How to build a treehouse

This particular design requires two or three trees (or branches) in close proximity. It was made over the course of several weekends using new, pressure-treated wood for the support structure and floor and an old fence was recycled for the sides. The roof is a camouflage-pattern tarp. It's not weather-proof, but it stays pretty dry inside: a three-season treehouse, but best for summer! It was made with my 4, 6 and 8-year old children in mind, but has been a hit with visitors of all ages.

Step 1 Pick your trees

There are definite advantages in using more than one tree for your treehouse - the treehouse can be bigger, and you have to use less bracing. The trees you see here (behind the magnolia!) are a very tightly grown group of three - they all touch at the base, and splay out somewhat as they grow upwards. At the height of the treehouse - about 9 ft (2.7 m) off the ground - one pair of trunks are still almost touching, and the other one is about 4 ft (1.2 m) away. This means the design has been based on one for a close-spaced pair of trees, rather than for a group of three. The trees are Garry oaks, and they don't grow much further north than this (we're in the Pacific Northwest), so they grow slow here. A solid gnarly collection of old trees, each about 1 ft in diameter at 9 ft up.

Start by figuring out how high you want the treehouse. 9 feet is exciting for kids but not scary. You can of course go higher, but you'll have to take more account of movement.

Comments

[planetsideplayer14billion]

I have 10 aceres. about 2.5 is forstry. I have 2 forts. 1 in the trees and 1 on poles me and my sis have wars. im still upgrading my forts with rails, shelves, airsoft gun turrets, ext

[mitchblahman]

that sounds absolutely incredible man, kudos to you

[planetsideplayer14billion]

And i keep a dune buggy under it

[Winter-_-]

yikes. So many posts with people telling you off about how you did something or even someone just grumping about you "hurting trees" it has to be anoying- but im so impressed wih how each of your comments back are kind and to the point! :)
Its just so nice to see that even when others are being rude to you (and thats crazy as it is seeing that your posting a free gide and if they dont like it they can move on) your not lashing out.
Looks to me like your kids have two things to be proud of, a wonderful treehouse, and a dad who acts like a kind and levelminded adult. <3

[makendo]

Aw, shucks. Thanks. The vast majority of feedback on this site is positive, fortunately, but this ible did seem to get some people quite indignant - probably for the wrong reasons. The same people don't seem to mind projects built out of dead trees! :)

[cghale]

I'm at this point and am wondering the same thing as andrew...how do you attach the 2x4s to the platform? Deck screws or something more substantial?

[makendo]

Deck screws are fine; just drive them through the 6x2 into the 4x2 brace. The decking sits on top and also helps secure the brace.

[cghale]

For a house like this, what would the maximum safe width be? (i.e., between two trees) Working on this design now...

[makendo]

Not far at all. These trunks are within four feet, and don’t move much at all with respect to one another. If that’s not the case for you, taking account of movement is really important. The slots accommodate only a small amount of movement. If I was making a more widely spaced treehouse, I’d sit one end of the main supports on top of two really big lag screws (3/4” or bigger). There is a place you can buy them online now - http://www.treehousesupplies.com/. The other end could be screwed directly to the tree, as I show here. Good luck with your build!

[Ricardo Furioso]

More bolts, in slots, please.
Three per tree in each board are recommended.
Two would be better than what you have.
The problem with your application is that the trees in high winds can exert a HUGE horizontal torque force on the bolt heads that could bend, tear out, or shear them.
What we did in our very similar situation was to drill several holes (just a bit bigger than the bolt diameter) next to each other in the boards.
ooo
Then we chiseled them out into slots.
(___)
Then added a bolt with a BIG washer in the middle of each slot.
(_O_)
This design allows the trees to move in high winds independent of each other without snapping or bending the bolts.
Also the bolts should NOT be tightened. The washers should be able to rotate. This allows the bolts to move side to side in high winds, and for the whole structure to "give" a little.
If you think of the tree as a huge lever, and the distance the wind can move it both ways, you start to understand the amazing forces at work here.
We love your treehouse.
Come to think of it, we love all of them.

[makendo]

I disagree about the "3 bolts per tree per board argument" - see this page for why. As for the rest; read step 4.

[Ricardo Furioso]

Whooops.
You're right about Step 4.

