Is my treehouse safe?

[MikeD74T]

TNTractor1, Your failure mechanism will be tree growth. You didn't leave room for the diameter of the tree to increase. I'd have used longer lags & 1 1/2" long pipe spacers between the stringers & tree. This prediction is result of my experience where growth pulled the bolts (by forcing stringers out) right thru the stringers. Miked74t

 

[tungularafishcamp]

TNTractor1, Your failure mechanism will be tree growth. You didn't leave room for the diameter of the tree to increase. I'd have used longer lags & 1 1/2" long pipe spacers between the stringers & tree. This prediction is result of my experience where growth pulled the bolts (by forcing stringers out) right thru the stringers. Miked74t

Instead of lag bolts I have just made my own thru bolts from allthread and run the allthread thru both ends of the joist and maybe for saftey you could even bed in a scrap of metal under the nuts like supersized washers. Are your kids gettin to help on the project with you? Looks Great!

 

[mainegoatman]

I know it's already been pointed out but if it was mine I would lag bolt a block of wood or metal angle iron under the 2x10's so that the 2x10's are sitting on something. Right now you have basically lost 1/2 of the load carrying capacity of the 2x10 if it decides to split, which it might considering it is attached to growing trees. I would put at least 4 in the lag bolts in the 2x10's and a bunch more in whatever supports it.

It looks great, nicer than some people's houses!

 

[TNTractor1]

These are all some great ideas for me to consider. I am definitely going to attach something to the tree under the plank edges to provide support. I will probably attach the support with a couple of lag bolts. This should take care of it I think. Tree growth does concern me, but I guess I can monitor the situation over the years and repair/reinforce as necessary. Thanks

 

[TNTractor1]

Well, went to home depot and picked up 12 5/8" x 8" lag bolts and some 16 gauge galvanized steel straps. I think I am going to run 2 lag bolts through a block of wood and into the tree under the edge of each plank and then also connect the plank and block of wood with a metal plate (yet to be purchased). So now the ends of each plank will be "resting" on the blocks of wood to help support things better. I will also use the metal 16 gauge straps to link the ends of the planks together. Does that sound good for an easy reinforcement. I want to be able to sleep well knowing it is strong!

 

[RoMad]

Tree Houses - Fasteners & Bolts for Tree Houses - Construction of Treehouses
this site has some good looking attachments to the tree.

 

[TNTractor1]

Tree Houses - Fasteners & Bolts for Tree Houses - Construction of Treehouses
this site has some good looking attachments to the tree.

Wow, that is some good looking stuff... guess I broke every rule! lol I will just have to keep a close eye on it over the years. Live and learn. Actually though, that hardware is quite pricey. I wonder if I just loosen up the lag bolt a bit... maybe 1/4" from being tight against the wood/tree... would that allow for some growth room at least for a year or two?

 

[RoMad]

Wow, that is some good looking stuff... guess I broke every rule! lol I will just have to keep a close eye on it over the years. Live and learn. Actually though, that hardware is quite pricey. I wonder if I just loosen up the lag bolt a bit... maybe 1/4" from being tight against the wood/tree... would that allow for some growth room at least for a year or two?

I didn't look at the prices, I was thinking you could make some of your own, thats what I would do.
I don't think loosening the lage bolts would be a good Idea since you have alreade screwd them into the tree. If you back them out they will not be snug in the tree.
You could buy longer ones and make a bushing to put on the end of them to allow for movement.

We were at Calloway gardens recently and they have a really cool ropes course that has lots of platforms on trees. All of them had brackets going around the trees with the platforms setting on them. You might try a little Google searching for some other atttachment ideas.
By the way, the rest of it looks great.

 

[TNTractor1]

I am now trying to decide which one of 3 options to do with additional lag bolts... but I also want to minimize the # of additional bolts I put into the trees, I think.

option 1: put a block of wood under each plank end with two 5/8" x 8" lag bolts = 6 lag bolts per tree! (3 for each plank end... 1 through plank and 2 in support wood).

option 2: block of wood + 1 lag bolt under plank end + a bracket on the tree that fits above the plank end with 4 wood screws through the bracket into the tree and another 4 screws through the bracket and into the plank = 3 lag bolts per tree + 4 wood screws

Option 3: A 2 foot piece of 2x10 on the inner side of the tree (opposite side of the tree from where the plank ends meet on the outside) attach the wood piece to the tree with 2 lag bolts so that it spans the 2 plank ends... each end "resting" on an end of the 2 foot board.

I will also strap the ends of the planks to each other with a steel strap on all the options.

Which of these options will be the strongest? should I worry at all about putting a max of 6 bolts in each tree vs. the 2 in each tree currently?

Thanks.

 

[mdelmarcelle]

Great project!

A friend of mine built something similar for his kids. Instead of bolting the frame directly to the tree, he used big eye bolts and suspended the tree house with cable. I don't think that's all that necessary though. It looks like your trees are surrounded by others, so they probably won't bend much in the wind. And I've seen trees actually grow around things as they grow. So, if those trees grow much more, they'll probably just grow around the boards. ''

My friends tree house is square, with walls and a roof and only supported by four eye bolts. Probably weighs 4 times what yours weighs and so far no issues. Same height too and probably smaller trees.

Something else you could consider doing would be to run two more 2x10s under the existing ones. Run them from the inside of the trees on the bottom of the triangle to the outside of the tree at the tip of the triangle. This would give it a little more support over the span and also provide the shear strength that others expressed concern about.