9 Misconceptions about Treehouse Building

These 9 misconceptions are widely held by very intelligent people, so don’t feel bad if you learn something! In fact, we spend time with most of our clients to correct these misunderstandings during the design and construction process. Unless you are a professional treehouse builder, you will probably learn something useful about trees and tree houses by reading on.

Putting Bolts & Nails in Trees Will Kill Them.

Bolting and nailing into a tree will cause some damage, but healthy trees can respond quickly to compartmentalize around the injured area. Over time, trees will add structural material to strengthen the weak spot.

That Platform Doesn’t Look Level

crooked treehouseIt is very common for a client to see their partially built platform and question whether or not it is level. Don’t worry, it is. If the ground is sloped, even a little bit, then the platform will not be paralell to the ground, which makes it appear not level. By the way, the treehouse to the right really is out of level. 🙂

Treehouses Won’t Stay Level

The Truth is that if you put a nail in a tree at 10 feet above ground, then it will always be 10 feet above ground. Tree tissues only elongate at the tips of branches, not in the middle of the stem.

Treehouses Are Dangerous

When built with the proper hardware and techniques, treehouses are no more dangerous than being on a deck or back yard shed. The only exception is that you shouldn’t occupy treehouses during high wind or lightning storms.

Treehouses Never Require Permits

building permitIn reality, your building inspector may beg to differ, and he’s in charge unless you hire a lawyer. It is true that many municipalities do not require permits for tree structures, especially in more rural or country areas. However, some will still specify setback or total height requirements. If you are in doubt, you should check with your local township before begining any treehouse project just so you know what you’re getting into.

Treehouses Are Only For Kids

Nonsense! We find that most of our adult clients enjoy treehouses just as much as their kids, some even more so! We have also designed and built treehouses that are primarily adult-centered for a quiet woodland retreat.

You Can Only Enjoy A Treehouse In Nice Weather

By utilizing modern construction and insulation techniques, a treehouse can be built as a weatherproof year-round residence. Complete with plumbing, electricity, and climate control, you don’t need to leave the tree to be comfortable.

Treehouses Don’t Last Very Long

We design all our treehouses with the health and longevity of the tree as a priority. Long lasting materials such as cedar, mahogany, and pressure treated pine, allow our treehouses to last for 10, 15, and even 20+ years. Support posts can sometimes be added if the tree’s health unexpectedly declines, saving the treehouse.
expensive treehouse

A Quality Treehouse Is Too Expensive

Not everyone’s budget has the sky for a limit. We can create a safe, functional, and attractive treehouse starting around $5000, the same price as many full-sized play forts, and those aren’t custom or actually in a tree.

56 Responses to “9 Misconceptions about Treehouse Building”

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  1. Rob Smith says:

    I have already started my treehouse by bolting 2×10 12 foot beams on each side of my large maple tree (40 in diameter). Is it too late to correct any damage done? And how would I correct it?

    • thb98il1Tr3e says:

      Hi Rob,

      There are sometimes ways to improve this without causing too much excessive damage. Of course, it would have been optimal to start the right way, but a lot of people find us after it is too late…

      Assuming that the beams only are installed, and the installation was recent, then the bolts should be turned out and beams taken down. Then, you will likely want to install a TAB on either side of the tree with a pipe bracket to attach to the underside of each beam. This will allow you to space the beam 2-4 inches away from the trunk, allowing room for future tree growth.

      When determining where to set the TABs, you should use a water level (clear plastic tube filled with water) to mark spots on opposite sides of the tree. You will be marking the centers of the TABs. This will probably take 2 people. If the tree is fortunate, you will be able to mark the 2 spots right over the top of the existing bolts holes you made before. Sounds like it won’t work, but most DIYers use 1/2″ or 5/8″ lag bolts, and the TAB uses a 3″ hole, so you may be able to get the 3″ hole to overlap the smaller hole on both sides, in which case you will minimize the total damage done to the tree. At minimum, you will be able to overlap on at least one side of the tree. The new hole will be easier to drill if you start the center pilot in fresh wood. Keep in mind that this will raise the beam height above grade by some inches.