[cowmanpoke]

 in step 4 when you bolt the wood to the tree, are you drilling all the way through the branch? i'm confused about how that wood is staying on

[makendo]

No, they go in about 4". A lag screw is basically a giant screw with a bolt head on it. So the thread holds it in place - in fact, once you've put it in it is very hard to move again. Use the biggest ones you can find, and perch the supports as far away as you can while still being structurally sound. In this treehouse, the supports are only about 1/2" away, because the trees are mature and slow growing.

[Ricardo Furioso]

Honestly think you might rethink the length of your bolts.
A foot, yes 12-inches, would be recommended.
Why?
Because that treehouse may outlive all of us.
Because kids will be in it.
Because kids will invite their friends.
Because whole scout troops or classrooms full of kids might descend upon it (both have happened to ours).
Because adults have a habit of frequenting treehouses along with refreshing adult beverages that make them do silly dangerous things. In groups.
So.
I beg you to grab your socket and ratchet set, remove the 4-inch bolts, and replace them with big fat 12-inch galvanized lag bolts.
They're cheap.
It may sound like overkill, but the wind forces on treehouses are staggering, and if a storm weakens them, the next kids who venture up there could be in serious danger.
It is one thing for a kid to fall out of a treehouse.
It is another to have the treehouse fall or fail with a kid inside.
Thanks for considering this.
ricardo

[makendo]

I appreciate that you're anxious about the children, but if the treehouse is going to fail, I suspect it will do so during a storm, and it is not occupied during such events. It's survived over a year without any untoward events despite some overloading you'd doubtless be appalled by and a 110 km/h gale. It certainly won't outlive all of us, as it will be removed when my kids grow out of it.
A 12" lag screw would go clear through the tree (especially if I put in 3 per board per tree, as you counsel; that would seriously compromise the structural integrity of the trunk). As for the "cheap big fat lag bolts" - perhaps you can point out a source for the benefit of others? I certainly couldn't find them in hardware stores or even online; the pros have them custom-made.

[Ricardo Furioso]

Congrats on the gale survival.
I suspect you're right about the failure.
I hope you are.
We found huge cheap lag bolts at Home Depot.
Putting a bolt through the trunk shouldn't compromise it's integrity. You'd need to predrill it, and the great percentage of the trunk—excluding the live cambium which comprises the outermost layers—is dead wood anyway.
http://www.ces.ncsu.edu/depts/hort/consumer/factsheets/trees-new/text/tree_anatomy.html
Putting two or three bolts in a tree trunk vertically is a good solution if you do not have access to a custom fastener fabrication shop.
And it works just fine if you loosen the bolts annually to allow for growth and space between beams and trunk.

[Werner111]

I would have added another bolt in for each tree, but it looks good :)

[makendo]

I'm pretty comfortable with the bolts as they are for this little treehouse, but overengineering is no bad thing either. Better than putting extra bolts though would be to use bigger ones; this page explains why really well (and also points out that 1/2" lag screws are insufficient!).
Anyway, thanks - and I can confirm the treehouse is still standing :)

[andrewbhorton]

How do you secure the top of the bracing to the platform? Beneath it, on the outside, inside? I'm 15 and I have no idea what I'm doing... but decided that I really want to make a treehouse.

[makendo]

Beneath it and on the inside. Check out the hand-drawn plan and the second photo in step 9 (you can *just* see it). There are lots of other resources out there - on the web, books, etc. Best of luck in your build!

[Ricardo Furioso]

Please. Bungee cords and kids do not mix well. I have a close friend who's an eye surgeon. He begged me to eliminate bungee cords from my life because he's seen so many people--especially kids--who have lost their sight from bungee cords. I love your treehouse. Come to think of it, I love all treehouses. Thanks for sharing yours.

[makendo]

Thanks. The bungee cord is to accommodate the fact that at ~15' up, the trunks move appreciably with respect to each other, so I needed something stretchy so it and/or the tarp wouldn't break. To remove the bungee, the tarp has to be removed first, not something a child can do. In the unlikely event of the bungee breaking while the house is occupied, the metal ends will remain tethered. Any scenario involving a child being blinded by this particular bungee cord would be pretty bizarre, and vanishingly small compared to the risk of, say, falling out :)

[blackjimmy]

Nice! And well done for going with a proper treehouse instead of a crappy 'house on stilts'. I don't see the point of them.. they are to treehouses what margarine is to butter; tasteless unexciting unnatural imitation for people who are afraid of a little fat! I don't think people should worry about a few bits of metal going through a tree either.. it won't do much harm as long as you don't go crazy. Bolts are much better than nails for strength and for the tree. Tree's can survive having half their branches being cut off, being half burned, lightening strikes (well sometimes).. they just carry on growing, especially if you're talking about a big, well established tree, which most of the time you are with treehouses. Most people don't build in rare-specimen trees either so don't see the problem really.

