Welcome to “Ask the Tree House Experts”

We plan to use this category to answer all Tree House Questions that you have. Please leave a comment here with your question or email to treetopbuilders@verizon.net. We will then respond publically to all relevant tree house, tree platform, or tree house accessory questions. We are experts in attaching things to trees, and so we probably won’t answer questions about general construction or trees unless we can answer the question in a way that would be interesting to other readers looking for tree house building information.

For Quick answers to common questions, please check out this tree house questions page. Otherwise, ask away and we will respond for everyone to read…

74 Responses to “Welcome to “Ask the Tree House Experts””

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  1. I am building a treehouse in a Bald Cypress tree. The trunk splits at about 8′ from the ground. At about twenty feet the two trunks are about six feet apart from each other and about 14″ in diameter each. I want to build a small, 5’x8′ treehouse between the trunks. I was thinking of running a 1″x8′ galvanized rod through both trunks instead of individual tabs, bolted at each end. A beam would be centered above this rod beside each truck creating two support beams. The beams would slide on the rod as the tree grew in girth. Each beam would have two braces angling back to their perspective trunks. These angled braces would fit into a bracket mounted on top of a tab at each trunk about six feet below the beam. The joists would be attached permanently to one beam and “float” on top of the other beam, through loose, upside down U shaped brackets that would allow movement but prevent uplift. Does this sound possible or ridiculous or somewhere in between?

    • thb98il1Tr3e says:

      Hello Richard,

      I’m going to have to go with somewhere in between on that one. I never recommend all thread for shear or bending loads. In trees, shear is more theoretical as all perched loads are bending loads. I advise making a sketch and sending it in, but it sounds like four of our 5/4″ lag bolts with 2 floating brackets and 2 fixed pipe brackets would do the trick. There isn’t much reason under normal circumstances to use TABs to support a 40 square foot platform, because while they are stronger, they do more damage to the tree. The trick is to use reasonably strong connections for the load, without overwhelming the tree.


  2. M says:


    We’re thinking of building a treehouse in our backyard. We have a good amount of trees back there, and we wanted to get an idea of how much our treehouse idea would cost. It would be two crows nests, about ten feet off the ground, and the crows nests would be connected by a bigger platform in the middle. Kind of like a Mickey Mouse face. The trees in our backyard are proper trees, not the tiny ones that you see in landscaped parks, and some rise up to about fifty feet and have a 1-2 ft diameter. If the price is reasonable, we might hire you guys to build it. Thanks!

    • thb98il1Tr3e says:


      We can’t give out exact pricing without collecting more information, which conversation we should probably take offline. Please contact us directly and we’ll do our best to provide you with a quote.

      In general terms, three platforms like you describe might cost around $10,000 – 40,000 depending on location, sizes of platforms, type of materials, whether round shapes or square or octagons, height above ground, and perhaps other factors.

      If you build yourself, then we can supply plans and hardware for most projects in the range of $300 to $1500 per treehouse.

      Thank you and good luck with your project.


  3. Ashley says:

    I am looking to purchase land to have a treehouse built. I am looking to live in this full time/year round. Could someone please help me with a checklist of what I would need to look for when buying land. Such as specific trees that may be better than others. And I would need water and electricity. This would be very helpful! Thank you 🙂

    • thb98il1Tr3e says:

      There are many factors when selecting land. Here are a few preliminary things to consider:

      1. Buy land with many large trees
      2. Healthy trees are more important than any particular species. If you aren’t sure, then hire an arborist to help assess the trees.
      3. Talk with the building inspector to ensure that you will be allowed to build and live in a treehouse on that parcel of land.
      4. Ensure that the tree species are not protected by law.
      5. Trees should be over 12″ in diameter and it will take many of them in a tight cluster to hold the weight of a permanent house. Many end up needing ground support as well, but those considerations can be dealt with once you have trees in mind. Give us a call when you get closer to moving forward with the project.

      Thank you,

  4. Isabel Thomas says:

    I built a 9′ x 6′ platform a few years ago. I put railings and a roof on it made out of plastic corrugated panels. I am going to redo it and put up walls and a new roof, and I was wondering if you have any suggestions for materials for roofing and walls that would last at least 10 years and not be crazily expensive? It needs to be water and snow proof since I live in ohio.

    • thb98il1Tr3e says:


      It sounds like you want inexpensive and durable materials. For roofing, I like corrugated panels but the polycarbonate ones get brittle due to ultraviolet light, and the asphalt/felt ones will puncture easily from small/medium branch falls. I suggest metal for the roofing – harder to cut, but much more durable. For siding on inexpensive projects, it’s hard to beat the value of T1-11. It is very strong, and will last over 10 years if you have a roof over the walls and all cuts are covered with some sort of trim. I recommend staining the T1-11 as it will look a lot nicer and last longer.

      Best Wishes,

  5. Mike says:

    I recently moved and had a son (he’s only 9 months old). I’m wondering what tree you would recommmed for the DC Metro area that would grow fast enough that he would be able to enjoy it (so maybe 8-10 years?) and good for my area.