      We can supply the treehouse bolts and hardware should you decide to take this route.

      Good luck with your project,

  2. Mike J says:

    We just had a tree house platform built and after reading your site I’m questioning a little bit the way it was attached to the trees. Two 8×12 boards were attached between two trees about 10 feet apart and the platform was built on them. The boards were attached to the trees by three 1 x 4 1/2 in lag bolts on each board on either side of each tree. Then, two V brackets were placed to support the platform beneath each side of the platform on either tree using 2×4’s attached to the tree the same size lag bolts and underside of the platform. Im reading now that the recommended method is to use only one lag bolt to minimize damage to the tree.

    So two questions: are the bolt sizes and v brackets used sufficient to support the 8′ x 6′ platform? I’ve jumped up and down on the platform putting plenty of weight on it and it feels sturdy. And will the method used end up damaging the tree?

    • thb98il1Tr3e says:

      Hello Mike,

      Most treehouses I have encountered built by homeowners or contractors provide sufficient initial strength for the intended uses. The bad news with more conventionally built tree structures is that the tree typically has reduced growth opportunities, and the long term health and/or structural stability of the trees are threatened. How long do you plan to have the treehouse for? How much do you care whether the trees are still in good shape when you are done with the treehouse?

      I am sorry I can’t be too specific about your situation, there are too many things that can be missed from written descriptions like this – for instance, I assume that “Two 8×12 boards” is a typo because those are really big sticks for a small backyard treehouse, but I don’t know what you meant to write. Also, V brackets can be very helpful when installed well. I’d have to see them to know. If you feel that you need further consulting on this matter, please get in touch with the office and be prepared to send in photos of the structure and the attachment points and we will be better able to comment on the specifics of your installation.

      Good luck,

  3. Brian says:

    Hopefully this is the correct place to post to your blog. I have a 16 inch diameter water Oak tree with an almost vertical trunk – I live in North Florida. I’d like to build a 10′ X 10′ platform for an enclosed treehouse. I’ve been researching building in trees for about a year and from reading through your site, I have come to agree with your assessment that pinning planks directly to trees is not a good idea. The part I need most help with is attaching the platform – do I need tabs for this size treehouse? Could I use pipe brackets and lag bolts instead? Usage will be kids/adults. I have also read on your site that a tree going through the roof is not a good idea, although your portfolio shows a number of treehouses built this way. Other sites suggest rubber inner tubes wrapped around the trunk where it protrudes through the roof.

    • Hi Brian,

      Waterproofing with a tree in the center: The waterproofing can be kept up, but it will require maintenance as the tree grows. If you are willing to maintain it, then go ahead. Another consideration is that if the structure will air out, then perhaps a little water getting in won’t bother you. If it’s a backyard kids treehouse, then perhaps 90% water proof is good enough. However, if you’re putting electric and finished interior walls or drywall on the ceiling, then you may want to rethink the design.

      Bolt Size: I build most 10×10 treehouses with TABs under the floor, and lag bolts at the bottoms of the knee braces. You might be okay with lag bolts everywhere, but it just comes down to how much of a safety factor do you need, how much will all of your materials weight, and how many people are allowed up there at a time. There are many variables, and all I can say is that skipping the tabs to use lag bolts instead may or may not be okay for you. http://www.treehousesupplies.com, our sister company, has 5/4″ lag bolts which support around 400-2000 lbs in various typical treehouse building scenarios. We sometimes use those instead of TABs, when the loads are smaller.

      Best Wishes,

  4. Brian says:

    Thanks for the response Dan. I don’t want to compromise safety, but regarding your comment of a non leaking roof, I may consider building the platform on posts on another part of my property, and using a smaller tree as one of the supports. The tree being considered is 9 inches in diameter. Is this too small to use as one of the supports? If not, what size TAB should I consider? I would like your opinion on the support methods used for treehouse plans at this site: http://treehouseguides.com/

    I recently purchased your book – looking forward to a good read!

