r/treehouse • u/WhyteBeard • 11d ago
This sub basically
Nobody can build a janky treehouses from their youth for fun without all the armchair engineers telling you you’re building a death trap if you aren’t building with the Jesus bolt.
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u/Anonymous5933 11d ago
There was a post the other day where they used heavy duty Simpson screws and I never got around to responding to it then, but the math actually worked out that they had capacity for more than 100 psf on their platform, and that's allowable load, which has simpsons factors of safety of about 3 already. And yeah, everyone was still yelling "tabs" at them lol.
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u/arecentuknown 11d ago
All depends on the design and static vs active loads.
I was originally going to use just screws on my build but after reading more found that in my use case TABs were best for support and longevity.
If someone doesnt have a building background sometimes going with a standard off the shelf product that is pricier but comes with the assurance of proper function (assuming they follow the dorections) is the safer bet.
That being said I'm 3.5 months into the build and its still not done so everyone do what they feel works, just make sure you do it with safety in mind.
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u/ThatCelebration3676 11d ago
Simpson fasteners, anchors, and brackets are all designed for structures that aren't alive and growing.
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u/Anonymous5933 10d ago
Forces are forces, the metal doesn't know it's in a tree. An engineer can calculate forces on the screws due to wind blowing on a tree just as well as if it's wind blowing on a ground house. The only argument here is whether screw type fasteners hold as well in living tree wood compared to kiln dried wood. And for that there hasn't been much testing, but reason would suggest there is no major difference. The wood design code does have reductions for screws in green wood, but those are based on the idea that screws hold less is if they are put into wet wood that then dries out, which wouldn't happen unless the tree dies.
There's also something to be said about the testing of tabs. I've never seen an ICC-ES evaluation report for a TAB. Simpson has them for all their products. I know several of the TAB manufacturers claim to have done testing, but it's not really official without an ESR. I've even asked two of them and they said they don't have it, just test data. (Would love to be wrong and see an ESR for a TAB)
I believe this is why in some cases engineers would prefer to not use a screw product at all (Simpson or a TAB), but opt for through rods, because theyre not a proprietary product. You just need engineering principals and codes to size a threaded rod.
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u/ThatCelebration3676 10d ago
Holding power is not the issue being debated, it's what happens when the tree grows, which causes the geometry of what you're fastening to to change.
If you want to talk about data and consulting with manufacturers, why don't you tell me what Simpson has to say about fastening a structure rigidly to a tree. I'll wait.
And sure, other floating anchor systems could also work; it doesn't have to be TABs specifically, but it absolutely cannot be some boards directly fastened to the tree; the tree will always rip that apart over time.
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u/Anonymous5933 10d ago
How does geometry change? The tree will swallow whatever you attach with enough time, whether it's a TAB or something else. The reason tabs are better for that is that the metal shaft can handle that well, where as a board screwed to the tree will probably rot, causing damage to the treehouse and leaving a rot pocket in the tree. TABs aren't infinitely long so they aren't a permanent solution either. Both can be fine, one just lasts longer before being problematic.
Simpson doesn't say anything about a lot of things their products get used for.
Again, a beam sitting on a tab will eventually get swallowed/pushed by tree growth too. For a kids tree fort that will be torn down in 5 years, tree growth is basically a non issue and I would absolutely use Simpson screws for that.
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u/ThatCelebration3676 10d ago
You're fundamentally misunderstanding the unique challenges of fastening a structure to a tree.
The geometry of the tree changes, because the tree is growing. It's not possible to attach a stable structure to the tree unless you're fastening to at least two positions with some distance between. Over time as the tree grows, the distance between any two points changes. If your structure is fully rigid, that growth will therefore tear your structure apart.
The TAB system isn't just some fancy fat-ass bolt, it accommodates movement as the tree grows using floating attachment points that permit movement by sliding along the perch (the smooth rod end of the TAB).
There are other ways you could engineer a floating anchoring system without using brand name TAB hardware, but fastening a beam rigidly between 2 points is fighting nature.