    • Hi Mike,

      There are a lot of trees that will add value to your yard in 8-10 years, with shade and O2. However, there aren’t any that you can plant with 2-4″ calipers that you’ll be able to build a treehouse in that soon. We’re working on some experimental methods for building treehouses in smaller trees, but they are not ready for market yet. Perhaps in 8 years… Given current methods, you’ll need the trees to be at least 7-10″ diameters to use them for a treehouse. The best method would be to build the treehouse on posts, and then plant trees around it to shelter and shade it.

      Best Wishes,

  6. dan says:

    I live in southwest ohio, and really have only one suitable tree for my tree house. Its an eastern cottonwood the 4 ft. high diameter is about 28 inches and 20 ft. up is about 24 inches, The first branch on the trunk is about 35 ft. up. My platform is going to be 20 ft. up, and 16 by 12 and the house would be 12 by 10 My main question is that from researching, the general consensus is eastern cottonwood is not the best tree for tree houses but its all i have. Is this project something I should abandon, or can I increase the size of my tabs to compensate for the softer wood , or any other suggestions you might have for building in an eastern cottonwood.

    • As you may have guessed, there is no absolute yes or no answer to whether or not to build a treehouse in a cottonwood. It’s a matter of how much risk are you willing to tolerate. Cottonwoods are good at being cottonwoods and can grow to great size, but they aren’t the longest lived trees, and they can lose branches in storms. However, they do better in wet areas than most eastern woodland trees do. I would rather have a healthy cottonwood than a white oak with a major structural defect.

      I do NOT think you are nuts for proceeding with the project. It’s a higher risk tree, but any tree could fail in a storm tomorrow without warning. What I might do is consider toning down the overall size, weight, height, and expense of the project to only what you need to make the project a success. Treehouses are close to the tiny home movement in spirit.

      And yes, bigger TABs or more of them is a perfect compensation for softer wood. I can’t advise exactly which TABs or which placements without more information, but our treehouse supply company does sell TABs and offers support to help you design you treehouse in the most tree friendly way. Most questions and advice do not incur any design fees at all for customers who buy hardware from us (still at competitive prices with free shipping).

      Happy Treehouse Building,

  7. Linda Diemer says:

    Area around each limb is leaking when it rains. What is the best way to seal around the limbs and prevent interior damage.

    • Hi Linda,

      This is a tough one. Most of us treehouse builders started out building around limbs and then inventing ways to seal out the weather. Then, as the treehouses got nicer inside, we stopped designing treehouses that have limbs through the walls and roofs. I find the trunk dead center on a hip roof is the easiest to deal with, but still not easy.

      The best methods involve something to prevent friction between the tree and the structure, such as thick rubber or horse stall matting. Then, fashion a gasket out of more rubber, plastic, a tarp, or something to interface between the flashing and the branch, over the friction barrier. Then affix to the branch with bungee cords, and then caulk it with the thickest possible bead of silicone. This usually stops the water for a while without killing the branch. However, it is not a permanent fix. No permanent fix exists to my knowledge. If you find an improvement, please let us know.

      Best Wishes,

  8. Carl says:

    I have a large elm tree in my back yard. I’d say it’s 40 feet tall. I was going to build a tree house around it and not connect anything to it but thought I should check into the health of the tree since some of the branches are dead or thinning. I have had a few opinions from tree trimmers stating that elms are known to spit at the forks and drop branches which it did 8 years ago. They all offered to trim or cut the tree down to size. I had an abrist say that it would be OK to leave a 15 foot tall trunk up so that I could have something to build around and hang a rope from, and cut the rest off. Then another tree trimmer said it would decay too quickly and would then have to be removed from inside the treehouse. So I’m not sure who to believe. Any advice about elms and tree houses would be awesome.

    • For the arborists to be recommending serious pruning or removal, the tree must be in rough shape. I would support the treehouse completely from the ground, and if you top the tree down to 15′, then you can rigidly connect the trunk to the house, which will make it easier to waterproof, and when the tree rots, it will be held up by the house for a long time. The downside to that is the mess. If, however, the tree can be saved, then you could remove the dead parts and cable the forked sections together up high. It’s all so hard for me to weigh in on specifically without being there and seeing it, so I’ll have to defer to the local experts on whether or not the tree can be saved.

      Good luck,

  9. BJ Anderson says:

    When placing siding on the exterior walls, due you attach them directly to the studs or do you place exterior plywood on first, then attach the siding?

    • Hi BJ,

      It depends on how waterproof you need the structure to be, and how much shear strength you want to add to the walls. For basic treehouses, we often skip the plywood sheathing. If you are running electric and finishing the interior, then it’s probably a good idea to use sheathing, house wrap paper, etc… just like you would on a ground house.

      Good luck,

  10. Dave McMaster says:

    Hi, I have just build a treehouse platform framed with 6 x 2 timber. the spacing between joists is 16”. My question is what thickness flooring can i get away with? I am looking at roofing the whole thing and so slippy surfaces are not an issue (don’t need decking). I hear 1” boards mentioned at lot as a minimum. Would this be okay with the joist spacing? Also as I live in the UK a lot of timber is quoted in metric sizes. Here 1” equivalent is generally 19mm which seems puzzling, since an inch is 25.4mm. The next size up is 34mm. Cost is a lot more for the 34mm though.