    • Hello Brian: I would not put a 10×10 treehouse on a 9″ tree. I would look for a 12-20″ tree. I do not recommend the plans on that website you mentioned – they pin boards to trees which doesn’t leave them any room to grow. You can do whatever you want, but our advice to to build in a safe and tree friendly fashion. It’s harder and costs a bit more money, but you get a better, longer lasting result. That’s our niche in this market – the highest quality, the best for the trees, and the safest treehouses out there. Good luck, -Dan

  5. sean says:

    I’m building a square footprint treehouse using 3 trees and a post. It will be about 8′ above the groond. the trees are all around 12″ in diameter. I put 8″ lag screws through 2×10’s directly around the structure. Is this thing more than likely going to pull apart in the wind?

    • Hi Sean,

      What diameter lag screws did you use? The tree will sway, and when that happens, it will either shear the lag screws or drag the structure with it. I can’t be sure which will happen. From reading our website, you probably know that we use different techniques that allow tree movement and future growth. Bolting 2x10s right to the tree usually creates medium to long term issues.

      Good luck,

  6. Judi Brosey says:

    I understand about the tree growth occuring at the outer edges of the branches, but don’t the trunk and the branches widen as they grow? How does this effect where the pkatform is attached ?

    • Hi Judy: Yes, every part of the tree increases in girth or thickness each year that the plant is alive. This means that the tree grows around everything that is solidly anchored into it. Our methods incorporate this habit of trees into the overall design and can accommodate a lot of tree growth before maintenance is required. The platform height will remain the same. -Dan

  7. Jon Tonti says:

    I want to build some large liveable treehouses, but there’s a ton of lightning storms where I live. Does it even make sense to build them? Thanks


    • Hi Jon,

      I wouldn’t let the threat of lightning stop you. Lightning protection is available for individual trees and/or towers to protect a whole property. So there are options… Now your larger question, does it make sense to build them… that is a topic for greater conversation. Treehouses are not the most cost effective or practical living spaces. We build them for other reasons, desires that cannot be fulfilled by ground houses.

      Best Wishes,

  8. Josh says:

    I’ve started on my tree house and it’s being supported by two 2×6’s and it’s bolted I not the tree by lag bolts, I’m just worrying about the treehouse swaying in the wind.

    • Hi Josh,

      I need a lot more information to give you an intelligent response. Double 2×6 might be sufficient for a small treehouse beam. Lag bolts have pros & cons versus the TABs that we normally use. Wind and resulting tree movement need to be allowed for in the attachment systems or else you risk damaging the trees or creating an unsafe situation. We can help if you give us more information.

      Thank you,

  9. MustelidRex says:

    You mention that one should not place bolts too close to each other but when building a single-tree treehouse mustn’t one place bolts on either side of a tree at exactly the same elevation?

    • That’s a great question. Trees compartmentalize better circumferentially than they do vertically. It makes sense because plant vascular cells are longer (in the direction of the trunk / branch), and so a hole severs the flow of resources vertically more than the around the circumference. Two bolts touching side be side or one partially over the other would be worse for the tree than the situation you mentioned with 2 opposing bolts.

      • Jeff says:

        What spacing do you recommend between bolts, both circumferentially and vertically? Suppose a white oak trunk larger than 30″ in diameter.

        • Hi Jeff,

          There is no black and white as it depends on the codit response in the tree at the time. For TAB installations, I generally recommend several inches circumferentially (horizontal), and several feet axially (vertical).

          Happy Building!

  10. Gaylord Helms says:

    I would like attach a4x6 to a 30in oak tree trunk with 2 long lags or 2 long 1/2 in all thread clear thru and double nutted on other side. The 4×6 will run out horizontally to a 6×6 post 4ft in the ground to support the attachment of a swing for kids and adults alike. Does this sound okay.

    • It sounds like it would be fine for 2-5 years. Then the tree will have visibly deformed growth, or it will start destroying the beam or the all thread connections. We would use 2 TABs with floating brackets. If the platform is small, then perhaps the 5/4 lag bolts instead of TABs, but you shouldn’t put your beams directly on the trunk if you want the tree and the structure to last.

      • Claire says:

        We had a swing attached to a board that was bolted to two very large poplar trees. About 6 years after buying the house (don’t know how long the swing had been there before that), the board rotted through on one side and came loose from the tree. My husband rehung the swing using a similar method. It appears to be quite sturdy now, but the whole thing creaks something fierce! Is this a sign of something amiss, or is this normal growing pains as the tree adjusts to the bolts?