[starwing123]

Although a lightning strike will blow the bark off of ones side. The tree in the front of my house got hit by lightning. The bright flash of lightning just rips bark and a bit of internal wood to shreds

[ElvenChild]

 I built a tree house at my neibhors once just for the sake of it being there
they had a small wooden fence right by a tree and it just so happened a branch and the fence ran paralell so I  just added a bunch of boards there as the floor 
added a door and after I added a tarp for the roof I was finished

ION (in other news) I can't stop listening to nox hej dunarol

[fullhouse]

Very nice Structable! bet Dad and Kids love it!

[fullhouse]

Very cool ladder idea!

[fullhouse]

in my experience building decks on homes. If you are using PT decking that has a high moisture content, I would recommend placing the decking boards tight together when assembling the floor. Now for my reasoning , as the deck boards dry out from being pressure treated they tend to SHRINK up,therefore makeing the gaps alot larger. It only takes a few weeks of summer sun to do this. Placing them right next to each other once they dry out will give adequate spacing. This is only my opinion from my own experience.

[Gegelooz]

(removed by author or community request)

[noobiefied]

 u sir need to think beneath the onion skin. By building a tree house you are preserving the tree that is there to let the tree live on and prosper! If people that build "tree houses" did not care about trees then they could have just CUT DOWN THAT TREE and built a column supported "building"! Makendo Great job!

[makendo]

 I think it’s fair to say that the vast majority of people who build treehouses greatly respect trees – after all, they’re planning to spend some serious time IN one. I like the fact that much of the structure of this house comes from a healthy, living tree rather than a dead one (the case for homes constructed from lumber).
And thanks to instructables4ever, lukeea, paganwonder and m15cell for your comments.

[lukeea]

Who cares if it damages the tree? Plant another one if you're that concerned.

Thanks for the instructable makendo. I hope to build an awesome tree house like yours for my kids someday.

[paganwonder]

So you're saying all those anti-logging activists who spiked trees to discourage loggers from cutting the trees down were in reality killing the trees with spikes?  Bummer,  here we thought they were trying to save trees when in fact they were only killing them in their own devious way.  The Horror!

I've dug all manner of metal fencing and nails and bolts out of rather old trees that finally toppled after decades of unbridled growth- a literature search of the subject does not support your protest.

[instructables4ever]

Great Instructables, well written, and nice pictures. Sure your kids love it!

[m15cell]

Good job!!

[bruc33ef]

There ought to be a way to do this without putting holes in the tree. This can damage the tree.

[denotsKO]

In reality, ANY extended contact with the tree could damage it. If the tree is healthy and strong when the tree-house is built screwing into it will not cause it any great stress. Trees have bark for a reason just like people have skin for a reason. Piercing an ear is very, very, very unlikely to cause a person's death. The same goes for trees. The center of a tree is essentially dead. the growth takes place in the layer between the trunk and the bark. Efforts to "protect the tree" by using hoses or straps (even if the tension is monitored) are immensely more likely to stress the tree in the long run. Use galvanized bolts like you would use a hypoallergenic earring post. Use a bolt that is actually larger than you would think necessary so it goes deeper into the trunk. This will allow it to handle more stress without being wobbled back and forth which would enlarge the hole and allow pests and rot in. Clean and seal the hole. Build in the spring so the tree has a growing season following in which it can swell it's bark to seal around the bolt. Foresters routinely tap into trees with a bore drill to remove cores that are used to age the tree. From experience I can tell you that waiting even just a few minutes before removing that bore means it is not coming out. Trees are very good at healing and the wood around that bore drill swells almost instantly to seal the wound. So fast that it can actually clamp down on the tool and prevent its removal.

[gardenwife]

Chaining would actually cause more damage than making small holes for the bolts. You don't want to girdle the tree, which is what will happen. The tree will grow over and around the chain eventually, anyway.

[scouttster]

How will the chain grow around the chain when I am there to give it slack or tighten it? When I am done with my tree house fun ( I get bored with stuff after a year or two ) I will remove all that I have built.. You ask why? Becuase I am a responsible person like that and I like my nature natural and free from the hand of man