    • Hi Dave,

      You are better off asking this question to a contractor or building supplier who is located and well versed with building codes in the UK. Here in the USA, for 16″ O.C. joists, we would use a 5/4″ decking board, which is actually 1″ thick, not 5/4″, due to the planing process – lumber is usually quoted in the rough dimensions, not the final thickness on the shelf.

      Sorry that I can’t definitively answer your question. Perhaps someone else will chime in and help…


  11. nicholas bevens says:

    hello my name is nick i have a couple questions to ask, after beams are in place, can you put truss instead of joists? would it be a bad idea to build in a three foot round bearch at one corner of the tree house, a two foot round bearch, and a white oak on the third making a triangle? and lastly what wound be to much for these trees to load?

    • nicholas bevens says:

      i meant beach sorry and the triangle stands 9yds by 17yds by 18yds from tree to tree to tree

      • Hi Nick,

        That is a long span. Now I am changing my tune. You will be better off using ground support in the middle to help. While possible to create a beam or truss to span that distance, it really isn’t practical to build 17 or 18 yard spans. It would take really large steel beams and a crane to set them. If you’re really going to try it, please send us pictures when it’s done, I’ve never seen anyone build anything like that in trees without ground support.


    • Hi Nick,

      I have never used trusses instead of joists, but I don’t fully understand what you are suggesting. I don’t see any issues with the sizes or species of trees you mention – they sound like good trees so far. I would assume that the trees can hold a lot of weight tens of thousands of pounds when loaded onto the lower portions of the trunk – the only question is how to attach the loads to the trees sufficiently. We can help with that, but not for free over the blog. You should start by sending pictures of the trees and sketches of your project to Scott at http://www.treehousesupplies.com and he will help point you in the right direction. If you need plans made, he can help with that too.

      Good luck,

  12. David Widawsky says:

    Hi Dan – My wife and I took your workshop in Sept. 2014 and ended up building a two-story open-platform treehouse. First level is 9’x12′ platform with launch platform for 160′ zipline and second level is 8.5’x7.5′ crow’s nest. Both are independently supported with TABs, knee-braces (for platform), and cables (for crow’s nest). Very solid. Had many people up there and everyone loves it!

    I put in two 3×9 TABS into a big hickory tree last spring, to give the tree time to compartmentalize before building a 16′ octagon next spring, using your plan for the octagon. I want to build an enclosed treehouse on the 16′ octagon, and have it include a loft. At the workshop and with the plans, we didn’t discuss the logistics of a 2-story (loft included) structure and only really worked on framing a 1-story house.

    So, my questions:
    – do I need to use wider beams to sit on the TABs to support the larger structure?
    – do you have plans/suggestions for framing a two story structure on the 16′ octagon (vs. a one-story structure), and things I need to be wary of?

    Thanks a million! You guys are great!

    – Dave
    Annandale, VA

    • Hi Dave,

      We can definitely help you, but we probably need to switch to email and phone to get this dialed in for you. There are various ways that you could add a loft to this structure, and the size and location of the loft will affect the advice we give you. First you draw what you want, and then we follow the loads down to the TABs, and we identify any parts of the frame that appear overloaded and beef them up. I’ll email you shortly…


  13. Rob Guenard says:


    I have a question about how close you can place tabs near one another. I am in the planning and design stage of building a tree house between two 18 inch diameter loblolly pines which here in North Carolina. The trees are 16 feet apart so my thought was to run two parallel beams across the trees upon which to set the platform.

    To do this I would need to put two tabs in each tree oriented at the same level but on opposite sides of the trunk. Given the depth of the tabs, would this weaken the tree too much, given that the tabs would be close to meeting in the middle of the heartwood?

    Thanks for any insight you can provide!

    • Hi Rob,

      The bark and phloem for 18″ Loblolly Pines are usually around an inch, so you only have about 16″ of wood diameter. The small TABs with 1″ collars will not “crash” in the middle, our 3×9 TABs might crash, and the 6×12 TABs will crash unless you slightly offset them or cut some of the interior threaded portion of the TAB off.

      Looking at the tree, the more wood that is removed, the more of an initial structural weakness is created. If the tree remains healthy and growing, then it will adjust for that weakness over time. Lots of time, in this case, because Loblolly Pines that size have a slow growth rate. There is nothing qualitatively different about a bolt going through the pith of the tree, or about 2 drill holes meeting in the center. We have built with parallel beams on trees this size many times, and have yet to hear of a tree failure in the area of the tree attachments. In your design, make sure to use 2 fixed brackets on one tree and 2 floating brackets on the other tree. This will allow the trees to sway and rotate a little without damaging the structure.

      Good Luck,

      • Brett Godush says:

        I have a similar, but I think slightly different question. I started on a tree house and made an error. I am using two trees and my intent was to use floating brackets. I attached a 2×10 on each side of the two trees, basically sandwiching the trees in the middle. I was then going to put the platform on top of that.
        Unfortunately, I attached one bracket to one tree and the other to the 2nd tree. And didn’t even think until after that, that once I attach the platform, I will lose the floating aspect intended by using the brackets.

