Building a tree house - attachment to tree suggestions??

Discussion in 'Workshop and Home Improvement' started by IdahoDoug, Apr 22, 2009.

  1. IdahoDoug

    IdahoDoug

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    I've got two 15" trees about 15 feet apart and plan to build a ladder frame across the gap and then build a tree house atop that that will be 36" wide and perhaps 8 feet long. It will be 10 feet off the ground. The trees move in the wind obviously, and I'm looking for a good way to attach the two main frame rails to them. The easy way would be to sink a heavy lag bolt through each main rail into the tree, but I'm worried I'll damage the tree. Some think it's no big deal to put something straight into the tree, that it's things that girdle a tree that cause it to die. I tend to agree with this.

    My other thought would be to wrap the tree at the attachment point with rubber or wood and cinch a chain or cable around that with an eye toward not cutting into the tree over the years. Unfortunately that won't provide as solid an attachment as a big bolt directly to the tree and with perhaps several kids up there and 10 feet to fall I'm hesitant.

    Anyone think of or used another way to attach boards to a tree trunk for this type of thing? I'll also be doing the old fashioned "rungs up the tree trunk" so more screws into the trunk. Does it matter if they're in line with each other (I seem to recall the flow of trees is in lines up the center and down the bark)?

    Any arborists out there?

    DougM
     
  2. 2mbb

    2mbb SILVER Star

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    There are lot's of tree house ideas on the interweb. Here's just one: The Treehouse Guide - Two tree support example for a tree house

    I think the key in this case is to allow for the independent movement of the two trees. If you try to constrain the trees with your house foundation, I would expect a sizable wind will twist the foundation apart.
     
  3. D'Animal

    D'Animal Rescuer of Beagle and Landcruisers Moderator

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    I would build the lodge independent of the trees but have them wrap around the trees. Long uprights or pillars from the ground would hold the actual tree house.

    Chains and cables will cut into the tree over time. It can and will damage the cambient layer of the tree slowly choking it out. The chains or cables will go around the tree so it will damage at least 1/2 of the cambient layer of the tree. The possible down side of this is that 1/2 the tree dies over a period of time. I have seen some trees actually grow over the cables and chains. Internally the chains and cables will rust through. I have seen some bore through the tree and insert a cable. It looks tramatic and the tree is weakend but it is healthier for the tree than cutting 1/2 the cambient layer.
     
  4. IdahoDoug

    IdahoDoug

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    D'Animal,

    Is there anything about the center of the tree that's vital? There's no reason to actually drill through the center to place a bolt - I could offset it by a couple inches if there's any point. I have no idea what the functions of tree internals are but it occurs to me the very center may be different than the layers around it? If not - I'll drill through the center but this is not covered on any of the treehouse stuff I've found online.

    Thanks for your input.

    DougM
     
  5. D'Animal

    D'Animal Rescuer of Beagle and Landcruisers Moderator

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    I assume by your original description that you were going to make it a hammok style where it will move with the trees. The center of the trees will give you strength and reduce the risk of splitting one side of the tree in a heavy wind/snow storm.
     
  6. MOfj40

    MOfj40

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    When I was a kid my dad and I built a treehouse between (4) 8-10" diameter trees. We used chain between the trees and 8 foot 2x4s to create huge turnbuckles and drew the trees together several inches. Then we built the floor framing snugly around the trees and slackened/removed the turnbuckles. The trees tried to return to their original positions but remained compressed within the floor frame.

    Zero penetrations into the trees and the treehouse was still standing strong 10 years later.
     
  7. D'Animal

    D'Animal Rescuer of Beagle and Landcruisers Moderator

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    I'm assuming IdahoDoug has conifer trees. A lot softer and less forgiving than an Oak tree in Kansas City.


    Again, these are just assumptions on my part.
     
  8. MOfj40

    MOfj40

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    I grew up in North Carolina. The trees were eastern white pine.
     
  9. D'Animal

    D'Animal Rescuer of Beagle and Landcruisers Moderator

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    Crap

    I wish I had pictures of the 3 story tree house I built as a kid. My mom would not let me use the Kodak Brownie camera since it was new.
     
  10. IdahoDoug

    IdahoDoug

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    Yeah, these are pines - 12 to 14" in diameter. So, through the center will be the choice I guess. Probably smart to use some of that tar like substance to seal the tree and prevent insect intrusion.