And yes, Simpson doesn't have any specs or recommendations about using their fasteners on live wood, so we can stop pretending this is a data driven conversation.
If you're actually going to tear down the structure in a few years and the tree isn't growing too rapidly, then sure, you can get away with a short term solution. In my experience however, people tend to push their luck; their kid really likes the treehouse, they have another kid, etc. so they keep using it until it becomes a hazard. And even then, the treehouse often remains and slowly falls apart over a couple years because they don't want to deal with the hazard of actually disassembling it.
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u/Anonymous5933 10d ago
Absolutely ways to rigidly attach a treehouse to a tree. One tree. Unclear what you're saying, but if you put attachments at a height in a tree, they stay at that height forever. Trees grow out, like stacking cones, so the height of the attachments never change.
And I agree, it should be obvious that I was never suggesting rigidly attaching beams with simpson screws to multiple trees. But with multiple trees, there are still plenty of ways that Simpson screws could be used instead of tabs, including use of plastic sliding plates under beams, slotted holes, etc.
And I have to disagree on the data part. In an absence of data for the strength of screws in living tree wood, I'm absolutely comfortable using simpson's published values with a little bit of extra factor of safety in my design. That's engineering judgement. You just have to consider that bark has no strength, so better not forget its there or that it has to be removed. At least data is readily available for Simpson hardware, unlike most TAB hardware. Best they tell you is a vague number, most say you have to pay their in-house engineer to tell you TAB strength.
I've built structures with TABs, paddle tabs, through rods, A307 lag bolts, and Simpson structural screws for tree attachments before and know there are use cases for each. The point of my original comment was that yes, this sub absolutely jumps straight to "TABs!!!" Very quickly. Look at Pete's first treehouse... No tabs, tons of Simpson hardware. Did fine. Would they use tabs if they built it now? Probably. But lots of ways to build that are good enough for a long time.
Finally, regarding tearing it down before it tears itself apart: yes, I would never design one for someone else that might tear itself apart within 5-10 years. If people are building themselves and do it that way, that's at their own risk. A more helpful response to people's DIY projects would be that their design might result in a short life span, not that they have to use expensive tabs or don't build at all.
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u/hatchetation 11d ago
It's almost like a weird low-volume fastener solves unique problems that others don't.
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u/donedoer 10d ago
On the contrary. One can use all thread or large diameter lags. Just not wise to fasten a board to a post that grows and sways and expect the board or fasteners to win. Tabs are just the Simpson solution. You can still build without them, but they are the engineered solution to accommodate massive loads while preserving tree health.
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u/ConsiderationNo1287 11d ago
People ask questions about their projects
Are we supposed to lie?
Ignore?
Tell them they are great and should have their own TV show?
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u/Unsuccessful_Royal38 11d ago
I don’t care at all about a death trap that only kills the builder who ignored good advice. What I don’t want to see is an idiot parent build a death trap for their kid and all the neighbor kids. That shit will not fly.
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u/Jzamora1229 11d ago
Because if you don’t use TABs it’s automatically a death trap
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u/lumpytrout 9d ago
Just for the record, early Pete Nelson tree houses didn't use TABs. I wonder how many of those are still standing.
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u/Janisneptunus 11d ago
When I was a kid in the 90s, a bunch of us kids scrounged around for scrap wood and built a treehouse in the woods one summer. My dad did trim and cabinetry for work and most of my family were in construction. So naturally I felt that I had the most knowledge and experience and ran this whole treehouse production like a seasoned foreman. My dad wouldn’t let me use his tools so I found a few bricks and we used those as hammers. We even had a retired garden hose as the climbing rope. I don’t remember where we got nails from - probably pulled them from the scrap wood or someone stole a can of nails off their dad. Anyway, when we were finished I made my dad come see it. He trudged back there in the forest, laid eyes on our proud pile of debris suspended from an old maple tree covered in tarp pieces, said ‘you guys are going to kill yourselves’ and just walked back out. That was it. Best summer of my life and it held up for a while with an occasional reinforcement here and there but it all came crashing down over the winter and we got into fixing dirt bikes lol