        At this point, I see three solutions:
        1) I move one of the brackets so that both are on the same tree. However, the tree is only about 10″ in diameter, so my 8″ lag bolts obviously wont work. My thought at that point is to use threaded rod and just go all the way through the tree, attaching a bracket on each side. However, I have not really seen this done and am wondering/assuming that this would not be a good option.

        2) I basically start over and use a different approach. This is the one i am leaning toward, but I’m not sure if its better than option 1 or not. I would be removing 2, 5/8 x 8″ lags from each tree and i honestly do not know what that will do to the health of the tree and subsequent safety of the tree house. If i make my “new” connections to the tree far enough away from the prior holes, is that “acceptable” and even if it is, is there anything i need to do to the old holes to try and ensure they heal over, if in fact they will?

        3) My last thought is to create a new bracket that has a higher attachment point to the tree so that when i put both brackets on the same tree, i ensure the location where they are attached to the tree are far enough apart as to not cause compartmentalization?

        Thank You

        • Hi Brett,

          Thanks for reaching out to us. I would not use all thread – there are safer and better solutions. Normally we would fix to one tree and let both beams on tree #2 float. Have you already installed a TAB in both trees? There are definitely good ways to recover from mistakes (which we have made), but I think we need to talk with you to get more information. You can offset TABs/Brackets so they don’t crash in the tree, for one. Please contact our supply/design affiliate: Treehouse Supplies

          Good luck,

  14. Samuel Baker says:

    I would like to start off by saying thank you for all of the great info on your website. I have read through it but still have a few questions if you wouldn’t mind answering.


    The above link contains4 pictures of my first support board attached to tree and 2 pictures of my frame mockup and 1 picture of my finished design I did in Sketchup. This part of the treehouse will only be a deck with a railing so there will not be much weight. The tree we are using is a southern red oak and the location is in South Carolina. This is a treehouse I am building for my children and I do have a budget.

    Here are my questions/concerns

    I purchased 3/4″ x 10″ galvanized lag bolts and 3/4″ galvanized washers for the main support. I am trying to minimize the amount of screws going into the tree and with this design I will have six. four on the lower left and right beams and two on the upper cross beams. For my main beams I am using 2x10x12 pressure treated boards. After getting the one board up, as seen in the pictures, I was unsure if this was the best way to attach it. I did look at the TAB’s but they were too expensive and I will not have that much weight so felt it would be overkill. Then i started reading you pinning and perch info and even though i am spacing the 2x10x12 with spacers to provide a gap from the tree it still seemed I was pinning it.

    Question 1: Based on the pictures of my first board being fastened to tree do you think is this a good method?
    I was hoping for more of a gap (1″) but that is what we ended up with (1/2″). I understand that our tree will grow a little less than an inch every 5 years based on my research. I had originally purchased 3/4″ dia x1″ long spacers but they would not fit on my lag bolts so I just put six of my washers together to simulate the 1″ spacer.

    Question 2: Will the tree grow around the washers or is it going to push them out along with the board?

    Question 3: I saw on treehousesupplies.com website they offer this 1″ Pipe Bracket which seems to be an alternative to the TAB. They also make a floating bracket for multiple trees. This is a single tree but we are attaching to two separate main trunks. Would either of these be the better option to what I am currently doing? I know I would have to purchase bigger lag bolts if I went with either of these because I have 3/4″ now.

    Question 4: As you can see in my Sketchup mockup I have another 2x10x12 that will be notched and placed on top of my two main lower supports. It will also be attached to the tree with lag bolts. By doing that will I be restricting the tree to grow?

    I understand this is not a lot of weight or a big treehouse project but want to do it correctly. I would like it to last as long as possible. Any help you can provide would be greatly appreciated.

    • Hi Samuel,

      There are definitely ways to improve this design, as the trees appear to be supporting at least 75% of the structure. With offset 3/4 bolts, I’d be surprised if they aren’t bending downward, putting them at risk for failure. If you decide to allocate some budget to doing a better job, then I’ll be happy to get more involved. If not, then the washers you have used can be left in place and let the tree grow around them. I wouldn’t buy the pipe brackets or floating brackets unless you have the money for the fasteners (Tabs or 5/4″ lags) as well. When the tree grows outward over the washers and is pressing against the 2x10s, then you’ll have some reattachment options at that time.

      Good luck,

  15. Paul Bertucci says:

    I built a very simple treehouse measuring 8×8 on four 4×4 treated lumber posts. Height is 6 ft in back and 8 ft in front. I dug the holes for the posts 18 inches and used one 80 lb bag cement per hole.
    I cut a 2×6 20 inches long for angle brackets from deck to posts. The deck feels very solid. However someone told me I might need to make a big x with 2×4 across the posts all around. That would ruin the looks, what are your thoughts?
    Paul Bertuci

    • Hi Paul,

      If we built it, we would have dug deeper holes, used more concrete, and not needed any large X bracing. However, given that the holes are shallow and have only one bag of concrete, the structure might be more wobbly than normal. If you can shake the structure back and forth and it doesn’t feel stable, then you need more bracing. If, as you say, the deck feels very solid, then you probably don’t have to worry about additional bracing. One note, make sure that you used appropriate fasteners (nails, screws, bolts) on the angle braces.