    DougM
     
  11. D'Animal

    D'Animal Rescuer of Beagle and Landcruisers Moderator

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  12. IdahoDoug

    IdahoDoug

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    Nice. Looks like dead center is the de facto standard.
     
  13. bigndn

    bigndn

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    Doug, fact of the matter is that the only growing part of the tree is the outermost circumference, just under the bark. The cambium (as D'Animal said) is what carries the water and nutrients up from the soil.

    The center of the tree is vital only in the fact that it's good for stabilization.......otherwise it's just woody material. :cheers:
     
  14. titanpat57

    titanpat57 SILVER Star

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    I'm sure from an early age she had figured out you would try to mod it or put some tricked carb on it...smart woman...lol :p

    I had also through bolted framing members to the larger branches as a base..which I think helped the tree to move as a unit and causing less stress on the treehouse itself...sometimes in hard winds the branches swaying independently can cause framing to tear apart Plus bolts you can always inspect and snug up as needed.
     
  15. Cattledog

    Cattledog

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    Well I have been working on this issue too.

    Here is my solution.

    Drill through the tree using a 1 1/4 ship auger drill bit, Here

    Insert and bolt using 1 1/4 inch grade 8 threaded rod and nuts, Here

    Then weld up or buy 3/8" timber hangers, Here

    Set main floating beams in the timber hangers and builds off the beam as desired.

    A less expensive way would to use coated wire rope with fittings that are lifting load rated, here

    then suspend the treehouse from the cables.

    Hope this help others looking to secure a treehouse safely to a tree. Finding the grade 8 threaded rod was a PITA.

    Using lag screws was out of the question in IMO. Lag screws are not load or shear rated. By using a 1/2" By 8" screw lag or variation you are at the mercy of the far east manufacturer that made them for the lowest price vs highest profit margin.... Don't trust them and avoid them IMO, they are crap steel and not heat treated. On the other hand the Grade 8 threaded rod is load and shear rated, the original application is for u bolts in semi trucks.

    :beer:
     
    Last edited: Jun 1, 2009
  16. e rock

    e rock

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    Lots of good info, but a few thoughts:

    For where you are, I'd avoid boring a big hole unless your design completely covers it. i.e. no chain/cable through a 1.5" hole. If beetles kill your tree in a year or two, fun's over.

    There is no problem with lag bolts right into the middle of the tree. As mentioned, the bark/wood interface is the most sensitive area. You won't hurt anything attaching through it, but girdling by wrapping something around will cause death in time.

    No problem putting rungs up the tree in a line. The transport passages do run up and down, but not perfectly vertical - they actually twist as they go up. But you're not really hurting it anyway.

    Don't use tar or anything else to cover wounds to the tree. The natural pitch response is the best thing for it.

    I would use 5" LedgerLok bolts - thinner shank, treated for corrosion resistance, plenty of shear load capability. If the bark is thick at the attachment point, I would hit it with a belt sander to take off the flaky outer layer and make a flat surface. You should be able to get LedgerLoks at good lumber suppliers.




    When I was a kid, we always found 3 trees spaced close anough to make a triangle-floor fort (4 would have been cool, but it never worked out). Perhaps you could use the two trees and a vertical fence post or two to eliminate the leverage problems associated with putting a 36" (which is pretty narrow IMO) platform on a 15"-wide support beam? Basically build your beam across the trees and build the fort platform like a second-floor deck on a house.
     
  17. treehouseguy

    treehouseguy

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    tree house bolt systems

    Bolting into the trees does a lot less damage over time than wrapping around them. You are correct that girdling is the main concern. With chain, rope, or cable, the girdling begins instantly. When you bolt through a board and "Pin" it to the side of the tree tangentially, you interfere with one small spot of the tree's growth. As the tree adds rings, then amount of that interference grows up to 25-30% of the tree, as a worst case scenario (double that if you put a board on each side).

    My preferred way to do this is to use a large treehouse bolt on each side. Then use a fixed tree house bracket on one tree (both sides of one tree) and then floating tree house brackets on both sides of the other tree. Those above are just examples and there are other places to buy them, or you can make them yourself.

    I am an arborist and I've built hundreds of structures in trees and there are pros & cons to each method, but I prefer the large hardware because it keeps the wood out away from the tree which minimizes the long term interference. Check out some of the tree houses I've built over the years... Good luck with yours!
     
  18. D'Animal

    D'Animal Rescuer of Beagle and Landcruisers Moderator

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  19. agomez

    agomez

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    those are really cool tree houses...
     
  20. PAToyota

    PAToyota

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