        • Hi Claire,

          The squeaking is common when the trees sway or the swing is in use – both of them cause movement. We have developed a better method, and I just installed 2 of them last week. Here is a link to the hardware our store sells for that purpose: Treehouse Swing Kit. One side is fixed and the other floats back and forth, which allows the tree to sway without squeaking, but still holds the beam firm enough to permit swinging.

          Good luck,

  11. Aaron Reilly says:

    I am planning a 8′ x 12′ single story enclosed treehouse built on a triangular platform supported by 3 mature Ponderosa Pine trees approximately 12″ diameter at the platform height. The plan so far is to have two main perimeter support beams on level with each other supported by TABS at each end, and then the third main perimeter beam will rest on top of the other two spaced away from the two trees it spans. The result is that I would need 4 TABS (1 in each of two trees, and 2 in the common tree that has both level beams attached to it). My primary question is whether two tabs can be installed into a 12″ Ponderosa Pine trunk level with each other at approximately 135 degrees separation around the trunk without being concerned about the structural integrity or long term health of the tree. Should I consider attaching blocking to the underside of one of the beams to get some vertical separation of the 2 TABS in the common trunk, or does my current plan seem adequate?

    • Aaron – the plan sounds good. Fixed pipe brackets on the tree with 2 tabs, and floating brackets on the other 2 trees to allow for movement. If the tree with 2 TABs is only 12″, then the 2 TABs will probably crash in the middle, and offsetting them would be a good idea. I have done that before on a 3.5″ beam by attaching an 18″ long 4×4 with chamfered edges to the underside of the beam. That gives you 3.5″ of separation for the TABs. The TAB collar is 3″, but where the TABs would crash, the metal is only 1.25″, so that’s plenty of space. On young trees like that, if they are healthy and not crowded, then the growth rate should help the tree recover well enough from that. Good luck, -Dan

  12. Joshua Morgan says:

    I have a very tall red oak behind my house with a 40″ diameter trunk, I want to build a two story 14’x16′ treehouse in it. My main question is how high up is too high? The best sets of limbs to build above are about 40 feet off the ground, to me it looks like the perfect spot for it but I have never built a treehouse. I am planning on having a spiral staircase around the tree if that makes any difference. Thanks in advance.

    • Hi Joshua – First off, that is a really ambitious project for your first treehouse. That would take me months to build. There is no black & white limit on height, practically speaking. Of course, the higher you go with a large project, the more dead load and wind load you will add to the tree, increasing the chances of tree failure. With old red oaks, you should have an arborist evaluate the base before starting the project – many of them develop basal decay when they get large and I see them occasionally uprooted or broken near the base. Good luck, -Dan

  13. Cord Awtry says:


    I’m curious on your opinion of the minimum width for a tree with tabs on opposite sides at the same height. I want to build a 2-tree treehouse with a pair of main beams on either side of the trees then building the platform on top of that. I’ve read varying opinions on how thick a tree needs to be to support opposite-side tabs. The trees in question are pines in New England.

    Thanks a lot,


    • Hello Cord,

      My opinion varies too! There are different sizes of TABs. Ours all have 6″ on the inside of the tree, with collars between 1″ and 6″. In white pine, you should not use 1″ collars – the growth rate on these trees is 3/8 to 1/2 per year until they get very old. Also, the white pine is one of the softest wood species in your area, so avoid 1″ collars. Assuming you use a 6×12 TAB, and sink the collar 4″ past the bark, you’ll have 4+6=10″ inside the tree. So if you put 2 at the same level, you need a 20″ tree. I have occasionally cut 1″ off the threaded metal of the TABs, which would get you down to 18″. If you use a 3×9 TAB, sinking 2″, you would be 2+6=8″, or 16″ minimum tree, or 14″ if you cut 1″ off the TABs. There are other tricks such as offsetting the TABs with blocking, but I don’t recommend that on a single tree platform because if the tree is less than 14″ then you’re going to have some increasing rotational issues which get worse with a large ratio of platform size to trunk diameter.