      Good luck!

  16. Paul Bertucci says:

    I placed 2 stainless 3/8 2 inch long lag screws in my tree. Problem is I put them 4 inches apart. Then read they should of been 12 inches apart. I did not take one back out and place it again, I just left them both. Think It will be ok for the tree. They only go in about one inch. Tree is 2 feet in diameter.

    • Hi Paul: You are not likely to kill your tree from the 2 small lag bolts. The 12″ rule of thumb depends on the size of fastener and vertical / horizontal spacing. The bigger problem with pinning beams to trees is the lack of space for growth & tree swaying. We just spent 3 days and $6000 repairing a poorly built treehouse. Every single tree attachment had to be changed out after only 4 years of use. Had it been built properly in the first place, then none of that would have been necessary. I read your other comment and I am guessing that these 2 lag bolts are not for the structural support of the treehouse – are they for a small accessory that is not safety related? -Dan

  17. Bern says:

    Hi Dan,

    This website is great, such a great resource of information and inspiration for dreams!

    I would seriously love to build a proper “house” in the trees for my kids with TABs and an engineered plan, but for this build, a simple 10′ x 14′ platform with a railing in the trees seems reasonable.

    I’m on the Canadian west coast and I have a 24″ Douglas Fir and a 20″ Hemlock 8 feet apart. I have free access to 1 inch B7 (125ksi) threaded rod in 36 inch lengths and appropriate hardware.

    My thought is to drill completely through each tree at 2 points vertically apart by 60″ and put the rod through the tree. Then I’ll secure a “triangle” on each side of both trees (doubled 2x10s to hold the joists with doubled 2x6s for the knee braces). The triangles in the one tree will be secured tightly spaced 1.5″ away from the trunk, while the triangles in the other tree will be allowed to float.

    Assuming I have enough building experience to build a safe structure, doing you think my tree attachment (the four 1″ rods supporting load on both ends) will be adequate?

    Thanks for your consideration!

    • Hi Bern,

      I used to use 1″ and 1.25″ B7 rod for certain applications, but over 10 years ago I realized that they are not good choices for main support systems on trees. They are not made for shear loads or bending loads. 1″ rod will definitely bend when loaded as you describe in the tree. Bending fatigues the metal and it can break.

      Thank you,

  18. Tom says:

    Hello, I recently constructed a treehouse (with help from friends) that sits on 3 cantilevered beams, which sit on a TAB at each end – a 20′ 4×10 and two 22′ 2×12’s. After experiencing some bounce and sag on the one 2×12 beam, we sistered a second 2×12 beam to it (as well as the other 2×12 beam that didn’t need it). There is still some bounce and minor sag to the sistered 2×12 beams. My question is how bad is some bounce (for adults) and minor sag? I wonder if a 20′ span is too much for this lumber (pressure treated hem-fir), but I’m trying to avoid a post. Any suggestions?

    • Hi Tom,

      I’d love to see a picture to help me understand the specifics. Without more detail, I can only give general advice. We use a lot of pressure treated beams – usually PT Paralam or Anthony PPGL. A PPGL of 3.5″ x 12″ is much stiffer and more stable than a doubles 2×12. However, you might need a larger one depending on the span between support points. If the span is really 20′, then we have used PPGLs around 5.5″ x 15″, but I really need to see a picture or drawing to say what I would use. Those are expensive beams. Another option is to put a post in the middle. If you’re near West Chester PA, you should stop at Treehouse World and check out how we built the pavillion treehouse – there are knee braces that stiffen a 26′ span. How bouncy is too bouncy? If it’s deflecting an inch or two in the middle then you probably won’t fee safe up there and will want to improve it – it may not fall down or break but it will sag over time. The relevant term is deflection. Deflection limits are what govern the size of beam and joist that you would be told to use by an engineer following local building codes. The deflection limit is not the point above which a board will break, but rather when you start feeling more than normal bounciness.


  19. Jennifer Trawick says:

    We are still working on the inside of our treehouse but our kids are already enjoying it. They have spent two nights in it already. Our problem is we have a tree growing close to the staircase and every time one of them comes down the stairs they knock some bark off the tree. Is there something we can put on the tree like a sealer that won’t hurt the tree?


    • Hi Jennifer,

      I am not aware of a sealer like that to protect trees. I have used netting or fabric to protect trees at high traffic areas before – like putting a loose sock on the tree. I think the only other hope is in training people not to do it. Even still, people sometimes insist on carving initials into trees or picking at bark. Maybe place a sign nearby: “Be nice to trees – don’t peel my bark!”

      Good Luck,

  20. Larry says:

    Hello, I started a tree house and as I came across your blog I seen #1 do not use threaded rod. So I’ve stopped progress to ask. I drilled 25″ through my tree 4 times to install threaded rod. I’ve got post on the back and cantalever the front. As well as wrapped cable to the top of tree were it forks, with 3/8cable fist grips and wire tighteners. Should I leave the rod in as it is already installed or should I remove it and put a tab system in?

