

      Good Luck,
      -Dan

  45. Amy says:

    We are trying to build a treehouse between two pine trees. We have fixed center beams to one tree and they rest on a support on the other tree that lets them slide and then the platform sits on this. We are going to put knee braces to support the platform but isn’t it a problem to secure both sides of the platform with knee braces since that would create a fixed platform instead of allowing movement? Would cables make more sense because they would allow for more movement?

    • Hi Amy,

      If the knee braces attach near the base of the tree then they won’t restrict significant movement. I’ve installed this with braces that only cover 3-6′ vertical and not had any problems. Wood can flex a little. With longer braces, however, I think you could have a problem in high wind.

      The problem with cables is that they load unevenly as the wind blows, so as long as you don’t occupy the treehouse during high wind events, they are a good choice. Just don’t attach them too high or they will lift the platform when the wind blows, which caused a problem with one of my early treehouses in Virginia.

      Thanks for the question,
      -Dan

  46. James T Burke says:

    Hello Dan, I’m building a treehouse 20′ off the ground in three Redwoods. The trees are in a triangle pattern. The two larger trees (24″ dia) are 8′ apart. The other tree is approx. 10′ away 20″ dia. I ran 6x12s 20′ long on floating brackets and tabs. On the single tree I built a tri- beam out of 4×8 beam and 4×6 bracing, setting on two tabs with fixed brackets. The floor is 16×20. The floor joists are 2x10x16′ on 16″ centers. I bracketed the tri- beam to the girders. I’ve noticed that the tri-beam is torqued and the floor slightly off level. I believe it was caused by wind and I should have used a floating bracket on the tri-beam. What do you think? I’ve since removed the bolts to the fixed bracket to allow for some movement. I also removed the brackets from the tri-beam to the girders. I going to relevel the floor and put up another tri-beam on the other side of the tree. Thanks, Jim

    • Hi Jim,

      Interesting. If you unbolt the fixed (top) bracket of a tribeam, then it can move laterally a little bit, but if it moves a lot then it will bind. I’ve never undone them as a permanent solution – just loosened in order to adjust level on a platform. The trees are large enough for the second tribeam and it sounds like it would help.

      Also, keep in mind how soft redwood trees at and you might consider extra support on the other two trees as well given the size of the structure. We will often connect to a doubled joist at 90 degrees in addition to a main beam and then connect structurally the beam and that double joist.

      Good luck,
      -Dan

  47. Sam Iamo says:

    I just found your site and read this document. I’m impressed by the level of expertise. I have a couple of initial questions about a specific prospective build. As i am not at my build site and am working from memory, I am certain I will need to follow up on specifics later. I am planning to build an observation platform in a tree on my vacation property. The platform ideally would be ~100 sq ft. I don’t plan any “walls,” but I might ultimately want a soft canopy, or possibly just a 2-man tent perched on it. The tree I have in mind is quite large. The base is >25 ft in circumference. I can’t be sure about the species until I can climb it – it’s too tall, and the canopy is too “busy” with other trees to clearly see the leaves. My best guess based on bark, shape, and the distribution of other trees on the property is either oak or tulip tree. About 20 ft off the ground, there is a limb that is an estimated 2.5 – 3 ft in diameter (at the trunk,) and is nearly horizontal (>5 deg angle at a guess.) I would like to design a platform that would be above that limb and use it as primary support in addition to the trunk. Is that something that is commonly done? Is there such a thing as a tree that is “too big” for this kind of structure? Thanks!

    • Hello Sam,

      No tree is too large, however, the growth rate must still be good for the tree to accept the TABs. Make sure that the branch unions are free of excluded bark, that the trunk is solid, and free of structural defects. We can certainly help you design and/or build your platform. We also supply all of the materials you will need to safely attach to the tree. Please get in touch with us when you are ready to start designing the platform.

      Best Wishes,
      -Dan

  48. Jason says:

    Thank you, Dan for sharing your wealth of knowledge. I am building an 8×10 platform between two 12” diameter hackberry trees that are 7ft apart. The deck of the platform will only be about 6ft off the ground. I am using two standard tabs 1×12. I’m Using 2 2x8x12 for beam spanning between both trees. And then 2x6s on 24 centers for joists. I was planning on 4 knee braces one on each side of both trees. Can I use 2 2x4s for the knees or should use 2×6?

    I was planning on using pressure treated wood for the entire platform. Do you have a suggestion on how to keep the lumber from warping or splitting? Especially the beam and joists.

    What’s your opinion on hackberry for treehouses?

    Thanks again, sorry this is so random.

    • Hi Jason,

      It sounds like this will work for a small treehouse. We normally use larger lumber and go 16″ OC, but if it’s a play structure for kids then it may be exempt from building codes. I would stick with the larger knee braces – we actually use 4×6 for most knee braces, and 2×4 sounds sketchy to me. To protect PT wood, you can stain it with semi trans or solid color stain to afford some UV and weather protection, but make sure the wood is dried out somewhat before application so that the treatment penetrates and doesn’t peel off the surface. I have built in Hackberry several times and it is a good tree for treehouses.

      Good luck,
      -Dan

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