      Happy Treehousing!

  14. George says:

    Not tree house related. But interesting info i discovered cutting up a tree that fell for firewood. After I cut a 30″ diameter redoak that fell in a storm l. I discovered black staines in the ends of every round for a 20′ span of the trunk. I didn’t think much of it till I started splitting the wood down to firewood size. That is when I noticed where the blackish purple stains came from. There where nails and bolts in the tree but since they where in the 12″ center portion of the 30″ round tree these nails shed there iron over the course of the life of the tree. This left a very purplish color through out the 20′ trunk.

    • Hi George, I have never seen purple staining like you describe. Black or grey staining is from decay spread. If the nails were installed at the time that the tree was 12″, and it grew to 30″ at removal, then the tissues at 12″ were heartwood or non-conductive, so further spreading or discoloration would be more likely due to decay. Was the purple wood softer than surrounding tissues? -Dan

  15. Bryan Vargo says:

    Hi Dan,
    Great site – love all the useful info. I’m in the planning stages of building an 8×10 or 10×10 backyard, fully enclosed treehouse for our family of 4. My concern and question is in regards to our tree of choice. The tree is a very mature 9.58-foot circumference poplar (or tulip) tree. I’m a firm believe in the TAB and plan to use them for attaching the platform. The tree, however, is about 25 feet from our house. The canopy is quite large and looms over our house (great for cooling the house in the Georgia heat) and the tree appears to be in excellent health (no signs of deadwood or any other issues). We love the tree and love our house and don’t want to endanger either – or obviously anyone who uses the treehouse. Is this tree too big for a single-tree treehouse? The tree would be in the center of the treehouse and reinforced with 4 knee braces that are attached to the tree with lag bolts.

    I’m also curious if 2 double 10′ 2″x10″ beams would suffice as the main supports? We appreciate all your insights.


    • Hello Bryan,

      We have had great luck with tulip poplars of that size. Of course, any perfectly good tree still has risks, but poplars often grow larger than yours, so if the tree is healthy and structurally sound now, then it could provide a secure foundation for decades.

      Regarding support options, there are many ways to frame platforms in trees. Sometimes for your type & size of tree we use a double tribeam configuration, other times a number of single knee braces, and an older but effective beam & brace combo still works. Our treehouse supplies store offers all of the TABs, plans, and phone support that you’ll need.

      Good luck,

  16. Dion says:

    Hi Dan,
    Just a quick question, how do you know how far a bolt has to go in the tree? Making my own TABs but not sure what length I have to get. It’s for an oak tree.

    • Hi Dion,

      I never recommend building your own TABs. Of course, we sell them, so we’re biased. However I’ve also seen too many people build them wrong and I am no longer willing to give advice on how to build them except to engineers, machinists, or builders that I know. If you are a welder, then go ahead and make your own brackets if you want to save a few bucks, but I recommend purchasing the TABs from . However, if you insist, we build ours to install 6+ inches into the tree. Depending on your thread count and size, you need enough to hold the TAB in the tree. Also, depending on your load, you need a certain collar size for surface area to hold the load. Those are the variables you need to consider.


  17. Katherine Rosenberg says:

    Hi Dan – funny little question. I have a large/mature ficus tree that I’d like to make a climbing tree for my kids. Can I put 10 “rock climbing” holds on the trunk of the tree? What screws would I use to minimize damage/risk of disease? Thanks!
    10 Large Screw on Climbing Holds. https://www.amazon.com/dp/B004JQZEAW/ref=cm_sw_r_cp_api_tbTNBb0TBRD1T

    • Hi Katherine,

      We actually strap the holds onto the trees. No matter how you bolt/screw holds on, the tree will quickly grow around them. The growth rate of our trees is slow to moderate, so the straps stretch a little on their own and don’t constrict our trees. But if you notice a small bulge of tree growth, then loosen and/or move the strap a few inches and you’re all set. Here is the product we use: Rock Climbing Holds on Trees