    • Hi Larry,

      This is a good question. It is going to depend on the size of the platform and the positioning on the fasteners. If it’s relatively heavy, then you can alter the predrilled holes to accept tabs. Otherwise, proceed with all-thread. All thread is never the best fastener, but for very small platforms and large diameter all thread, you’re not likely to have a problem. We can offer design help and/or specific consulting if you need more than this response gives you.

      Good Luck,

  21. Tom says:

    I have a question that I also emailed earlier, but this is in regards to me fixing myself. My treehouse sits on 3 cantilevered beams, the main bottom one a 20′ 4×10 pressure hem-fir. Before I even started the treehouse, the main beam started checking and formed a crack against the grain in the middle bottom (like a third of the way up and over). The lumber provider (Dunn Lumber) assured us the structural integrity is still there and it’s mostly a cosmetic thing. We put in a couple timber locks to close the crack and added a couple plates to sister the beam to the one above it. But as I look at this 18′ span that holds everything up, what else could I do to reinforce it? I was thinking either a sistered 2×10 hem-fir for the whole span or maybe a 2-3′ Simpson strong tie plate over the crack. Any ideas? Is one better than the other?

    • Hi Tom,

      Good Question. Cracks & checks are normal as a beam dries out. They are seldom a structural problem, but of course I can’t offer an opinion on your beam without seeing it. However, if you can shield the beam from sunlight it will help reduce the uneven drying of the beam. If you would like to reinforce the beam, you can sister boards on the side as you suggested, but consider getting a taller board for more strength, such as a 2×12 on each side (keep tops flush) and screw or bolt the whole thing together. I don’t like predrilling a lot of large holes, so I tend to use a quality self-tapping timber screws for projects like this, and stagger fasteners up/down/up/etc…

      Good Luck,

  22. Anthony Ferrer says:

    Hi, Dan,
    Bought your book, reading your blog. I’m still in the design stage. I’m planning a roughly 10′ octagonal platform around a roughly 26″ diameter, very straight, maple. I can’t figure out how to include an image here, but my original design is 8 wedge shaped frames bolted together around the frame. The octagons I’ve seen, though, including in your book, have straight framing. Is there any reason not to do the 8 wedge frames? I like the way the floor lays out that way, and I think it would be easier to modify if needed years down the road for tree growth.
    Second question regards knee braces. Again, I have a drawing but I don’t know how to upload it. My plan has two tabs, one on each side of the tree, holding two beams that are built into a box. The knee braces support the member going between the beams. But most things I’ve seen show the knee brace coming in under the beam directly and going to the center of the tree on the perpendicular side. Wouldn’t that rack the knee brace? Or am I better off with a tribeam? In which case, do I need a beam on either side of the tree?

    • Hi Anthony,

      There are other ways to build octagons besides our preferred method from my book or our store, but they are tougher to build so we don’t sell plans for them. In my early years, I used radial beam & brace pairs, and joists could be set on top or fitted in between. The method required more time, more wood, and more fasteners, so we haven’t done that in a while.

      If you are set on radial beams with wedges, then our shop has all the parts you’ll need to attach it to the tree. It’s an unusual request, so I suggest calling the shop M-F 8-4 to discuss a custom kit instead of ordering online…

      Good luck,

  23. Georgina says:

    We had a treehouse built in our peartree about 10n years ago. Sadly the tree is now dead but has a strong trunk. The treehouse has not been used for a few years as I am worried that it creaks and sways a bit now. Would it be possible to stabilise the treehouse with vertical supports to extend the life of the treehouse or is that completely unreasonable thinking? I could send you photos.

    • Hi Georgina,

      We have done exactly what you are thinking many, many times. Trees do die, sadly, often before we are done with our treehouses. I can’t say how many posts/beams you will need without evaluating the structure (something we can do for a reasonable fee). But the concept of supporting it from the ground and then removing parts or the whole dead tree afterward is what you will need to do, if not now, then eventually.

      Sorry to hear the news,

  24. Sam Johnson says:


    So I was planning on building a “club” house rather than a tree house since we have a lot of smaller trees on our property. I was curios on your thought about this plan. I was going to place four 6x6x10’s post in an eight foot square. Then saying we have two sides I was going to notch the tops of the 6×6’s and place two 2x10x16 on each side. Bracing the the individual sides together creating two beams 16 feet long 8 feet a part. On top of this I was going to place 2x8x12 on 16″ centers perpendicular to the 2x10x16 beams making the deck of the club house once covered with deck boards. The club house will be 8×8 with the corners over the post leaving 2ft of overhang on the sides and 4 feet of overhang on the ends. The house its self will be just one story maybe with a small loft eventually. The 6×6’s will also either be braced or have a landing below the deck. I am still working on entry and exit ideas. Oh, the base will be concrete pillars below the 6×6’s — 3-4ft deep, 10″ in diameter.

    Thoughts, ideas…..
    Appreciate your time….

