How to build a treehouse

Step 4 Mount the main supports

Get a strip of light wood and nail one end to one of your trees at a height about 1 ft lower than you want the floor of your treehouse (to save a future concussion, it should also be at least 1 ft higher than your head!). Get it perfectly horizontal with the help of a level and nail the other end to the other tree. Drill 3/8" holes straight into the tree just above the strip of wood. Do the same on the other side of the trees, this time taking the extra precaution of first ensuring the new strip is not only horizontal but also level with the strip on the other side of the tree.

Now, take down the strips and measure the exact distance between the holes. Subtract this distance from 10', halve the remainder, and make a mark this distance away from one end of your 2 x 10. Drill a 5/8" hole in the middle of the board. Make another mark using the between-the-holes measurement . Now drill two 5/8" holes, each 2" either side of your mark and both in the middle of the board. Get a jigsaw and make two cuts between the holes to make 4" long slot. Repeat for the other side of the tree. The slot allows the trees to move without tearing your treehouse apart - the more your trees move, the longer the slot ought to be (note that the slots I cut are only about 2" long, not 4", but these trees don't move perceptibly at the height of the treehouse, even in a strong wind. If your trees move appreciably, and/or if you're planning to build higher up, use a sliding beam support).

Now, screw your boards to the tree with a wrench. Use washers, and don't bolt hard against the tree. The space you're giving it to grow is the gap between the support and the tree. The longer you want your treehouse to last, the further you should perch the support away - and the more substantial your lag screws ought to be!

Edit June 2011: there is now a place where you can buy big lag screws and other treehouse stuff online: http://www.treehousesupplies.com/

Comments

[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.

[davegriff]

Wont drilling and screwing bolts into tree kill it?

[makendo]

Well, if you read the comments section, you'll see there are two schools of thought: people who have built treehouses say no, those that haven't say you risk exactly that. I will comment that I went treetop ziplining today, with a operation that has been around for years and who have a strong commercial interest in the health of their trees. They have bolts into the trees, through the trees, all over the place - and their trees are in great health. I asked them whether the bolts do any damage, and they clearly thought it was a barmy question. After checking I wasn't joking, they said, "less than pruning off a small branch, so no".