      Have Fun,

  18. Ralph Hohmann says:

    Hi Dan-
    I have a 8×8 treehouse built about three years ago on a 30 inch diameter pinoak. (My son always wanted one but I finally had time to build it for his kids.) I followed the instructions in The Complete Guide to Treehouses, Black and Decker. This meant 3/4 inch lag bolts for the 2×8 lower and upper platform beams (one bolt for each), directly on the trunk. Came out well and grandkids love it as we do. But now tree is growing, bark is growing around the brackets for the knee braces, the beams are bending. Still room for the decking around the tree (started with 3 inch gap). Will the tree be damaged? Any suggestions? I guess I could unscrew (used only screws) many of the boards and screw them in new positions for another few years. And cut (shorten) the knee braces. Thanks. You’re a great resource for us DIY folks.


    • Hi Ralph,

      Your experience is typical when using the plan – it makes a safe treehouse initially, but the tree suffers more as time passes, and it eventually becomes unsafe. The boards pinned to the trees with 3/4 lag bolts are the bigger problem for the tree – it will either have a structural problem there or it will break the boards, depending on your carpentry methods. The knee braces described in that book are sometimes okay, sometimes not, depending on the specific tree and the way they are fastened. If you are of a mind to fix these issues, then you can contact our treehouse design & supply company for help. Or, if you want more info first, then you can pick up my treehouse book which is better than the B&D book you got your plan from. I hope you all continue to enjoy your project and that you all stay safe.

      Good Luck,

  19. Renee Riddell says:

    Hi, I’ve got two live oak trees that are approximately 400 years old in my back yard that my son and a friend built a fort in. They used alot of nails and I am very concerned that this might be damaging the tree. They also have a zip line at the top of it but have the cable secured around it, of which now that I have read some on this website, believe we need to take down and reinstall some other way. If we take the fort/zip line down and redo it, will that cause more trauma to the tree, and if we leave the fort as is with all the nails, will it kill the tree? And when I say alot of nails, I don’t mean an overly excessive amount but still…there are quite a few holding up the 2×4 ladder and big planks they sit on. Thanks for the help!

    • Hi Renee,

      I can’t really answer this question without seeing it or at least having some photos & measurements. When I repair poorly build treehouses, sometimes it is easier to take it down and start over, but other times we prefer to add new supports in place. Regarding the zipline – if they wrapped the cable around the tree, then this is bad for the tree, but not necessarily unsafe for the rider if the rest was installed properly. If you need more help than that, then please collect some photos & measurements and email them in to our treehouse design & supply company where they help people in your situation all the time.

      Good Luck,

  20. Ken Holet says:

    I’m looking to build a tree house with my grandson. I plan to mount it onto 3 trees, with the longest side of the triangle on the inside of 2 trees and the other two sides joining on the far side of the third tree. I was thinking of connecting these other two sides together using a 4×6 “wedge” between them I would mount the wedge to the backside of the third tree, on a plane that is parallel to the long side board attached to the other two trees. My hope is this: as the trees grow, they will tend push the structure away from all three trees in the same direction, with the angled end being pushed in the direction such that the distance between the sides is increasing.

    My questions are: 1) does this make sense at all? and 2) since the hardwood growth is what is pushing against the tree house, can I simply unscrew the bolts a turn or so (the thickness of the growth ring) each year to relieve stress on the bark? If I were to coat the bolts in grease, or vaseline, or vegetable oil prior to insertion would that hurt the tree?


  21. Scott says:

    I have a friend who wants to build 2 Tree houses on his property in rural Colorado. He asked for my help because I’ve built a large workshop for and by myself. I have woodworking and metal working experience. But all the stuff I build stays on the ground. Tree houses is a whole new ballgame. The trees he wants to use are 30″ diameter cedar trees. They appear healthy, they appear strong but I’m not an aborist. Also the trees are on 40° slope. I believe the soil is expansive clay on granite bedrock. My question is how to tell if the trees and their roots will be able to support a structure? I’m confident in my ability to build the tree houses but not sure about the trees.