    Thanks Sam

    • Hi Sam,

      I normally don’t like to talk engineering specifics on a public forum, but you described it well and it sounds like a safe design. You may need cross bracing on the posts, and the 4′ cantilevers may be a tad bouncy without extra bracing. We would build it with utility poles and larger ground footings, but you’re probably okay for a lightweight residential structure.

      Good luck,

  25. Sam Johnson says:

    Thanks Dan,

    I appreciate your feedback and input.


  26. Matt K. says:

    I have a massive sweet gum tree – the main trunk is probably about 3′ in diameter.

    Planning to use tree as one half of a two-support tree house (posts for the other side).

    Is a sweet gum a suitable tree for a treehouse? And any thoughts on putting 2 tabs at same level (opposite each other) into a 3′ diameter trunk?


    Matt K.

  27. Sanja says:

    A single mom newbie here trying to plan my tree house (posts only, no actual tree included in the plan). My question is if I’m making it about 10 feet above ground, the treehouse is about 12 x 24 feet in size, and I’m using round trees as posts instead of the sawed square shaped posts, how many posts do I need for this treehouse? I’m talking to several builder guys and they really don’t seem to equal on how many posts to use, so I’m coming here for third opinion 🙂

  28. Brandon says:

    Is it okay to attached one end of a beam to a tree (using a tab) and the other end to a fixed post?

    I’m planning a treehouse using two trees and two posts, but, because of how I want to cantilever the joists, I’d prefer to have my two beams run from tree-to-post, rather than from tree-to-tree and post-to-post.

    All the plans I’ve seen online for treehouses supported by two trees and two posts have the beams running between the trees and posts. I wasn’t sure if that was just coincidence or if there is some rule against running beams from a tree to a post.


    • Brandon,

      You are right – most of our 2 tree & 2 post plans have beams running the other way. HOWEVER, there really isn’t a good reason for it. You can absolutely do what you are talking about. We would run the beams past the center of the trees and attach with a TAB & Floating bracket on each tree. If you get one of our treehouse plans, then our staff could easily redraw the beam & joist layout for you and help with beam/joist sizing if you need that.

  29. Jaye says:


    We’re considering building our kiddo a tree fort in a stand of cottonwood trees. Due to the configuration of the trees, we may need to use some additional support posts, but this would require us to dig a 2′ post hole where tree roots would be. Is this okay to do, or should we consider other options? My other half recommended using concrete post support piers instead of digging, but I’m concerned that would not be a good enough foundation for the posts.

    Any words of wisdom? We’d really like to keep our trees happy and healthy as long as possible.

    Thank you,


    • Hi Jaye,

      Very good question. In general, pouring concrete on top of grade is not the greatest idea – it will likely settle and sink down, leaving that part of the treehouse sagging down. You generally have to dig below the frost line to find reliable footing. Cottonwood trees can often grow well in wetlands, and so this is even more true if the ground is muddy or soft at grade.

      So, I would go ahead and dig. If you want to be the most careful, then dig with a shovel and dig slowly. If you encounter roots, then move the hole to the side to avoid cutting large roots. Try not to cut anything bigger than 1/2″ diameter if possible. Sometimes that not possible so do the best you can. The most careful way to dig is with an air spade, but that requires a large air compressor and it’s probably not going to happen for most backyard applications. Also, the further you can locate the post holes from the base of the tree, the less likely you are to encounter large roots.

      Lastly, in some cases, we may be able to help you come up with a better configuration that uses only tree based support. Make a quick sketch of your tree trunk locations and send them in to Treehouse Supplies and they will help you figure out what you need.

      Good luck,

  30. RL says:

    I am in the planning phase of building a tree house. I have two trees – tree A is 13″ diameter and tree B is 13″ as well. They are separated by 12 ft span. My plan is to build two parallel beams (double 2 x 12) using 2 tabs/pipe brackets on tree A, and 2 tabs/floating brackets on tree B. I would like to place an 8 ft wide x 12 ft long platform (2×8 joists) on the parallel beams. I am planning on building a simple ‘A’ frame tree house on top of the platform for my kids. The A frame will be 8×8 and will not have a second floor.

    My questions are as follows:
    1. Are my supporting beams going to be too narrow for my 8×12 platform? I have seen many photos of tree houses built on narrow parallel supporting beams but my beams will be only two feet apart given the width of my trees. Will I need to add knee braces? Should I make the platform 6×12 instead?
    2. Am I better off using a tribeam on tree A and B as my tree attachments? If tribeams are used as attachment points to trees A and B, will the tribeams allow for tree movement (as tribeams seem to be attached using fixed brackets on the tabs not floating brackets). I am assuming if I use tribeams I would then attach my double 2 x 12 beams to the tribeams to span the distance between tree A and B, then build the platform on top of the 2 x 12 beams – which adds more weight overall.

    Thanks for any advice!

    • Hello,

      Great questions, it sounds like you’re on the right track. If you secure the joists to the 2x12s and ensure that they don’t topple, then you might get away with the 8×12 as described – especially since the A frame design prevents walking on the edge of the cantilever due to lack of head room. In such cases, we add blocking from each beam outward on an upward 45 degree angle, which reduces the cantilever by 1-2 feet on each side and keeps beams from toppling.