    • Hi Scott,

      Colorado is one of the few states where we haven’t yet built a treehouse. When I go somewhere new and evaluate a new tree or environment, I research the tree species (either online or in a tree guide), and then walk around a few acres of similar terrain to get a sense for the age of the forest and how other trees of that species appear to be doing. Are other trees of that species on a 40 degree slope and growing larger? Or do you see many larger trees uprooted and blown over? If you really want an arborist’s opinion to rest on, then you should probably hire an arborist or a forester.

      Best Wishes,

  22. Hawk Stone says:

    I’ve been scouring the web for advice on a proposed treehouse idea, but not had much luck.
    Basically, I plan a square(ish) platform between several large branches, with 3 of the 4 corners hung from the nearest branch (the 4th will be fixed). I have not had much luck finding information about hanging.

    It seems that hanging would make sense, because, so long as the cable does not touch the bark, it avoids most of the growth-related expansion problems. I imagine a big lag bolt combined with appropriate shackles, crimps, and strong cable, will be sufficient to support each corner of the platform.

    My question is – do you have experience with hanging a treehouse platform, rather than the more conventional undermounting, and if so, what are your concerns? Have you seen situations where this went badly wrong, and if so, how? Thank you for your advice.


  23. Ben Watkins says:

    Hi Dan,
    Planning on building a treehouse between two large, healthy oak trees. At the base, the trees are about 20 feet apart. I would like to build an enclosed 8’x12′ treehouse that is supported by 2 26′ 2″x12″ treated boards. I would then build a platform with the flooring joists and put the treehouse on the platform about 8-10′ off of the ground.
    1. Should the two 26′ boards be able to hold a typical 8’x12′ treehouse?
    2. Assuming you would recommend attaching them to the trees using TABs? Any other specific things to think about when attaching those?


    • Hi Ben,

      Parallel 2x12s, even doubled up, are not going to safely support a treehouse like this on a 20′ span. If the trees are 20′ apart (inside to inside), and the TABs are in the center of the trunks, then the span from TAB to TAB will be closer to 22′ – 24′. The platform will probably be very bouncy, and part way through construction, you’ll be wondering what you can do to add additional support. I suggest large PT Glu-Lam beams or adding more support in some way. This is actually a long conversation to have, and the guys at my supply warehouse can help you design something safe for reasonable rates – currently $75 per hour and usually 1-3 hours will be sufficient for a platform and basic house layout. See the custom treehouse design page.

      Good Luck,

  24. Kirk says:

    I am building a treehouse using 2 – persimmons trees. (approximately 36″ circumference).
    I will be using a bracket type sliding anchor for each to place my floor support beam on. ( With 4X4 post for the opposing end)
    I am unsure what type / size bolts or screws to secure the sliding anchor to the trees?
    I have bought 2 – 5/8″ threaded rods which are long enough to go thru the trunks. I am unsure if this is the best application or would it be better to have lag bolts into the trunk without going all the way thru?
    The treehouse will be 5′ x 8″

    Thanks for any insight!

  25. Kirk says:

    Just found the fastener section of your website. I withdraw my question about the threaded rod! I will go with lag bolts.

  26. Scott J. Smith says:

    Okay, so trees heal after lag bolts run through…

    … But how does it affect the structural integrity of the tree? Though hurricanes don’t come through here often, would mounting a tree house reduce the tree’s ability to sustain such strong winds, especially at that point?

    Thinking of just planting a shed on stilts among the trees, instead.

    • Scott: It affects structural integrity in a few ways initially, however, trees do grow extra material around wounds to compensate for the initial loss of strength. Pretty amazing, huh? But if you prefer stilts, go ahead and build that way. If you attach to the trees properly, it won’t make much of a difference in whether or not your trees blow over in a flood, tornado, or hurricane. Good luck, -Dan

  27. Joe hardy says:

    Something worth mentioning: I also considered fabricating my own version of a TAB. Glad that I bit the bullet and bought from this company. The installation required a massive amount of force which would have snapped a lesser product that wasn’t case hardened. They are worth the money.

    • Joe,

      Thanks for sharing this. We have seen a lot of “home-made” fastening systems which are not as safe and reliable as the real thing. It takes expensive equipment and experience to do it right. Small batches are not practical even for experienced machinists. Furthermore, we give pro-deals to anyone ordering a large quantity.

      Best wishes,

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