      However, your #2 of using two tribeams also works. Some movement is allowed since the pipe brackets can slide in relation to each other, and I am not aware of any movement problems with this design (I wouldn’t do it 20′ high where lots of movement is expected). You might also consider laying joists out directly on the tops of the tribeams and skipping the 2x12s. At 12′ span you would want 2×8 joists, any longer and you would jump to 2x10s.

      Good Luck,

      • I should have mentioned above – that if you go with the first plan, make sure that the joists are connected very well to each beam. This way if people walk out to the perimeter, once beam is loaded normally with compression at cantilevered leverage, and the other beam is holding in tension / uplift. Of course, depending on the dead load of the house, this may not be an issue.

        Another option is knee braces as you pointed out, or angled support cables from above.

        • RL says:

          Thanks – I was planning on using plenty of simpson hurricane ties to secure the joists to the beams for plan 1. The 45 degree blocking that you mention to decrease the cantilever – is that cut lumber for the blocking?

          • Yes, that is cut lumber – we sometimes have cut offs to use, other times we buy a couple extra boards. We use the same lumber as the joist material and make trapezoids, securing one end to the side of the beam, and one end to the side of each joist. This reduces the cantilever and lessens the odds of the beams toppling over.

  31. Kyle deperasinski says:

    Hello my name is kyle and I am building a treehouse on a 6″4 by 7″6 platform. I need roof ideas. I am in canada and so it should be able to withstand a bit of snow. How much of a slope do you think is needed and what type roof? Thank you very much!

    • Hi Kyle,

      This question is best posed to a builder in your area who understands local codes and snowfall loads. Canada is a big place and snowfall amounts vary in different parts of the country. However, you can get an idea by looking at (or measuring) the slope on houses or sheds in your area. What kinds of roofs do similar sized sheds in your area use? That is a good guideline and probably better than any advice I could give you.

      Good Luck!

  32. Beth says:

    Hello, my name is Beth and we have started building a treehouse in our backyard using 3 medium size trees. The beams we used were 4 x 6, with the shortest being about 12′ and the longer two being closer to 14′ and 15′ – all anchored using Garnier Limbs. The platform is 8.325′ x 12′ and we used 2 x 10 joists spaced at 15″. We do intend on decking the platform, putting up railing, and putting a roof over two-thirds . Our question is about the 4 x 6 beams – we are wondering if they will support our intended structure. If they should be larger, like 4 x 12, we have found it to be challenging to find anything in stock. We talked about putting posts mid-way under the longer beams to help with support, but not sure how difficult that would be now that the everything is coming together. We appreciate your thoughts on our situation. Thank you!

  33. Mike says:

    We have some creek bottom property we want to build a small tree house on for camping and hunting. The only large trees we have are cottonwoods. And we have some spaced appropriately for a 2 or 3 tree house. Any special advice you can give us as far as cotton wood trees goes?

  34. Justin says:

    Hi, i am looking for some advice regarding design and which hardware to purchase.

    I am considering two options:

    1) Two Very tall pines 17 feet apart (first one 14 feet diameter, the second one, 24 feet diameter). Was considering two 20 feet parallel beams on each side of each tree (each beam would be two 20 ft 2×12 PT bolted together). 10 ft Joists 16 inches apart (PT 2×8) . On top of this platform, single level 10×15 house, the remaining platform would be deck.


    2. Same configuration as 1 but bigger second tree ( (first one 24 feet diameter, the second one, 28 feet diameter). also 17 feet apart

    For above configurations was thinking of 4 1×9 TABS, Floating 1.25 brackets on one tree and fixed pipe 1.25 brackets on the other tree.
    Does above sound ok or would you add/substitute with tri beam/knee braces , suspension brackets, or posts?
    This is in New England so need to consider snow load.


  35. Eric says:

    I’m building 2 treehouses in a eucalyptus forest. The trees are massive and the limbs and branches dont start until about 15 meters off the ground. So we are only using the trunks.

    Each treehouse will be supported by 3 trees per treehouse which are positioned in an equalateral triangle formation.

    However, the trees are about 10 meters apart. We want to build about 6 meters off the ground. I’ve found span charts for pratt trusses and other open web trusses that go well over 10 meters but they are all based on multiple trusses placed 24″ on center or something like that.

    Is it possible to fabricate three 10 meter trusses from angle iron that will span that distance to hold a treehouse load?

    I’m thinking the Pratt truss will need to be about a meter tall and I would fasten all 3 of them together at the corners for stabilization.

    • Marketing says:

      I have forwarded this to our team, one of our team members will be following up with you.

    • Marketing says:

      Eric – Here is a response from Joe Salinas, our Director of Operations for Tree Top Builders.

      Eric, 10 meters is a significant span, but not an insurmountable challenge. I would not recommend fabricating your own steel trusses, unless this is something you do for a living. However, there are several approaches that I could recommend using engineered timbers or steel members. There are many considerations that would go into the design process, to include size of your treehouses, anticipated live and dead loads, site logistics, and product availability in your area. Calculating the exact size and type of beams you would require, as well as designing the structural attachment points is a service we can provide, if interested.


      Joe Salinas PE, PMP
      TTB Operations

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